rustic_core/repofile/

snapshotfile.rs

pub mod grouping;
mod modification;

pub use modification::SnapshotModification;

use std::{
    cmp::Ordering,
    collections::{BTreeMap, BTreeSet},
    fmt::{self, Display},
    path::{Path, PathBuf},
    str::FromStr,
};

use derive_setters::Setters;
use dunce::canonicalize;
use gethostname::gethostname;
use itertools::Itertools;
use jiff::{Span, Unit, Zoned};
use log::{info, warn};
use path_dedot::ParseDot;
use serde::{Deserialize, Serialize};
use serde_with::{DisplayFromStr, serde_as, skip_serializing_none};

#[cfg(feature = "clap")]
use clap::ValueHint;

use crate::{
    Id,
    backend::{FileType, FindInBackend, decrypt::DecryptReadBackend},
    blob::tree::TreeId,
    error::{ErrorKind, RusticError, RusticResult},
    id::{FindUniqueMultiple, FindUniqueResults, constants::HEX_LEN},
    impl_repofile,
    progress::Progress,
    repofile::{RepoFile, RusticTime},
};

/// [`SnapshotFileErrorKind`] describes the errors that can be returned for `SnapshotFile`s
#[derive(thiserror::Error, Debug, displaydoc::Display)]
#[non_exhaustive]
pub enum SnapshotFileErrorKind {
    /// non-unicode path `{0:?}`
    NonUnicodePath(PathBuf),
    /// value `{0:?}` not allowed
    ValueNotAllowed(String),
    /// removing dots from paths failed: `{0:?}`
    RemovingDotsFromPathFailed(std::io::Error),
    /// canonicalizing path failed: `{0:?}`
    CanonicalizingPathFailed(std::io::Error),
}

pub(crate) type SnapshotFileResult<T> = Result<T, SnapshotFileErrorKind>;

/// Options for creating a new [`SnapshotFile`] structure for a new backup snapshot.
///
/// This struct derives [`serde::Deserialize`] allowing to use it in config files.
///
/// # Features
///
/// * With the feature `merge` enabled, this also derives [`conflate::Merge`] to allow merging [`SnapshotOptions`] from multiple sources.
/// * With the feature `clap` enabled, this also derives [`clap::Parser`] allowing it to be used as CLI options.
///
/// # Note
///
/// The preferred way is to use [`SnapshotFile::from_options`] to create a `SnapshotFile` for a new backup.
#[serde_as]
#[cfg_attr(feature = "merge", derive(conflate::Merge))]
#[cfg_attr(feature = "clap", derive(clap::Parser))]
#[derive(Deserialize, Serialize, Clone, Default, Debug, Setters)]
#[serde(default, rename_all = "kebab-case", deny_unknown_fields)]
#[setters(into)]
#[non_exhaustive]
pub struct SnapshotOptions {
    /// Label snapshot with given label
    #[cfg_attr(feature = "clap", clap(long, value_name = "LABEL"))]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::option::overwrite_none))]
    pub label: Option<String>,

    /// Tags to add to snapshot (can be specified multiple times)
    #[serde_as(as = "Vec<DisplayFromStr>")]
    #[cfg_attr(feature = "clap", clap(long = "tag", value_name = "TAG[,TAG,..]"))]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::vec::overwrite_empty))]
    pub tags: Vec<StringList>,

    /// Add description to snapshot
    #[cfg_attr(feature = "clap", clap(long, value_name = "DESCRIPTION"))]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::option::overwrite_none))]
    pub description: Option<String>,

    /// Add description to snapshot from file
    #[cfg_attr(
        feature = "clap",
        clap(long, value_name = "FILE", conflicts_with = "description", value_hint = ValueHint::FilePath)
    )]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::option::overwrite_none))]
    pub description_from: Option<PathBuf>,

    /// Set the backup time manually (e.g. "2021-01-21 14:15:23+0000")
    #[cfg_attr(feature = "clap", clap(long,value_parser = RusticTime::parse_system))]
    #[serde_as(as = "Option<RusticTime>")]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::option::overwrite_none))]
    pub time: Option<Zoned>,

    /// Mark snapshot as uneraseable
    #[cfg_attr(feature = "clap", clap(long, conflicts_with = "delete_after"))]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::bool::overwrite_false))]
    pub delete_never: bool,

    /// Mark snapshot to be deleted after given duration (e.g. 10d)
    #[cfg_attr(feature = "clap", clap(long, value_name = "DURATION"))]
    #[serde_as(as = "Option<DisplayFromStr>")]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::option::overwrite_none))]
    pub delete_after: Option<Span>,

    /// Set the host name manually
    #[cfg_attr(feature = "clap", clap(long, value_name = "NAME"))]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::option::overwrite_none))]
    pub host: Option<String>,

    /// Set the backup command manually
    #[cfg_attr(feature = "clap", clap(long))]
    #[cfg_attr(feature = "merge", merge(strategy = conflate::option::overwrite_none))]
    pub command: Option<String>,
}

impl SnapshotOptions {
    /// Add tags to this [`SnapshotOptions`]
    ///
    /// # Arguments
    ///
    /// * `tag` - The tag to add
    ///
    /// # Errors
    ///
    /// * If the tag is not valid unicode
    ///
    /// # Returns
    ///
    /// The modified [`SnapshotOptions`]
    pub fn add_tags(mut self, tag: &str) -> RusticResult<Self> {
        self.tags.push(StringList::from_str(tag).map_err(|err| {
            RusticError::with_source(
                ErrorKind::InvalidInput,
                "Failed to create string list from tag `{tag}`. The value must be a valid unicode string.",
                err,
            )
            .attach_context("tag", tag)
        })?);
        Ok(self)
    }

    /// Create a new [`SnapshotFile`] using this `SnapshotOption`s
    ///
    /// # Errors
    ///
    /// * If the hostname is not valid unicode
    ///
    /// # Returns
    ///
    /// The new [`SnapshotFile`]
    pub fn to_snapshot(&self) -> RusticResult<SnapshotFile> {
        SnapshotFile::from_options(self)
    }
}

/// Summary information about a snapshot.
///
/// This is an extended version of the summaryOutput structure of restic in
/// restic/internal/ui/backup$/json.go
#[serde_as]
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
#[serde(default)]
#[non_exhaustive]
pub struct SnapshotSummary {
    /// New files compared to the last (i.e. parent) snapshot
    pub files_new: u64,

