rustfs-filemeta 1.0.1

// Copyright 2024 RustFS Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::replication::{
    MAX_REPLICATION_TARGET_ARN_LEN, MAX_REPLICATION_TARGET_VERSION_ENTRIES, MAX_REPLICATION_TARGET_VERSION_ID_LEN,
};
use crate::{
    ErasureAlgo, ErasureInfo, Error, FileInfo, FileInfoVersions, InlineData, NULL_VERSION_ID, ObjectPartInfo, RawFileInfo,
    ReplicationState, ReplicationStatusType, Result, VersionPurgeStatusType, is_restored_object_on_disk, metadata_keys,
    replication_statuses_map, version_purge_statuses_map,
};
use byteorder::ByteOrder;
use bytes::Bytes;
use rustfs_utils::http::headers::{AMZ_META_UNENCRYPTED_CONTENT_LENGTH, AMZ_META_UNENCRYPTED_CONTENT_MD5};
use rustfs_utils::http::{
    MINIO_INTERNAL_PREFIX, RUSTFS_INTERNAL_PREFIX, SUFFIX_CRC, SUFFIX_DATA_MOV, SUFFIX_HEALING, SUFFIX_PURGESTATUS,
    SUFFIX_REPLICA_STATUS, SUFFIX_REPLICA_TIMESTAMP, SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX,
    SUFFIX_REPLICATION_RESET, SUFFIX_REPLICATION_STATUS, SUFFIX_REPLICATION_TIMESTAMP, SUFFIX_RESTORE_OPERATION_ID,
    SUFFIX_RESTORE_WORKER_LOCK, contains_key_str, has_internal_suffix, insert_bytes, is_internal_key, remove_bytes,
};
use serde::{Deserialize, Serialize};
#[cfg(test)]
use std::cell::Cell;
use std::cmp::Ordering;
use std::collections::BTreeMap;
use std::convert::TryFrom;
use std::hash::Hasher;
use std::io::{Read, Write};
use std::sync::atomic::{AtomicUsize, Ordering as AtomicOrdering};
use std::{collections::HashMap, io::Cursor};
use time::OffsetDateTime;
use time::format_description::well_known::Rfc3339;
use tokio::io::AsyncRead;
use tracing::{error, warn};
use uuid::Uuid;
use xxhash_rust::xxh64;

mod transition_reconcile;
pub use transition_reconcile::TransitionStateReconcileTarget;

// XL header specifies the format
pub static XL_FILE_HEADER: [u8; 4] = *b"XL2 ";
// pub static XL_FILE_VERSION_CURRENT: [u8; 4] = [0; 4];

// Current version being written.
// static XL_FILE_VERSION: [u8; 4] = [1, 0, 3, 0];
static XL_FILE_VERSION_MAJOR: u16 = 1;
static XL_FILE_VERSION_MINOR: u16 = 3;
static XL_HEADER_VERSION: u8 = 3;
pub static XL_META_VERSION: u8 = 3;
/// Legacy format (main branch): meta_ver=2 with file/header versions 1.3.3.
static XXHASH_SEED: u64 = 0;

const XL_FLAG_FREE_VERSION: u8 = 1 << 0;
// const XL_FLAG_USES_DATA_DIR: u8 = 1 << 1;
const _XL_FLAG_INLINE_DATA: u8 = 1 << 2;

const META_DATA_READ_DEFAULT: usize = 4 << 10;
const MSGP_UINT32_SIZE: usize = 5;

/// Default max object versions per object.
pub const DEFAULT_OBJECT_MAX_VERSIONS: usize = rustfs_config::DEFAULT_API_OBJECT_MAX_VERSIONS;

static OBJECT_MAX_VERSIONS: AtomicUsize = AtomicUsize::new(DEFAULT_OBJECT_MAX_VERSIONS);

#[cfg(test)]
thread_local! {
    static OBJECT_MAX_VERSIONS_OVERRIDE: Cell<Option<usize>> = const { Cell::new(None) };
}

#[inline]
pub fn object_max_versions() -> usize {
    #[cfg(test)]
    if let Some(limit) = OBJECT_MAX_VERSIONS_OVERRIDE.with(Cell::get) {
        return limit;
    }

    OBJECT_MAX_VERSIONS.load(AtomicOrdering::Relaxed)
}

pub fn set_object_max_versions(limit: usize) -> Result<()> {
    if limit == 0 {
        return Err(Error::other("object max versions must be greater than 0"));
    }
    OBJECT_MAX_VERSIONS.store(limit, AtomicOrdering::Relaxed);
    Ok(())
}

#[cfg(test)]
fn set_object_max_versions_override_for_test(limit: Option<usize>) -> Option<usize> {
    OBJECT_MAX_VERSIONS_OVERRIDE.with(|override_limit| {
        let previous = override_limit.get();
        override_limit.set(limit);
        previous
    })
}

/// Returns the inline data map key for a version_id. "null" for null version.
pub(crate) fn data_key_for_version(version_id: Option<Uuid>) -> String {
    if version_id.is_none() || version_id == Some(Uuid::nil()) {
        NULL_VERSION_ID.to_string()
    } else {
        version_id.unwrap_or_default().to_string()
    }
}

fn legacy_data_key_for_version(version_id: Option<Uuid>) -> Option<String> {
    if version_id.is_none() || version_id == Some(Uuid::nil()) {
        Some(Uuid::nil().to_string())
    } else {
        None
    }
}

pub const TRANSITION_COMPLETE: &str = "complete";
pub const TRANSITION_PENDING: &str = "pending";

/// xl.meta key marking a tier free-version record.
///
/// A free version is a delete-marker-shaped cleanup hint appended by
/// [`MetaObject::delete_version`] when a version whose remote transition
/// completed is removed from xl.meta; it carries the remote tier identity for
/// an idempotent remote delete and is never a user-visible version
/// (`num_versions` excludes it). While the record exists it is consumed by the
/// lifecycle free-version recovery scan and the usage scanner, which re-enqueue
/// the pending remote delete, and by heal metadata walks. On S3 and lifecycle
/// delete paths the same obligation is also carried by a committed tier-journal
/// entry; deletes without such an entry (for example a removed version whose
/// transition state decodes as unknown) rely on this record alone until the
/// worker removes it after a successful remote delete. Decommission preserves
/// the record and its remote identity on the target pool before source cleanup
/// — see docs/architecture/decommission-compatibility.md.
pub const FREE_VERSION: &str = "free-version";

pub const TRANSITION_STATUS: &str = "transition-status";
pub const TRANSITIONED_OBJECTNAME: &str = "transitioned-object";
pub const TRANSITIONED_VERSION_ID: &str = "transitioned-versionID";
pub const TRANSITION_TIER: &str = "transition-tier";

/// Returns true if the key is a transient internal flag that should not be persisted to meta_sys.
pub fn is_skip_meta_key(key: &str) -> bool {
    has_internal_suffix(key, SUFFIX_HEALING) || has_internal_suffix(key, SUFFIX_DATA_MOV)
}

mod codec;
mod inline_data;
pub(crate) mod msgp_decode;
mod validation;
mod version;

pub use validation::{DetailedVersionStats, VersionStats};
pub use version::*;

// type ScanHeaderVersionFn = Box<dyn Fn(usize, &[u8], &[u8]) -> Result<()>>;

/// Order two shallow versions newest-first, deriving a total order from the
/// canonical `FileMetaVersionHeader::sorts_before` predicate.
///
/// This MUST match `sorts_before` exactly: the header-only merge path
/// (`metacache`) and latest-version selection (`version.rs`) both key off
/// `sorts_before`, so any divergence here makes different code paths disagree
/// on which version is latest when several share a `mod_time` — e.g. an object
/// and a delete marker with identical timestamps flipping between "present" and
/// "deleted" depending on which path last sorted (backlog#799 B15).
fn cmp_shallow_versions_for_order(a: &FileMetaShallowVersion, b: &FileMetaShallowVersion) -> Ordering {
    if a.header.sorts_before(&b.header) {
        Ordering::Less
    } else if b.header.sorts_before(&a.header) {
        Ordering::Greater
    } else {
        Ordering::Equal
    }
}

/// Persists replication reset state into `meta_sys` under BOTH internal
/// prefixes (`x-rustfs-internal-*` and `x-minio-internal-*`).
///
/// Reset entries reach this point keyed either by a bare ARN
/// (`ObjectInfo::replication_state`) or by an already-prefixed internal key
/// (`get_internal_replication_state` / `target_reset_header`). The old code
/// inserted the key verbatim: a bare ARN was written with no internal prefix at
/// all, so read-back — which only recognizes prefixed keys — silently dropped
/// the reset state, and a rustfs-only key was invisible to MinIO-compatible
/// readers (backlog#799 B16). Normalize every entry to the canonical
/// `replication-reset-<arn>` suffix and write both prefixes.
fn valid_target_delete_marker_version(arn: &str, version_id: &str) -> bool {
    arn.starts_with("arn:")
        && arn.len() <= MAX_REPLICATION_TARGET_ARN_LEN
        && !version_id.is_empty()
        && version_id.len() <= MAX_REPLICATION_TARGET_VERSION_ID_LEN
}

/// Merge-only, never destructive.
///
/// `ReplicationState::target_delete_marker_version_ids` is skipped by the
/// positional `FileInfo` wire form, so a delete that arrives over internode RPC
/// carries an empty map. Treating that as authoritative would let a remote disk
/// erase an exact target version that the local disk still holds. The key is
/// included in the quorum hash, so such a divergence does surface — but as a
/// quorum failure on an otherwise healthy object, which is not a state worth
/// reaching. Merge the RPC metadata carrier instead, and only ever insert.
fn persist_target_delete_marker_versions(
    meta_sys: &mut HashMap<String, Vec<u8>>,
    versions: &HashMap<String, String>,
    transport_metadata: &HashMap<String, String>,
) {
    let mut bounded = BTreeMap::new();
    // A corrupt carrier means the dual internal prefixes disagreed. Do not merge
    // anything derived from it: this helper only ever inserts, so declining to
    // merge leaves whatever durable keys the object already carries untouched,
    // which is strictly safer than committing a mapping we cannot trust.
    let (transport_versions, transport_corrupt) = rustfs_utils::http::target_delete_marker_versions(transport_metadata);
    if transport_corrupt {
        warn!("delete-marker target version transport metadata is inconsistent; leaving the persisted mapping unchanged");
        return;
    }
    for (arn, version_id) in transport_versions.iter().chain(versions.iter()) {
        if !valid_target_delete_marker_version(arn, version_id)
            || (bounded.len() >= MAX_REPLICATION_TARGET_VERSION_ENTRIES
                && bounded.last_key_value().is_some_and(|(largest, _)| arn >= *largest))
        {
            continue;
        }
        bounded.insert(arn, version_id);
        if bounded.len() > MAX_REPLICATION_TARGET_VERSION_ENTRIES {
            bounded.pop_last();
        }
    }
    for (arn, version_id) in bounded {
        insert_bytes(
            meta_sys,
            &format!("{SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX}{arn}"),
            version_id.as_bytes().to_vec(),
        );
    }
}

fn persist_reset_statuses(meta_sys: &mut HashMap<String, Vec<u8>>, reset_statuses_map: &HashMap<String, String>) {
    for (k, v) in reset_statuses_map {
        let suffix = k
            .strip_prefix(RUSTFS_INTERNAL_PREFIX)
            .or_else(|| k.strip_prefix(MINIO_INTERNAL_PREFIX))
            .map(str::to_string)
            .unwrap_or_else(|| format!("{SUFFIX_REPLICATION_RESET}-{k}"));
        insert_bytes(meta_sys, &suffix, v.as_bytes().to_vec());
    }
}

pub fn parse_replication_timestamp(value: &str) -> Option<OffsetDateTime> {
    const DISPLAY_FORMAT: &[time::format_description::BorrowedFormatItem<'_>] = time::macros::format_description!(
        "[year sign:automatic]-[month]-[day] [hour padding:none]:[minute]:[second].[subsecond] [offset_hour sign:mandatory]:[offset_minute]:[offset_second]"
    );
    OffsetDateTime::parse(value, &Rfc3339)
        .or_else(|_| OffsetDateTime::parse(value, DISPLAY_FORMAT))
        .ok()
}

fn format_replication_timestamp(value: Option<OffsetDateTime>) -> String {
    let value = value.unwrap_or(OffsetDateTime::UNIX_EPOCH);
    value
        .to_offset(time::UtcOffset::UTC)
        .format(&Rfc3339)
        .unwrap_or_else(|_| value.to_string())
}

fn persist_delete_marker_replication_state(meta_sys: &mut HashMap<String, Vec<u8>>, state: &ReplicationState) {
    if !state.replica_status.is_empty() {
        insert_bytes(meta_sys, SUFFIX_REPLICA_STATUS, state.replica_status.as_str().as_bytes().to_vec());
        insert_bytes(
            meta_sys,
            SUFFIX_REPLICA_TIMESTAMP,
            format_replication_timestamp(state.replica_timestamp).into_bytes(),
        );
    }
    if let Some(status) = state.replication_status_internal.as_ref().filter(|status| !status.is_empty()) {
        insert_bytes(meta_sys, SUFFIX_REPLICATION_STATUS, status.as_bytes().to_vec());
        insert_bytes(
            meta_sys,
            SUFFIX_REPLICATION_TIMESTAMP,
            format_replication_timestamp(state.replication_timestamp).into_bytes(),
        );
    }
}

#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
pub struct FileMeta {
    pub versions: Vec<FileMetaShallowVersion>,
    pub data: InlineData,
    pub meta_ver: u8,
}

struct FileInfoDecodeOptions {
    read_data: bool,
    include_free_versions: bool,
    all_parts: bool,
    include_part_checksums: bool,
}

impl FileMeta {
    pub fn new() -> Self {
        Self {
            meta_ver: XL_META_VERSION,
            data: InlineData::new(),
            ..Default::default()
        }
    }

    fn get_idx(&self, idx: usize) -> Result<FileMetaVersion> {
        if idx >= self.versions.len() {
            return Err(Error::FileNotFound);
        }

        FileMetaVersion::try_from(self.versions[idx].meta.as_slice())
    }

    fn set_idx(&mut self, idx: usize, ver: FileMetaVersion) -> Result<()> {
        if idx >= self.versions.len() {
            return Err(Error::FileNotFound);
        }

        // TODO: use old buf
        let meta_buf = ver.marshal_msg()?;

        self.versions[idx].header = ver.header();
        self.versions[idx].meta = meta_buf;
        self.sort_by_mod_time();

        Ok(())
    }

    fn sort_by_mod_time(&mut self) {
        if self.versions.len() <= 1 {
            return;
        }

        self.versions.sort_by(cmp_shallow_versions_for_order);
    }

    fn find_inline_data_for_version(&self, version_id: Option<Uuid>) -> Result<Option<Vec<u8>>> {
        let key = data_key_for_version(version_id);
        if let Some(data) = self.data.find(key.as_str())? {
            return Ok(Some(data));
        }

        if let Some(legacy_key) = legacy_data_key_for_version(version_id)
            && legacy_key != key
        {
            return self.data.find(legacy_key.as_str());
        }

        Ok(None)
    }

    // Find version
    pub fn find_version(&self, vid: Option<Uuid>) -> Result<(usize, FileMetaVersion)> {
        let vid = vid.unwrap_or_default();
        for (i, fver) in self.versions.iter().enumerate() {
            if fver.header.version_id == Some(vid) {
                let version = self.get_idx(i)?;
                return Ok((i, version));
            }
        }

        Err(Error::FileVersionNotFound)
    }

    pub fn update_object_version(&mut self, fi: FileInfo) -> Result<()> {
        self.update_object_version_with_opts(fi, false)
    }

    pub fn update_object_version_with_opts(&mut self, fi: FileInfo, replace_user_metadata: bool) -> Result<()> {
        for version in self.versions.iter_mut() {
            match version.header.version_type {
                VersionType::Invalid | VersionType::Legacy => (),
                VersionType::Object => {
                    // For non-versioned buckets, treat None as Uuid::nil()
                    let fi_vid = fi.version_id.or(Some(Uuid::nil()));
                    let ver_vid = version.header.version_id.or(Some(Uuid::nil()));

                    if ver_vid == fi_vid {
                        let mut ver = FileMetaVersion::try_from(version.meta.as_slice())?;
                        let previous = ver
                            .object
                            .as_ref()
                            .is_some_and(|object| {
                                rustfs_utils::http::contains_key_bytes(
                                    &object.meta_sys,
                                    rustfs_utils::http::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
                                )
                            })
                            .then(|| ver.clone());

                        if let Some(ref mut obj) = ver.object {
                            if replace_user_metadata {
                                obj.meta_user.clear();
                                for suffix in [SUFFIX_RESTORE_OPERATION_ID, SUFFIX_RESTORE_WORKER_LOCK] {
                                    if !contains_key_str(&fi.metadata, suffix) {
                                        remove_bytes(&mut obj.meta_sys, suffix);
                                    }
                                }
                            }

                            // `fi.metadata` is the authoritative replacement
                            // for every internal suffix it carries. Remove all
                            // existing RustFS/MinIO and mixed-case aliases for
                            // those suffixes before inserting the new map;
                            // otherwise an old MinIO key survives this RMW and
                            // conflicts with newly written canonical aliases.
                            let replaced_internal_suffixes = fi
                                .metadata
                                .keys()
                                .filter_map(|key| rustfs_utils::http::strip_internal_prefix_preserving_case(key))
                                .map(str::to_ascii_lowercase)
                                .collect::<std::collections::HashSet<_>>();
                            if !replaced_internal_suffixes.is_empty() {
                                obj.meta_sys.retain(|key, _| {
                                    rustfs_utils::http::strip_internal_prefix_preserving_case(key)
                                        .is_none_or(|suffix| !replaced_internal_suffixes.contains(&suffix.to_ascii_lowercase()))
                                });
                            }

                            for (k, v) in fi.metadata.iter() {
                                // Split metadata into meta_user and meta_sys based on prefix
                                // This logic must match From<FileInfo> for MetaObject
                                let is_system = is_internal_key(k);
                                if is_system {
                                    // Skip internal flags that shouldn't be persisted
                                    if is_skip_meta_key(k) {
                                        continue;
                                    }
                                    // Insert into meta_sys
                                    obj.meta_sys.insert(k.clone(), v.as_bytes().to_vec());
                                } else {
                                    // Insert into meta_user
                                    obj.meta_user.insert(k.clone(), v.clone());
                                }
                            }

                            if let Some(mod_time) = fi.mod_time {
                                obj.mod_time = Some(mod_time);
                            }

                            if let Some(content_hash) = fi.checksum.as_ref() {
                                insert_bytes(&mut obj.meta_sys, SUFFIX_CRC, content_hash.to_vec());
                            }
                        }

