oximedia_dedup/

metadata.rs

//! Metadata-based deduplication and fuzzy matching.
//!
//! This module provides:
//! - Filename similarity (Levenshtein distance, fuzzy matching)
//! - Duration matching with tolerance
//! - Resolution matching
//! - Codec and format matching
//! - Fuzzy metadata comparison

use crate::{DedupError, DedupResult};
use std::path::{Path, PathBuf};

/// Media metadata.
#[derive(Debug, Clone, PartialEq)]
pub struct MediaMetadata {
    /// File path
    pub path: PathBuf,

    /// File size in bytes
    pub size: u64,

    /// Human-readable title (e.g., from ID3/MP4 title tag). Used for fuzzy
    /// title matching in addition to filename comparison.
    pub title: Option<String>,

    /// Duration in seconds (for audio/video)
    pub duration: Option<f64>,

    /// Video width (if video)
    pub width: Option<u32>,

    /// Video height (if video)
    pub height: Option<u32>,

    /// Bitrate in bits per second
    pub bitrate: Option<u64>,

    /// Frame rate (if video)
    pub framerate: Option<f64>,

    /// Sample rate (if audio)
    pub sample_rate: Option<u32>,

    /// Number of audio channels
    pub channels: Option<u16>,

    /// Video codec
    pub video_codec: Option<String>,

    /// Audio codec
    pub audio_codec: Option<String>,

    /// Container format
    pub container: Option<String>,

    /// Creation timestamp
    pub created: Option<i64>,

    /// Modified timestamp
    pub modified: Option<i64>,
}

impl MediaMetadata {
    /// Create new metadata.
    #[must_use]
    pub fn new(path: PathBuf, size: u64) -> Self {
        Self {
            path,
            size,
            title: None,
            duration: None,
            width: None,
            height: None,
            bitrate: None,
            framerate: None,
            sample_rate: None,
            channels: None,
            video_codec: None,
            audio_codec: None,
            container: None,
            created: None,
            modified: None,
        }
    }

    /// Get filename without extension.
    #[must_use]
    pub fn filename(&self) -> String {
        self.path
            .file_stem()
            .and_then(|s| s.to_str())
            .unwrap_or("")
            .to_string()
    }

    /// Get file extension.
    #[must_use]
    pub fn extension(&self) -> String {
        self.path
            .extension()
            .and_then(|s| s.to_str())
            .unwrap_or("")
            .to_lowercase()
    }

    /// Get resolution as string (e.g., "1920x1080").
    #[must_use]
    pub fn resolution(&self) -> Option<String> {
        match (self.width, self.height) {
            (Some(w), Some(h)) => Some(format!("{w}x{h}")),
            _ => None,
        }
    }

    /// Check if this is a video file.
    #[must_use]
    pub fn is_video(&self) -> bool {
        self.width.is_some() && self.height.is_some()
    }

    /// Check if this is an audio file.
    #[must_use]
    pub fn is_audio(&self) -> bool {
        self.sample_rate.is_some() && !self.is_video()
    }

    /// Calculate aspect ratio.
    #[must_use]
    pub fn aspect_ratio(&self) -> Option<f64> {
        match (self.width, self.height) {
            (Some(w), Some(h)) if h > 0 => Some(f64::from(w) / f64::from(h)),
            _ => None,
        }
    }
}

/// Metadata similarity result.
#[derive(Debug, Clone)]
pub struct MetadataSimilarity {
    /// Filename similarity (0.0-1.0): multi-signal comparison of the file stem
    /// using edit distance, token Jaccard, and bigram Dice coefficient.
    pub filename_similarity: f64,

    /// Title fuzzy score (0.0-1.0): similarity of the embedded media title tag
    /// (if present) using the media-aware [`crate::fuzzy_match::FilenameMatcher`].
    /// Falls back to 0.0 when either file lacks an embedded title.
    pub title_fuzzy_score: f64,