    /// Changed files compared to the last (i.e. parent) snapshot
    pub files_changed: u64,

    /// Unchanged files compared to the last (i.e. parent) snapshot
    pub files_unmodified: u64,

    /// Total processed files
    pub total_files_processed: u64,

    /// Total size of all processed files
    pub total_bytes_processed: u64,

    /// New directories compared to the last (i.e. parent) snapshot
    pub dirs_new: u64,

    /// Changed directories compared to the last (i.e. parent) snapshot
    pub dirs_changed: u64,

    /// Unchanged directories compared to the last (i.e. parent) snapshot
    pub dirs_unmodified: u64,

    /// Total processed directories
    pub total_dirs_processed: u64,

    /// Total size of all processed dirs
    pub total_dirsize_processed: u64,

    /// Total number of data blobs added by this snapshot
    pub data_blobs: u64,

    /// Total number of tree blobs added by this snapshot
    pub tree_blobs: u64,

    /// Total uncompressed bytes added by this snapshot
    pub data_added: u64,

    /// Total bytes added to the repository by this snapshot
    pub data_added_packed: u64,

    /// Total uncompressed bytes (new/changed files) added by this snapshot
    pub data_added_files: u64,

    /// Total bytes for new/changed files added to the repository by this snapshot
    pub data_added_files_packed: u64,

    /// Total uncompressed bytes (new/changed directories) added by this snapshot
    pub data_added_trees: u64,

    /// Total bytes (new/changed directories) added to the repository by this snapshot
    pub data_added_trees_packed: u64,

    /// The command used to make this backup
    pub command: String,

    /// Start time of the backup.
    ///
    /// # Note
    ///
    /// This may differ from the snapshot `time`.
    #[serde_as(as = "RusticTime")]
    pub backup_start: Zoned,

    /// The time that the backup has been finished.
    #[serde_as(as = "RusticTime")]
    pub backup_end: Zoned,

    /// Total duration of the backup in seconds, i.e. the time between `backup_start` and `backup_end`
    pub backup_duration: f64,

    /// Total duration that the rustic command ran in seconds
    pub total_duration: f64,
}

impl Default for SnapshotSummary {
    fn default() -> Self {
        Self {
            files_new: Default::default(),
            files_changed: Default::default(),
            files_unmodified: Default::default(),
            total_files_processed: Default::default(),
            total_bytes_processed: Default::default(),
            dirs_new: Default::default(),
            dirs_changed: Default::default(),
            dirs_unmodified: Default::default(),
            total_dirs_processed: Default::default(),
            total_dirsize_processed: Default::default(),
            data_blobs: Default::default(),
            tree_blobs: Default::default(),
            data_added: Default::default(),
            data_added_packed: Default::default(),
            data_added_files: Default::default(),
            data_added_files_packed: Default::default(),
            data_added_trees: Default::default(),
            data_added_trees_packed: Default::default(),
            command: String::default(),
            backup_start: Zoned::now(),
            backup_end: Zoned::now(),
            backup_duration: Default::default(),
            total_duration: Default::default(),
        }
    }
}

impl SnapshotSummary {
    /// Create a new [`SnapshotSummary`].
    ///
    /// # Arguments
    ///
    /// * `snap_time` - The time of the snapshot
    ///
    /// # Errors
    ///
    /// * If the time is not in the range of `Local::now()`
    pub(crate) fn finalize(&mut self, snap_time: &Zoned) {
        let end_time = Zoned::now();
        self.backup_duration = end_time
            .since(&self.backup_start)
            .and_then(|span| span.total(Unit::Second))
            .inspect_err(|err| warn!("ignoring Datetime error: {err}"))
            .unwrap_or_default();
        self.total_duration = end_time
            .since(snap_time)
            .and_then(|span| span.total(Unit::Second))
            .inspect_err(|err| warn!("ignoring Datetime error: {err}"))
            .unwrap_or_default();
        self.backup_end = end_time;
    }
}

/// Options for deleting snapshots.
#[derive(Serialize, Default, Deserialize, Debug, Clone, PartialEq, Eq)]
pub enum DeleteOption {
    /// No delete option set.
    #[default]
    NotSet,
    /// This snapshot should be never deleted (remove-protection).
    Never,
    /// Remove this snapshot after the given timestamp, but prevent removing it before.
    After(Zoned),
}

impl DeleteOption {
    /// Returns whether the delete option is set to `NotSet`.
    const fn is_not_set(&self) -> bool {
        matches!(self, Self::NotSet)
    }
}

impl_repofile!(SnapshotId, FileType::Snapshot, SnapshotFile);

#[serde_as]
#[skip_serializing_none]
#[derive(Debug, Clone, Serialize, Deserialize)]
/// A [`SnapshotFile`] is the repository representation of the snapshot metadata saved in a repository.
///
/// It is usually saved in the repository under `snapshot/<ID>`
///
/// # Note
///
/// [`SnapshotFile`] implements [`Eq`], [`PartialEq`], [`Ord`], [`PartialOrd`] by comparing only the `time` field.
/// If you need another ordering, you have to implement that yourself.
pub struct SnapshotFile {
    /// Timestamp of this snapshot
    #[serde_as(as = "RusticTime")]
    pub time: Zoned,

    /// Program identifier and its version that have been used to create this snapshot.
    #[serde(default, skip_serializing_if = "String::is_empty")]
    pub program_version: String,

    /// The Id of the first parent snapshot that this snapshot has been based on
    pub parent: Option<SnapshotId>,

    /// The Ids of all parent snapshots that this snapshot has been based on
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub parents: Vec<SnapshotId>,

    /// The tree blob id where the contents of this snapshot are stored
    pub tree: TreeId,

    /// Label for the snapshot
    #[serde(default, skip_serializing_if = "String::is_empty")]
    pub label: String,

    /// The list of paths contained in this snapshot
    pub paths: StringList,

    /// The hostname of the device on which the snapshot has been created
    #[serde(default)]
    pub hostname: String,

    /// The username that started the backup run
    #[serde(default)]
    pub username: String,

    /// The uid of the username that started the backup run
    #[serde(default)]
    pub uid: u32,

    /// The gid of the username that started the backup run
    #[serde(default)]
    pub gid: u32,

    /// A list of tags for this snapshot
    #[serde(default)]
    pub tags: StringList,

    /// The original Id of this snapshot. This is stored when the snapshot is modified.
    pub original: Option<SnapshotId>,