                        if let Some(previous) = previous {
                            transition_reconcile::preserve_reconciled_transition(&previous, &mut ver)?;
                        }
                        // Update
                        version.header = ver.header();
                        version.meta = ver.marshal_msg()?;
                    }
                }
                VersionType::Delete => {
                    if version.header.version_id == fi.version_id {
                        return Err(Error::MethodNotAllowed);
                    }
                }
            }
        }

        self.versions.sort_by(cmp_shallow_versions_for_order);
        Ok(())
    }

    pub fn add_version(&mut self, fi: FileInfo) -> Result<()> {
        if let Some(free_version) = self.overwritten_tier_free_version(&fi)? {
            // The replacement and its cleanup owner must share one xl.meta
            // commit. Keep the original intact if either insertion fails.
            let mut next = self.clone();
            next.add_version_inner(fi)?;
            next.add_version_filemata(free_version)?;
            *self = next;
            return Ok(());
        }
        self.add_version_inner(fi)
    }

    fn overwritten_tier_free_version(&self, fi: &FileInfo) -> Result<Option<FileMetaVersion>> {
        use rustfs_utils::http::{
            SUFFIX_TIER_FV_ID, SUFFIX_TRANSITION_STATUS, SUFFIX_TRANSITION_TIER, SUFFIX_TRANSITION_TIER_DESTINATION_ID,
            SUFFIX_TRANSITIONED_OBJECTNAME, SUFFIX_TRANSITIONED_VERSION_ID, SUFFIX_TRANSITIONED_VERSION_STATE,
            get_consistent_bytes, get_consistent_str, has_internal_suffix, strip_internal_prefix_preserving_case,
        };

        if fi.version_id.is_some_and(|id| !id.is_nil()) {
            return Ok(None);
        }
        let legacy_id = if contains_key_str(&fi.metadata, SUFFIX_TIER_FV_ID) {
            Some(Uuid::parse_str(
                get_consistent_str(&fi.metadata, SUFFIX_TIER_FV_ID).ok_or(Error::FileCorrupt)?,
            )?)
        } else {
            None
        };
        let id = match (fi.overwrite_tier_free_version_id, legacy_id) {
            (Some(current), Some(legacy)) if current != legacy => return Err(Error::FileCorrupt),
            (Some(id), _) | (_, Some(id)) if !id.is_nil() => id,
            (None, None) => return Ok(None),
            _ => return Err(Error::FileCorrupt),
        };
        let Some(existing) = self
            .versions
            .iter()
            .find(|v| v.header.version_id.is_none_or(|id| id.is_nil()))
        else {
            return Ok(None);
        };
        let old = existing.parse_version_meta()?;
        let Some(mut object) = old.object else {
            return Ok(None);
        };
        let status = get_consistent_bytes(&object.meta_sys, SUFFIX_TRANSITION_STATUS);
        if status.is_none()
            && object
                .meta_sys
                .keys()
                .any(|key| has_internal_suffix(key, SUFFIX_TRANSITION_STATUS))
        {
            // Empty status is a valid local object. The reader distinguishes
            // it from conflicting aliases before the ordinary overwrite.
            object.into_fileinfo(&fi.volume, &fi.name, false)?;
            return Ok(None);
        }
        if status != Some(TRANSITION_COMPLETE.as_bytes()) {
            return Ok(None);
        }
        // Reuse the reader's alias/state validation. A legacy empty remote
        // version is valid and must not be mistaken for conflicting aliases.
        object.into_fileinfo(&fi.volume, &fi.name, false)?;
        if object
            .meta_sys
            .keys()
            .any(|key| has_internal_suffix(key, SUFFIX_TRANSITION_TIER_DESTINATION_ID))
            && get_consistent_bytes(&object.meta_sys, SUFFIX_TRANSITION_TIER_DESTINATION_ID).is_none()
        {
            return Err(Error::FileCorrupt);
        }
        let transition_suffixes = [
            SUFFIX_TRANSITION_STATUS,
            SUFFIX_TRANSITION_TIER,
            SUFFIX_TRANSITION_TIER_DESTINATION_ID,
            SUFFIX_TRANSITIONED_OBJECTNAME,
            SUFFIX_TRANSITIONED_VERSION_ID,
            SUFFIX_TRANSITIONED_VERSION_STATE,
        ];
        let replacement = MetaObject::from(fi.clone());
        if transition_suffixes
            .iter()
            .all(|suffix| get_consistent_bytes(&object.meta_sys, suffix) == get_consistent_bytes(&replacement.meta_sys, suffix))
        {
            return Ok(None);
        }
        if self.versions.iter().any(|version| version.header.version_id == Some(id)) {
            return Err(Error::FileCorrupt);
        }
        // The reader also accepts legacy key casing. Canonicalize only this
        // cleanup source so init_free_version preserves every accepted field,
        // including an explicitly empty unversioned remote version.
        for suffix in transition_suffixes {
            let value = object
                .meta_sys
                .iter()
                .find(|(key, _)| {
                    strip_internal_prefix_preserving_case(key).is_some_and(|found| found.eq_ignore_ascii_case(suffix))
                })
                .map(|(_, value)| value.clone());
            if let Some(value) = value {
                rustfs_utils::http::insert_bytes(&mut object.meta_sys, suffix, value);
            }
        }
        let mut cleanup_request = fi.clone();
        cleanup_request.set_tier_free_version_id(&id.to_string());
        let (free_version, created) = object.init_free_version(&cleanup_request)?;
        if !created {
            return Err(Error::FileCorrupt);
        }
        Ok(Some(free_version))
    }

    fn add_version_inner(&mut self, mut fi: FileInfo) -> Result<()> {
        rustfs_utils::http::remove_str(&mut fi.metadata, rustfs_utils::http::SUFFIX_TIER_FV_ID);
        // empty version_id means "null" (versioning disabled/suspended)
        if fi.version_id.is_none() {
            fi.version_id = Some(Uuid::nil());
        }

        if fi.data.is_none() && self.data.after_version().is_empty() {
            let version = FileMetaVersion::from(fi);
            return self.add_version_filemata(version);
        }

        let version_key = data_key_for_version(fi.version_id);
        let mut next_data = self.data.clone();

        if let Some(ref data) = fi.data {
            next_data.replace(&version_key, data.to_vec())?;
        } else {
            let _ = next_data.remove_key(&version_key)?;
        }

        let version = FileMetaVersion::from(fi);

        self.add_version_filemata(version)?;
        self.data = next_data;

        Ok(())
    }

    pub fn add_version_filemata(&mut self, mut version: FileMetaVersion) -> Result<()> {
        if !version.valid() {
            return Err(Error::other("file meta version invalid"));
        }

        let vid = version.get_version_id();
        let vid_is_null = vid.is_none() || vid == Some(Uuid::nil());
        let existing_idx = if vid_is_null {
            self.versions
                .iter()
                .position(|v| v.header.version_id.is_none() || v.header.version_id == Some(Uuid::nil()))
        } else {
            self.versions.iter().position(|v| v.header.version_id == vid)
        };

        if let Some(fidx) = existing_idx {
            let existing = self.versions[fidx].parse_version_meta()?;
            if existing.free_version() != version.free_version() {
                return Err(Error::other("cannot replace a free version with a non-free version"));
            }
            transition_reconcile::preserve_reconciled_transition(&existing, &mut version)?;
            return self.set_idx(fidx, version);
        }

        if self.versions.len() >= object_max_versions() {
            return Err(Error::MaxVersionsExceeded);
        }

        if self.versions.is_empty() {
            self.versions.push(FileMetaShallowVersion::try_from(version)?);
            return Ok(());
        }

        let new_shallow = FileMetaShallowVersion::try_from(version)?;
        let insert_pos = self
            .versions
            .partition_point(|existing| existing.header.sorts_before(&new_shallow.header));
        self.versions.insert(insert_pos, new_shallow);
        // `partition_point` only returns the canonical slot when `versions` is
        // already canonically ordered, and nothing establishes that: `FileMeta::load`
        // replays the on-disk order verbatim, and metadata written before the
        // canonical-order fix ordered equal-`mod_time` ties by insertion rather than
        // by `sorts_before`. Re-sort so an insert leaves the list canonical either
        // way, matching what `set_idx` already does on the replace path. Cheap: after
        // a correctly placed insert the slice is a single sorted run.
        self.sort_by_mod_time();
        Ok(())

        // if !ver.valid() {
        //     return Err(Error::other("attempted to add invalid version"));
        // }

        // if self.versions.len() + 1 >= 100 {
        //     return Err(Error::other(
        //         "You've exceeded the limit on the number of versions you can create on this object",
        //     ));
        // }

        // let mod_time = ver.get_mod_time();
        // let encoded = ver.marshal_msg()?;
        // let new_version = FileMetaShallowVersion {
        //     header: ver.header(),
        //     meta: encoded,
        // };

        // // Find the insertion position: insert before the first element with mod_time >= new mod_time
        // // This maintains descending order by mod_time (newest first)
        // let insert_pos = self
        //     .versions
        //     .iter()
        //     .position(|existing| existing.header.mod_time <= mod_time)
        //     .unwrap_or(self.versions.len());
        // self.versions.insert(insert_pos, new_version);
        // Ok(())
    }

    // delete_version deletes version, returns data_dir
    #[tracing::instrument(level = "debug", skip(self))]
    pub fn delete_version(&mut self, fi: &FileInfo) -> Result<Option<Uuid>> {
        fi.validate_for_delete_operation()?;

        let vid = Some(fi.version_id.unwrap_or(Uuid::nil()));
        if fi.deleted && fi.tier_free_version() {
            let Some(index) = self.versions.iter().position(|version| {
                version.header.version_id == vid
                    && version.header.version_type == VersionType::Delete
                    && version.header.free_version()
                    && version
                        .parse_version_meta()
                        .is_ok_and(|decoded| decoded.free_version() && decoded.header().version_id == vid)
            }) else {
                return Err(Error::FileVersionNotFound);
            };
            self.versions.remove(index);
            return Ok(None);
        }

        let target_is_delete_marker = self
            .versions
            .iter()
            .find(|ver| ver.header.version_id == vid)
            .is_some_and(|ver| ver.header.version_type == VersionType::Delete);

        let mut ventry = FileMetaVersion::default();
        if fi.deleted {
            ventry.version_type = VersionType::Delete;
            ventry.delete_marker = Some(MetaDeleteMarker {
                version_id: vid,
                mod_time: fi.mod_time,
                ..Default::default()
            });
            if let Some(incarnation) = fi.delete_marker_incarnation()
                && let Some(marker) = ventry.delete_marker.as_mut()
            {
                insert_bytes(
                    &mut marker.meta_sys,
                    rustfs_utils::http::metadata_compat::SUFFIX_BUCKET_INCARNATION_ID,
                    incarnation.to_string().into_bytes(),
                );
            }
        }

        let mut update_version = false;
        if fi.version_purge_status().is_empty()
            && (fi.delete_marker_replication_status() == ReplicationStatusType::Replica
                || fi.delete_marker_replication_status() == ReplicationStatusType::Empty)
        {
            update_version = fi.mark_deleted;
        } else {
            if fi.deleted
                && fi.version_purge_status() != VersionPurgeStatusType::Complete
                && (!fi.version_purge_status().is_empty() || fi.delete_marker_replication_status().is_empty())
            {
                update_version = true;
            }

            if !fi.version_purge_status().is_empty() && fi.version_purge_status() != VersionPurgeStatusType::Complete {
                update_version = true;
            }
        }

        if target_is_delete_marker && !fi.deleted && !fi.version_purge_status().is_empty() {
            update_version = false;
        }

        if fi.deleted {
            if let (Some(delete_marker), Some(state)) = (ventry.delete_marker.as_mut(), fi.replication_state_internal.as_ref()) {
                persist_delete_marker_replication_state(&mut delete_marker.meta_sys, state);
            }

            if !fi.version_purge_status().is_empty()
                && let Some(delete_marker) = ventry.delete_marker.as_mut()
            {
                let value = fi
                    .replication_state_internal
                    .as_ref()
                    .map(|v| v.version_purge_status_internal.clone().unwrap_or_default())
                    .unwrap_or_default()
                    .as_bytes()
                    .to_vec();
                insert_bytes(&mut delete_marker.meta_sys, SUFFIX_PURGESTATUS, value);
            }

            if let Some(delete_marker) = ventry.delete_marker.as_mut()
                && let Some(state) = fi.replication_state_internal.as_ref()
            {
                persist_reset_statuses(&mut delete_marker.meta_sys, &state.reset_statuses_map);
                persist_target_delete_marker_versions(
                    &mut delete_marker.meta_sys,
                    &state.target_delete_marker_version_ids,
                    &fi.metadata,
                );
            }
        }

        let mut found_index = None;

        for (i, ver) in self.versions.iter().enumerate() {
            if ver.header.version_id != vid {
                continue;
            }
            if fi.tier_free_version() && !ver.header.free_version() {
                return Err(Error::FileVersionNotFound);
            }

            match ver.header.version_type {
                VersionType::Invalid | VersionType::Legacy => return Err(Error::other("invalid file meta version")),
                VersionType::Delete => {
                    if update_version {
                        let mut v = self.get_idx(i)?;
                        if v.delete_marker.is_none() {
                            v.delete_marker = Some(MetaDeleteMarker {
                                version_id: vid,
                                mod_time: fi.mod_time,
                                meta_sys: HashMap::new(),
                            });
                        }

                        if let Some(delete_marker) = v.delete_marker.as_mut() {
                            if let Some(state) = fi.replication_state_internal.as_ref() {
                                persist_delete_marker_replication_state(&mut delete_marker.meta_sys, state);
                            }

                            if let Some(state) = fi.replication_state_internal.as_ref() {
                                persist_reset_statuses(&mut delete_marker.meta_sys, &state.reset_statuses_map);
                                persist_target_delete_marker_versions(
                                    &mut delete_marker.meta_sys,
                                    &state.target_delete_marker_version_ids,
                                    &fi.metadata,
                                );
                            }
                        }

                        self.set_idx(i, v)?;
                        return Ok(None);
                    }
                    self.versions.remove(i);

                    if (fi.mark_deleted && fi.version_purge_status() != VersionPurgeStatusType::Complete)
                        || (fi.deleted && vid == Some(Uuid::nil()))
                    {
                        self.add_version_filemata(ventry)?;
                    }

                    return Ok(None);
                }
                VersionType::Object => {
                    if update_version && !fi.deleted {
                        let mut v = self.get_idx(i)?;

                        if let Some(obj) = v.object.as_mut() {
                            let value = fi
                                .replication_state_internal
                                .as_ref()
                                .map(|v| v.version_purge_status_internal.clone().unwrap_or_default())
                                .unwrap_or_default()
                                .as_bytes()
                                .to_vec();
                            insert_bytes(&mut obj.meta_sys, SUFFIX_PURGESTATUS, value);
                            if let Some(state) = fi.replication_state_internal.as_ref() {
                                persist_reset_statuses(&mut obj.meta_sys, &state.reset_statuses_map);
                            }
                        }

                        // The version stays on disk while the purge replicates
                        // (status PENDING/FAILED); its data dir must stay with
                        // it. Returning the dir here made the disk layer delete
                        // it, which turned every non-inline retained version
                        // into an unreadable zombie: the purge state could never
                        // be applied and the bucket could never be deleted.
                        self.set_idx(i, v)?;

                        return Ok(None);
                    }
                    found_index = Some(i);
                }
            }
        }

        let Some(i) = found_index else {
            if fi.deleted {
                self.add_version_filemata(ventry)?;
                return Ok(None);
            }
            return Err(Error::FileVersionNotFound);
        };

        let mut ver = self.get_idx(i)?;

        let Some(obj) = &mut ver.object else {
            if fi.deleted {
                self.add_version_filemata(ventry)?;
                return Ok(None);
            }
            return Err(Error::FileVersionNotFound);
        };

        let obj_version_id = obj.version_id;
        let obj_data_dir = obj.data_dir;

        let mut err = if fi.expire_restored {
            obj.remove_restore_hdrs();
            self.set_idx(i, ver).err()
        } else if fi.transition_status == TRANSITION_COMPLETE {
            obj.set_transition(fi);
            obj.reset_inline_data();
            self.set_idx(i, ver).err()
        } else {
            self.versions.remove(i);

            let (free_version, to_free) = obj.init_free_version(fi)?;

            if to_free {
                self.add_version_filemata(free_version).err()
            } else {
                None
            }
        };

        if fi.deleted {
            err = self.add_version_filemata(ventry).err();
        }

        // A failed delete-marker insertion must surface even when the data dir is
        // shared: reporting success here silently turns the delete into a permanent
        // delete that replication never propagates.
        if let Some(e) = err {
            return Err(e);
        }

        if self.shared_data_dir_count(obj_version_id, obj_data_dir) > 0 {
            return Ok(None);
        }

        Ok(obj_data_dir)
    }

    pub fn into_fileinfo(
        &self,
        volume: &str,
        path: &str,
        version_id: &str,
        read_data: bool,
        include_free_versions: bool,
        all_parts: bool,
    ) -> Result<FileInfo> {
        self.to_fileinfo_with_part_checksums(
            volume,
            path,
            version_id,
            FileInfoDecodeOptions {
                read_data,
                include_free_versions,
                all_parts,
                include_part_checksums: true,
            },
        )
    }

    pub fn into_fileinfo_without_part_checksums(
        &self,
        volume: &str,
        path: &str,
        version_id: &str,
        read_data: bool,
        include_free_versions: bool,
    ) -> Result<FileInfo> {
        self.to_fileinfo_with_part_checksums(
            volume,
            path,
            version_id,
            FileInfoDecodeOptions {
                read_data,
                include_free_versions,
                all_parts: true,
                include_part_checksums: false,
            },
        )
    }

    fn to_fileinfo_with_part_checksums(
        &self,
        volume: &str,
        path: &str,
        version_id: &str,
        opts: FileInfoDecodeOptions,
    ) -> Result<FileInfo> {
        let vid = {
            if !version_id.is_empty() {
                Uuid::parse_str(version_id)?
            } else {
                Uuid::nil()
            }
        };
        // A nil selector denotes the null version slot, which legacy metadata
        // may encode as either an absent UUID or an explicit nil UUID.
        let matches_version = |actual: Option<Uuid>| {
            if vid.is_nil() {
                actual.is_none_or(|version_id| version_id.is_nil())
            } else {
                actual == Some(vid)
            }
        };

        let mut is_latest = true;
        let mut succ_mod_time = None;
        let mut non_free_versions = self.versions.len();

        let mut found = false;
        let mut found_free_version = None;
        let mut found_fi = None;

        for ver in self.versions.iter() {
            let header = &ver.header;

            if header.free_version() {
                non_free_versions -= 1;
                if opts.include_free_versions
                    && found_free_version.is_none()
                    && let Ok(found_free_fi) = ver.parse_version_meta()
                    && found_free_fi.version_type != VersionType::Invalid
                {
                    // Graceful degradation: the free-version replication-accounting record
                    // is auxiliary metadata; a corrupt one must not tank an otherwise
                    // healthy primary-version read. Log and skip rather than propagate.
                    // Known side effect: if a disk holds only free versions and they are
                    // corrupt, `into_fileinfo` falls through to `FileNotFound` (not
                    // `FileCorrupt`), so that disk is not enqueued for heal.
                    match found_free_fi.to_fileinfo_with_part_checksums(volume, path, opts.all_parts, opts.include_part_checksums)
                    {
                        Ok(mut free_fi) => {
                            free_fi.is_latest = true;
                            found_free_version = Some(free_fi);
                        }
                        Err(e) => {
                            warn!(volume, path, error = %e, "skipping corrupt free version during into_fileinfo");
                        }
                    }
                }

                if !matches_version(header.version_id) {
                    continue;
                }
            }

            if found {
                continue;
            }

            if !version_id.is_empty() && !matches_version(header.version_id) {
                is_latest = false;
                succ_mod_time = header.mod_time;
                continue;
            }

            found = true;

            let mut fi = ver.to_fileinfo_with_part_checksums(volume, path, opts.all_parts, opts.include_part_checksums)?;
            fi.is_latest = is_latest;

            if let Some(_d) = succ_mod_time {
                fi.successor_mod_time = succ_mod_time;
            }

            if opts.read_data && fi.inline_data() {
                fi.data = self.find_inline_data_for_version(fi.version_id)?.map(bytes::Bytes::from);
            }

            found_fi = Some(fi);
        }

        if !found {
            if version_id.is_empty() {
                if opts.include_free_versions
                    && non_free_versions == 0
                    && let Some(free_version) = found_free_version
                {
                    return Ok(free_version);
                }
                return Err(Error::FileNotFound);
            } else {
                return Err(Error::FileVersionNotFound);
            }
        }

        if let Some(mut fi) = found_fi {
            fi.num_versions = non_free_versions;

            return Ok(fi);
        }

        if version_id.is_empty() {
            Err(Error::FileNotFound)
        } else {
            Err(Error::FileVersionNotFound)
        }
    }

    pub fn get_file_info_versions(&self, volume: &str, path: &str, include_free_versions: bool) -> Result<FileInfoVersions> {
        let mut versions = self.into_file_info_versions(volume, path, true)?;

        let mut n = 0;

        let mut versions_vec = Vec::new();

        for fi in versions.versions.iter() {
            if fi.tier_free_version() {
                if !include_free_versions {
                    versions.free_versions.push(fi.clone());
                }
            } else {
                if !include_free_versions {
                    versions_vec.push(fi.clone());
                }
                n += 1;
            }
        }

        if !include_free_versions {
            versions.versions = versions_vec;

            for fi in versions.versions.iter_mut() {
                fi.num_versions = n;
            }
            for fi in versions.free_versions.iter_mut() {
                fi.num_versions = n;
            }
        }