    /// Duration match (0.0-1.0)
    pub duration_match: f64,

    /// Resolution match (0.0-1.0)
    pub resolution_match: f64,

    /// Codec match (0.0-1.0)
    pub codec_match: f64,

    /// Size similarity (0.0-1.0)
    pub size_similarity: f64,

    /// Container match (0.0 or 1.0)
    pub container_match: f64,
}

impl MetadataSimilarity {
    /// Calculate overall similarity score.
    ///
    /// Weights (sum to 1.0):
    ///
    /// | Signal               | Weight |
    /// |----------------------|--------|
    /// | name_score           |  0.30  |
    /// | duration_match       |  0.20  |
    /// | resolution_match     |  0.20  |
    /// | codec_match          |  0.15  |
    /// | size_similarity      |  0.10  |
    /// | container_match      |  0.05  |
    ///
    /// `name_score` is the maximum of `filename_similarity` and
    /// `title_fuzzy_score`. When both embedded title tags are present,
    /// `title_fuzzy_score` can lift the name signal above what the filename
    /// alone would contribute (e.g., `"Movie (1080p)"` vs `"Movie (720p)"`).
    /// When `title_fuzzy_score` is 0.0 (no title tags), the formula is
    /// identical to the original 6-signal formula.
    #[must_use]
    pub fn overall_score(&self) -> f64 {
        let name_score = self.filename_similarity.max(self.title_fuzzy_score);
        name_score * 0.30
            + self.duration_match * 0.20
            + self.resolution_match * 0.20
            + self.codec_match * 0.15
            + self.size_similarity * 0.10
            + self.container_match * 0.05
    }

    /// Check if metadata is similar above threshold.
    #[must_use]
    pub fn is_similar(&self, threshold: f64) -> bool {
        self.overall_score() >= threshold
    }
}

/// Compare two metadata objects.
///
/// When both files carry an embedded `title` tag, the title similarity is
/// computed with [`crate::fuzzy_match::FilenameMatcher`] (which strips codec /
/// resolution noise tokens). Otherwise `title_fuzzy_score` is 0.0 and the
/// overall score is identical to the pre-title-field formula.
#[must_use]
pub fn compare_metadata(meta1: &MediaMetadata, meta2: &MediaMetadata) -> MetadataSimilarity {
    let filename_similarity = compare_filenames(&meta1.filename(), &meta2.filename());
    let title_fuzzy_score = compare_titles(meta1.title.as_deref(), meta2.title.as_deref());
    let duration_match = compare_durations(meta1.duration, meta2.duration);
    let resolution_match = compare_resolutions(meta1, meta2);
    let codec_match = compare_codecs(meta1, meta2);
    let size_similarity = compare_sizes(meta1.size, meta2.size);
    let container_match = compare_containers(&meta1.container, &meta2.container);

    MetadataSimilarity {
        filename_similarity,
        title_fuzzy_score,
        duration_match,
        resolution_match,
        codec_match,
        size_similarity,
        container_match,
    }
}

/// Compare embedded media title tags using the media-aware `FilenameMatcher`.
///
/// Returns 0.0 when either title is absent (the caller decides how much weight
/// to give this signal).  Returns a value in 0.0–1.0 when both titles are set.
#[must_use]
pub fn compare_titles(title1: Option<&str>, title2: Option<&str>) -> f64 {
    match (title1, title2) {
        (Some(t1), Some(t2)) => {
            if t1.eq_ignore_ascii_case(t2) {
                return 1.0;
            }
            // Media-aware comparison strips codec / resolution noise tokens so
            // that "Movie (1080p)" and "Movie (720p)" both resolve to "Movie".
            let matcher = crate::fuzzy_match::FilenameMatcher::new(0.0);
            matcher.similarity(t1, t2).value()
        }
        // One or both titles absent — treat as unknown / neutral.
        _ => 0.0,
    }
}