    /// Options for deletion of the snapshot
    #[serde(default, skip_serializing_if = "DeleteOption::is_not_set")]
    pub delete: DeleteOption,

    /// Summary information about the backup run
    pub summary: Option<SnapshotSummary>,

    /// A description of what is contained in this snapshot
    pub description: Option<String>,

    /// The snapshot Id (not stored within the JSON)
    #[serde(default, skip_serializing_if = "Id::is_null")]
    pub id: SnapshotId,
}

impl Default for SnapshotFile {
    fn default() -> Self {
        Self {
            time: Zoned::now(),
            program_version: {
                let project_version =
                    option_env!("PROJECT_VERSION").unwrap_or(env!("CARGO_PKG_VERSION"));
                format!("rustic {project_version}")
            },
            parent: Option::default(),
            parents: Vec::default(),
            tree: TreeId::default(),
            label: String::default(),
            paths: StringList::default(),
            hostname: String::default(),
            username: String::default(),
            uid: Default::default(),
            gid: Default::default(),
            tags: StringList::default(),
            original: Option::default(),
            delete: DeleteOption::default(),
            summary: Option::default(),
            description: Option::default(),
            id: SnapshotId::default(),
        }
    }
}

enum SnapshotRequest {
    Latest(usize),
    StartsWith(String),
    Id(SnapshotId),
}

impl FromStr for SnapshotRequest {
    type Err = Box<RusticError>;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let err = || {
            RusticError::new(
                    ErrorKind::InvalidInput,
                    "Invalid snapshot identifier \"{input}\". Expected either a snapshot id: \"01a2b3c4\" or \"latest\" or \"latest~N\" (N >= 0).",
                )
                .attach_context("input", s)
        };

        let result = match s.strip_prefix("latest") {
            Some(suffix) => {
                if suffix.is_empty() {
                    Self::Latest(0)
                } else {
                    let latest_index = suffix.strip_prefix("~").ok_or_else(err)?;
                    let n = latest_index.parse::<usize>().map_err(|_| err())?;
                    Self::Latest(n)
                }
            }
            None => {
                if s.len() < HEX_LEN {
                    Self::StartsWith(s.to_string())
                } else {
                    Self::Id(s.parse()?)
                }
            }
        };
        Ok(result)
    }
}

struct SnapshotRequests {
    requests: Vec<SnapshotRequest>,
    max_n_latest: Option<usize>,
    starts_with: Vec<String>,
    ids: Vec<SnapshotId>,
}

impl SnapshotRequests {
    fn from_strs<S: AsRef<str>>(strings: &[S]) -> RusticResult<Self> {
        let requests: Vec<SnapshotRequest> = strings
            .iter()
            .map(|s| s.as_ref().parse())
            .collect::<RusticResult<_>>()?;

        let mut max_n_latest: Option<usize> = None;
        let mut starts_with = Vec::new();
        let mut ids = Vec::new();
        for r in &requests {
            match r {
                SnapshotRequest::Latest(n) => {
                    max_n_latest = Some(max_n_latest.unwrap_or_default().max(*n));
                }
                SnapshotRequest::StartsWith(s) => starts_with.push(s.clone()),
                SnapshotRequest::Id(id) => ids.push(*id),
            }
        }
        Ok(Self {
            requests,
            max_n_latest,
            starts_with,
            ids,
        })
    }

    fn map_results<T: Clone>(
        self,
        latest: &[T],
        vec_ids_starts_with: Vec<T>,
        vec_ids: Vec<T>,
    ) -> Vec<T> {
        let mut snaps_ids = vec_ids.into_iter();
        let mut snaps_ids_start_with = vec_ids_starts_with.into_iter();
        self.requests
            .into_iter()
            .map(|r| match r {
                SnapshotRequest::Latest(n) => latest[n].clone(),
                SnapshotRequest::StartsWith(..) => snaps_ids_start_with.next().unwrap(),
                SnapshotRequest::Id(..) => snaps_ids.next().unwrap(),
            })
            .collect()
    }
}

impl SnapshotFile {
    /// Create a [`SnapshotFile`] from [`SnapshotOptions`].
    ///
    /// # Arguments
    ///
    /// * `opts` - The [`SnapshotOptions`] to use
    ///
    /// # Errors
    ///
    /// * If the hostname is not valid unicode
    /// * If the delete time is not in the range of `Local::now()`
    /// * If the description file could not be read
    ///
    /// # Note
    ///
    /// This is the preferred way to create a new [`SnapshotFile`] to be used within [`crate::Repository::backup`].
    pub fn from_options(opts: &SnapshotOptions) -> RusticResult<Self> {
        let hostname = if let Some(host) = &opts.host {
            host.clone()
        } else {
            let hostname = gethostname();
            hostname
                .to_str()
                .ok_or_else(|| {
                    RusticError::new(
                        ErrorKind::InvalidInput,
                        "Failed to convert hostname `{hostname}` to string. The value must be a valid unicode string.",
                    )
                    .attach_context("hostname", hostname.to_string_lossy().to_string())
                })?
                .to_string()
        };

        let time = opts.time.clone().unwrap_or_else(Zoned::now);

        let delete = match (opts.delete_never, opts.delete_after) {
            (true, _) => DeleteOption::Never,
            (_, Some(duration)) => DeleteOption::After(time.saturating_add(duration)),
            (false, None) => DeleteOption::NotSet,
        };

        let command: String = opts.command.as_ref().map_or_else(
            || {
                std::env::args_os()
                    .map(|s| s.to_string_lossy().to_string())
                    .collect::<Vec<_>>()
                    .join(" ")
            },
            Clone::clone,
        );

        let mut snap = Self {
            time,
            hostname,
            label: opts.label.clone().unwrap_or_default(),
            delete,
            summary: Some(SnapshotSummary {
                command,
                ..Default::default()
            }),
            description: opts.description.clone(),
            ..Default::default()
        };

        // use description from description file if it is given
        if let Some(ref path) = opts.description_from {
            snap.description = Some(std::fs::read_to_string(path).map_err(|err| {
                RusticError::with_source(
                    ErrorKind::InvalidInput,
                    "Failed to read description file `{path}`. Please make sure the file exists and is readable.",
                    err,
                )
                .attach_context("path", path.to_string_lossy().to_string())
            })?);
        }

        _ = snap.set_tags(opts.tags.clone());

