use std::path::Path;
use walkdir::DirEntry;

/// Supported image file extensions
pub const IMAGE_EXTENSIONS: &[&str] = &[
    "jpg", "jpeg", "png", "webp", "tiff", "tif", "heif", "heic", "avif", "nef", "arw",
];

/// Extensions the `image` crate cannot decode — we fall back to ffmpeg to
/// extract an embedded preview or decode the frame.
pub const FFMPEG_THUMBNAIL_EXTENSIONS: &[&str] = &["heif", "heic", "nef", "arw"];

/// Returns true if thumbnail generation should go through ffmpeg instead of
/// the `image` crate (RAW formats, HEIF/HEIC).
pub fn needs_ffmpeg_thumbnail(path: &Path) -> bool {
    match path.extension().and_then(|e| e.to_str()) {
        Some(ext) => FFMPEG_THUMBNAIL_EXTENSIONS.contains(&ext.to_lowercase().as_str()),
        None => false,
    }
}

/// Supported video file extensions
pub const VIDEO_EXTENSIONS: &[&str] = &["mp4", "mov", "avi", "mkv"];

/// Audio file extensions accepted as voice-clone references (TTS). Mirrors
/// the formats Chatterbox can decode (wav/mp3/flac/m4a/aac/ogg).
pub const AUDIO_EXTENSIONS: &[&str] = &["wav", "mp3", "flac", "m4a", "aac", "ogg", "oga", "opus"];

/// Filenames that are filesystem metadata, not real media — exact
/// basename match. Extend if a new platform sidecar appears (Windows
/// Thumbs.db / desktop.ini live here too if those libraries land).
const METADATA_FILENAMES: &[&str] = &[".DS_Store"];

/// True if the basename is a filesystem metadata sidecar that should be
/// invisible to every media predicate.
///
/// macOS writes `._<name>` AppleDouble companions when copying to
/// non-HFS volumes — each holds the extended attributes of `<name>`,
/// NOT a copy of the bytes. Same extension as the real file, so a
/// pure-extension match treats `._photo.jpg` as a JPEG, ships it to
/// the decoder, and accumulates failed rows: face_detections
/// `status='failed'`, clip_embedding `status='failed'`, plus a
/// pointless `image_exif` row whose `content_hash` will be the hash
/// of the metadata blob. The downstream noise (failed-row counts that
/// never go to zero, 422 bursts to Apollo, evictor timer reset by
/// those 422s) is the visible damage. `.DS_Store` is the per-directory
/// version (Finder view state) — no extension, but cheap to guard
/// here too in case some future predicate matches by content type.
pub fn is_filesystem_metadata(path: &Path) -> bool {
    let Some(name) = path.file_name().and_then(|n| n.to_str()) else {
        return false;
    };
    name.starts_with("._") || METADATA_FILENAMES.contains(&name)
}

/// Check if a path has an image extension
pub fn is_image_file(path: &Path) -> bool {
    if is_filesystem_metadata(path) {
        return false;
    }
    if let Some(ext) = path.extension().and_then(|e| e.to_str()) {
        let ext_lower = ext.to_lowercase();
        IMAGE_EXTENSIONS.contains(&ext_lower.as_str())
    } else {
        false
    }
}

/// Check if a path has a video extension
pub fn is_video_file(path: &Path) -> bool {
    if is_filesystem_metadata(path) {
        return false;
    }
    if let Some(ext) = path.extension().and_then(|e| e.to_str()) {
        let ext_lower = ext.to_lowercase();
        VIDEO_EXTENSIONS.contains(&ext_lower.as_str())
    } else {
        false
    }
}

/// Check if a path has an audio extension (voice-clone references)
pub fn is_audio_file(path: &Path) -> bool {
    if is_filesystem_metadata(path) {
        return false;
    }
    if let Some(ext) = path.extension().and_then(|e| e.to_str()) {
        let ext_lower = ext.to_lowercase();
        AUDIO_EXTENSIONS.contains(&ext_lower.as_str())
    } else {
        false
    }
}