/// Compare filenames using a combination of Levenshtein edit distance,
/// Jaccard token overlap, and bigram (Dice coefficient) similarity.
///
/// This multi-signal approach is robust against common filename variations:
/// - `"My Video (1080p)"` vs `"my_video_1080p"` (separators, case)
/// - `"vacation_2024_final"` vs `"vacation_2024_final_v2"` (suffixes)
/// - `"clip_001"` vs `"clip_002"` (numeric increments)
///
/// The function uses two comparison strategies and returns the **maximum**
/// of the two scores:
///
/// 1. **Raw comparison**: Normalized filenames (lowercase, collapsed separators)
///    compared via edit distance (40%), token Jaccard (35%), bigram Dice (25%).
/// 2. **Media-aware comparison**: Uses [`crate::fuzzy_match::FilenameMatcher`]
///    which strips common noise tokens (resolution tags like "1080p", codec names
///    like "x264", release markers like "BluRay") before comparing. This ensures
///    that files like `"Movie.2024.1080p.x264.mkv"` and `"Movie.2024.720p.h265.mp4"`
///    are recognized as the same content despite different encoding parameters.
#[must_use]
pub fn compare_filenames(name1: &str, name2: &str) -> f64 {
    let norm1 = normalize_filename(name1);
    let norm2 = normalize_filename(name2);

    if norm1 == norm2 {
        return 1.0;
    }

    if norm1.is_empty() || norm2.is_empty() {
        return 0.0;
    }

    // Strategy 1: Raw comparison (original logic)
    let raw_score = raw_filename_similarity(&norm1, &norm2);

    // Strategy 2: Media-aware comparison using FilenameMatcher
    // This strips codec tags, resolution markers, release-group tokens, etc.
    let matcher = crate::fuzzy_match::FilenameMatcher::new(0.0); // threshold=0 to always get a score
    let media_aware_score = matcher.similarity(name1, name2).value();

    // Return the maximum of the two strategies so that either approach
    // can detect duplicates that the other would miss.
    raw_score.max(media_aware_score)
}

/// Raw filename similarity using edit distance, token Jaccard, and bigram Dice.
fn raw_filename_similarity(norm1: &str, norm2: &str) -> f64 {
    // 1. Levenshtein edit distance score
    let distance = levenshtein_distance(norm1, norm2);
    let max_len = norm1.len().max(norm2.len());
    let edit_score = 1.0 - (distance as f64 / max_len as f64);

    // 2. Token Jaccard index (bag-of-words overlap)
    let tokens1 = tokenize_filename(norm1);
    let tokens2 = tokenize_filename(norm2);
    let token_score = if tokens1.is_empty() && tokens2.is_empty() {
        1.0
    } else {
        let intersection = tokens1.intersection(&tokens2).count();
        let union = tokens1.union(&tokens2).count();
        if union == 0 {
            0.0
        } else {
            intersection as f64 / union as f64
        }
    };

    // 3. Bigram Dice coefficient
    let bigrams1 = char_bigrams(norm1);
    let bigrams2 = char_bigrams(norm2);
    let bigram_score = if bigrams1.is_empty() && bigrams2.is_empty() {
        1.0
    } else {
        let mut overlap = 0usize;
        for (bg, count_a) in &bigrams1 {
            if let Some(count_b) = bigrams2.get(bg) {
                overlap += (*count_a).min(*count_b);
            }
        }
        let total_a: usize = bigrams1.values().sum();
        let total_b: usize = bigrams2.values().sum();
        let denom = total_a + total_b;
        if denom == 0 {
            0.0
        } else {
            2.0 * overlap as f64 / denom as f64
        }
    };

    // Weighted combination
    edit_score * 0.40 + token_score * 0.35 + bigram_score * 0.25
}

/// Normalize filename for comparison: lowercase, strip separators, collapse whitespace.
fn normalize_filename(name: &str) -> String {
    name.to_lowercase()
        .chars()
        .map(|c| {
            if c.is_alphanumeric() {
                c
            } else {
                // Replace separators (underscore, dot, dash, etc.) with space
                ' '
            }
        })
        .collect::<String>()
        .split_whitespace()
        .collect::<Vec<_>>()
        .join(" ")
}

/// Tokenize a normalized filename into a set of words (split on whitespace).
fn tokenize_filename(name: &str) -> std::collections::HashSet<String> {
    name.split_whitespace().map(|s| s.to_string()).collect()
}

/// Extract character bigrams with counts from a string.
fn char_bigrams(s: &str) -> std::collections::HashMap<(char, char), usize> {
    let chars: Vec<char> = s.chars().collect();
    let mut map = std::collections::HashMap::new();
    if chars.len() >= 2 {
        for pair in chars.windows(2) {
            *map.entry((pair[0], pair[1])).or_insert(0) += 1;
        }
    }
    map
}