        Ok(snap)
    }

    /// Create a [`SnapshotFile`] from a given [`Id`] and [`RepoFile`].
    ///
    /// # Arguments
    ///
    /// * `tuple` - A tuple of the [`Id`] and the [`RepoFile`] to use
    fn set_id(tuple: (SnapshotId, Self)) -> Self {
        let (id, mut snap) = tuple;
        snap.id = id;
        _ = snap.original.get_or_insert(id);
        snap
    }

    /// Get a [`SnapshotFile`] from the backend
    ///
    /// # Arguments
    ///
    /// * `be` - The backend to use
    /// * `id` - The id of the snapshot
    fn from_backend<B: DecryptReadBackend>(be: &B, id: &SnapshotId) -> RusticResult<Self> {
        Ok(Self::set_id((*id, be.get_file(id)?)))
    }

    /// Get a [`SnapshotFile`] from the backend by (part of the) Id
    ///
    /// Works with a snapshot `Id` or a `latest` indexed syntax: `latest` or `latest~N` with N >= 0
    ///
    /// # Arguments
    ///
    /// * `be` - The backend to use
    /// * `string` - The (part of the) id of the snapshot
    /// * `predicate` - A predicate to filter the snapshots
    /// * `p` - A progress bar to use
    ///
    /// # Errors
    ///
    /// * If the string is not a valid hexadecimal string
    /// * If no id could be found.
    /// * If the id is not unique.
    /// * If the `latest` syntax is "detected" but inexact
    pub(crate) fn from_str<B: DecryptReadBackend>(
        be: &B,
        string: &str,
        predicate: impl FnMut(&Self) -> bool + Send + Sync,
        p: &Progress,
    ) -> RusticResult<Self> {
        match string.parse()? {
            SnapshotRequest::Latest(n) => Self::latest_n(be, predicate, p, n),
            SnapshotRequest::StartsWith(id) => Self::from_id(be, &id),
            SnapshotRequest::Id(id) => Self::from_backend(be, &id),
        }
    }

    /// Get a [`Vec<SnapshotFile>`] from the backend by (part of the) Ids
    ///
    /// Works with a snapshot `Id` or a `latest` indexed syntax: `latest` or `latest~N` with N >= 0
    ///
    /// # Arguments
    ///
    /// * `be` - The backend to use
    /// * `string` - The (part of the) id of the snapshot
    /// * `predicate` - A predicate to filter the snapshots
    /// * `p` - A progress bar to use
    ///
    /// # Errors
    ///
    /// * If the string is not a valid hexadecimal string
    /// * If no id could be found.
    /// * If the id is not unique.
    /// * If the `latest` syntax is "detected" but inexact
    pub(crate) fn from_strs<B: DecryptReadBackend, S: AsRef<str>>(
        be: &B,
        strings: &[S],
        predicate: impl FnMut(&Self) -> bool + Send + Sync,
        p: &Progress,
    ) -> RusticResult<Vec<Self>> {
        let requests = SnapshotRequests::from_strs(strings)?;

        match requests.max_n_latest {
            None => {
                //  specialize for only start_with and ids
                let ids_starts_with = if requests.starts_with.is_empty() {
                    Vec::new()
                } else {
                    be.list(FileType::Snapshot)?
                        .into_iter()
                        .find_unique_multiple(
                            |id, v| id.to_hex().starts_with(v),
                            &requests.starts_with,
                        )
                        .assert_found(&requests.starts_with)?
                };

                let ids: Vec<Id> = requests.ids.iter().map(|sn| **sn).collect();
                let all_ids = requests.map_results(&[], ids_starts_with, ids);

                Self::fill_missing(be, Vec::new(), all_ids.as_slice(), |_| true, p)
            }
            Some(max_n) => {
                let ids: BTreeMap<_, _> = requests
                    .ids
                    .iter()
                    .enumerate()
                    .map(|(num, r)| (r, num))
                    .collect();
                let mut vec_ids = vec![Self::default(); ids.len()];
                let mut ids_starts_with = FindUniqueResults::new(&requests.starts_with);

                // search for id names while iterating snapshots to get latest ones
                let iter = Self::iter_all_from_backend(be, predicate, p)?.inspect(|sn| {
                    if let Some(idx) = ids.get(&sn.id) {
                        vec_ids[*idx] = sn.clone();
                    }
                    ids_starts_with.add_item(
                        sn.clone(),
                        |sn, v| sn.id.to_hex().starts_with(v),
                        &requests.starts_with,
                    );
                });
                let latest = Self::latest_n_from_iter(max_n, iter)?;
                let vec_ids_starts_with = ids_starts_with.assert_found(&requests.starts_with)?;
                Ok(requests.map_results(&latest, vec_ids_starts_with, vec_ids))
            }
        }
    }

    /// Get the latest [`SnapshotFile`] from the backend
    ///
    /// # Arguments
    ///
    /// * `be` - The backend to use
    /// * `predicate` - A predicate to filter the snapshots
    /// * `p` - A progress bar to use
    ///
    /// # Errors
    ///
    /// * If no snapshots are found
    pub(crate) fn latest<B: DecryptReadBackend>(
        be: &B,
        predicate: impl FnMut(&Self) -> bool + Send + Sync,
        p: &Progress,
    ) -> RusticResult<Self> {
        Self::latest_n(be, predicate, p, 0)
    }

    fn latest_n_from_iter(
        n: usize,
        iter: impl IntoIterator<Item = Self>,
    ) -> RusticResult<Vec<Self>> {
        let latest: Vec<_> = iter
            .into_iter()
            // find n+1 smallest elements when sorting in decreasing time order
            .k_smallest_by(n + 1, |s1, s2| s2.time.cmp(&s1.time))
            .collect();

        if latest.len() > n {
            Ok(latest)
        } else if n == 0 {
            Err(RusticError::new(
                ErrorKind::Repository,
                "No snapshots found. Please make sure there are snapshots in the repository.",
            ))
        } else {
            Err(RusticError::new(
                ErrorKind::Repository,
                "No snapshots found for latest~{n}. Please make sure there are more than {n} snapshots in the repository.",
            ).attach_context("n", n.to_string()))
        }
    }