        Ok(versions)
    }

    pub fn get_all_file_info_versions(&self, volume: &str, path: &str, all_parts: bool) -> Result<FileInfoVersions> {
        self.into_file_info_versions(volume, path, all_parts)
    }

    pub fn into_file_info_versions(&self, volume: &str, path: &str, all_parts: bool) -> Result<FileInfoVersions> {
        let mut versions = Vec::new();
        for version in self.versions.iter() {
            let fi = version.into_fileinfo(volume, path, all_parts)?;
            versions.push(fi);
        }

        let num = versions.len();
        let mut prev_mod_time = None;
        for (i, fi) in versions.iter_mut().enumerate() {
            if i == 0 {
                fi.is_latest = true;
            } else {
                fi.successor_mod_time = prev_mod_time;
            }
            fi.num_versions = num;
            prev_mod_time = fi.mod_time;
        }

        if versions.is_empty() {
            versions.push(FileInfo {
                name: path.to_string(),
                volume: volume.to_string(),
                deleted: true,
                is_latest: true,
                ..Default::default()
            });
        }

        Ok(FileInfoVersions {
            volume: volume.to_string(),
            name: path.to_string(),
            latest_mod_time: versions[0].mod_time,
            versions,
            ..Default::default()
        })
    }

    pub fn latest_mod_time(&self) -> Option<OffsetDateTime> {
        if self.versions.is_empty() {
            return None;
        }

        self.versions.first().unwrap().header.mod_time
    }

    /// Load or convert from buffer. Handles both current (meta_ver=3) and legacy (meta_ver=2) formats.
    pub fn load_or_convert(buf: &[u8]) -> Result<Self> {
        Self::load(buf)
    }

    /// List all versions as FileInfo
    pub fn list_versions(&self, volume: &str, path: &str, all_parts: bool) -> Result<Vec<FileInfo>> {
        let mut file_infos = Vec::new();
        for (i, version) in self.versions.iter().enumerate() {
            let mut fi = version.into_fileinfo(volume, path, all_parts)?;
            fi.is_latest = i == 0;
            file_infos.push(fi);
        }
        Ok(file_infos)
    }

    /// Check if all versions are hidden
    pub fn all_hidden(&self, top_delete_marker: bool) -> bool {
        if self.versions.is_empty() {
            return true;
        }

        if top_delete_marker && self.versions[0].header.version_type != VersionType::Delete {
            return false;
        }

        // Check if all versions are either delete markers or free versions
        self.versions
            .iter()
            .all(|v| v.header.version_type == VersionType::Delete || v.header.free_version())
    }

    /// Append metadata to buffer
    pub fn append_to(&self, dst: &mut Vec<u8>) -> Result<()> {
        let data = self.marshal_msg()?;
        dst.extend_from_slice(&data);
        Ok(())
    }

    /// Find version by string ID
    pub fn find_version_str(&self, version_id: &str) -> Result<(usize, FileMetaVersion)> {
        if version_id.is_empty() {
            return Err(Error::other("empty version ID"));
        }

        let uuid = Uuid::parse_str(version_id)?;
        self.find_version(Some(uuid))
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::test_data::*;
    use proptest::collection::vec;
    use proptest::prelude::*;

    /// A restore header meaning "restored copy is on disk until far in the future".
    /// Format produced by `RestoreStatusOps::to_string` and consumed by
    /// `parse_restore_obj_status` (fileinfo.rs).
    const RESTORED_ON_DISK: &str = "ongoing-request=\"false\", expiry-date=\"9999-01-01T00:00:00Z\"";

    /// backlog#1733 g-key-003: a restored-to-local object must keep its data
    /// dir. The restore marker lives under the pinned `x-amz-restore` key; if
    /// the key ever drifts this flips to `false` and the data dir becomes
    /// eligible for reclamation while the restored copy is still being served.
    #[test]
    fn restored_object_keeps_using_data_dir() {
        let mut obj = MetaObject::default();
        obj.meta_user
            .insert("x-amz-restore".to_string(), RESTORED_ON_DISK.to_string());
        assert!(obj.uses_data_dir(), "restored object's data dir must be considered in use");

        // The same fail-open shape the pin protects against: without the marker
        // the data dir is judged unused — exactly what a key drift would cause.
        let bare = MetaObject::default();
        assert!(!bare.uses_data_dir(), "object without restore marker reports data dir unused");
    }

    /// backlog#1733 g-key-004: a transition-complete object short-circuits to
    /// `false` even when the restore marker is present — the existing
    /// precedence must not change.
    #[test]
    fn transition_complete_object_does_not_use_data_dir() {
        use rustfs_utils::http::{SUFFIX_TRANSITION_STATUS, insert_bytes};
        let mut obj = MetaObject::default();
        obj.meta_user
            .insert("x-amz-restore".to_string(), RESTORED_ON_DISK.to_string());
        insert_bytes(&mut obj.meta_sys, SUFFIX_TRANSITION_STATUS, TRANSITION_COMPLETE.as_bytes().to_vec());
        assert!(!obj.uses_data_dir(), "transition-complete short-circuit must win over the restore marker");
    }

    /// The restore-header parser and the pinned key literal must agree: the
    /// marker written under `x-amz-restore` is only meaningful if the parser
    /// accepts it.
    #[test]
    fn restore_marker_roundtrips_through_parser() {
        let mut meta = HashMap::new();
        meta.insert(metadata_keys::RESTORE.to_string(), RESTORED_ON_DISK.to_string());
        assert!(crate::is_restored_object_on_disk(&meta));

        // An in-progress restore is not "on disk".
        meta.insert(metadata_keys::RESTORE.to_string(), "ongoing-request=\"true\"".to_string());
        assert!(!crate::is_restored_object_on_disk(&meta));
    }

    /// backlog#580: RustFS parses real MinIO-written object xl.meta (inline,
    /// versioned, and multipart) into equivalent `FileInfo`. Object metadata is
    /// the strong part of MinIO interop; this pins it against real fixtures.
    #[test]
    fn parses_real_minio_object_xlmeta() {
        // Small inlined object.
        let small = create_minio_small_object_xlmeta().expect("load small fixture");
        let (major, _minor, _hdr, meta_ver) = FileMeta::read_format_versions(&small).unwrap();
        assert_eq!(major, 1);
        assert_eq!(meta_ver, FileMeta::load(&small).unwrap().meta_ver);
        let fm = FileMeta::load(&small).expect("parse small MinIO xl.meta");
        assert_eq!(fm.versions.len(), 1);
        let fi = fm
            .into_fileinfo("interop", "small.txt", "", false, false, true)
            .expect("small fileinfo");
        assert_eq!(fi.size, 19, "small.txt size");
        assert_eq!(fi.num_versions, 1);
        assert!(fi.is_latest);

        // Versioned object: two object versions plus a delete marker (latest).
        let versioned = create_minio_versioned_object_xlmeta().expect("load versioned fixture");
        let fm = FileMeta::load(&versioned).expect("parse versioned MinIO xl.meta");
        assert_eq!(fm.versions.len(), 3, "two object versions + one delete marker");
        let delete_markers = fm
            .versions
            .iter()
            .filter(|v| v.header.version_type == VersionType::Delete)
            .count();
        assert_eq!(delete_markers, 1, "delete marker parsed from MinIO xl.meta");
        let fi = fm
            .into_fileinfo("interop", "versioned.txt", "", false, false, true)
            .expect("versioned fileinfo");
        assert_eq!(fi.num_versions, 3);
        assert!(fi.version_id.is_some(), "versioned object carries a version id");

        // Larger object stored as an erasure-coded part (not inlined).
        let large = create_minio_large_object_xlmeta().expect("load large fixture");
        let fm = FileMeta::load(&large).expect("parse large MinIO xl.meta");
        assert_eq!(fm.versions.len(), 1);
        let fi = fm
            .into_fileinfo("interop", "large.bin", "", false, false, true)
            .expect("large fileinfo");
        assert_eq!(fi.size, 300_000, "large.bin size");
        assert!(!fi.parts.is_empty(), "multipart/part layout present");
    }

    /// Compatibility guard for the tightened `validate_for_metadata_read()` decode
    /// boundary (the rolling-upgrade / MinIO-migration risk): every version of
    /// every real, historically-written `xl.meta` fixture must still be *accepted*
    /// on read, never rejected as `FileCorrupt`. This is the empirical companion to
    /// the code-reasoned decode-tolerance invariants in
    /// `docs/architecture/erasure-coding.md` §11 — reverting the tolerant handling
    /// (delete-marker shape, legacy per-part checksums, string/short
    /// `transitioned-versionID`, negative `actual_size`) turns one of these red.
    /// It covers real MinIO-written objects (inline, versioned incl. a delete
    /// marker, and multipart), a legacy V1 (`xl.json`-derived) object, and a legacy
    /// meta_ver 2 object.
    #[test]
    fn real_historical_xlmeta_versions_pass_metadata_read_validation() {
        let fixtures: [(&str, Vec<u8>); 5] = [
            ("minio-small-inline", create_minio_small_object_xlmeta().expect("small fixture")),
            (
                "minio-versioned+delete-marker",
                create_minio_versioned_object_xlmeta().expect("versioned fixture"),
            ),
            ("minio-large-multipart", create_minio_large_object_xlmeta().expect("large fixture")),
            ("legacy-v1-object", create_legacy_v1_object_xlmeta().expect("legacy v1 fixture")),
            (
                "legacy-meta-v2-object",
                create_issue_2265_legacy_meta_v2_object_xlmeta().expect("legacy meta v2 fixture"),
            ),
        ];

        for (label, bytes) in fixtures {
            let fm = FileMeta::load(&bytes).unwrap_or_else(|e| panic!("{label}: load real xl.meta failed: {e}"));
            // `all_parts = true` materializes the part arrays so the checksum/part and
            // shard-size checks in `validate_for_metadata_read` are actually exercised.
            let versions = fm
                .list_versions("interop", "object", true)
                .unwrap_or_else(|e| panic!("{label}: list_versions failed: {e}"));
            assert!(!versions.is_empty(), "{label}: fixture must contain at least one version");
            for (i, fi) in versions.iter().enumerate() {
                fi.validate_for_metadata_read().unwrap_or_else(|e| {
                    panic!(
                        "{label}: version {i} (deleted={}) rejected by validate_for_metadata_read: {e:?}",
                        fi.deleted
                    )
                });
            }
        }
    }

    /// Wraps a raw meta block in a valid XL2 container (header, bin32 length
    /// prefix, and CRC trailer) so decode tests exercise the meta parsing
    /// itself rather than the envelope checks.
    fn build_xl_buffer(meta: &[u8]) -> Vec<u8> {
        let mut buf = Vec::new();
        buf.extend_from_slice(&XL_FILE_HEADER);
        buf.extend_from_slice(&XL_FILE_VERSION_MAJOR.to_le_bytes());
        buf.extend_from_slice(&XL_FILE_VERSION_MINOR.to_le_bytes());
        buf.push(0xc6); // bin32
        buf.extend_from_slice(&(meta.len() as u32).to_be_bytes());
        buf.extend_from_slice(meta);
        let crc = xxh64::xxh64(meta, XXHASH_SEED) as u32;
        buf.push(0xce); // u32
        buf.extend_from_slice(&crc.to_be_bytes());
        buf
    }

    /// Regression for backlog#799 B15: `sort_by_mod_time` must order versions
    /// identically to `FileMetaVersionHeader::sorts_before`. When an object and
    /// a delete marker share a `mod_time`, the old tie-break sorted the delete
    /// marker first (so the object looked deleted) while `sorts_before` — used
    /// by the metacache merge and latest-version selection — puts the object
    /// first. That divergence made different code paths disagree on latest.
    #[test]
    fn sort_by_mod_time_matches_sorts_before_on_equal_mod_time() {
        let mod_time = Some(OffsetDateTime::from_unix_timestamp(1_700_000_000).unwrap());
        let obj_id = Uuid::from_u128(1);
        let del_id = Uuid::from_u128(2);

        let object = FileMetaShallowVersion {
            header: FileMetaVersionHeader {
                version_id: Some(obj_id),
                mod_time,
                version_type: VersionType::Object,
                ..Default::default()
            },
            meta: Vec::new(),
        };
        let delete_marker = FileMetaShallowVersion {
            header: FileMetaVersionHeader {
                version_id: Some(del_id),
                mod_time,
                version_type: VersionType::Delete,
                ..Default::default()
            },
            meta: Vec::new(),
        };

        // sorts_before is the canonical predicate: object precedes the marker.
        assert!(object.header.sorts_before(&delete_marker.header));
        assert!(!delete_marker.header.sorts_before(&object.header));

        // Insert marker-first so a wrong tie-break would leave it at index 0.
        let mut fm = FileMeta {
            versions: vec![delete_marker, object],
            ..Default::default()
        };
        fm.sort_by_mod_time();

        assert_eq!(
            fm.versions[0].header.version_type,
            VersionType::Object,
            "object must sort before an equal-mod_time delete marker, matching sorts_before"
        );
        assert_eq!(fm.versions[1].header.version_type, VersionType::Delete);
        assert!(fm.is_sorted_by_mod_time());
    }

    fn version_for_ordering(
        version_type: VersionType,
        version_id: Uuid,
        mod_time: OffsetDateTime,
        marker: u8,
    ) -> FileMetaVersion {
        match version_type {
            VersionType::Object => FileMetaVersion {
                version_type,
                object: Some(MetaObject {
                    version_id: Some(version_id),
                    erasure_algorithm: ErasureAlgo::ReedSolomon,
                    erasure_m: 2,
                    erasure_n: 2,
                    erasure_block_size: 1 << 20,
                    bitrot_checksum_algo: ChecksumAlgo::HighwayHash,
                    mod_time: Some(mod_time),
                    meta_sys: HashMap::from([("ordering-marker".to_string(), vec![marker])]),
                    ..Default::default()
                }),
                ..Default::default()
            },
            VersionType::Delete => FileMetaVersion {
                version_type,
                delete_marker: Some(MetaDeleteMarker {
                    version_id: Some(version_id),
                    mod_time: Some(mod_time),
                    meta_sys: HashMap::from([("ordering-marker".to_string(), vec![marker])]),
                }),
                ..Default::default()
            },
            _ => unreachable!("ordering regression only constructs object and delete versions"),
        }
    }

    struct ObjectMaxVersionsRestore {
        previous: Option<usize>,
    }

    impl Drop for ObjectMaxVersionsRestore {
        fn drop(&mut self) {
            set_object_max_versions_override_for_test(self.previous);
        }
    }

    fn with_object_max_versions_for_test<R>(limit: usize, test: impl FnOnce() -> R) -> R {
        let previous = set_object_max_versions_override_for_test(Some(limit));
        let _restore = ObjectMaxVersionsRestore { previous };
        test()
    }

    #[test]
    fn add_version_filemata_rejects_new_version_above_configured_limit() {
        with_object_max_versions_for_test(2, || {
            let mut fm = FileMeta::new();
            fm.add_version_filemata(valid_object_version(Uuid::from_u128(1), vec![10, 20]))
                .expect("add first version within limit");
            fm.add_version_filemata(valid_object_version(Uuid::from_u128(2), vec![10, 20]))
                .expect("add second version at limit");

            let err = fm
                .add_version_filemata(valid_object_version(Uuid::from_u128(3), vec![10, 20]))
                .expect_err("new version above limit must fail");

            assert_eq!(err, Error::MaxVersionsExceeded);
            assert_eq!(fm.versions.len(), 2, "failed insert must not mutate version list");
        });
    }

    #[test]
    fn add_version_filemata_allows_same_version_replacement_at_limit() {
        with_object_max_versions_for_test(2, || {
            let mut fm = FileMeta::new();
            let target = Uuid::from_u128(10);
            fm.add_version_filemata(valid_object_version(target, vec![10, 20]))
                .expect("add target version");
            fm.add_version_filemata(valid_object_version(Uuid::from_u128(20), vec![10, 20]))
                .expect("add peer version at limit");

            fm.add_version_filemata(valid_object_version(target, vec![30, 40]))
                .expect("same version replacement at limit must succeed");

            assert_eq!(fm.versions.len(), 2);
            let replaced = fm
                .versions
                .iter()
                .find(|version| version.header.version_id == Some(target))
                .expect("target version must remain present")
                .parse_version_meta()
                .expect("parse replaced version");
            assert_eq!(replaced.object.expect("object version").part_sizes, vec![30, 40]);
        });
    }

    #[test]
    fn add_version_allows_null_version_replacement_at_limit() {
        with_object_max_versions_for_test(1, || {
            let mut fm = FileMeta::new();
            let mut first = FileInfo::new("object", 2, 2);
            first.mod_time = Some(OffsetDateTime::now_utc());
            first.version_id = None;
            fm.add_version(first).expect("add initial null version");

            let mut replacement = FileInfo::new("object", 2, 2);
            replacement.mod_time = Some(OffsetDateTime::now_utc());
            replacement.version_id = None;
            replacement.size = 42;
            fm.add_version(replacement)
                .expect("null version replacement at limit must succeed");

            assert_eq!(fm.versions.len(), 1);
            assert_eq!(fm.versions[0].header.version_id, Some(Uuid::nil()));
            let replaced = fm.versions[0].parse_version_meta().expect("parse null replacement");
            assert_eq!(replaced.object.expect("object version").size, 42);
        });
    }

    fn tier_overwrite_fixture(state: crate::TransitionVersionState) -> (FileMeta, FileInfo) {
        let mut source = FileInfo::new("object", 2, 2);
        source.erasure.index = 1;
        source.mod_time = Some(OffsetDateTime::from_unix_timestamp(1_700_000_000).expect("fixture timestamp"));
        source.data_dir = Some(Uuid::new_v4());
        source.transition_status = TRANSITION_COMPLETE.to_string();
        source.transition_tier = "WARM".to_string();
        source.transitioned_objname = "remote/old-object".to_string();
        source.transition_version_state = state;
        source.transition_version = match state {
            crate::TransitionVersionState::Exact => Some("opaque-provider-version".to_string()),
            crate::TransitionVersionState::SuspendedNull => Some("null".to_string()),
            _ => None,
        };
        rustfs_utils::http::insert_str(
            &mut source.metadata,
            rustfs_utils::http::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
            "ab".repeat(32),
        );
        if state == crate::TransitionVersionState::KnownDisabled {
            rustfs_utils::http::insert_str(
                &mut source.metadata,
                rustfs_utils::http::SUFFIX_TRANSITIONED_VERSION_ID,
                String::new(),
            );
        }
        let mut meta = FileMeta::new();
        meta.add_version(source.clone()).expect("seed transitioned null version");
        (meta, source)
    }