/// Calculate Levenshtein distance between two strings.
fn levenshtein_distance(s1: &str, s2: &str) -> usize {
    let len1 = s1.chars().count();
    let len2 = s2.chars().count();

    if len1 == 0 {
        return len2;
    }
    if len2 == 0 {
        return len1;
    }

    let mut matrix = vec![vec![0usize; len2 + 1]; len1 + 1];

    // Initialize first row and column
    for i in 0..=len1 {
        matrix[i][0] = i;
    }
    for j in 0..=len2 {
        matrix[0][j] = j;
    }

    // Fill matrix
    let s1_chars: Vec<char> = s1.chars().collect();
    let s2_chars: Vec<char> = s2.chars().collect();

    for i in 1..=len1 {
        for j in 1..=len2 {
            let cost = if s1_chars[i - 1] == s2_chars[j - 1] {
                0
            } else {
                1
            };

            matrix[i][j] = (matrix[i - 1][j] + 1) // deletion
                .min(matrix[i][j - 1] + 1) // insertion
                .min(matrix[i - 1][j - 1] + cost); // substitution
        }
    }

    matrix[len1][len2]
}

/// Compare durations with tolerance.
#[must_use]
pub fn compare_durations(dur1: Option<f64>, dur2: Option<f64>) -> f64 {
    match (dur1, dur2) {
        (Some(d1), Some(d2)) => {
            if d1 == 0.0 && d2 == 0.0 {
                return 1.0;
            }

            let max_dur = d1.max(d2);
            if max_dur == 0.0 {
                return 1.0;
            }

            let diff = (d1 - d2).abs();
            let tolerance = max_dur * 0.02; // 2% tolerance

            if diff <= tolerance {
                1.0
            } else {
                (1.0 - diff / max_dur).max(0.0)
            }
        }
        (None, None) => 0.5, // Unknown
        _ => 0.0,            // One has duration, other doesn't
    }
}

/// Compare resolutions.
#[must_use]
pub fn compare_resolutions(meta1: &MediaMetadata, meta2: &MediaMetadata) -> f64 {
    match ((meta1.width, meta1.height), (meta2.width, meta2.height)) {
        ((Some(w1), Some(h1)), (Some(w2), Some(h2))) => {
            if w1 == w2 && h1 == h2 {
                1.0
            } else {
                // Compare aspect ratios
                let ar1 = f64::from(w1) / f64::from(h1);
                let ar2 = f64::from(w2) / f64::from(h2);

                let ar_diff = (ar1 - ar2).abs();
                if ar_diff < 0.01 {
                    // Same aspect ratio, different resolution
                    0.5
                } else {
                    0.0
                }
            }
        }
        ((None, None), (None, None)) => 0.5, // Both unknown
        _ => 0.0,                            // One has resolution, other doesn't
    }
}

/// Compare codecs.
#[must_use]
pub fn compare_codecs(meta1: &MediaMetadata, meta2: &MediaMetadata) -> f64 {
    let video_match = compare_strings(&meta1.video_codec, &meta2.video_codec);
    let audio_match = compare_strings(&meta1.audio_codec, &meta2.audio_codec);

    // Average of video and audio codec matches
    (video_match + audio_match) / 2.0
}

/// Compare optional strings.
fn compare_strings(s1: &Option<String>, s2: &Option<String>) -> f64 {
    match (s1, s2) {
        (Some(a), Some(b)) => {
            if a.eq_ignore_ascii_case(b) {
                1.0
            } else {
                0.0
            }
        }
        (None, None) => 0.5, // Both unknown
        _ => 0.0,            // One known, other unknown
    }
}

/// Compare file sizes.
#[must_use]
pub fn compare_sizes(size1: u64, size2: u64) -> f64 {
    if size1 == 0 && size2 == 0 {
        return 1.0;
    }

    let max_size = size1.max(size2);
    if max_size == 0 {
        return 1.0;
    }

    let diff = (size1 as i64 - size2 as i64).unsigned_abs();
    let tolerance = (max_size as f64 * 0.05) as u64; // 5% tolerance

    if diff <= tolerance {
        1.0
    } else {
        (1.0 - diff as f64 / max_size as f64).max(0.0)
    }
}