    /// Get the latest [`SnapshotFile`] from the backend
    ///
    /// # Arguments
    ///
    /// * `be` - The backend to use
    /// * `predicate` - A predicate to filter the snapshots
    /// * `p` - A progress bar to use
    /// * `n` - The n-latest index to go back for snapshot
    ///
    /// # Errors
    ///
    /// * If no snapshots are found
    pub(crate) fn latest_n<B: DecryptReadBackend>(
        be: &B,
        predicate: impl FnMut(&Self) -> bool + Send + Sync,
        p: &Progress,
        n: usize,
    ) -> RusticResult<Self> {
        if n == 0 {
            p.set_title("getting latest snapshot...");
        } else {
            p.set_title("getting latest~N snapshot...");
        }
        let mut snapshots =
            Self::latest_n_from_iter(n, Self::iter_all_from_backend(be, predicate, p)?)?;

        p.finish();
        Ok(snapshots.pop().unwrap()) // we want the latest element if we found n+1 snapshots
    }

    /// Get a [`SnapshotFile`] from the backend by (part of the) id
    ///
    /// # Arguments
    ///
    /// * `be` - The backend to use
    /// * `id` - The (part of the) id of the snapshot
    ///
    /// # Errors
    ///
    /// * If the string is not a valid hexadecimal string
    /// * If no id could be found.
    /// * If the id is not unique.
    pub(crate) fn from_id<B: DecryptReadBackend>(be: &B, id: &str) -> RusticResult<Self> {
        info!("getting snapshot ...");
        let id = be.find_id(FileType::Snapshot, id)?;
        Self::from_backend(be, &SnapshotId::from(id))
    }

    /// Get a list of [`SnapshotFile`]s from the backend by supplying a list of/parts of their Ids
    ///
    /// # Arguments
    ///
    /// * `be` - The backend to use
    /// * `ids` - The list of (parts of the) ids of the snapshots
    /// * `p` - A progress bar to use
    ///
    /// # Errors
    ///
    /// * If the string is not a valid hexadecimal string
    /// * If no id could be found.
    /// * If the id is not unique.
    pub(crate) fn from_ids<B: DecryptReadBackend, T: AsRef<str>>(
        be: &B,
        ids: &[T],
        p: &Progress,
    ) -> RusticResult<Vec<Self>> {
        Self::update_from_ids(be, Vec::new(), ids, p)
    }

    /// Update a list of [`SnapshotFile`]s from the backend by supplying a list of/parts of their Ids
    ///
    /// # Arguments
    ///
    /// * `be` - The backend to use
    /// * `ids` - The list of (parts of the) ids of the snapshots
    /// * `p` - A progress bar to use
    ///
    /// # Errors
    ///
    /// * If the string is not a valid hexadecimal string
    /// * If no id could be found.
    /// * If the id is not unique.
    pub(crate) fn update_from_ids<B: DecryptReadBackend, T: AsRef<str>>(
        be: &B,
        current: Vec<Self>,
        ids: &[T],
        p: &Progress,
    ) -> RusticResult<Vec<Self>> {
        let ids = be.find_ids(FileType::Snapshot, ids)?;
        Self::fill_missing(be, current, &ids, |_| true, p)
    }

    // helper func
    fn fill_missing<B, F>(
        be: &B,
        current: Vec<Self>,
        ids: &[Id],
        mut filter: F,
        p: &Progress,
    ) -> RusticResult<Vec<Self>>
    where
        B: DecryptReadBackend,
        F: FnMut(&Self) -> bool,
    {
        let mut snaps: BTreeMap<_, _> = current.into_iter().map(|snap| (snap.id, snap)).collect();
        let missing_ids: Vec<_> = ids
            .iter()
            .map(|id| SnapshotId::from(*id))
            .filter(|id| !snaps.contains_key(id))
            .collect();
        for res in be.stream_list::<Self>(&missing_ids, p)? {
            let (id, snap) = res?;
            if filter(&snap) {
                let _ = snaps.insert(id, snap);
            }
        }
        // sort back to original order + handle duplicates
        Ok(ids
            .iter()
            .filter_map(|id| {
                let id = SnapshotId::from(*id);
                snaps.get(&id).map(|sn| Self::set_id((id, sn.clone())))
            })
            .collect())
    }

    // TODO: add documentation!
    pub(crate) fn iter_all_from_backend<B, F>(
        be: &B,
        filter: F,
        p: &Progress,
    ) -> RusticResult<impl Iterator<Item = Self>>
    where
        B: DecryptReadBackend,
        F: FnMut(&Self) -> bool,
    {
        Ok(be
            .stream_all::<Self>(p)?
            .into_iter()
            .map(|item| item.inspect_err(|err| warn!("Error reading snapshot: {err}")))
            .filter_map(Result::ok)
            .map(Self::set_id)
            .filter(filter))
    }

    // TODO: add documentation!
    pub(crate) fn update_from_backend<B, F>(
        be: &B,
        current: Vec<Self>,
        filter: F,
        p: &Progress,
    ) -> RusticResult<Vec<Self>>
    where
        B: DecryptReadBackend,
        F: FnMut(&Self) -> bool,
    {
        let ids = be.list(FileType::Snapshot)?;
        Self::fill_missing(be, current, &ids, filter, p)
    }

    /// Add tag lists to snapshot.
    ///
    /// # Arguments
    ///
    /// * `tag_lists` - The tag lists to add
    ///
    /// # Returns
    ///
    /// Returns whether snapshot was changed.
    pub fn add_tags(&mut self, tag_lists: Vec<StringList>) -> bool {
        let old_tags = self.tags.clone();
        self.tags.add_all(tag_lists);

        old_tags != self.tags
    }

    /// Set tag lists to snapshot.
    ///
    /// # Arguments
    ///
    /// * `tag_lists` - The tag lists to set
    ///
    /// # Returns
    ///
    /// Returns whether snapshot was changed.
    pub fn set_tags(&mut self, tag_lists: Vec<StringList>) -> bool {
        let old_tags = std::mem::take(&mut self.tags);
        self.tags.add_all(tag_lists);

        old_tags != self.tags
    }

    /// Remove tag lists from snapshot.
    ///
    /// # Arguments
    ///
    /// * `tag_lists` - The tag lists to remove
    ///
    /// # Returns
    ///
    /// Returns whether snapshot was changed.
    pub fn remove_tags(&mut self, tag_lists: &[StringList]) -> bool {
        let old_tags = self.tags.clone();
        self.tags.remove_all(tag_lists);

        old_tags != self.tags
    }

    /// Returns whether a snapshot must be deleted now
    ///
    /// # Arguments
    ///
    /// * `now` - The current time
    #[must_use]
    pub fn must_delete(&self, now: &Zoned) -> bool {
        matches!(&self.delete, DeleteOption::After(time) if time < now)
    }

