weavatrix-scan 0.4.6

use crate::report::FileVersion;
use std::ffi::OsStr;
use std::fmt;
use std::io;
use std::path::{Path, PathBuf};

mod entry;

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub(crate) struct FileSystemId(pub(crate) u64);

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub(crate) struct DirectoryIdentity {
    pub(crate) file_system: FileSystemId,
    pub(crate) file: u64,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ErrorPolicy {
    Continue,
    Abort,
}

/// Controls whether the explicitly supplied root itself may be a symlink.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum RootSymlinkPolicy {
    /// Resolve or traverse the requested root for backward compatibility.
    Follow,
    /// Reject a symlink at the final root path component.
    Reject,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct WalkOptions {
    pub min_depth: usize,
    pub max_depth: Option<usize>,
    pub max_open: usize,
    pub same_file_system: bool,
    pub follow_links: bool,
    pub collect_metadata: bool,
    pub error_policy: ErrorPolicy,
    pub root_symlink_policy: RootSymlinkPolicy,
}

impl Default for WalkOptions {
    fn default() -> Self {
        Self {
            min_depth: 0,
            max_depth: None,
            max_open: Self::DEFAULT_MAX_OPEN,
            same_file_system: false,
            follow_links: false,
            collect_metadata: false,
            error_policy: ErrorPolicy::Continue,
            root_symlink_policy: RootSymlinkPolicy::Follow,
        }
    }
}

impl WalkOptions {
    /// Default hard upper bound for simultaneously open directory handles.
    pub const DEFAULT_MAX_OPEN: usize = 64;

    #[must_use]
    pub const fn with_min_depth(mut self, min_depth: usize) -> Self {
        self.min_depth = min_depth;
        self
    }

    #[must_use]
    pub const fn with_max_depth(mut self, max_depth: Option<usize>) -> Self {
        self.max_depth = max_depth;
        self
    }

    #[must_use]
    pub const fn with_max_open(mut self, max_open: usize) -> Self {
        self.max_open = if max_open == 0 { 1 } else { max_open };
        self
    }

    #[must_use]
    pub const fn with_same_file_system(mut self, enabled: bool) -> Self {
        self.same_file_system = enabled;
        self
    }

    #[must_use]
    pub const fn with_follow_links(mut self, enabled: bool) -> Self {
        self.follow_links = enabled;
        self
    }

    #[must_use]
    pub const fn with_metadata(mut self, enabled: bool) -> Self {
        self.collect_metadata = enabled;
        self
    }

    #[must_use]
    pub const fn with_error_policy(mut self, policy: ErrorPolicy) -> Self {
        self.error_policy = policy;
        self
    }

    #[must_use]
    pub const fn with_root_symlink_policy(mut self, policy: RootSymlinkPolicy) -> Self {
        self.root_symlink_policy = policy;
        self
    }

    pub(crate) fn normalized(mut self) -> Self {
        self.max_open = self.max_open.max(1);
        if let Some(max_depth) = self.max_depth
            && self.min_depth > max_depth
        {
            self.min_depth = max_depth;
        }
        self
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum WalkOperation {
    Canonicalize,
    ReadDirectory,
    ReadEntry,
    ReadMetadata,
    ScheduleWorker,
}

#[derive(Debug)]
pub struct WalkError {
    pub(crate) path: PathBuf,
    pub(crate) depth: usize,
    pub(crate) operation: WalkOperation,
    pub(crate) source: io::Error,
}

impl WalkError {
    pub(crate) fn new(
        path: impl Into<PathBuf>,
        depth: usize,
        operation: WalkOperation,
        source: io::Error,
    ) -> Self {
        Self {
            path: path.into(),
            depth,
            operation,
            source,
        }
    }

    #[must_use]
    pub fn path(&self) -> &Path {
        &self.path
    }

    #[must_use]
    pub const fn depth(&self) -> usize {
        self.depth
    }

    #[must_use]
    pub const fn operation(&self) -> WalkOperation {
        self.operation
    }

    #[must_use]
    pub const fn io_error(&self) -> &io::Error {
        &self.source
    }

    pub(crate) fn into_parts(self) -> (PathBuf, io::Error) {
        (self.path, self.source)
    }

    pub(crate) fn rebase_depth(&mut self, depth_offset: usize) {
        self.depth += depth_offset;
    }
}

impl fmt::Display for WalkError {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            formatter,
            "{} at depth {} for {}: {}",
            operation_name(self.operation),
            self.depth,
            self.path.display(),
            self.source
        )
    }
}

impl std::error::Error for WalkError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        Some(&self.source)
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum WalkSkipReason {
    MaxDepth,
    FileSystemBoundary,
    PathEscape,
    SymlinkLoop,
}

#[derive(Debug, Clone)]
pub struct WalkEntry {
    pub(crate) root_components: usize,
    pub(crate) path: PathBuf,
    pub(crate) depth: usize,
    pub(crate) is_file: bool,
    pub(crate) is_directory: bool,
    pub(crate) is_symlink: bool,
    pub(crate) bytes: Option<u64>,
    pub(crate) version: Option<FileVersion>,
    pub(crate) hidden: Option<bool>,
    pub(crate) directory_identity: Option<DirectoryIdentity>,
    pub(crate) skip_reason: Option<WalkSkipReason>,
}

const fn operation_name(operation: WalkOperation) -> &'static str {
    match operation {
        WalkOperation::Canonicalize => "canonicalize",
        WalkOperation::ReadDirectory => "read directory",
        WalkOperation::ReadEntry => "read entry",
        WalkOperation::ReadMetadata => "read metadata",
        WalkOperation::ScheduleWorker => "schedule worker",
    }
}