/// Compare containers.
#[must_use]
pub fn compare_containers(cont1: &Option<String>, cont2: &Option<String>) -> f64 {
    compare_strings(cont1, cont2)
}

/// Extract metadata from file.
///
/// # Errors
///
/// Returns an error if the file cannot be read.
pub fn extract_metadata(path: impl AsRef<Path>) -> DedupResult<MediaMetadata> {
    let path = path.as_ref();

    if !path.exists() {
        return Err(DedupError::FileNotFound(path.to_path_buf()));
    }

    let file_metadata = std::fs::metadata(path)?;
    let size = file_metadata.len();

    let mut metadata = MediaMetadata::new(path.to_path_buf(), size);

    // Get timestamps
    if let Ok(created) = file_metadata.created() {
        if let Ok(duration) = created.duration_since(std::time::UNIX_EPOCH) {
            metadata.created = Some(duration.as_secs() as i64);
        }
    }

    if let Ok(modified) = file_metadata.modified() {
        if let Ok(duration) = modified.duration_since(std::time::UNIX_EPOCH) {
            metadata.modified = Some(duration.as_secs() as i64);
        }
    }

    // Set container based on file extension
    let ext = path
        .extension()
        .and_then(|s| s.to_str())
        .unwrap_or("")
        .to_lowercase();

    metadata.container = Some(ext);

    // Extract detailed metadata using magic-byte detection
    detect_format_from_magic(path, &mut metadata);

    Ok(metadata)
}

/// Detect media format and codec information from file magic bytes.
fn detect_format_from_magic(path: &Path, metadata: &mut MediaMetadata) {
    use std::io::Read;

    let mut file = match std::fs::File::open(path) {
        Ok(f) => f,
        Err(_) => return,
    };

    let mut buf = [0u8; 64];
    let n = match file.read(&mut buf) {
        Ok(n) => n,
        Err(_) => return,
    };

    if n < 4 {
        return;
    }

    let bytes = &buf[..n];

    // EBML / Matroska / WebM: magic [0x1A, 0x45, 0xDF, 0xA3]
    if bytes.starts_with(&[0x1A, 0x45, 0xDF, 0xA3]) {
        // Look for "webm" string in the header area (bytes 4..32)
        let search_range = &bytes[4..n.min(32)];
        let is_webm = search_range.windows(4).any(|w| w == b"webm");
        if is_webm {
            metadata.container = Some("webm".to_string());
        } else {
            metadata.container = Some("mkv".to_string());
        }
        metadata.video_codec = Some("vp9".to_string());
        metadata.audio_codec = Some("opus".to_string());
        return;
    }

    // ftyp box: MP4 family — bytes[4..8] == b"ftyp"
    if n >= 12 && &bytes[4..8] == b"ftyp" {
        let brand = &bytes[8..12];
        if brand == b"qt  " {
            metadata.container = Some("mov".to_string());
        } else if brand == b"M4A " {
            metadata.container = Some("m4a".to_string());
        } else if brand == b"M4V " {
            metadata.container = Some("m4v".to_string());
        } else {
            metadata.container = Some("mp4".to_string());
        }
        metadata.video_codec = Some("h264".to_string());
        metadata.audio_codec = Some("aac".to_string());
        return;
    }

    // RIFF / WAV: b"RIFF" at start and bytes[8..12] == b"WAVE"
    if n >= 12 && bytes.starts_with(b"RIFF") && &bytes[8..12] == b"WAVE" {
        metadata.container = Some("wav".to_string());
        metadata.audio_codec = Some("pcm".to_string());
        // Parse WAV fmt chunk: channels at bytes 22..24 (u16 LE),
        // sample_rate at bytes 24..28 (u32 LE).
        if n >= 28 {
            let channels = u16::from_le_bytes([bytes[22], bytes[23]]);
            let sample_rate = u32::from_le_bytes([bytes[24], bytes[25], bytes[26], bytes[27]]);
            if channels > 0 {
                metadata.channels = Some(channels);
            }
            if sample_rate > 0 {
                metadata.sample_rate = Some(sample_rate);
            }
        }
        return;
    }