    /// Returns whether a snapshot must be kept now
    ///
    /// # Arguments
    ///
    /// * `now` - The current time
    #[must_use]
    pub fn must_keep(&self, now: &Zoned) -> bool {
        match &self.delete {
            DeleteOption::Never => true,
            DeleteOption::After(time) if time >= now => true,
            _ => false,
        }
    }

    /// Modifies the snapshot according to a [`SnapshotModification`].
    ///
    /// # Arguments
    ///
    /// * `modification` - The modification(s) to make
    ///
    /// # Returns
    ///
    /// `true` if the snapshot was changed.
    ///
    /// # Errors
    /// if reading a description from a file failed
    pub fn modify(&mut self, modification: &SnapshotModification) -> RusticResult<bool> {
        modification.apply_to(self)
    }

    /// Clear ids which are not saved by the copy command (and not compared when checking if snapshots already exist in the copy target)
    ///
    /// # Arguments
    ///
    /// * `sn` - The snapshot to clear the ids from
    #[must_use]
    pub(crate) fn clear_ids(mut sn: Self) -> Self {
        sn.id = SnapshotId::default();
        sn.parent = None;
        sn.parents = Vec::new();
        sn
    }

    /// Convenience method to get parent snapshots which are stored in the `parent` or `parents` field.
    #[must_use]
    pub fn get_parents(&self) -> &[SnapshotId] {
        if self.parents.is_empty() {
            self.parent.as_slice()
        } else {
            &self.parents
        }
    }
}

impl PartialEq<Self> for SnapshotFile {
    fn eq(&self, other: &Self) -> bool {
        self.time.eq(&other.time)
    }
}

impl Eq for SnapshotFile {}

impl PartialOrd for SnapshotFile {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}
impl Ord for SnapshotFile {
    fn cmp(&self, other: &Self) -> Ordering {
        self.time.cmp(&other.time)
    }
}

/// `StringList` is a rustic-internal list of Strings. It is used within [`SnapshotFile`]
#[derive(Serialize, Deserialize, Default, Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
pub struct StringList(pub(crate) BTreeSet<String>);

impl FromStr for StringList {
    type Err = SnapshotFileErrorKind;
    fn from_str(s: &str) -> SnapshotFileResult<Self> {
        Ok(Self(s.split(',').map(ToString::to_string).collect()))
    }
}

impl Display for StringList {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.0.iter().join(","))?;
        Ok(())
    }
}

impl StringList {
    /// Returns whether a [`StringList`] contains a given String.
    ///
    /// # Arguments
    ///
    /// * `s` - The String to check
    #[must_use]
    pub fn contains(&self, s: &str) -> bool {
        self.0.contains(s)
    }

    /// Returns whether a [`StringList`] contains all Strings of another [`StringList`].
    ///
    /// # Arguments
    ///
    /// * `sl` - The [`StringList`] to check
    #[must_use]
    pub fn contains_all(&self, sl: &Self) -> bool {
        sl.0.is_subset(&self.0)
    }

    /// Returns whether a [`StringList`] matches a list of [`StringList`]s,
    /// i.e. whether it contains all Strings of one the given [`StringList`]s.
    ///
    /// # Arguments
    ///
    /// * `sls` - The list of [`StringList`]s to check
    #[must_use]
    pub fn matches(&self, sls: &[Self]) -> bool {
        sls.is_empty() || sls.iter().any(|sl| self.contains_all(sl))
    }

    /// Add a String to a [`StringList`].
    ///
    /// # Arguments
    ///
    /// * `s` - The String to add
    pub fn add(&mut self, s: String) {
        _ = self.0.insert(s);
    }

    /// Add all Strings from another [`StringList`] to this [`StringList`].
    ///
    /// # Arguments
    ///
    /// * `sl` - The [`StringList`] to add
    pub fn add_list(&mut self, mut sl: Self) {
        self.0.append(&mut sl.0);
    }

    /// Add all Strings from all given [`StringList`]s to this [`StringList`].
    ///
    /// # Arguments
    ///
    /// * `string_lists` - The [`StringList`]s to add
    pub fn add_all(&mut self, string_lists: Vec<Self>) {
        for sl in string_lists {
            self.add_list(sl);
        }
    }

    /// Adds the given Paths as Strings to this [`StringList`].
    ///
    /// # Arguments
    ///
    /// * `paths` - The Paths to add
    ///
    /// # Errors
    ///
    /// * If a path is not valid unicode
    pub(crate) fn set_paths<T: AsRef<Path>>(&mut self, paths: &[T]) -> SnapshotFileResult<()> {
        self.0 = paths
            .iter()
            .map(|p| {
                Ok(p.as_ref()
                    .to_str()
                    .ok_or_else(|| SnapshotFileErrorKind::NonUnicodePath(p.as_ref().to_path_buf()))?
                    .to_string())
            })
            .collect::<SnapshotFileResult<BTreeSet<_>>>()?;
        Ok(())
    }

    /// Remove all Strings from all given [`StringList`]s from this [`StringList`].
    ///
    /// # Arguments
    ///
    /// * `string_lists` - The [`StringList`]s to remove
    pub fn remove_all(&mut self, string_lists: &[Self]) {
        for sl in string_lists {
            self.0 = &self.0 - &sl.0;
        }
    }

    #[allow(clippy::needless_pass_by_ref_mut)]
    #[deprecated(note = "StringLists are now automatically sorted")]
    /// Sort the Strings in the [`StringList`]
    pub fn sort(&mut self) {}

    /// Format this [`StringList`] using newlines
    #[must_use]
    pub fn formatln(&self) -> String {
        self.0.iter().join("\n")
    }

    /// Turn this [`StringList`] into an Iterator
    pub fn iter(&self) -> impl Iterator<Item = &String> {
        self.0.iter()
    }
}

impl<'str> IntoIterator for &'str StringList {
    type Item = &'str String;
    type IntoIter = std::collections::btree_set::Iter<'str, String>;

    fn into_iter(self) -> Self::IntoIter {
        self.0.iter()
    }
}

/// `PathList` is a rustic-internal list of `PathBuf`s. It is used in the [`crate::Repository::backup`] command.
#[derive(Default, Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
pub struct PathList(Vec<PathBuf>);

impl Display for PathList {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0
            .iter()
            .map(|p| p.to_string_lossy())
            .format(",")
            .fmt(f)
    }
}

impl<T: Into<PathBuf>> FromIterator<T> for PathList {
    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
        Self(iter.into_iter().map(T::into).collect())
    }
}

impl PathList {
    /// Create a `PathList` from a String containing a single path
    /// Note: for multiple paths, use `PathList::from_iter`.
    ///
    /// # Arguments
    ///
    /// * `source` - The String to parse
    ///
    /// # Errors
    ///
    /// * no errors can occur here
    /// * [`RusticResult`] is used for consistency and future compatibility
    pub fn from_string(source: &str) -> RusticResult<Self> {
        Ok(Self(vec![source.into()]))
    }