    #[test]
    fn tier_overwrite_preserves_exact_cleanup_owner_across_reload() {
        use crate::TransitionVersionState::{Exact, KnownDisabled, SuspendedNull, Unknown};
        use rustfs_utils::http::{MINIO_INTERNAL_PREFIX, RUSTFS_INTERNAL_PREFIX, SUFFIX_TIER_FV_ID};

        for state in [Exact, KnownDisabled, SuspendedNull, Unknown] {
            for inline in [false, true] {
                let (mut meta, _) = tier_overwrite_fixture(state);
                let old = meta.versions[0].parse_version_meta().expect("old metadata");
                let old = old.object.expect("old object");
                let id = Uuid::new_v4();
                let mut replacement = FileInfo::new("object", 2, 2);
                replacement.version_id = inline.then_some(Uuid::nil());
                replacement.mod_time = Some(OffsetDateTime::from_unix_timestamp(1_700_000_001).expect("fixture timestamp"));
                replacement.data_dir = Some(Uuid::new_v4());
                replacement.size = 3;
                if inline {
                    replacement.data = Some(Bytes::from_static(b"new"));
                }
                replacement.set_tier_free_version_id(&id.to_string());

                meta.add_version(replacement.clone())
                    .expect("replace transitioned null version");
                let bytes = meta.marshal_msg().expect("persist replacement and cleanup owner");
                let mut reopened = FileMeta::load(&bytes).expect("reopen committed metadata");
                assert_eq!(reopened.versions.len(), 2);
                let (_, free) = reopened.find_version(Some(id)).expect("durable cleanup owner");
                assert!(free.free_version());
                let marker = free.delete_marker.expect("cleanup marker");
                for suffix in [
                    rustfs_utils::http::SUFFIX_TRANSITION_TIER,
                    rustfs_utils::http::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
                    rustfs_utils::http::SUFFIX_TRANSITIONED_OBJECTNAME,
                    rustfs_utils::http::SUFFIX_TRANSITIONED_VERSION_ID,
                    rustfs_utils::http::SUFFIX_TRANSITIONED_VERSION_STATE,
                ] {
                    for prefix in [RUSTFS_INTERNAL_PREFIX, MINIO_INTERNAL_PREFIX] {
                        let key = format!("{prefix}{suffix}");
                        assert_eq!(marker.meta_sys.get(&key), old.meta_sys.get(&key), "{state:?}: {key}");
                    }
                }
                let (_, current) = reopened.find_version(None).expect("replacement survives restart");
                let current = current.object.expect("replacement object");
                assert_eq!(current.size, 3);
                assert!(!rustfs_utils::http::contains_key_bytes(&current.meta_sys, SUFFIX_TIER_FV_ID));
                reopened
                    .add_version(replacement)
                    .expect("replaying replacement is idempotent");
                assert_eq!(reopened.versions.len(), 2);
            }
        }
    }

    #[test]
    fn tier_overwrite_rpc_intent_matches_legacy_cleanup_owner_and_replay() {
        use crate::TransitionVersionState::{Exact, KnownDisabled, SuspendedNull, Unknown};

        for state in [Exact, KnownDisabled, SuspendedNull, Unknown] {
            for inline in [false, true] {
                let (mut current, _) = tier_overwrite_fixture(state);
                let mut legacy = current.clone();
                let id = Uuid::new_v4();
                let mut replacement = FileInfo::new("object", 2, 2);
                replacement.mod_time = Some(OffsetDateTime::from_unix_timestamp(1_700_000_001).expect("fixture timestamp"));
                replacement.data_dir = Some(Uuid::new_v4());
                replacement.size = 3;
                replacement.data = inline.then(|| Bytes::from_static(b"new"));
                replacement.overwrite_tier_free_version_id = Some(id);
                let mut legacy_replacement = replacement.clone();
                legacy_replacement.overwrite_tier_free_version_id = None;
                legacy_replacement.set_tier_free_version_id(&id.to_string());

                legacy.add_version(legacy_replacement).expect("legacy cleanup intent");
                current.add_version(replacement.clone()).expect("RPC cleanup intent");
                let mut reopened = FileMeta::load(&current.marshal_msg().expect("persist both versions")).expect("reload");
                assert_eq!(
                    reopened.find_version(Some(id)).expect("RPC cleanup owner").1,
                    legacy.find_version(Some(id)).expect("legacy cleanup owner").1
                );
                let info = reopened
                    .into_fileinfo("bucket", "object", "", false, false, true)
                    .expect("replacement remains readable");
                assert!(info.overwrite_tier_free_version_id.is_none(), "the RPC intent must not persist");
                assert!(!rustfs_utils::http::contains_key_str(
                    &info.metadata,
                    rustfs_utils::http::SUFFIX_TIER_FV_ID
                ));
                reopened.add_version(replacement).expect("same-intent replay");
                assert_eq!(reopened.versions.len(), 2, "replay retains exactly one cleanup owner");
                assert!(
                    reopened
                        .find_version(Some(id))
                        .expect("owner survives replay")
                        .1
                        .free_version()
                );
            }
        }
    }

    #[test]
    fn tier_overwrite_rejects_conflicting_or_nil_rpc_intent_without_mutation() {
        for (intent, legacy) in [(Uuid::nil(), None), (Uuid::new_v4(), Some(Uuid::new_v4()))] {
            let (mut meta, _) = tier_overwrite_fixture(crate::TransitionVersionState::Exact);
            let before = meta.clone();
            let mut replacement = FileInfo::new("object", 2, 2);
            replacement.overwrite_tier_free_version_id = Some(intent);
            if let Some(legacy) = legacy {
                replacement.set_tier_free_version_id(&legacy.to_string());
            }
            assert_eq!(meta.add_version(replacement), Err(Error::FileCorrupt));
            assert_eq!(meta, before);
        }
    }

    #[test]
    fn tier_overwrite_rejects_cleanup_failure_without_mutating_source() {
        for id in ["not-a-uuid".to_string(), Uuid::nil().to_string()] {
            let (mut meta, _) = tier_overwrite_fixture(crate::TransitionVersionState::Exact);
            let before = meta.clone();
            let mut replacement = FileInfo::new("object", 2, 2);
            replacement.mod_time = Some(OffsetDateTime::now_utc());
            replacement.set_tier_free_version_id(&id);
            assert!(meta.add_version(replacement).is_err());
            assert_eq!(meta, before, "invalid cleanup identity must preserve source");
        }
        with_object_max_versions_for_test(1, || {
            let (mut meta, _) = tier_overwrite_fixture(crate::TransitionVersionState::KnownDisabled);
            let before = meta.clone();
            let mut replacement = FileInfo::new("object", 2, 2);
            replacement.mod_time = Some(OffsetDateTime::now_utc());
            replacement.data = Some(Bytes::from_static(b"new"));
            replacement.set_tier_free_version_id(&Uuid::new_v4().to_string());
            assert_eq!(
                meta.add_version(replacement)
                    .expect_err("cleanup owner exceeds version limit"),
                Error::MaxVersionsExceeded
            );
            assert_eq!(meta, before, "failed cleanup insertion must also preserve inline bytes");
        });
    }

    #[test]
    fn tier_overwrite_allows_empty_transition_status_on_local_source() {
        let mut source = FileInfo::new("object", 2, 2);
        source.mod_time = Some(OffsetDateTime::now_utc());
        source.data = Some(Bytes::from_static(b"old"));
        rustfs_utils::http::insert_str(&mut source.metadata, rustfs_utils::http::SUFFIX_TRANSITION_STATUS, String::new());
        let mut meta = FileMeta::new();
        meta.add_version(source)
            .expect("seed readable local metadata with empty status");
        let mut replacement = FileInfo::new("object", 2, 2);
        replacement.mod_time = Some(OffsetDateTime::now_utc());
        replacement.size = 3;
        replacement.data = Some(Bytes::from_static(b"new"));
        replacement.set_tier_free_version_id(&Uuid::new_v4().to_string());
        meta.add_version(replacement)
            .expect("an ordinary overwrite must still succeed");
        assert_eq!(meta.versions.len(), 1);
        let (_, current) = meta.find_version(None).expect("replacement remains visible");
        assert_eq!(current.object.expect("ordinary object").size, 3);
        assert!(!meta.versions[0].header.free_version());
    }

    #[test]
    fn tier_overwrite_preserves_legacy_metadata_casing() {
        use rustfs_utils::http::{MINIO_INTERNAL_PREFIX, RUSTFS_INTERNAL_PREFIX};

        for state in [
            crate::TransitionVersionState::Exact,
            crate::TransitionVersionState::KnownDisabled,
        ] {
            let (mut meta, _) = tier_overwrite_fixture(state);
            let mut source = meta.versions[0].parse_version_meta().expect("seeded source");
            let object = source.object.as_mut().expect("transitioned source");
            let expected = object.meta_sys.clone();
            object.meta_sys = object
                .meta_sys
                .drain()
                .map(|(key, value)| (key.to_ascii_uppercase(), value))
                .collect();
            meta.versions[0] = FileMetaShallowVersion::try_from(source).expect("legacy key casing");
            let id = Uuid::new_v4();
            let mut replacement = FileInfo::new("object", 2, 2);
            replacement.mod_time = Some(OffsetDateTime::now_utc());
            replacement.set_tier_free_version_id(&id.to_string());
            meta.add_version(replacement).expect("overwrite readable legacy source");
            let reopened = FileMeta::load(&meta.marshal_msg().expect("persist overwrite")).expect("reopen overwrite");
            let (_, owner) = reopened
                .find_version(Some(id))
                .expect("legacy source must retain cleanup ownership");
            let marker = owner.delete_marker.expect("cleanup marker");
            for suffix in [
                rustfs_utils::http::SUFFIX_TRANSITION_TIER,
                rustfs_utils::http::SUFFIX_TRANSITION_TIER_DESTINATION_ID,
                rustfs_utils::http::SUFFIX_TRANSITIONED_OBJECTNAME,
                rustfs_utils::http::SUFFIX_TRANSITIONED_VERSION_ID,
                rustfs_utils::http::SUFFIX_TRANSITIONED_VERSION_STATE,
            ] {
                for prefix in [RUSTFS_INTERNAL_PREFIX, MINIO_INTERNAL_PREFIX] {
                    let key = format!("{prefix}{suffix}");
                    assert_eq!(marker.meta_sys.get(&key), expected.get(&key), "legacy {state:?}: {key}");
                }
            }
        }
    }

    #[test]
    fn tier_overwrite_rejects_conflicting_remote_metadata_aliases() {
        use rustfs_utils::http::{
            MINIO_INTERNAL_PREFIX, SUFFIX_TRANSITION_STATUS, SUFFIX_TRANSITION_TIER, SUFFIX_TRANSITION_TIER_DESTINATION_ID,
            SUFFIX_TRANSITIONED_OBJECTNAME, SUFFIX_TRANSITIONED_VERSION_ID, SUFFIX_TRANSITIONED_VERSION_STATE,
        };
        for suffix in [
            SUFFIX_TRANSITION_STATUS,
            SUFFIX_TRANSITION_TIER,
            SUFFIX_TRANSITION_TIER_DESTINATION_ID,
            SUFFIX_TRANSITIONED_OBJECTNAME,
            SUFFIX_TRANSITIONED_VERSION_ID,
            SUFFIX_TRANSITIONED_VERSION_STATE,
        ] {
            let (mut meta, _) = tier_overwrite_fixture(crate::TransitionVersionState::Exact);
            let mut old = meta.versions[0].parse_version_meta().expect("seeded source metadata");
            old.object
                .as_mut()
                .expect("transitioned source")
                .meta_sys
                .insert(format!("{MINIO_INTERNAL_PREFIX}{suffix}"), b"conflicting-value".to_vec());
            meta.versions[0] = FileMetaShallowVersion::try_from(old).expect("encode conflicting aliases");
            let before = meta.clone();
            let mut replacement = FileInfo::new("object", 2, 2);
            replacement.mod_time = Some(OffsetDateTime::now_utc());
            replacement.set_tier_free_version_id(&Uuid::new_v4().to_string());
            assert_eq!(
                meta.add_version(replacement)
                    .expect_err("ambiguous ownership must fail closed"),
                Error::FileCorrupt
            );
            assert_eq!(meta, before, "conflicting {suffix} must not erase the old remote tuple");
        }
    }

    #[test]
    fn tier_overwrite_keeps_retained_remote_and_versioned_copy_ownership() {
        let (mut meta, mut source) = tier_overwrite_fixture(crate::TransitionVersionState::Exact);
        source.set_tier_free_version_id(&Uuid::new_v4().to_string());
        meta.add_version(source.clone())
            .expect("restore retains the same remote owner");
        assert_eq!(meta.versions.len(), 1);
        source.version_id = Some(Uuid::new_v4());
        source.transition_status.clear();
        source.transition_tier.clear();
        source.transitioned_objname.clear();
        source.transition_version = None;
        source.transition_version_state = crate::TransitionVersionState::Unknown;
        meta.add_version(source).expect("versioned write retains historical source");
        assert_eq!(meta.versions.len(), 2);
        assert!(meta.versions.iter().all(|version| !version.header.free_version()));
    }

    #[test]
    fn add_version_filemata_uses_canonical_equal_time_order() {
        let mod_time = OffsetDateTime::from_unix_timestamp(1_700_000_000).expect("valid test timestamp");
        let object = version_for_ordering(VersionType::Object, Uuid::from_u128(1), mod_time, 1);
        let delete_marker = version_for_ordering(VersionType::Delete, Uuid::from_u128(2), mod_time, 2);

        for versions in [[object.clone(), delete_marker.clone()], [delete_marker, object]] {
            let mut fm = FileMeta::new();
            for version in versions {
                fm.add_version_filemata(version).expect("add equal-time version");
            }

            assert_eq!(fm.versions[0].header.version_type, VersionType::Object);
            assert_eq!(fm.versions[1].header.version_type, VersionType::Delete);
            assert!(fm.versions[0].header.sorts_before(&fm.versions[1].header));
        }
    }

    #[test]
    fn add_version_filemata_preserves_tie_breaks_after_reload() {
        let mod_time = OffsetDateTime::from_unix_timestamp(1_700_000_000).expect("valid test timestamp");
        let versions = [
            version_for_ordering(VersionType::Object, Uuid::from_u128(10), mod_time, 10),
            version_for_ordering(VersionType::Object, Uuid::from_u128(20), mod_time, 20),
            version_for_ordering(VersionType::Delete, Uuid::from_u128(30), mod_time, 30),
        ];
        let mut expected = versions.iter().map(FileMetaVersion::header).collect::<Vec<_>>();
        expected.sort_by(|a, b| {
            if a.sorts_before(b) {
                Ordering::Less
            } else if b.sorts_before(a) {
                Ordering::Greater
            } else {
                Ordering::Equal
            }
        });

        let mut fm = FileMeta::new();
        for version in versions.into_iter().rev() {
            fm.add_version_filemata(version).expect("add equal-time version");
        }
        let loaded = FileMeta::load(&fm.marshal_msg().expect("serialize file metadata")).expect("reload file metadata");
        let actual = loaded
            .versions
            .iter()
            .map(|version| version.header.clone())
            .collect::<Vec<_>>();

        assert_ne!(expected[0].signature, expected[1].signature, "fixture must exercise signature ordering");
        assert_eq!(actual, expected);
        assert!(actual.windows(2).all(|pair| pair[0].sorts_before(&pair[1])));
    }

    #[test]
    fn add_version_filemata_reorders_equal_time_replacement() {
        let mod_time = OffsetDateTime::from_unix_timestamp(1_700_000_000).expect("valid test timestamp");
        let first = version_for_ordering(VersionType::Object, Uuid::from_u128(40), mod_time, 40);
        let second = version_for_ordering(VersionType::Object, Uuid::from_u128(50), mod_time, 50);
        let (target, peer) = if first.header().sorts_before(&second.header()) {
            (first, second)
        } else {
            (second, first)
        };
        let target_id = target.header().version_id.expect("test version id");

        let mut fm = FileMeta::new();
        fm.add_version_filemata(peer).expect("add peer object");
        fm.add_version_filemata(target).expect("add target object");
        assert_eq!(fm.versions[0].header.version_id, Some(target_id));

        fm.add_version_filemata(version_for_ordering(VersionType::Delete, target_id, mod_time, 60))
            .expect("replace target with equal-time delete marker");

        assert_eq!(fm.versions[0].header.version_type, VersionType::Object);
        assert_eq!(fm.versions[1].header.version_type, VersionType::Delete);
        assert!(fm.versions[0].header.sorts_before(&fm.versions[1].header));
    }

    #[test]
    fn add_version_filemata_rejects_free_and_ordinary_same_id_replacement() {
        let version_id = Uuid::new_v4();
        let mut free_meta_sys = HashMap::new();
        insert_bytes(&mut free_meta_sys, rustfs_utils::http::SUFFIX_FREE_VERSION, Vec::new());
        let free_version = FileMetaVersion {
            version_type: VersionType::Delete,
            delete_marker: Some(MetaDeleteMarker {
                version_id: Some(version_id),
                mod_time: Some(OffsetDateTime::now_utc()),
                meta_sys: free_meta_sys,
            }),
            ..Default::default()
        };
        let ordinary_version = valid_object_version(version_id, vec![10, 20]);

        for (existing, replacement) in [
            (free_version.clone(), ordinary_version.clone()),
            (ordinary_version, free_version),
        ] {
            let mut fm = FileMeta::new();
            fm.add_version_filemata(existing).expect("seed same-id version");
            let before = fm.marshal_msg().expect("serialize original metadata");

            let err = fm
                .add_version_filemata(replacement)
                .expect_err("free and ordinary versions with the same ID must not replace each other");

            assert!(err.to_string().contains("cannot replace a free version"));
            assert_eq!(fm.marshal_msg().expect("serialize rejected metadata"), before);
        }
    }

    /// `add_version_filemata` positions an inserted version with
    /// `partition_point(sorts_before)`, which only yields the canonical slot when
    /// `versions` is already canonically ordered. Nothing establishes that
    /// precondition on load: `FileMeta::unmarshal_msg` pushes versions in file
    /// order, and metadata written before the canonical-order fix ordered
    /// equal-`mod_time` ties by insertion instead of by `sorts_before`. An insert
    /// into such a list must still leave it canonical, the same way `set_idx`
    /// already re-sorts on the replace path.
    #[test]
    fn add_version_filemata_canonicalizes_versions_loaded_out_of_order() {
        let mod_time = OffsetDateTime::from_unix_timestamp(1_700_000_000).expect("valid test timestamp");
        let first = version_for_ordering(VersionType::Object, Uuid::from_u128(70), mod_time, 70);
        let second = version_for_ordering(VersionType::Object, Uuid::from_u128(80), mod_time, 80);
        let (early, late) = if first.header().sorts_before(&second.header()) {
            (first, second)
        } else {
            (second, first)
        };