/// Check if a path has a supported media extension (image or video)
pub fn is_media_file(path: &Path) -> bool {
    is_image_file(path) || is_video_file(path)
}

/// Check if a DirEntry is an image file (for walkdir usage)
#[allow(dead_code)]
pub fn direntry_is_image(entry: &DirEntry) -> bool {
    is_image_file(entry.path())
}

/// Check if a DirEntry is a video file (for walkdir usage)
#[allow(dead_code)]
pub fn direntry_is_video(entry: &DirEntry) -> bool {
    is_video_file(entry.path())
}

/// Check if a DirEntry is a media file (for walkdir usage)
#[allow(dead_code)]
pub fn direntry_is_media(entry: &DirEntry) -> bool {
    is_media_file(entry.path())
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::path::Path;

    #[test]
    fn test_is_image_file() {
        assert!(is_image_file(Path::new("photo.jpg")));
        assert!(is_image_file(Path::new("photo.JPG")));
        assert!(is_image_file(Path::new("photo.png")));
        assert!(is_image_file(Path::new("photo.nef")));
        assert!(!is_image_file(Path::new("video.mp4")));
        assert!(!is_image_file(Path::new("document.txt")));
    }

    #[test]
    fn test_is_video_file() {
        assert!(is_video_file(Path::new("video.mp4")));
        assert!(is_video_file(Path::new("video.MP4")));
        assert!(is_video_file(Path::new("video.mov")));
        assert!(is_video_file(Path::new("video.avi")));
        assert!(!is_video_file(Path::new("photo.jpg")));
        assert!(!is_video_file(Path::new("document.txt")));
    }

    #[test]
    fn test_is_media_file() {
        assert!(is_media_file(Path::new("photo.jpg")));
        assert!(is_media_file(Path::new("video.mp4")));
        assert!(is_media_file(Path::new("photo.PNG")));
        assert!(!is_media_file(Path::new("document.txt")));
        assert!(!is_media_file(Path::new("no_extension")));
    }

    #[test]
    fn test_apple_double_excluded_from_media() {
        // The bug-of-record: ImageApi was shipping macOS AppleDouble
        // sidecars to Apollo's CLIP/face decoders, accumulating failed
        // rows and pinning Apollo's eviction timer with the 422 burst.
        // Predicate-level guard means every downstream walker
        // (face_watch, backfill, clip_watch, watcher) inherits the fix
        // without touching their filters.
        assert!(!is_image_file(Path::new("._photo.jpg")));
        assert!(!is_image_file(Path::new("dir/._photo.JPG")));
        assert!(!is_image_file(Path::new("a/b/._DSC_2182-S.jpg")));
        assert!(!is_video_file(Path::new("._video.mp4")));
        assert!(!is_media_file(Path::new("._photo.png")));
        // A real file that merely starts with "_" (no leading dot) is
        // not AppleDouble — must NOT be filtered.
        assert!(is_image_file(Path::new("_photo.jpg")));
    }

    #[test]
    fn test_ds_store_excluded() {
        // Finder per-directory metadata. No image extension so
        // is_image_file would already say false; the guard makes the
        // predicate's *reason* explicit and covers a hypothetical
        // future caller matching by basename.
        assert!(!is_image_file(Path::new(".DS_Store")));
        assert!(!is_video_file(Path::new(".DS_Store")));
        assert!(!is_media_file(Path::new("some/dir/.DS_Store")));
        assert!(is_filesystem_metadata(Path::new(".DS_Store")));
        assert!(is_filesystem_metadata(Path::new("dir/.DS_Store")));
    }

    #[test]
    fn test_dotfiles_other_than_apple_double_are_unaffected() {
        // We deliberately scope to `._*` + the exact .DS_Store name —
        // not all dotfiles — because a user could plausibly name a
        // cover image `.cover.jpg` and we shouldn't silently drop it.
        // If that turns out to be wrong, broaden here; for now,
        // narrow + explicit > broad + surprising.
        assert!(is_image_file(Path::new(".cover.jpg")));
        assert!(!is_filesystem_metadata(Path::new(".cover.jpg")));
    }
}