    /// Number of paths in the `PathList`.
    #[must_use]
    pub fn len(&self) -> usize {
        self.0.len()
    }

    /// Returns whether the `PathList` is empty.
    #[must_use]
    pub fn is_empty(&self) -> bool {
        self.0.len() == 0
    }

    /// Clone the internal `Vec<PathBuf>`.
    #[must_use]
    pub(crate) fn paths(&self) -> Vec<PathBuf> {
        self.0.clone()
    }

    /// Sanitize paths: Parse dots, absolutize if needed and merge paths.
    ///
    /// # Errors
    ///
    /// * If removing dots from path failed
    /// * If canonicalizing path failed
    pub fn sanitize(mut self) -> SnapshotFileResult<Self> {
        for path in &mut self.0 {
            *path = sanitize_dot(path)?;
        }
        if self.0.iter().any(|p| p.is_absolute()) {
            self.0 = self
                .0
                .into_iter()
                .map(|p| canonicalize(p).map_err(SnapshotFileErrorKind::CanonicalizingPathFailed))
                .collect::<Result<_, _>>()?;
        }
        Ok(self.merge())
    }

    /// Sort paths and filters out subpaths of already existing paths.
    #[must_use]
    pub fn merge(self) -> Self {
        let mut paths = self.0;
        // sort paths
        paths.sort_unstable();

        let mut root_path = None;

        // filter out subpaths
        paths.retain(|path| match &root_path {
            Some(root_path) if path.starts_with(root_path) => false,
            _ => {
                root_path = Some(path.clone());
                true
            }
        });

        Self(paths)
    }
}

// helper function to sanitize paths containing dots
fn sanitize_dot(path: &Path) -> SnapshotFileResult<PathBuf> {
    if path == Path::new(".") || path == Path::new("./") {
        return Ok(PathBuf::from("."));
    }

    let path = if path.starts_with("./") {
        path.strip_prefix("./").unwrap()
    } else {
        path
    };

    let path = path
        .parse_dot()
        .map_err(SnapshotFileErrorKind::RemovingDotsFromPathFailed)?
        .to_path_buf();

    Ok(path)
}

#[cfg(test)]
mod tests {
    use std::{collections::HashMap, sync::Arc};

    use super::*;
    use crate::{
        backend::{
            MockBackend,
            decrypt::{DecryptBackend, DecryptWriteBackend},
        },
        crypto::{CryptoKey, aespoly1305::Key},
        progress::NoProgress,
    };
    use anyhow::Result;
    use bytes::Bytes;
    use jiff::{Timestamp, tz::TimeZone};
    use rstest::rstest;

    #[rstest]
    #[case(".", ".")]
    #[case("./", ".")]
    #[case("test", "test")]
    #[case("test/", "test")]
    #[case("./test", "test")]
    #[case("./test/", "test")]
    fn sanitize_dot_cases(#[case] input: &str, #[case] expected: &str) {
        let path = Path::new(input);
        let expected = PathBuf::from(expected);

        assert_eq!(expected, sanitize_dot(path).unwrap());
    }

    #[rstest]
    #[case("abc", vec!["abc".to_string()])]
    #[case("abc,def", vec!["abc".to_string(), "def".to_string()])]
    #[case("abc,abc", vec!["abc".to_string()])]
    fn test_set_tags(#[case] tag: &str, #[case] expected: Vec<String>) -> Result<()> {
        let mut snap = SnapshotFile::from_options(&SnapshotOptions::default())?;
        let tags = StringList::from_str(tag)?;
        let expected = StringList(expected.into_iter().collect());
        assert!(snap.set_tags(vec![tags]));
        assert_eq!(snap.tags, expected);
        Ok(())
    }

    #[test]
    fn test_add_tags() -> Result<()> {
        let tags = vec![StringList::from_str("abc")?];
        let mut snap = SnapshotFile::from_options(&SnapshotOptions::default().tags(tags))?;
        let tags = StringList::from_str("def,abc")?;
        assert!(snap.add_tags(vec![tags]));
        let expected = StringList::from_str("abc,def")?;
        assert_eq!(snap.tags, expected);
        Ok(())
    }

    #[rstest]
    #[case(vec![], "")]
    #[case(vec!["test"], "test")]
    #[case(vec!["test", "test", "test"], "test,test,test")]
    fn test_display_path_list_passes(#[case] input: Vec<&str>, #[case] expected: &str) {
        let path_list = PathList::from_iter(input);
        let result = path_list.to_string();
        assert_eq!(expected, &result);
    }

    fn fake_snapshot_file_with_id_time(
        id_time_vec: Vec<(Id, Zoned)>,
        key: &Key,
    ) -> HashMap<Id, Bytes> {
        let mut res = HashMap::new();
        for (id, time) in id_time_vec {
            let snapshot_file = SnapshotFile {
                id: SnapshotId(id),
                time,
                ..Default::default()
            };
            let encrypted = Bytes::from(
                key.encrypt_data(serde_json::to_string(&snapshot_file).unwrap().as_bytes())
                    .unwrap(),
            );
            let _ = res.insert(id, encrypted);
        }
        res
    }

    fn setup_mock_backend() -> (DecryptBackend<Key>, [Id; 3]) {
        let key = Key::new();

        let id1 = Id::from_str("0011223344556677001122334455667700112233445566770000000000000001")
            .unwrap();
        let id2 = Id::from_str("0021223344556677001122334455667700112233445566770000000000000002")
            .unwrap();
        let id3 = Id::from_str("0031223344556677001122334455667700112233445566770000000000000003")
            .unwrap();

        let snapshot_files = fake_snapshot_file_with_id_time(
            vec![
                (
                    id1,
                    Timestamp::from_second(1_752_483_600)
                        .unwrap()
                        .to_zoned(TimeZone::UTC),
                ),
                (
                    id2,
                    Timestamp::from_second(1_752_483_700)
                        .unwrap()
                        .to_zoned(TimeZone::UTC),
                ),
                // this is the latest
                (
                    id3,
                    Timestamp::from_second(1_752_483_800)
                        .unwrap()
                        .to_zoned(TimeZone::UTC),
                ),
            ],
            &key,
        );
        let mut back = MockBackend::new();
        let _ = back.expect_list_with_size().returning(move |_| {
            // unordered ids
            Ok(vec![(id2, 0), (id3, 0), (id1, 0)])
        });
        let _ = back
            .expect_read_full()
            .returning(move |_tpe, id| Ok(snapshot_files.get(id).unwrap().clone()));

        let mut be = DecryptBackend::new(Arc::new(back), key);
        be.set_zstd(None);