        // Persist the pair the wrong way round to emulate a pre-canonical-order
        // xl.meta, bypassing add_version_filemata so the bad order really lands on
        // the wire.
        let mut legacy = FileMeta::new();
        legacy
            .versions
            .push(FileMetaShallowVersion::try_from(late).expect("shallow later version"));
        legacy
            .versions
            .push(FileMetaShallowVersion::try_from(early).expect("shallow earlier version"));

        let mut loaded =
            FileMeta::load(&legacy.marshal_msg().expect("serialize legacy metadata")).expect("reload legacy metadata");
        assert!(
            !loaded.versions[0].header.sorts_before(&loaded.versions[1].header),
            "fixture must reach add_version_filemata non-canonically ordered"
        );

        loaded
            .add_version_filemata(version_for_ordering(VersionType::Delete, Uuid::from_u128(90), mod_time, 90))
            .expect("insert equal-time delete marker");

        assert_eq!(loaded.versions.len(), 3);
        assert!(
            loaded
                .versions
                .windows(2)
                .all(|pair| pair[0].header.sorts_before(&pair[1].header)),
            "insert must leave the version list canonically ordered"
        );
    }

    /// Regression for backlog#799 B16: replication reset state must be
    /// persisted under both internal prefixes, never as a bare ARN. A bare-ARN
    /// key (produced by `ObjectInfo::replication_state`) has no internal prefix,
    /// so read-back — which only recognizes prefixed keys — silently dropped it.
    #[test]
    fn persist_target_delete_marker_versions_uses_bounded_dual_prefixed_keys() {
        let arn = "arn:rustfs:replication::target:bucket";
        let version_id = "opaque-target-version";
        let suffix = format!("{SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX}{arn}");
        let versions = HashMap::from([
            (arn.to_string(), version_id.to_string()),
            ("not-an-arn".to_string(), "ignored".to_string()),
            ("arn:too-long".to_string(), "x".repeat(MAX_REPLICATION_TARGET_VERSION_ID_LEN + 1)),
        ]);
        let mut meta_sys = HashMap::new();

        persist_target_delete_marker_versions(&mut meta_sys, &versions, &HashMap::new());

        assert_eq!(
            meta_sys.get(&format!("{RUSTFS_INTERNAL_PREFIX}{suffix}")).map(Vec::as_slice),
            Some(version_id.as_bytes())
        );
        assert_eq!(
            meta_sys.get(&format!("{MINIO_INTERNAL_PREFIX}{suffix}")).map(Vec::as_slice),
            Some(version_id.as_bytes())
        );
        assert_eq!(meta_sys.len(), 2, "invalid or oversized mappings must not expand xl.meta");
    }

    #[test]
    fn persist_target_delete_marker_versions_caps_target_count() {
        let versions = (0..=MAX_REPLICATION_TARGET_VERSION_ENTRIES)
            .map(|index| (format!("arn:rustfs:replication::target:{index:04}"), format!("version-{index}")))
            .collect();
        let mut meta_sys = HashMap::new();

        persist_target_delete_marker_versions(&mut meta_sys, &versions, &HashMap::new());

        assert_eq!(meta_sys.len(), MAX_REPLICATION_TARGET_VERSION_ENTRIES * 2);
        let excluded_suffix = format!(
            "{SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX}arn:rustfs:replication::target:{MAX_REPLICATION_TARGET_VERSION_ENTRIES:04}"
        );
        assert!(!meta_sys.contains_key(&format!("{RUSTFS_INTERNAL_PREFIX}{excluded_suffix}")));
        assert!(!meta_sys.contains_key(&format!("{MINIO_INTERNAL_PREFIX}{excluded_suffix}")));
    }

    #[test]
    fn persist_target_delete_marker_versions_preserves_existing_targets_on_empty_update() {
        let stale_suffix = format!("{SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX}arn:rustfs:replication::target:stale");
        let mut meta_sys = HashMap::from([
            (format!("{RUSTFS_INTERNAL_PREFIX}{stale_suffix}"), b"stale-rustfs".to_vec()),
            (format!("{MINIO_INTERNAL_PREFIX}{stale_suffix}"), b"stale-minio".to_vec()),
            ("unrelated".to_string(), b"kept".to_vec()),
        ]);

        persist_target_delete_marker_versions(&mut meta_sys, &HashMap::new(), &HashMap::new());

        assert_eq!(
            meta_sys,
            HashMap::from([
                (format!("{RUSTFS_INTERNAL_PREFIX}{stale_suffix}"), b"stale-rustfs".to_vec()),
                (format!("{MINIO_INTERNAL_PREFIX}{stale_suffix}"), b"stale-minio".to_vec()),
                ("unrelated".to_string(), b"kept".to_vec()),
            ])
        );
    }

    #[test]
    fn persist_target_delete_marker_versions_reads_rpc_transport_metadata() {
        let arn = "arn:rustfs:replication::target:remote";
        let version_id = "opaque-remote-version";
        let suffix = format!("{SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX}{arn}");
        let mut transport_metadata = HashMap::new();
        rustfs_utils::http::insert_str(&mut transport_metadata, &suffix, version_id.to_string());
        let mut meta_sys = HashMap::new();

        persist_target_delete_marker_versions(&mut meta_sys, &HashMap::new(), &transport_metadata);

        assert_eq!(
            meta_sys.get(&format!("{RUSTFS_INTERNAL_PREFIX}{suffix}")).map(Vec::as_slice),
            Some(version_id.as_bytes())
        );
        assert_eq!(
            meta_sys.get(&format!("{MINIO_INTERNAL_PREFIX}{suffix}")).map(Vec::as_slice),
            Some(version_id.as_bytes())
        );
    }

    #[test]
    fn persist_reset_statuses_normalizes_to_dual_prefixed_keys() {
        let arn = "arn:rustfs:replication::target:bucket";
        let ts = "2026-06-30T00:00:00Z;reset-1";
        let suffix = format!("{SUFFIX_REPLICATION_RESET}-{arn}");
        let rustfs_key = format!("{RUSTFS_INTERNAL_PREFIX}{suffix}");
        let minio_key = format!("{MINIO_INTERNAL_PREFIX}{suffix}");

        // Bare-ARN key must be normalized to prefixed keys, never written raw.
        let mut bare = HashMap::new();
        bare.insert(arn.to_string(), ts.to_string());
        let mut meta_sys = HashMap::new();
        persist_reset_statuses(&mut meta_sys, &bare);
        assert_eq!(meta_sys.get(&rustfs_key).map(Vec::as_slice), Some(ts.as_bytes()));
        assert_eq!(meta_sys.get(&minio_key).map(Vec::as_slice), Some(ts.as_bytes()));
        assert!(
            !meta_sys.contains_key(arn),
            "bare ARN key must never be persisted (it is dropped on read)"
        );
        assert_eq!(meta_sys.len(), 2);

        // An already-prefixed key must land on the same canonical dual keys,
        // not gain a second prefix.
        let mut prefixed = HashMap::new();
        prefixed.insert(rustfs_key.clone(), ts.to_string());
        let mut meta_sys2 = HashMap::new();
        persist_reset_statuses(&mut meta_sys2, &prefixed);
        assert_eq!(meta_sys2.get(&rustfs_key).map(Vec::as_slice), Some(ts.as_bytes()));
        assert_eq!(meta_sys2.get(&minio_key).map(Vec::as_slice), Some(ts.as_bytes()));
        assert_eq!(meta_sys2.len(), 2, "must not create a double-prefixed key");
    }

    #[test]
    fn persist_delete_marker_replication_state_keeps_replica_and_target_statuses() {
        let replica_timestamp = OffsetDateTime::UNIX_EPOCH + time::Duration::SECOND;
        let replication_timestamp = replica_timestamp + time::Duration::SECOND;
        let state = ReplicationState {
            replica_status: ReplicationStatusType::Replica,
            replica_timestamp: Some(replica_timestamp),
            replication_status_internal: Some("arn:target=COMPLETED;".to_string()),
            replication_timestamp: Some(replication_timestamp),
            ..Default::default()
        };
        let mut meta_sys = HashMap::new();
        let replica_timestamp_string = replica_timestamp
            .format(&Rfc3339)
            .expect("timestamp should format as RFC3339");
        let replication_timestamp_string = replication_timestamp
            .format(&Rfc3339)
            .expect("timestamp should format as RFC3339");

        persist_delete_marker_replication_state(&mut meta_sys, &state);

        assert_eq!(
            rustfs_utils::http::get_bytes(&meta_sys, SUFFIX_REPLICA_STATUS).as_deref(),
            Some(b"REPLICA".as_slice())
        );
        assert_eq!(
            rustfs_utils::http::get_bytes(&meta_sys, SUFFIX_REPLICA_TIMESTAMP).as_deref(),
            Some(replica_timestamp_string.as_bytes())
        );
        assert_eq!(
            rustfs_utils::http::get_bytes(&meta_sys, SUFFIX_REPLICATION_STATUS).as_deref(),
            Some(b"arn:target=COMPLETED;".as_slice())
        );
        assert_eq!(
            rustfs_utils::http::get_bytes(&meta_sys, SUFFIX_REPLICATION_TIMESTAMP).as_deref(),
            Some(replication_timestamp_string.as_bytes())
        );
    }

    #[test]
    fn persist_delete_marker_replication_timestamp_normalizes_second_offset_to_utc() {
        let timestamp = OffsetDateTime::UNIX_EPOCH.to_offset(time::UtcOffset::from_hms(5, 30, 15).expect("valid offset"));
        assert_eq!(parse_replication_timestamp(&timestamp.to_string()), Some(timestamp));
        let state = ReplicationState {
            replica_status: ReplicationStatusType::Replica,
            replica_timestamp: Some(timestamp),
            replication_status_internal: Some("arn:target=COMPLETED;".to_string()),
            replication_timestamp: Some(timestamp),
            ..Default::default()
        };
        let mut meta_sys = HashMap::new();

        persist_delete_marker_replication_state(&mut meta_sys, &state);

        for suffix in [SUFFIX_REPLICA_TIMESTAMP, SUFFIX_REPLICATION_TIMESTAMP] {
            let persisted = rustfs_utils::http::get_bytes(&meta_sys, suffix).expect("timestamp must be persisted");
            let persisted = std::str::from_utf8(&persisted).expect("timestamp must be UTF-8");
            assert_eq!(parse_replication_timestamp(persisted), Some(timestamp));
            assert_ne!(persisted, OffsetDateTime::UNIX_EPOCH.to_string());
        }
    }

    #[test]
    fn truncated_xlmeta_framing_is_file_corrupt() {
        let buf = FileMeta::default()
            .marshal_msg()
            .expect("serialize metadata without inline data");
        FileMeta::load(&buf).expect("complete metadata must decode");
        for cut in 0..buf.len() {
            assert_eq!(
                FileMeta::load(&buf[..cut]).expect_err("every incomplete metadata frame must fail"),
                Error::FileCorrupt,
                "truncation at byte {cut} must remain repairable"
            );
        }
    }

    #[test]
    fn truncated_xlmeta_index_and_format_reads_are_file_corrupt() {
        let buf = FileMeta::default()
            .marshal_msg()
            .expect("serialize metadata without inline data");
        FileMeta::is_indexed_meta(&buf).expect("complete indexed metadata must decode");
        FileMeta::read_format_versions(&buf).expect("complete format header must decode");
        for cut in 0..buf.len() {
            assert_eq!(
                FileMeta::is_indexed_meta(&buf[..cut]).expect_err("incomplete index must fail"),
                Error::FileCorrupt,
                "index truncation at byte {cut}"
            );
            if cut < buf.len() - 5 {
                assert_eq!(
                    FileMeta::read_format_versions(&buf[..cut]).expect_err("incomplete metadata block must fail"),
                    Error::FileCorrupt,
                    "format truncation at byte {cut}"
                );
            }
        }
        for cut in 0..5 {
            assert_eq!(
                FileMeta::read_bytes_header(&buf[8..8 + cut]).expect_err("incomplete bin32 prefix must fail"),
                Error::FileCorrupt
            );
        }
    }

    #[test]
    fn malformed_xlmeta_framing_is_file_corrupt() {
        let original = FileMeta::default()
            .marshal_msg()
            .expect("serialize metadata without inline data");
        for offset in [8, original.len() - 5] {
            let mut buf = original.clone();
            buf[offset] = 0xc0; // nil cannot encode a bin length or a CRC integer.
            assert_eq!(FileMeta::load(&buf).expect_err("invalid framing marker"), Error::FileCorrupt);
            assert_eq!(
                FileMeta::is_indexed_meta(&buf).expect_err("invalid index framing marker"),
                Error::FileCorrupt
            );
            if offset == 8 {
                assert_eq!(
                    FileMeta::read_format_versions(&buf).expect_err("invalid format framing marker"),
                    Error::FileCorrupt
                );
                assert_eq!(
                    FileMeta::read_bytes_header(&buf[8..]).expect_err("invalid bin framing marker"),
                    Error::FileCorrupt
                );
            }
        }
    }

    #[test]
    fn unsupported_xlmeta_versions_are_not_classified_as_corruption() {
        let mut buf = FileMeta::default().marshal_msg().expect("serialize metadata");
        buf[4..6].copy_from_slice(&(XL_FILE_VERSION_MAJOR + 1).to_le_bytes());
        assert_ne!(FileMeta::load(&buf).expect_err("unsupported file version"), Error::FileCorrupt);
        for (header_ver, meta_ver) in [
            (XL_HEADER_VERSION + 1, XL_META_VERSION),
            (XL_HEADER_VERSION, XL_META_VERSION + 1),
        ] {
            let mut meta = Vec::new();
            rmp::encode::write_uint(&mut meta, u64::from(header_ver)).expect("write header version");
            rmp::encode::write_uint(&mut meta, u64::from(meta_ver)).expect("write metadata version");
            rmp::encode::write_uint(&mut meta, 0).expect("write empty version count");
            let buf = build_xl_buffer(&meta);
            assert_ne!(FileMeta::load(&buf).expect_err("unsupported schema version"), Error::FileCorrupt);
        }
    }

    /// Regression test for rustfs/rustfs#2715: a corrupted version count in
    /// xl.meta must yield a decode error instead of sizing a huge allocation
    /// from the bogus count (which aborts the whole process).
    /// A CRC mismatch means the bytes on disk are not the bytes that were
    /// written — bitrot. It must surface as `Error::FileCorrupt` specifically:
    /// that variant converts to `DiskError::FileCorrupt`, which is the only
    /// corruption signal `should_heal_object_on_disk` recognises. As a generic
    /// error the drive is skipped, the heal reports success, and the damaged
    /// `xl.meta` is never rewritten.
    #[test]
    fn test_unmarshal_reports_file_corrupt_on_crc_mismatch() {
        let mut fm = FileMeta::default();
        let mut buf = fm.marshal_msg().expect("serialize default FileMeta");
        // Flip one byte inside the meta blob: past the 8-byte XL2 header and
        // the 5-byte bin32 length prefix, before the CRC trailer.
        let idx = 8 + 5;
        buf[idx] ^= 0xff;
        let err = fm.unmarshal_msg(&buf).expect_err("corrupted meta must fail to decode");
        assert_eq!(err, Error::FileCorrupt, "CRC mismatch must classify as FileCorrupt, got: {err}");
    }

    #[test]
    fn test_is_indexed_meta_reports_file_corrupt_on_crc_mismatch() {
        let fm = FileMeta::default();
        let mut buf = fm.marshal_msg().expect("serialize default FileMeta");
        let idx = 8 + 5;
        buf[idx] ^= 0xff;

        let err = FileMeta::is_indexed_meta(&buf).expect_err("corrupted indexed metadata must fail");
        assert_eq!(err, Error::FileCorrupt, "indexed CRC mismatch must classify as FileCorrupt, got: {err}");
    }

    #[test]
    fn test_unmarshal_rejects_absurd_version_count() {
        let mut meta = Vec::new();
        rmp::encode::write_uint(&mut meta, XL_HEADER_VERSION as u64).unwrap();
        rmp::encode::write_uint(&mut meta, XL_META_VERSION as u64).unwrap();
        // Claim ~10^15 versions with no version data behind it.
        rmp::encode::write_sint(&mut meta, 1i64 << 50).unwrap();

        let buf = build_xl_buffer(&meta);
        let mut fm = FileMeta::default();
        let err = fm.unmarshal_msg(&buf).expect_err("absurd version count must fail to decode");
        assert!(err.to_string().contains("version count"), "unexpected error: {err}");
    }

    /// Regression test for rustfs/rustfs#2715: a corrupted per-version binary
    /// length must yield a decode error instead of a giant allocation.
    #[test]
    fn test_unmarshal_rejects_absurd_version_header_length() {
        let mut meta = Vec::new();
        rmp::encode::write_uint(&mut meta, XL_HEADER_VERSION as u64).unwrap();
        rmp::encode::write_uint(&mut meta, XL_META_VERSION as u64).unwrap();
        rmp::encode::write_sint(&mut meta, 1).unwrap();
        // One version whose header claims to be u32::MAX bytes long.
        meta.push(0xc6); // bin32
        meta.extend_from_slice(&u32::MAX.to_be_bytes());

        let buf = build_xl_buffer(&meta);
        let mut fm = FileMeta::default();
        let err = fm
            .unmarshal_msg(&buf)
            .expect_err("absurd version header length must fail to decode");
        assert!(err.to_string().contains("version header length"), "unexpected error: {err}");
    }

    #[test]
    fn test_new_file_meta() {
        let mut fm = FileMeta::new();

        let (m, n) = (3, 2);

        for i in 0..5 {
            let mut fi = FileInfo::new(i.to_string().as_str(), m, n);
            fi.mod_time = Some(OffsetDateTime::now_utc());

            fm.add_version(fi).unwrap();
        }

        let buff = fm.marshal_msg().unwrap();

        let mut newfm = FileMeta::default();
        newfm.unmarshal_msg(&buff).unwrap();

        assert_eq!(fm, newfm)
    }

    /// Regression for rustfs/backlog#1302: `delete_version` with
    /// `expire_restored` must only strip the `x-amz-restore` headers and hand
    /// back the local data dir for cleanup; the version itself must survive
    /// with its transition metadata (and thus the remote tier copy) intact.
    #[test]
    fn test_delete_version_expire_restored_keeps_transitioned_version() {
        use crate::metadata_keys::{RESTORE, RESTORE_EXPIRY_DAYS, RESTORE_REQUEST_DATE};

        let mut fm = FileMeta::new();
        let vid = Uuid::new_v4();
        let data_dir = Uuid::new_v4();

        let mut fi = FileInfo::new("restored.bin", 3, 2);
        fi.version_id = Some(vid);
        fi.data_dir = Some(data_dir);
        fi.mod_time = Some(OffsetDateTime::now_utc());
        fi.transition_status = TRANSITION_COMPLETE.to_string();
        fi.transitioned_objname = "remote/obj".to_string();
        fi.transition_tier = "COLDTIER".to_string();
        fi.metadata.insert(
            RESTORE.to_string(),
            "ongoing-request=\"false\", expiry-date=\"Fri, 17 Jul 2026 00:00:00 GMT\"".to_string(),
        );
        fi.metadata.insert(RESTORE_EXPIRY_DAYS.to_string(), "1".to_string());
        fi.metadata
            .insert(RESTORE_REQUEST_DATE.to_string(), "Thu, 16 Jul 2026 00:00:00 GMT".to_string());
        rustfs_utils::http::insert_str(&mut fi.metadata, SUFFIX_RESTORE_OPERATION_ID, Uuid::from_u128(1).to_string());
        rustfs_utils::http::insert_str(
            &mut fi.metadata,
            SUFFIX_RESTORE_WORKER_LOCK,
            rustfs_utils::http::RESTORE_WORKER_LOCK_PROTOCOL_V1.to_string(),
        );
        fm.add_version(fi).unwrap();

        let expire_fi = FileInfo {
            name: "restored.bin".to_string(),
            version_id: Some(vid),
            expire_restored: true,
            ..Default::default()
        };
        let freed = fm.delete_version(&expire_fi).unwrap();
        assert_eq!(freed, Some(data_dir), "the restored copy's local data dir must be handed back");

        assert_eq!(fm.versions.len(), 1, "the version must survive restored-copy expiry");
        let after = fm.into_fileinfo("vol", "restored.bin", "", false, false, true).unwrap();
        assert!(!after.metadata.contains_key(RESTORE), "x-amz-restore must be stripped");
        assert!(!after.metadata.contains_key(RESTORE_EXPIRY_DAYS));
        assert!(!after.metadata.contains_key(RESTORE_REQUEST_DATE));
        assert!(
            rustfs_utils::http::get_str(&after.metadata, SUFFIX_RESTORE_OPERATION_ID).is_none(),
            "expired restore must not retain its operation generation"
        );
        assert!(
            rustfs_utils::http::get_str(&after.metadata, SUFFIX_RESTORE_WORKER_LOCK).is_none(),
            "expired restore must not retain the worker-liveness protocol marker"
        );
        assert_eq!(after.transition_status, TRANSITION_COMPLETE);
        assert_eq!(after.transitioned_objname, "remote/obj");
        assert_eq!(after.transition_tier, "COLDTIER");
    }