    // FLAC: b"fLaC" at start
    if bytes.starts_with(b"fLaC") {
        metadata.container = Some("flac".to_string());
        metadata.audio_codec = Some("flac".to_string());
        // STREAMINFO block begins at byte 4.
        // Bytes 4: block type/last-metadata-block flag (0x00 = STREAMINFO, not last).
        // Sample rate is stored as a 20-bit big-endian field starting at offset 18
        // within the STREAMINFO data (i.e., file byte 4+4+14 = 22).
        // Layout: bytes[8..10] = min block size, bytes[10..12] = max block size,
        //         bytes[12..15] = min frame size (24-bit),
        //         bytes[15..18] = max frame size (24-bit),
        //         bytes[18..21] = sample_rate (20 bits) | channels (3 bits) | bits/sample-1 (5 bits)
        // We need offset 18 within STREAMINFO which is file offset 4 (fLaC) + 4 (block header) + 18 = 26.
        if n >= 29 {
            // sample_rate is top 20 bits of 3 bytes at file offsets 26,27,28
            let b0 = bytes[26] as u32;
            let b1 = bytes[27] as u32;
            let b2 = bytes[28] as u32;
            let sample_rate = (b0 << 12) | (b1 << 4) | (b2 >> 4);
            if sample_rate > 0 {
                metadata.sample_rate = Some(sample_rate);
            }
            // channels: bits [3:1] of byte 28 (3 bits, value+1)
            let channels = ((b2 >> 1) & 0x07) + 1;
            metadata.channels = Some(channels as u16);
        }
        return;
    }

    // OGG: b"OggS" at start
    if bytes.starts_with(b"OggS") {
        metadata.container = Some("ogg".to_string());
        // Check for Opus or Vorbis identification in the first page payload.
        // The first page data typically starts around byte 28.
        let page_data = if n > 28 { &bytes[28..] } else { &bytes[4..] };
        if page_data.windows(8).any(|w| w == b"OpusHead") {
            metadata.audio_codec = Some("opus".to_string());
        } else if page_data
            .windows(7)
            .any(|w| w == b"\x01vorbis" || w == b"\x03vorbis")
        {
            metadata.audio_codec = Some("vorbis".to_string());
        } else if page_data.windows(6).any(|w| w == b"vorbis") {
            metadata.audio_codec = Some("vorbis".to_string());
        } else {
            metadata.audio_codec = Some("vorbis".to_string());
        }
        return;
    }

    // MPEG-TS: sync byte 0x47 at intervals of 188 bytes
    if n >= 1 && bytes[0] == 0x47 {
        // Check if additional sync bytes appear at expected 188-byte intervals.
        let is_ts = (n >= 189 && bytes[188] == 0x47) || (n >= 1 && bytes[0] == 0x47 && n < 189);
        if is_ts {
            metadata.container = Some("ts".to_string());
            metadata.video_codec = Some("h264".to_string());
            metadata.audio_codec = Some("aac".to_string());
            return;
        }
    }

    // ID3 tag (MP3): b"ID3"
    if bytes.starts_with(b"ID3") {
        metadata.container = Some("mp3".to_string());
        metadata.audio_codec = Some("mp3".to_string());
        return;
    }

    // MP3 sync word: 0xFF followed by 0xE0..=0xFF
    if n >= 2 && bytes[0] == 0xFF && bytes[1] >= 0xE0 {
        metadata.container = Some("mp3".to_string());
        metadata.audio_codec = Some("mp3".to_string());
    }
}

/// Find potential duplicates based on metadata.
#[must_use]
pub fn find_metadata_duplicates(
    metadata_list: &[MediaMetadata],
    threshold: f64,
) -> Vec<Vec<usize>> {
    let mut groups = Vec::new();
    let mut processed = vec![false; metadata_list.len()];

    for i in 0..metadata_list.len() {
        if processed[i] {
            continue;
        }

        let mut group = vec![i];

        for j in (i + 1)..metadata_list.len() {
            if processed[j] {
                continue;
            }

            let similarity = compare_metadata(&metadata_list[i], &metadata_list[j]);

            if similarity.is_similar(threshold) {
                group.push(j);
                processed[j] = true;
            }
        }

        if group.len() > 1 {
            groups.push(group);
        }

        processed[i] = true;
    }

    groups
}

/// Fuzzy search for similar filenames.
#[must_use]
pub fn fuzzy_search(query: &str, candidates: &[String], threshold: f64) -> Vec<(usize, f64)> {
    let mut results = Vec::new();

    for (i, candidate) in candidates.iter().enumerate() {
        let similarity = compare_filenames(query, candidate);

        if similarity >= threshold {
            results.push((i, similarity));
        }
    }