        (be, [id1, id2, id3])
    }

    #[rstest]
    fn test_snapshot_file_latest() {
        let p = Progress::new(NoProgress);
        let (be, [id1, id2, id3]) = setup_mock_backend();
        let latest = SnapshotFile::latest(&be, |_sn| true, &p).unwrap();
        assert_eq!(latest.id, SnapshotId(id3));

        let latest_n0 = SnapshotFile::latest_n(&be, |_sn| true, &p, 0).unwrap();
        assert_eq!(latest_n0, latest);

        let latest_n1 = SnapshotFile::latest_n(&be, |_sn| true, &p, 1).unwrap();
        assert_eq!(latest_n1.id, SnapshotId(id2));

        let latest_n2 = SnapshotFile::latest_n(&be, |_sn| true, &p, 2).unwrap();
        assert_eq!(latest_n2.id, SnapshotId(id1));

        let latest_n3 = SnapshotFile::latest_n(&be, |_sn| true, &p, 3);
        let latest_n3_err = latest_n3.unwrap_err().to_string();
        let expected = "No snapshots found for latest~3.";
        assert!(
            latest_n3_err.contains(expected),
            "Err is: {latest_n3_err}\n\nShould contain: {expected}",
        );
    }

    #[rstest]
    fn test_snapshot_file_from_str() {
        let p = Progress::new(NoProgress);
        let (be, [id1, id2, id3]) = setup_mock_backend();

        let latest = SnapshotFile::from_str(&be, "latest", |_sn| true, &p).unwrap();
        assert_eq!(latest.id, SnapshotId(id3));

        let latest_n0 = SnapshotFile::from_str(&be, "latest~0", |_sn| true, &p).unwrap();
        assert_eq!(latest_n0, latest);

        let snap_id3 = SnapshotFile::from_str(
            &be,
            "0031223344556677001122334455667700112233445566770000000000000003",
            |_sn| true,
            &p,
        )
        .unwrap();
        assert_eq!(latest, snap_id3);

        let snap_id3 = SnapshotFile::from_str(&be, "003", |_sn| true, &p).unwrap();
        assert_eq!(latest, snap_id3);

        let latest_n1 = SnapshotFile::from_str(&be, "latest~1", |_sn| true, &p).unwrap();
        assert_eq!(latest_n1.id, SnapshotId(id2));

        let latest_n2 = SnapshotFile::from_str(&be, "latest~2", |_sn| true, &p).unwrap();
        assert_eq!(latest_n2.id, SnapshotId(id1));

        let latest_n3 = SnapshotFile::from_str(&be, "latest~3", |_sn| true, &p);
        let latest_n3_err = latest_n3.unwrap_err().to_string();
        let expected = "No snapshots found for latest~3.";
        assert!(
            latest_n3_err.contains(expected),
            "Err is: {latest_n3_err}\n\nShould contain: {expected}",
        );

        let latest_syntax_err = SnapshotFile::from_str(&be, "laztet~1", |_sn| true, &p)
            .unwrap_err()
            .to_string();
        let expected = "No suitable id found for `laztet~1`.";
        assert!(
            latest_syntax_err.contains(expected),
            "Err is: {latest_syntax_err}\n\nShould contain: {expected}",
        );
    }

    #[rstest]
    fn test_snapshot_file_from_strs() {
        let p = Progress::new(NoProgress);
        let (be, [id1, id2, id3]) = setup_mock_backend();

        // all kind of requests mixed
        let snaps = SnapshotFile::from_strs(
            &be,
            &[
                "latest~2",
                "002",
                "0031223344556677001122334455667700112233445566770000000000000003",
            ],
            |_sn| true,
            &p,
        )
        .unwrap();
        let ids: Vec<_> = snaps.iter().map(|sn| *sn.id).collect();
        assert_eq!(ids, vec![id1, id2, id3]);

        // all kind of requests mixed, with duplicates
        let snaps = SnapshotFile::from_strs(
            &be,
            &[
                "0021223344556677001122334455667700112233445566770000000000000002",
                "latest~1",
                "001",
            ],
            |_sn| true,
            &p,
        )
        .unwrap();
        let ids: Vec<_> = snaps.iter().map(|sn| *sn.id).collect();
        assert_eq!(ids, vec![id2, id2, id1]);

        // typical "last two" request
        let snaps = SnapshotFile::from_strs(&be, &["latest", "latest~1"], |_sn| true, &p).unwrap();
        let ids: Vec<_> = snaps.iter().map(|sn| *sn.id).collect();
        assert_eq!(ids, vec![id3, id2]);

        // not enough latest snapshots
        let latest_n3 = SnapshotFile::from_strs(&be, &["003", "latest~3"], |_sn| true, &p);
        let latest_n3_err = latest_n3.unwrap_err().to_string();
        let expected = "No snapshots found for latest~3.";
        assert!(
            latest_n3_err.contains(expected),
            "Err is: {latest_n3_err}\n\nShould contain: {expected}",
        );

        // only (parts of) ids
        let snaps = SnapshotFile::from_strs(
            &be,
            &[
                "0031223344556677001122334455667700112233445566770000000000000003",
                "001",
            ],
            |_sn| true,
            &p,
        )
        .unwrap();
        let ids: Vec<_> = snaps.iter().map(|sn| *sn.id).collect();
        assert_eq!(ids, vec![id3, id1]);

        // only full ids
        let snaps = SnapshotFile::from_strs(
            &be,
            &[
                "0031223344556677001122334455667700112233445566770000000000000003",
                "0011223344556677001122334455667700112233445566770000000000000001",
                "0031223344556677001122334455667700112233445566770000000000000003",
            ],
            |_sn| true,
            &p,
        )
        .unwrap();
        let ids: Vec<_> = snaps.iter().map(|sn| *sn.id).collect();
        assert_eq!(ids, vec![id3, id1, id3]);
    }
}