    #[test]
    fn test_get_idx_out_of_bounds_returns_error_without_panic() {
        let mut fm = FileMeta::new();

        let (m, n) = (3, 2);
        for i in 0..3 {
            let mut fi = FileInfo::new(i.to_string().as_str(), m, n);
            fi.version_id = Some(Uuid::from_u128(i + 1));
            fi.mod_time = Some(OffsetDateTime::now_utc());
            fm.add_version(fi).unwrap();
        }

        let len = fm.versions.len();
        assert_eq!(len, 3);

        // In-bounds indices resolve.
        assert!(fm.get_idx(0).is_ok());
        assert!(fm.get_idx(len - 1).is_ok());

        // idx == len must return FileNotFound rather than panic on the
        // out-of-bounds slice index, matching set_idx's guard.
        match fm.get_idx(len) {
            Err(Error::FileNotFound) => {}
            other => panic!("expected FileNotFound for idx == len, got {other:?}"),
        }
    }

    #[test]
    fn test_marshal_metaobject() {
        let obj = MetaObject {
            data_dir: Some(Uuid::new_v4()),
            ..Default::default()
        };

        // println!("obj {:?}", &obj);

        let encoded = obj.marshal_msg().unwrap();

        let mut obj2 = MetaObject::default();
        obj2.unmarshal_msg(&encoded).unwrap();

        // println!("obj2 {:?}", &obj2);

        assert_eq!(obj, obj2);
        assert_eq!(obj.data_dir, obj2.data_dir);
    }

    #[test]
    fn test_marshal_metadeletemarker() {
        let obj = MetaDeleteMarker {
            version_id: Some(Uuid::new_v4()),
            ..Default::default()
        };

        // println!("obj {:?}", &obj);

        let encoded = obj.marshal_msg().unwrap();

        let mut obj2 = MetaDeleteMarker::default();
        obj2.unmarshal_msg(&encoded).unwrap();

        // println!("obj2 {:?}", &obj2);

        assert_eq!(obj, obj2);
        assert_eq!(obj.version_id, obj2.version_id);
    }

    #[test]
    fn test_marshal_metaversion() {
        let mut fi = FileInfo::new("tset", 3, 2);
        fi.version_id = Some(Uuid::new_v4());
        fi.mod_time = Some(OffsetDateTime::from_unix_timestamp(OffsetDateTime::now_utc().unix_timestamp()).unwrap());
        let mut obj = FileMetaVersion::from(fi);
        obj.write_version = 110;

        // println!("obj {:?}", &obj);

        let encoded = obj.marshal_msg().unwrap();

        let mut obj2 = FileMetaVersion::default();
        obj2.unmarshal_msg(&encoded).unwrap();

        // println!("obj2 {:?}", &obj2);

        // Timestamp inconsistency
        assert_eq!(obj, obj2);
        assert_eq!(obj.get_version_id(), obj2.get_version_id());
        assert_eq!(obj.write_version, obj2.write_version);
        assert_eq!(obj.write_version, 110);
    }

    #[test]
    fn test_marshal_metaversionheader() {
        let mut obj = FileMetaVersionHeader::default();
        let vid = Some(Uuid::new_v4());
        obj.version_id = vid;

        let encoded = obj.marshal_msg().unwrap();

        let mut obj2 = FileMetaVersionHeader::default();
        obj2.unmarshal_msg(&encoded).unwrap();

        // Timestamp inconsistency
        assert_eq!(obj, obj2);
        assert_eq!(obj.version_id, obj2.version_id);
        assert_eq!(obj.version_id, vid);
    }

    #[test]
    fn test_real_xlmeta_compatibility() {
        // Test compatibility with real xl.meta formats
        let data = create_real_xlmeta().expect("Failed to create realistic test data");

        // Verify the file header
        assert_eq!(&data[0..4], b"XL2 ", "File header should be 'XL2 '");
        assert_eq!(&data[4..8], &[1, 0, 3, 0], "Version number should be 1.3.0");

        // Parse metadata
        let fm = FileMeta::load(&data).expect("Failed to parse realistic data");

        // Verify basic properties
        assert_eq!(fm.meta_ver, XL_META_VERSION);
        assert_eq!(
            fm.versions.len(),
            3,
            "Should have three versions (one object, one delete marker, one Legacy)"
        );

        // Verify version types
        let mut object_count = 0;
        let mut delete_count = 0;
        let mut legacy_count = 0;

        for version in &fm.versions {
            match version.header.version_type {
                VersionType::Object => object_count += 1,
                VersionType::Delete => delete_count += 1,
                VersionType::Legacy => legacy_count += 1,
                VersionType::Invalid => panic!("No invalid versions should be present"),
            }
        }

        assert_eq!(object_count, 1, "Should have one object version");
        assert_eq!(delete_count, 1, "Should have one delete marker");
        assert_eq!(legacy_count, 1, "Should have one Legacy version");

        // Verify compatibility
        assert!(fm.is_compatible_with_meta(), "Should be compatible with the xl format");

        // Verify integrity
        fm.validate_integrity().expect("Integrity validation failed");

        // Verify version statistics
        let stats = fm.get_version_stats();
        assert_eq!(stats.total_versions, 3);
        assert_eq!(stats.object_versions, 1);
        assert_eq!(stats.delete_markers, 1);
        assert_eq!(stats.invalid_versions, 1); // Legacy is counted as invalid
    }

    #[test]
    fn test_issue_2288_legacy_xlmeta_compatibility() {
        let data = create_issue_2288_legacy_xlmeta().expect("Failed to load issue #2288 fixture");
        let (major, minor, header_ver, meta_ver) = FileMeta::read_format_versions(&data).unwrap();
        assert_eq!((major, minor, header_ver, meta_ver), (1, 3, 2, 1));

        let fm = FileMeta::load(&data).expect("Failed to parse legacy issue #2288 xl.meta");
        assert_eq!(fm.meta_ver, 1);
        assert_eq!(fm.versions.len(), 1);
        assert_eq!(fm.versions[0].header.version_type, VersionType::Object);
        assert_eq!(fm.versions[0].header.signature, [0x96, 0x33, 0x4c, 0x78]);
        assert_eq!(fm.versions[0].header.ec_n, 0);
        assert_eq!(fm.versions[0].header.ec_m, 0);

        let fi = fm
            .into_fileinfo("viscom", "test.txt", "", true, false, true)
            .expect("Failed to extract file info from legacy issue #2288 xl.meta");
        assert_eq!(fi.size, 35);
        assert_eq!(fi.num_versions, 1);
        assert!(fi.is_latest);
    }

    #[test]
    fn test_issue_2265_legacy_meta_v2_object_compatibility() {
        let data = create_issue_2265_legacy_meta_v2_object_xlmeta().expect("Failed to load issue #2265 object fixture");
        let (major, minor, header_ver, meta_ver) = FileMeta::read_format_versions(&data).unwrap();
        assert_eq!((major, minor, header_ver, meta_ver), (1, 3, 3, 2));

        let fm = FileMeta::load(&data).expect("Failed to parse legacy issue #2265 object xl.meta");
        assert_eq!(fm.meta_ver, 2);
        assert_eq!(fm.versions.len(), 1);
        assert_eq!(fm.versions[0].header.version_type, VersionType::Object);
        assert_eq!(fm.versions[0].header.ec_n, 0);
        assert_eq!(fm.versions[0].header.ec_m, 1);

        let fi = fm
            .into_fileinfo("bucket", ".metadata.bin", "", true, false, true)
            .expect("Failed to extract file info from legacy issue #2265 object xl.meta");
        assert_eq!(fi.size, 707);
        assert_eq!(fi.num_versions, 1);
        assert_eq!(fi.metadata.get("etag").map(String::as_str), Some("4359404618e32a0bd8944e9ff6802f53"));
        assert_eq!(
            fi.data_dir.map(|id| id.to_string()).as_deref(),
            Some("04bee19a-6eea-40c4-96fd-1f39257fcbdc")
        );
        assert!(fi.uses_legacy_checksum);
        assert!(fi.is_latest);
    }

    #[test]
    fn test_issue_2265_legacy_meta_v2_config_compatibility() {
        let data = create_issue_2265_legacy_meta_v2_config_xlmeta().expect("Failed to load issue #2265 config fixture");
        let (major, minor, header_ver, meta_ver) = FileMeta::read_format_versions(&data).unwrap();
        assert_eq!((major, minor, header_ver, meta_ver), (1, 3, 3, 2));

        let fm = FileMeta::load(&data).expect("Failed to parse legacy issue #2265 config xl.meta");
        assert_eq!(fm.meta_ver, 2);
        assert_eq!(fm.versions.len(), 1);
        assert_eq!(fm.versions[0].header.version_type, VersionType::Object);

        let fi = fm
            .into_fileinfo("config", "format.json", "", true, false, true)
            .expect("Failed to extract file info from legacy issue #2265 config xl.meta");
        assert_eq!(fi.size, 74);
        assert_eq!(fi.num_versions, 1);
        assert_eq!(fi.metadata.get("etag").map(String::as_str), Some("12b368ce52e496e61ac47b366c7c3b66"));
        assert_eq!(
            fi.data_dir.map(|id| id.to_string()).as_deref(),
            Some("fba8e4c3-3f42-4242-94e0-5ab84b83ae97")
        );
        assert!(fi.uses_legacy_checksum);
        assert!(fi.is_latest);
    }

    #[test]
    fn test_issue_2434_legacy_meta_v2_pool_compatibility() {
        let data = create_issue_2434_legacy_meta_v2_pool_xlmeta().expect("Failed to load issue #2434 pool fixture");
        let (major, minor, header_ver, meta_ver) = FileMeta::read_format_versions(&data).unwrap();
        assert_eq!((major, minor, header_ver, meta_ver), (1, 3, 3, 2));

        let fm = FileMeta::load(&data).expect("Failed to parse legacy issue #2434 pool xl.meta");
        assert_eq!(fm.meta_ver, 2);
        assert_eq!(fm.versions.len(), 1);
        assert_eq!(fm.versions[0].header.version_type, VersionType::Object);

        let fi = fm
            .into_fileinfo(".rustfs.sys", "pool.bin", "", true, false, true)
            .expect("Failed to extract file info from legacy issue #2434 pool xl.meta");
        assert_eq!(fi.size, 48);
        assert_eq!(fi.num_versions, 1);
        assert_eq!(fi.version_id, None);
        assert_eq!(fi.metadata.get("etag").map(String::as_str), Some("8d270d7a184cfa30cc0bf09ea74fd964"));
        assert_eq!(
            fi.data_dir.map(|id| id.to_string()).as_deref(),
            Some("2bcefaca-44dd-4f01-a79e-63eeb0dda396")
        );
        assert!(fi.uses_legacy_checksum);
        assert!(fi.is_latest);

        let selected = fm
            .into_fileinfo(".rustfs.sys", "pool.bin", &Uuid::nil().to_string(), true, false, true)
            .expect("nil selector should match the legacy null version");
        assert_eq!(selected.version_id, None);
    }

    #[test]
    fn nil_version_selector_matches_only_the_null_slot() {
        let mod_time = OffsetDateTime::from_unix_timestamp(1_700_000_000).expect("valid test timestamp");
        let version_id = Uuid::new_v4();
        let versioned = version_for_ordering(VersionType::Object, version_id, mod_time + time::Duration::seconds(1), 2);
        let mut null = version_for_ordering(VersionType::Object, Uuid::nil(), mod_time, 1);
        null.object
            .as_mut()
            .expect("ordering helper should construct an object")
            .version_id = None;

        let mut fm = FileMeta::new();
        fm.add_version_filemata(versioned.clone()).expect("add versioned object");
        fm.add_version_filemata(null).expect("add legacy null object");

        let selected_null = fm
            .into_fileinfo("bucket", "object", &Uuid::nil().to_string(), false, false, true)
            .expect("nil selector should match only the legacy null slot");
        assert_eq!(selected_null.version_id, None);

        let selected_versioned = fm
            .into_fileinfo("bucket", "object", &version_id.to_string(), false, false, true)
            .expect("non-nil selector should still match its exact version");
        assert_eq!(selected_versioned.version_id, Some(version_id));

        let mut versioned_only = FileMeta::new();
        versioned_only
            .add_version_filemata(versioned)
            .expect("add versioned object without a null slot");
        assert!(
            versioned_only
                .into_fileinfo("bucket", "object", &Uuid::nil().to_string(), false, false, true)
                .is_err(),
            "nil selector must not fall back to a non-nil latest version"
        );
    }

    #[test]
    fn test_legacy_v1_object_xlmeta_compatibility() {
        let data = create_legacy_v1_object_xlmeta().expect("Failed to create legacy v1 object xl.meta");
        let (major, minor, header_ver, meta_ver) = FileMeta::read_format_versions(&data).unwrap();
        assert_eq!((major, minor, header_ver, meta_ver), (1, 3, 1, 1));

        let fm = FileMeta::load(&data).expect("Failed to parse legacy v1 object xl.meta");
        assert_eq!(fm.meta_ver, 1);
        assert_eq!(fm.versions.len(), 1);
        assert_eq!(fm.versions[0].header.version_type, VersionType::Legacy);
        assert_eq!(fm.versions[0].header.ec_n, 0);
        assert_eq!(fm.versions[0].header.ec_m, 0);

        let fi = fm
            .into_fileinfo("bucket", "hello.txt", "", true, false, true)
            .expect("Failed to extract file info from legacy v1 object xl.meta");
        assert_eq!(fi.size, 11);
        assert_eq!(fi.num_versions, 1);
        assert_eq!(fi.mode, Some(0o644));
        assert_eq!(fi.parts.len(), 1);
        assert_eq!(fi.parts[0].etag, "etag-1");
        assert_eq!(fi.parts[0].size, 11);
        assert_eq!(fi.erasure.data_blocks, 4);
        assert_eq!(fi.erasure.parity_blocks, 2);
        assert_eq!(fi.metadata.get("content-type").map(String::as_str), Some("text/plain"));
        assert!(fi.is_latest);
    }

    #[test]
    fn test_complex_xlmeta_handling() {
        // Test complex xl.meta files with many versions
        let data = create_complex_xlmeta().expect("Failed to create complex test data");
        let fm = FileMeta::load(&data).expect("Failed to parse complex data");

        // Verify version count
        assert!(fm.versions.len() >= 10, "Should have at least 10 versions");

        // Verify version ordering
        assert!(fm.is_sorted_by_mod_time(), "Versions should be sorted by modification time");

        // Verify presence of different version types
        let stats = fm.get_version_stats();
        assert!(stats.object_versions > 0, "Should include object versions");
        assert!(stats.delete_markers > 0, "Should include delete markers");

        // Test version merge functionality
        let merged = merge_file_meta_versions(1, false, 0, std::slice::from_ref(&fm.versions));
        assert!(!merged.is_empty(), "Merged output should contain versions");
    }

    #[test]
    fn test_inline_data_handling() {
        // Test inline data handling
        let data = create_xlmeta_with_inline_data().expect("Failed to create inline test data");
        let fm = FileMeta::load(&data).expect("Failed to parse inline data");

        assert_eq!(fm.versions.len(), 1, "Should have one version");
        assert!(!fm.data.as_slice().is_empty(), "Should contain inline data");

        // Verify inline data contents
        let inline_data = fm.data.as_slice();
        assert!(!inline_data.is_empty(), "Inline data should not be empty");
    }

    #[test]
    fn test_into_fileinfo_reads_legacy_nil_uuid_inline_key() {
        let mut fm = FileMeta::new();
        let mut fi = FileInfo::new("test", 2, 1);
        fi.mod_time = Some(OffsetDateTime::now_utc());
        fi.data = Some(Bytes::from_static(b"legacy-inline"));
        fi.set_inline_data();
        fm.add_version(fi).unwrap();

        let current_key = data_key_for_version(Some(Uuid::nil()));
        let legacy_key = legacy_data_key_for_version(Some(Uuid::nil())).unwrap();
        let payload = fm.data.find(current_key.as_str()).unwrap().unwrap();

        fm.data.remove_key(current_key.as_str()).unwrap();
        fm.data.replace(legacy_key.as_str(), payload.clone()).unwrap();

        let restored = fm.into_fileinfo("bucket", "test", "", true, false, true).unwrap();

        assert!(restored.inline_data());
        assert_eq!(restored.data, Some(Bytes::from(payload)));
    }

    #[test]
    fn test_error_handling_and_recovery() {
        // Test error handling and recovery
        let corrupted_data = create_corrupted_xlmeta();
        let result = FileMeta::load(&corrupted_data);
        assert!(result.is_err(), "Corrupted data should fail to parse");

        // Test handling of empty files
        let empty_data = create_empty_xlmeta().expect("Failed to create empty test data");
        let fm = FileMeta::load(&empty_data).expect("Failed to parse empty data");
        assert_eq!(fm.versions.len(), 0, "An empty file should have no versions");
    }

    #[test]
    fn test_version_type_legacy_support() {
        // Validate support for Legacy version types
        assert_eq!(VersionType::Legacy.to_u8(), 3);
        assert_eq!(VersionType::from_u8(3), VersionType::Legacy);
        assert!(VersionType::Legacy.valid(), "Legacy type should be valid");

        // Exercise creation and handling of Legacy versions
        let legacy_version = FileMetaVersion {
            version_type: VersionType::Legacy,
            legacy_object: None,
            object: None,
            delete_marker: None,
            write_version: 1,
            uses_legacy_checksum: false,
        };

        assert!(legacy_version.is_legacy(), "Should be recognized as a Legacy version");
    }

    #[test]
    fn test_signature_calculation() {
        // Test signature calculation
        let data = create_real_xlmeta().expect("Failed to create test data");
        let fm = FileMeta::load(&data).expect("Parsing failed");

        for version in &fm.versions {
            let signature = version.header.get_signature();
            assert_eq!(signature.len(), 4, "Signature should be 4 bytes");

            // Verify signature consistency for identical versions
            let signature2 = version.header.get_signature();
            assert_eq!(signature, signature2, "Identical versions should produce identical signatures");
        }
    }

    #[test]
    fn test_metadata_validation() {
        // Test metadata validation
        let data = create_real_xlmeta().expect("Failed to create test data");
        let fm = FileMeta::load(&data).expect("Parsing failed");

        // Test integrity validation
        fm.validate_integrity().expect("Integrity validation should succeed");

        // Test compatibility checks
        assert!(fm.is_compatible_with_meta(), "Should be compatible with the xl format");