    // Sort by similarity (highest first)
    results.sort_by(|a, b| b.1.partial_cmp(&a.1).unwrap_or(std::cmp::Ordering::Equal));

    results
}

/// Calculate metadata quality score (completeness).
#[must_use]
pub fn metadata_quality(metadata: &MediaMetadata) -> f64 {
    let mut score = 0.0;
    let mut total = 0.0;

    // Check each field
    total += 1.0;
    if metadata.duration.is_some() {
        score += 1.0;
    }

    total += 1.0;
    if metadata.width.is_some() && metadata.height.is_some() {
        score += 1.0;
    }

    total += 1.0;
    if metadata.bitrate.is_some() {
        score += 1.0;
    }

    total += 1.0;
    if metadata.framerate.is_some() || metadata.sample_rate.is_some() {
        score += 1.0;
    }

    total += 1.0;
    if metadata.video_codec.is_some() || metadata.audio_codec.is_some() {
        score += 1.0;
    }

    total += 1.0;
    if metadata.container.is_some() {
        score += 1.0;
    }

    score / total
}

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

    fn create_test_metadata(name: &str, duration: f64, width: u32, height: u32) -> MediaMetadata {
        let mut meta = MediaMetadata::new(PathBuf::from(name), 1000000);
        meta.duration = Some(duration);
        meta.width = Some(width);
        meta.height = Some(height);
        meta
    }

    #[test]
    fn test_metadata_creation() {
        let meta = MediaMetadata::new(PathBuf::from("test.mp4"), 1000);
        assert_eq!(meta.size, 1000);
        assert_eq!(meta.extension(), "mp4");
    }

    #[test]
    fn test_filename_extraction() {
        let meta = MediaMetadata::new(PathBuf::from("/path/to/video.mp4"), 1000);
        assert_eq!(meta.filename(), "video");
        assert_eq!(meta.extension(), "mp4");
    }

    #[test]
    fn test_resolution() {
        let mut meta = MediaMetadata::new(PathBuf::from("test.mp4"), 1000);
        meta.width = Some(1920);
        meta.height = Some(1080);

        assert_eq!(meta.resolution(), Some("1920x1080".to_string()));
        assert!(meta.is_video());
    }

    #[test]
    fn test_aspect_ratio() {
        let mut meta = MediaMetadata::new(PathBuf::from("test.mp4"), 1000);
        meta.width = Some(1920);
        meta.height = Some(1080);

        let ar = meta.aspect_ratio().expect("operation should succeed");
        assert!((ar - 16.0 / 9.0).abs() < 0.01);
    }

    #[test]
    fn test_filename_comparison() {
        assert_eq!(compare_filenames("video", "video"), 1.0);
        assert!(compare_filenames("video1", "video2") > 0.5);
        assert!(compare_filenames("test", "completely_different") < 0.5);

        // Case insensitive
        assert_eq!(compare_filenames("VIDEO", "video"), 1.0);

        // Special characters ignored
        assert_eq!(compare_filenames("my-video", "my_video"), 1.0);
    }

    #[test]
    fn test_levenshtein_distance() {
        assert_eq!(levenshtein_distance("", ""), 0);
        assert_eq!(levenshtein_distance("abc", "abc"), 0);
        assert_eq!(levenshtein_distance("abc", "ab"), 1);
        assert_eq!(levenshtein_distance("abc", "def"), 3);
        assert_eq!(levenshtein_distance("kitten", "sitting"), 3);
    }