        // Test version ordering checks
        assert!(fm.is_sorted_by_mod_time(), "Versions should be time-ordered");
    }

    #[test]
    fn test_round_trip_serialization() {
        // Test round-trip serialization consistency
        let original_data = create_real_xlmeta().expect("Failed to create original test data");
        let fm = FileMeta::load(&original_data).expect("Failed to parse original data");

        // Serialize again
        let serialized_data = fm.marshal_msg().expect("Re-serialization failed");

        // Parse again
        let fm2 = FileMeta::load(&serialized_data).expect("Failed to parse serialized data");

        // Verify consistency
        assert_eq!(fm.versions.len(), fm2.versions.len(), "Version counts should match");
        assert_eq!(fm.meta_ver, fm2.meta_ver, "Metadata versions should match");

        // Verify version content consistency
        for (v1, v2) in fm.versions.iter().zip(fm2.versions.iter()) {
            assert_eq!(v1.header.version_type, v2.header.version_type, "Version types should match");
            assert_eq!(v1.header.version_id, v2.header.version_id, "Version IDs should match");
        }
    }

    proptest! {
        #[test]
        fn filemeta_load_never_panics_on_arbitrary_bytes(input in vec(any::<u8>(), 0..=4096)) {
            let result = std::panic::catch_unwind(|| FileMeta::load(&input));
            prop_assert!(result.is_ok(), "FileMeta::load panicked for arbitrary input");
        }
    }

    // ------------------------------------------------------------------
    // backlog#900: CRC-valid but semantically corrupt part arrays must
    // produce Err(FileCorrupt), never panic.
    // ------------------------------------------------------------------

    fn valid_object_version(version_id: Uuid, part_sizes: Vec<usize>) -> FileMetaVersion {
        FileMetaVersion {
            version_type: VersionType::Object,
            object: Some(MetaObject {
                version_id: Some(version_id),
                erasure_algorithm: ErasureAlgo::ReedSolomon,
                erasure_m: 2,
                erasure_n: 2,
                erasure_block_size: 1 << 20,
                bitrot_checksum_algo: ChecksumAlgo::HighwayHash,
                part_numbers: vec![1, 2],
                part_sizes, // caller-injected (short = corrupt)
                part_actual_sizes: vec![10, 20],
                mod_time: Some(OffsetDateTime::now_utc()),
                ..Default::default()
            }),
            ..Default::default()
        }
    }

    #[test]
    fn crc_valid_but_part_arrays_corrupt_into_fileinfo_errors_not_panics() {
        // A short part_sizes Object version round-trips through the real codec: the CRC is
        // valid and load succeeds, but into_fileinfo(all_parts) hits the length guard and
        // returns Err(FileCorrupt) rather than panicking.
        let mut fm = FileMeta::new();
        fm.add_version_filemata(valid_object_version(Uuid::new_v4(), vec![10]))
            .expect("add corrupt-parts version");

        let encoded = fm.marshal_msg().expect("marshal recomputes a valid CRC");
        let loaded = FileMeta::load(&encoded).expect("CRC-valid meta must load (lazy, parts not decoded yet)");

        let caught = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
            loaded.into_fileinfo("bucket", "key", "", true, false, true)
        }));
        let inner = caught.expect("into_fileinfo must not panic on CRC-valid but semantically corrupt parts");
        assert!(matches!(inner, Err(Error::FileCorrupt)), "expected FileCorrupt");
    }

    proptest! {
        #[test]
        fn into_fileinfo_never_panics_on_arbitrary_loaded_meta(input in vec(any::<u8>(), 0..=4096)) {
            // Complements filemeta_load_never_panics_on_arbitrary_bytes: for every FileMeta
            // that loads, into_fileinfo(all_parts=true) must not panic (Ok or Err).
            if let Ok(fm) = FileMeta::load(&input) {
                let caught = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
                    fm.into_fileinfo("b", "k", "", true, false, true)
                }));
                prop_assert!(caught.is_ok(), "into_fileinfo panicked on loaded meta");
            }
        }
    }

    #[test]
    fn into_file_info_versions_fails_whole_listing_on_one_corrupt_version() {
        // One corrupt version among healthy ones fails the whole listing (into_file_info_versions
        // uses `?`, so no partial results). This is the established failure semantics of the
        // merge-first exact-versions path (backlog#900 §3.3), strictly better than a panic.
        let healthy_id = Uuid::new_v4();
        let corrupt_id = Uuid::new_v4();
        let mut fm = FileMeta::new();
        fm.add_version_filemata(valid_object_version(healthy_id, vec![10, 20]))
            .expect("healthy");
        fm.add_version_filemata(valid_object_version(corrupt_id, vec![10]))
            .expect("corrupt"); // short part_sizes

        let fm = FileMeta::load(&fm.marshal_msg().expect("marshal")).expect("load");

        let caught = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| fm.into_file_info_versions("bucket", "key", true)));
        let inner = caught.expect("must not panic");
        assert!(matches!(inner, Err(Error::FileCorrupt)), "whole-listing must fail with FileCorrupt");
    }

    #[test]
    fn test_performance_with_large_metadata() {
        // Test performance with large metadata files
        use std::time::Instant;

        let start = Instant::now();
        let data = create_complex_xlmeta().expect("Failed to create large test data");
        let creation_time = start.elapsed();

        let start = Instant::now();
        let fm = FileMeta::load(&data).expect("Failed to parse large data");
        let parsing_time = start.elapsed();

        let start = Instant::now();
        let _serialized = fm.marshal_msg().expect("Serialization failed");
        let serialization_time = start.elapsed();

        println!("Performance results:");
        println!("  Creation time: {creation_time:?}");
        println!("  Parsing time: {parsing_time:?}");
        println!("  Serialization time: {serialization_time:?}");

        // Basic performance assertions (adjust as needed for real workloads)
        assert!(parsing_time.as_millis() < 100, "Parsing time should be under 100 ms");
        assert!(serialization_time.as_millis() < 100, "Serialization time should be under 100 ms");
    }

    #[test]
    fn test_edge_cases() {
        // Test edge cases

        // 1. Test empty version IDs
        let mut fm = FileMeta::new();
        let version = FileMetaVersion {
            version_type: VersionType::Object,
            legacy_object: None,
            object: Some(MetaObject {
                version_id: None, // Empty version ID
                data_dir: None,
                erasure_algorithm: crate::fileinfo::ErasureAlgo::ReedSolomon,
                erasure_m: 1,
                erasure_n: 1,
                erasure_block_size: 64 * 1024,
                erasure_index: 0,
                erasure_dist: vec![0],
                bitrot_checksum_algo: ChecksumAlgo::HighwayHash,
                part_numbers: vec![1],
                part_etags: Vec::new(),
                part_sizes: vec![0],
                part_actual_sizes: Vec::new(),
                part_indices: Vec::new(),
                size: 0,
                mod_time: None,
                meta_sys: HashMap::new(),
                meta_user: HashMap::new(),
            }),
            delete_marker: None,
            write_version: 1,
            uses_legacy_checksum: false,
        };

        let shallow_version = FileMetaShallowVersion::try_from(version).expect("Conversion failed");
        fm.versions.push(shallow_version);

        // Should support serialization and deserialization
        let data = fm.marshal_msg().expect("Serialization failed");
        let fm2 = FileMeta::load(&data).expect("Parsing failed");
        assert_eq!(fm2.versions.len(), 1);

        // 2. Test extremely large file sizes
        let large_object = MetaObject {
            size: i64::MAX,
            part_sizes: vec![usize::MAX],
            ..Default::default()
        };

        // Should handle very large numbers
        assert_eq!(large_object.size, i64::MAX);
    }

    #[tokio::test]
    async fn test_concurrent_operations() {
        // Test thread safety for concurrent operations
        use std::sync::Arc;
        use std::sync::Mutex;

        let fm = Arc::new(Mutex::new(FileMeta::new()));
        let mut handles = vec![];

        // Add versions concurrently
        for i in 0..10 {
            let fm_clone: Arc<Mutex<FileMeta>> = Arc::clone(&fm);
            let handle = tokio::spawn(async move {
                let mut fi = crate::fileinfo::FileInfo::new(&format!("test-{i}"), 2, 1);
                fi.version_id = Some(Uuid::new_v4());
                fi.mod_time = Some(OffsetDateTime::now_utc());

                let mut fm_guard = fm_clone.lock().unwrap();
                fm_guard.add_version(fi).unwrap();
            });
            handles.push(handle);
        }

        // Wait for all tasks to finish
        for handle in handles {
            handle.await.unwrap();
        }

        let fm_guard = fm.lock().unwrap();
        assert_eq!(fm_guard.versions.len(), 10);
    }

    #[test]
    fn test_memory_efficiency() {
        // Test memory efficiency
        use std::mem;

        // Measure memory usage for empty structs
        let empty_fm = FileMeta::new();
        let empty_size = mem::size_of_val(&empty_fm);
        println!("Empty FileMeta size: {empty_size} bytes");

        // Measure memory usage with many versions
        let mut large_fm = FileMeta::new();
        for i in 0..100 {
            let mut fi = crate::fileinfo::FileInfo::new(&format!("test-{i}"), 2, 1);
            fi.version_id = Some(Uuid::new_v4());
            fi.mod_time = Some(OffsetDateTime::now_utc());
            large_fm.add_version(fi).unwrap();
        }

        let large_size = mem::size_of_val(&large_fm);
        println!("Large FileMeta size: {large_size} bytes");

        // Ensure memory usage is reasonable (size_of_val covers only stack allocations)
        // For structs containing Vec, size_of_val may match because capacity lives on the heap
        println!("Number of versions: {}", large_fm.versions.len());
        assert!(!large_fm.versions.is_empty(), "Should contain version data");
    }

    #[test]
    fn test_version_ordering_edge_cases() {
        // Test boundary cases for version ordering
        let mut fm = FileMeta::new();

        // Add versions with identical timestamps
        let same_time = OffsetDateTime::now_utc();
        for i in 0..5 {
            let mut fi = crate::fileinfo::FileInfo::new(&format!("test-{i}"), 2, 1);
            fi.version_id = Some(Uuid::new_v4());
            fi.mod_time = Some(same_time);
            fm.add_version(fi).unwrap();
        }

        // Verify stable ordering
        let original_order = fm.versions.iter().map(|v| v.header.version_id).len();
        fm.sort_by_mod_time();
        let sorted_order = fm.versions.iter().map(|v| v.header.version_id).len();

        // Sorting should remain stable for identical timestamps
        assert_eq!(original_order, sorted_order);
    }

    #[test]
    fn test_checksum_algorithms() {
        // Test different checksum algorithms
        let algorithms = vec![ChecksumAlgo::Invalid, ChecksumAlgo::HighwayHash];

        for algo in algorithms {
            let obj = MetaObject {
                bitrot_checksum_algo: algo.clone(),
                ..Default::default()
            };

            // Verify checksum validation logic
            match algo {
                ChecksumAlgo::Invalid => assert!(!algo.valid()),
                ChecksumAlgo::HighwayHash => assert!(algo.valid()),
            }

            // Verify serialization and deserialization
            let data = obj.marshal_msg().unwrap();
            let mut obj2 = MetaObject::default();
            obj2.unmarshal_msg(&data).unwrap();
            assert_eq!(obj.bitrot_checksum_algo.to_u8(), obj2.bitrot_checksum_algo.to_u8());
        }
    }

    #[test]
    fn test_erasure_coding_parameters() {
        // Test combinations of erasure coding parameters
        let test_cases = vec![
            (1, 1), // Minimum configuration
            (2, 1), // Common configuration
            (4, 2), // Standard configuration
            (8, 4), // High redundancy configuration
        ];

        for (data_blocks, parity_blocks) in test_cases {
            let obj = MetaObject {
                erasure_m: data_blocks,
                erasure_n: parity_blocks,
                erasure_dist: (0..(data_blocks + parity_blocks)).map(|i| i as u8).collect(),
                ..Default::default()
            };

            // Verify parameter validity
            assert!(obj.erasure_m > 0, "Data block count must be greater than 0");
            assert!(obj.erasure_n > 0, "Parity block count must be greater than 0");
            assert_eq!(obj.erasure_dist.len(), data_blocks + parity_blocks);

            // Verify serialization and deserialization
            let data = obj.marshal_msg().unwrap();
            let mut obj2 = MetaObject::default();
            obj2.unmarshal_msg(&data).unwrap();
            assert_eq!(obj.erasure_m, obj2.erasure_m);
            assert_eq!(obj.erasure_n, obj2.erasure_n);
            assert_eq!(obj.erasure_dist, obj2.erasure_dist);
        }
    }

    #[test]
    fn test_metadata_size_limits() {
        // Test metadata size limits
        let mut obj = MetaObject::default();

        // Test moderate amounts of user metadata
        for i in 0..10 {
            obj.meta_user
                .insert(format!("key-{i:04}"), format!("value-{:04}-{}", i, "x".repeat(10)));
        }

        // Verify metadata can be serialized
        let data = obj.marshal_msg().unwrap();
        assert!(data.len() > 100, "Serialized data should have a reasonable size");

        // Verify deserialization succeeds
        let mut obj2 = MetaObject::default();
        obj2.unmarshal_msg(&data).unwrap();
        assert_eq!(obj.meta_user.len(), obj2.meta_user.len());
    }

    #[test]
    fn test_version_statistics_accuracy() {
        // Test accuracy of version statistics
        let mut fm = FileMeta::new();

        // Add different version types
        let object_count = 3;
        let delete_count = 2;

        // Add object versions
        for i in 0..object_count {
            let mut fi = crate::fileinfo::FileInfo::new(&format!("obj-{i}"), 2, 1);
            fi.version_id = Some(Uuid::new_v4());
            fi.mod_time = Some(OffsetDateTime::now_utc());
            fm.add_version(fi).unwrap();
        }

        // Add delete markers
        for i in 0..delete_count {
            let delete_marker = MetaDeleteMarker {
                version_id: Some(Uuid::new_v4()),
                mod_time: Some(OffsetDateTime::now_utc()),
                meta_sys: HashMap::new(),
            };

            let delete_version = FileMetaVersion {
                version_type: VersionType::Delete,
                legacy_object: None,
                object: None,
                delete_marker: Some(delete_marker),
                write_version: (i + 100) as u64,
                uses_legacy_checksum: false,
            };

            let shallow_version = FileMetaShallowVersion::try_from(delete_version).unwrap();
            fm.versions.push(shallow_version);
        }

        // Verify overall statistics
        let stats = fm.get_version_stats();
        assert_eq!(stats.total_versions, object_count + delete_count);
        assert_eq!(stats.object_versions, object_count);
        assert_eq!(stats.delete_markers, delete_count);

        // Verify detailed statistics
        let detailed_stats = fm.get_detailed_version_stats();
        assert_eq!(detailed_stats.total_versions, object_count + delete_count);
        assert_eq!(detailed_stats.object_versions, object_count);
        assert_eq!(detailed_stats.delete_markers, delete_count);
    }

    #[test]
    fn test_cross_platform_compatibility() {
        // Test cross-platform compatibility (endianness, separators, etc.)
        let mut fm = FileMeta::new();

        // Use platform-specific path styles
        let paths = vec![
            "unix/style/path",
            "windows\\style\\path",
            "mixed/style\\path",
            "unicode/path/test",
        ];

        for path in paths {
            let mut fi = crate::fileinfo::FileInfo::new(path, 2, 1);
            fi.version_id = Some(Uuid::new_v4());
            fi.mod_time = Some(OffsetDateTime::now_utc());
            fm.add_version(fi).unwrap();
        }

        // Verify serialization/deserialization consistency across platforms
        let data = fm.marshal_msg().unwrap();
        let mut fm2 = FileMeta::default();
        fm2.unmarshal_msg(&data).unwrap();

        assert_eq!(fm.versions.len(), fm2.versions.len());

        // Verify UUID endianness consistency
        for (v1, v2) in fm.versions.iter().zip(fm2.versions.iter()) {
            assert_eq!(v1.header.version_id, v2.header.version_id);
        }
    }

    #[test]
    fn delete_version_removes_delete_marker_during_version_purge_replication() {
        let version_id = Uuid::new_v4();
        let mut fm = FileMeta::new();
        fm.add_version_filemata(FileMetaVersion {
            version_type: VersionType::Delete,
            legacy_object: None,
            object: None,
            delete_marker: Some(MetaDeleteMarker {
                version_id: Some(version_id),
                mod_time: Some(OffsetDateTime::now_utc()),
                meta_sys: HashMap::new(),
            }),
            write_version: 1,
            uses_legacy_checksum: false,
        })
        .unwrap();

        let fi = FileInfo {
            deleted: false,
            mark_deleted: false,
            version_id: Some(version_id),
            replication_state_internal: Some(ReplicationState {
                version_purge_status_internal: Some("target=PENDING;".to_string()),
                purge_targets: version_purge_statuses_map("target=PENDING;"),
                ..Default::default()
            }),
            ..Default::default()
        };

        let result = fm.delete_version(&fi).unwrap();

        assert!(result.is_none());
        assert!(
            fm.versions.is_empty(),
            "delete-marker version purge should remove the local marker instead of rewriting purge metadata onto it"
        );
    }

    /// Regression for rustfs/backlog#2340: a version purge that still awaits
    /// the replication target keeps the object version on disk with a pending
    /// purge status. Its data dir must be retained with it; handing the dir
    /// back here made the disk layer delete it, leaving every non-inline
    /// retained version unreadable. The dir is released only once the purge
    /// completes and the version itself goes away.
    #[test]
    fn delete_version_pending_version_purge_retains_object_data_dir() {
        let version_id = Uuid::new_v4();
        let data_dir = Uuid::new_v4();
        let mut fm = FileMeta::new();
        let mut fi = FileInfo::new("object", 2, 2);
        fi.version_id = Some(version_id);
        fi.data_dir = Some(data_dir);
        fi.mod_time = Some(OffsetDateTime::now_utc());
        fm.add_version(fi).unwrap();

        let pending_purge = FileInfo {
            name: "object".to_string(),
            version_id: Some(version_id),
            mark_deleted: true,
            replication_state_internal: Some(ReplicationState {
                version_purge_status_internal: Some("target=PENDING;".to_string()),
                purge_targets: version_purge_statuses_map("target=PENDING;"),
                ..Default::default()
            }),
            ..Default::default()
        };
        let freed = fm.delete_version(&pending_purge).unwrap();
        assert_eq!(freed, None, "a pending purge must not release the retained version's data dir");
        assert_eq!(fm.versions.len(), 1, "the version must stay until the purge replicates");
        let retained = fm
            .into_fileinfo("vol", "object", &version_id.to_string(), false, false, true)
            .unwrap();
        assert_eq!(retained.data_dir, Some(data_dir));
        assert_eq!(retained.version_purge_status(), VersionPurgeStatusType::Pending);

        let completed_purge = FileInfo {
            name: "object".to_string(),
            version_id: Some(version_id),
            replication_state_internal: Some(ReplicationState {
                version_purge_status_internal: Some("target=COMPLETE;".to_string()),
                purge_targets: version_purge_statuses_map("target=COMPLETE;"),
                ..Default::default()
            }),
            ..Default::default()
        };
        let freed = fm.delete_version(&completed_purge).unwrap();
        assert_eq!(freed, Some(data_dir), "a completed purge removes the version and releases its data dir");
        assert!(fm.versions.is_empty());
    }

    #[test]
    fn delete_version_accepts_delete_only_marker_and_free_version_paths() {
        let marker_version_id = Uuid::new_v4();
        let mut marker_meta = FileMeta::new();
        marker_meta
            .delete_version(&FileInfo {
                version_id: Some(marker_version_id),
                deleted: true,
                mod_time: Some(OffsetDateTime::now_utc()),
                ..Default::default()
            })
            .expect("delete-marker metadata must not require a payload erasure layout");
        assert_eq!(marker_meta.versions.len(), 1);
        assert_eq!(marker_meta.versions[0].header.version_type, VersionType::Delete);

        let object_version_id = Uuid::new_v4();
        let remote_version_id = Uuid::new_v4();
        let free_version_id = Uuid::new_v4();
        let mut free_meta = FileMeta::new();
        free_meta
            .add_version(FileInfo {
                volume: "bucket".to_string(),
                name: "object".to_string(),
                version_id: Some(object_version_id),
                transition_status: TRANSITION_COMPLETE.to_string(),
                transitioned_objname: "remote/object".to_string(),
                transition_version_id: Some(remote_version_id),
                transition_tier: "WARM".to_string(),
                mod_time: Some(OffsetDateTime::now_utc()),
                ..Default::default()
            })
            .expect("transitioned object version must be seeded");

        let mut transition_delete = FileInfo {
            volume: "bucket".to_string(),
            name: "object".to_string(),
            version_id: Some(object_version_id),
            mod_time: Some(OffsetDateTime::now_utc()),
            ..Default::default()
        };
        transition_delete.set_tier_free_version_id(&free_version_id.to_string());
        free_meta
            .delete_version(&transition_delete)
            .expect("transitioned delete must persist free-version cleanup metadata");

        let mut free_version_delete = FileInfo {
            volume: "bucket".to_string(),
            name: "object".to_string(),
            version_id: Some(free_version_id),
            deleted: true,
            ..Default::default()
        };
        free_version_delete.set_tier_free_version();
        free_meta
            .delete_version(&free_version_delete)
            .expect("free-version cleanup must not require a payload erasure layout");

        let versions = free_meta
            .get_file_info_versions("bucket", "object", false)
            .expect("versions must remain readable after free-version cleanup");
        assert!(versions.free_versions.is_empty());
    }

    #[test]
    fn delete_version_validates_requests_before_mutation() {
        let version_id = Uuid::new_v4();
        let mut fm = FileMeta::new();
        fm.add_version(FileInfo {
            version_id: Some(version_id),
            mod_time: Some(OffsetDateTime::now_utc()),
            ..Default::default()
        })
        .expect("object version must be seeded");
        let original = fm.clone();

        let err = fm
            .delete_version(&FileInfo {
                version_id: Some(version_id),
                parts: vec![
                    ObjectPartInfo {
                        number: 1,
                        ..Default::default()
                    },
                    ObjectPartInfo {
                        number: 1,
                        ..Default::default()
                    },
                ],
                ..Default::default()
            })
            .expect_err("non-deleted requests must not bypass boundary validation");

        assert_eq!(err, Error::FileCorrupt);
        assert_eq!(fm, original, "failed validation must happen before metadata mutation");

        let err = fm
            .delete_version(&FileInfo {
                version_id: Some(version_id),
                deleted: true,
                mod_time: None,
                ..Default::default()
            })
            .expect_err("malformed delete markers must fail before removing the existing object version");

        assert_eq!(err, Error::FileCorrupt);
        assert_eq!(fm, original, "malformed delete-marker validation must precede metadata mutation");

        let mut free_version_delete = FileInfo {
            version_id: Some(version_id),
            deleted: true,
            ..Default::default()
        };
        free_version_delete.set_tier_free_version();
        let err = fm
            .delete_version(&free_version_delete)
            .expect_err("tier free-version cleanup must not remove an ordinary object version");

        assert_eq!(err, Error::FileVersionNotFound);
        assert_eq!(fm, original, "missing free-version cleanup must not mutate ordinary metadata");

        let mut poisoned_object_header = fm.clone();
        poisoned_object_header.versions[0].header.flags |= XL_FLAG_FREE_VERSION;
        let poisoned_original = poisoned_object_header.clone();
        let err = poisoned_object_header
            .delete_version(&free_version_delete)
            .expect_err("a free-version flag on an Object header must not authorize cleanup deletion");
        assert_eq!(err, Error::FileVersionNotFound);
        assert_eq!(
            poisoned_object_header, poisoned_original,
            "a poisoned Object header must remain unchanged after rejected cleanup"
        );

        let mut mismatched_delete_header = fm.clone();
        mismatched_delete_header.versions[0].header.flags |= XL_FLAG_FREE_VERSION;
        mismatched_delete_header.versions[0].header.version_type = VersionType::Delete;
        let mismatched_original = mismatched_delete_header.clone();
        let err = mismatched_delete_header
            .delete_version(&free_version_delete)
            .expect_err("a Delete/free header over an Object body must fail closed");
        assert_eq!(err, Error::FileVersionNotFound);
        assert_eq!(
            mismatched_delete_header, mismatched_original,
            "header/body mismatch must not mutate metadata"
        );
    }

    #[test]
    fn get_file_info_versions_excludes_free_versions_from_num_versions() {
        let object_version_id = Uuid::new_v4();
        let remote_version_id = Uuid::new_v4();
        let free_version_id = Uuid::new_v4();
        let delete_marker_id = Uuid::new_v4();
        let base_time = OffsetDateTime::now_utc();
        let mut fm = FileMeta::new();

        fm.add_version(FileInfo {
            volume: "bucket".to_string(),
            name: "object".to_string(),
            version_id: Some(object_version_id),
            transition_status: TRANSITION_COMPLETE.to_string(),
            transitioned_objname: "remote/object".to_string(),
            transition_version_id: Some(remote_version_id),
            transition_tier: "WARM".to_string(),
            mod_time: Some(base_time),
            ..Default::default()
        })
        .expect("transitioned object version should be added");

        let mut delete_fi = FileInfo {
            volume: "bucket".to_string(),
            name: "object".to_string(),
            version_id: Some(object_version_id),
            mod_time: Some(base_time),
            ..Default::default()
        };
        delete_fi.set_tier_free_version_id(&free_version_id.to_string());
        fm.delete_version(&delete_fi)
            .expect("transitioned delete should create a free-version record");

        fm.add_version(FileInfo {
            volume: "bucket".to_string(),
            name: "object".to_string(),
            version_id: Some(delete_marker_id),
            deleted: true,
            mod_time: Some(base_time + time::Duration::seconds(1)),
            ..Default::default()
        })
        .expect("delete marker should be added");

        let versions = fm
            .get_file_info_versions("bucket", "object", false)
            .expect("file info versions should parse");

        assert_eq!(versions.versions.len(), 1);
        assert_eq!(versions.free_versions.len(), 1);
        assert!(versions.versions[0].deleted);
        assert_eq!(versions.versions[0].num_versions, 1);
        assert_eq!(versions.free_versions[0].num_versions, 1);

        let versions_with_free = fm
            .get_file_info_versions("bucket", "object", true)
            .expect("file info versions should preserve all versions");

        assert_eq!(versions_with_free.versions.len(), 2);
        assert!(versions_with_free.free_versions.is_empty());
        assert!(versions_with_free.versions.iter().all(|version| version.num_versions == 2));
    }

    #[test]
    fn test_data_integrity_validation() {
        // Test data integrity checks
        let mut fm = FileMeta::new();

        // Add a normal version
        let mut fi = crate::fileinfo::FileInfo::new("test", 2, 1);
        fi.version_id = Some(Uuid::new_v4());
        fi.mod_time = Some(OffsetDateTime::now_utc());
        fm.add_version(fi).unwrap();

        // Verify integrity under normal conditions
        assert!(fm.validate_integrity().is_ok());
    }

    #[test]
    fn test_add_version_clears_stale_inline_data_for_null_version() {
        let mut fm = FileMeta::new();

        let mut inline_fi = crate::fileinfo::FileInfo::new("test", 2, 1);
        inline_fi.mod_time = Some(OffsetDateTime::now_utc());
        inline_fi.data = Some(Bytes::new());
        inline_fi.set_inline_data();
        fm.add_version(inline_fi).unwrap();

        let inline_version = fm.into_fileinfo("bucket", "test", "", true, false, true).unwrap();
        assert!(inline_version.inline_data());
        assert_eq!(inline_version.data, Some(Bytes::new()));

        let mut disk_fi = crate::fileinfo::FileInfo::new("test", 2, 1);
        disk_fi.mod_time = Some(OffsetDateTime::now_utc() + time::Duration::seconds(1));
        disk_fi.size = 1024;
        fm.add_version(disk_fi).unwrap();

        let latest = fm.into_fileinfo("bucket", "test", "", true, false, true).unwrap();
        assert!(!latest.inline_data());
        assert!(latest.data.is_none());
        assert!(
            fm.data
                .find(data_key_for_version(latest.version_id).as_str())
                .unwrap()
                .is_none()
        );
    }

    #[test]
    fn test_add_version_keeps_inline_data_when_version_insert_fails() {
        let mut fm = FileMeta::new();

        let mut inline_fi = crate::fileinfo::FileInfo::new("test", 2, 1);
        inline_fi.mod_time = Some(OffsetDateTime::now_utc());
        inline_fi.data = Some(Bytes::from_static(b"inline"));
        inline_fi.set_inline_data();
        fm.add_version(inline_fi).unwrap();

        let before = fm.data.find(data_key_for_version(Some(Uuid::nil())).as_str()).unwrap();
        assert_eq!(before, Some(Bytes::from_static(b"inline").to_vec()));

        let invalid_disk_fi = crate::fileinfo::FileInfo::new("test", 2, 1);
        let err = fm.add_version(invalid_disk_fi).unwrap_err();
        assert!(err.to_string().contains("file meta version invalid"));

        let after = fm.data.find(data_key_for_version(Some(Uuid::nil())).as_str()).unwrap();
        assert_eq!(after, Some(Bytes::from_static(b"inline").to_vec()));
    }

    #[test]
    fn test_update_object_version_persists_checksum_metadata() {
        let mut fm = FileMeta::new();
        let version_id = Some(Uuid::new_v4());

        let mut fi = crate::fileinfo::FileInfo::new("test", 2, 1);
        fi.version_id = version_id;
        fi.mod_time = Some(OffsetDateTime::now_utc());
        fm.add_version(fi).unwrap();

        let checksum = Bytes::from_static(b"resolved-checksum");
        let mut update = crate::fileinfo::FileInfo::new("test", 2, 1);
        update.version_id = version_id;
        update.metadata.insert("x-amz-meta-owner".to_string(), "alice".to_string());
        update.checksum = Some(checksum.clone());

        fm.update_object_version(update).unwrap();

        let (_, version) = fm.find_version(version_id).unwrap();
        let stored = version.into_fileinfo("bucket", "test", true).expect("into_fileinfo");
        assert_eq!(stored.metadata.get("x-amz-meta-owner"), Some(&"alice".to_string()));
        assert_eq!(stored.checksum, Some(checksum));
    }

    #[test]
    fn test_version_merge_scenarios() {
        // Test various version merge scenarios
        let mut versions1 = vec![];
        let mut versions2 = vec![];

        // Create two distinct sets of versions
        for i in 0..3 {
            let mut fi1 = crate::fileinfo::FileInfo::new(&format!("test1-{i}"), 2, 1);
            fi1.version_id = Some(Uuid::new_v4());
            fi1.mod_time = Some(OffsetDateTime::from_unix_timestamp(1000 + i * 10).unwrap());

            let mut fi2 = crate::fileinfo::FileInfo::new(&format!("test2-{i}"), 2, 1);
            fi2.version_id = Some(Uuid::new_v4());
            fi2.mod_time = Some(OffsetDateTime::from_unix_timestamp(1005 + i * 10).unwrap());

            let version1 = FileMetaVersion::from(fi1);
            let version2 = FileMetaVersion::from(fi2);

            versions1.push(FileMetaShallowVersion::try_from(version1).unwrap());
            versions2.push(FileMetaShallowVersion::try_from(version2).unwrap());
        }

        // Test a simple merge scenario
        let merged = merge_file_meta_versions(1, false, 0, &[versions1.clone()]);
        assert!(!merged.is_empty(), "Merging a single version list should not be empty");

        // Test merging multiple version lists
        let merged = merge_file_meta_versions(1, false, 0, &[versions1.clone(), versions2.clone()]);
        // Merge results may be empty depending on compatibility, which is acceptable
        println!("Merge result count: {}", merged.len());
    }

    #[test]
    fn test_flags_operations() {
        // Test flag operations
        let flags = vec![Flags::FreeVersion, Flags::UsesDataDir, Flags::InlineData];

        for flag in flags {
            let flag_value = flag as u8;
            assert!(flag_value > 0, "Flag value should be greater than 0");

            // Test flag combinations
            let combined = Flags::FreeVersion as u8 | Flags::UsesDataDir as u8;
            // For bitwise operations, combined values may not exceed individual ones; this is normal
            assert!(combined > 0, "Combined flag value should be greater than 0");
        }
    }

    #[test]
    fn test_uuid_handling_edge_cases() {
        // Test UUID edge cases
        let test_uuids = vec![
            Uuid::new_v4(), // Random UUID
        ];

        for uuid in test_uuids {
            let obj = MetaObject {
                version_id: Some(uuid),
                data_dir: Some(uuid),
                ..Default::default()
            };

            // Verify serialization and deserialization
            let data = obj.marshal_msg().unwrap();
            let mut obj2 = MetaObject::default();
            obj2.unmarshal_msg(&data).unwrap();

            assert_eq!(obj.version_id, obj2.version_id);
            assert_eq!(obj.data_dir, obj2.data_dir);
        }

        // Test nil UUID separately because serialization converts it to None
        let obj = MetaObject {
            version_id: Some(Uuid::nil()),
            data_dir: Some(Uuid::nil()),
            ..Default::default()
        };

        let data = obj.marshal_msg().unwrap();
        let mut obj2 = MetaObject::default();
        obj2.unmarshal_msg(&data).unwrap();

        // nil UUIDs may be converted to None during serialization; this is expected
        // Inspect the actual serialization behavior
        println!("Original version_id: {:?}", obj.version_id);
        println!("Deserialized version_id: {:?}", obj2.version_id);
        // Consider the test successful as long as deserialization succeeds
    }

    #[test]
    fn test_part_handling_edge_cases() {
        // Test edge cases for shard handling
        let mut obj = MetaObject::default();

        // Test an empty shard list
        assert!(obj.part_numbers.is_empty());
        assert!(obj.part_etags.is_empty());
        assert!(obj.part_sizes.is_empty());

        // Test a single shard
        obj.part_numbers = vec![1];
        obj.part_etags = vec!["etag1".to_string()];
        obj.part_sizes = vec![1024];
        obj.part_actual_sizes = vec![1024];

        let data = obj.marshal_msg().unwrap();
        let mut obj2 = MetaObject::default();
        obj2.unmarshal_msg(&data).unwrap();

        assert_eq!(obj.part_numbers, obj2.part_numbers);
        assert_eq!(obj.part_etags, obj2.part_etags);
        assert_eq!(obj.part_sizes, obj2.part_sizes);
        assert_eq!(obj.part_actual_sizes, obj2.part_actual_sizes);

        // Test multiple shards
        obj.part_numbers = vec![1, 2, 3];
        obj.part_etags = vec!["etag1".to_string(), "etag2".to_string(), "etag3".to_string()];
        obj.part_sizes = vec![1024, 2048, 512];
        obj.part_actual_sizes = vec![1024, 2048, 512];

        let data = obj.marshal_msg().unwrap();
        let mut obj2 = MetaObject::default();
        obj2.unmarshal_msg(&data).unwrap();

        assert_eq!(obj.part_numbers, obj2.part_numbers);
        assert_eq!(obj.part_etags, obj2.part_etags);
        assert_eq!(obj.part_sizes, obj2.part_sizes);
        assert_eq!(obj.part_actual_sizes, obj2.part_actual_sizes);
    }

    #[test]
    fn test_version_header_validation() {
        // Test version header validation
        let mut header = FileMetaVersionHeader {
            version_type: VersionType::Object,
            mod_time: Some(OffsetDateTime::now_utc()),
            ec_m: 2,
            ec_n: 1,
            ..Default::default()
        };
        assert!(header.is_valid());

        // Test invalid version types
        header.version_type = VersionType::Invalid;
        assert!(!header.is_valid());

        // Reset to a valid state
        header.version_type = VersionType::Object;
        assert!(header.is_valid());

        // Test invalid erasure coding parameters
        // When ec_m = 0, has_ec() returns false so parity parameters are skipped
        header.ec_m = 0;
        header.ec_n = 1;
        assert!(header.is_valid()); // Valid because erasure coding is disabled

        // Enable erasure coding with invalid parameters
        header.ec_m = 2;
        header.ec_n = 0;
        // When ec_n = 0, has_ec() returns false so parity parameters are skipped
        assert!(header.is_valid()); // This remains valid because has_ec() returns false

        // Reset to a valid state
        header.ec_n = 1;
        assert!(header.is_valid());
    }

    #[test]
    fn test_special_characters_in_metadata() {
        // Test special character handling in metadata
        let mut obj = MetaObject::default();

        // Test various special characters
        let special_cases = vec![
            ("empty", ""),
            ("unicode", "test🚀🎉"),
            ("newlines", "line1\nline2\nline3"),
            ("tabs", "col1\tcol2\tcol3"),
            ("quotes", "\"quoted\" and 'single'"),
            ("backslashes", "path\\to\\file"),
            ("mixed", "Mixed: Chinese, English, 123, !@#$%"),
        ];

        for (key, value) in special_cases {
            obj.meta_user.insert(key.to_string(), value.to_string());
        }

        // Verify serialization and deserialization
        let data = obj.marshal_msg().unwrap();
        let mut obj2 = MetaObject::default();
        obj2.unmarshal_msg(&data).unwrap();

        assert_eq!(obj.meta_user, obj2.meta_user);

        // Verify each special character is correctly saved
        for (key, expected_value) in [
            ("empty", ""),
            ("unicode", "test🚀🎉"),
            ("newlines", "line1\nline2\nline3"),
            ("tabs", "col1\tcol2\tcol3"),
            ("quotes", "\"quoted\" and 'single'"),
            ("backslashes", "path\\to\\file"),
            ("mixed", "Mixed: Chinese, English, 123, !@#$%"),
        ] {
            assert_eq!(obj2.meta_user.get(key), Some(&expected_value.to_string()));
        }
    }
}

#[tokio::test]
async fn test_read_xl_meta_no_data() {
    use tokio::fs::File;
    use tokio::io::AsyncWriteExt;

    let mut fm = FileMeta::new();

    let (m, n) = (3, 2);

    for i in 0..5 {
        let mut fi = FileInfo::new(i.to_string().as_str(), m, n);
        fi.mod_time = Some(OffsetDateTime::now_utc());

        fm.add_version(fi).unwrap();
    }

    let mut buff = fm.marshal_msg().unwrap();

    buff.resize(buff.len() + 100, 0);

    // Use tempfile to avoid conflicts with parallel tests or previous runs
    let dir = tempfile::tempdir().unwrap();
    let filepath = dir.path().join("test_xl.meta");

    let mut file = File::create(&filepath).await.unwrap();
    // Write string data
    file.write_all(&buff).await.unwrap();
    file.flush().await.unwrap();

    let mut f = File::open(&filepath).await.unwrap();

    let stat = f.metadata().await.unwrap();

    let data = read_xl_meta_no_data(&mut f, stat.len() as usize).await.unwrap();

    let mut newfm = FileMeta::default();
    newfm.unmarshal_msg(&data).unwrap();

    assert_eq!(fm, newfm)
}