    #[test]
    fn test_duration_comparison() {
        assert_eq!(compare_durations(Some(100.0), Some(100.0)), 1.0);
        assert!(compare_durations(Some(100.0), Some(101.0)) > 0.9); // Within tolerance
        assert!(compare_durations(Some(100.0), Some(200.0)) < 0.9);
        assert_eq!(compare_durations(None, None), 0.5);
        assert_eq!(compare_durations(Some(100.0), None), 0.0);
    }

    #[test]
    fn test_resolution_comparison() {
        let meta1 = create_test_metadata("video1.mp4", 100.0, 1920, 1080);
        let meta2 = create_test_metadata("video2.mp4", 100.0, 1920, 1080);
        let meta3 = create_test_metadata("video3.mp4", 100.0, 1280, 720);
        let meta4 = create_test_metadata("video4.mp4", 100.0, 3840, 2160);

        assert_eq!(compare_resolutions(&meta1, &meta2), 1.0); // Same resolution
        assert_eq!(compare_resolutions(&meta1, &meta4), 0.5); // Same aspect ratio
        assert_eq!(compare_resolutions(&meta1, &meta3), 0.5); // Same aspect ratio
    }

    #[test]
    fn test_size_comparison() {
        assert_eq!(compare_sizes(1000, 1000), 1.0);
        assert!(compare_sizes(1000, 1040) > 0.9); // Within 5% tolerance
        assert!(compare_sizes(1000, 2000) < 0.9);
    }

    #[test]
    fn test_codec_comparison() {
        let mut meta1 = create_test_metadata("video1.mp4", 100.0, 1920, 1080);
        meta1.video_codec = Some("av1".to_string());
        meta1.audio_codec = Some("opus".to_string());

        let mut meta2 = create_test_metadata("video2.mp4", 100.0, 1920, 1080);
        meta2.video_codec = Some("av1".to_string());
        meta2.audio_codec = Some("opus".to_string());

        let mut meta3 = create_test_metadata("video3.mp4", 100.0, 1920, 1080);
        meta3.video_codec = Some("vp9".to_string());
        meta3.audio_codec = Some("opus".to_string());

        let match12 = compare_codecs(&meta1, &meta2);
        let match13 = compare_codecs(&meta1, &meta3);

        assert_eq!(match12, 1.0); // Same codecs
        assert_eq!(match13, 0.5); // One codec different
    }

    #[test]
    fn test_metadata_similarity() {
        let meta1 = create_test_metadata("video_clip.mp4", 100.0, 1920, 1080);
        let meta2 = create_test_metadata("video_clip_copy.mp4", 100.0, 1920, 1080);

        let similarity = compare_metadata(&meta1, &meta2);

        assert!(similarity.filename_similarity > 0.6);
        assert_eq!(similarity.duration_match, 1.0);
        assert_eq!(similarity.resolution_match, 1.0);
        assert!(similarity.is_similar(0.8));
    }

    #[test]
    fn test_fuzzy_search() {
        let candidates = vec![
            "video_clip.mp4".to_string(),
            "audio_track.mp3".to_string(),
            "video_clip_2.mp4".to_string(),
            "completely_different.mov".to_string(),
        ];

        let results = fuzzy_search("video clip", &candidates, 0.5);

        assert!(!results.is_empty());
        assert!(results[0].1 > 0.5); // First result should be most similar
    }

    #[test]
    fn test_metadata_quality() {
        let mut meta = MediaMetadata::new(PathBuf::from("test.mp4"), 1000);
        assert!(metadata_quality(&meta) < 0.2); // Minimal metadata

        meta.duration = Some(100.0);
        meta.width = Some(1920);
        meta.height = Some(1080);
        meta.bitrate = Some(5000000);
        meta.framerate = Some(30.0);
        meta.video_codec = Some("av1".to_string());
        meta.container = Some("mp4".to_string());

        assert!(metadata_quality(&meta) > 0.9); // Complete metadata
    }

    #[test]
    fn test_find_metadata_duplicates() {
        let metadata_list = vec![
            create_test_metadata("video1.mp4", 100.0, 1920, 1080),
            create_test_metadata("video1_copy.mp4", 100.0, 1920, 1080),
            create_test_metadata("video2.mp4", 200.0, 1280, 720),
            create_test_metadata("video1_copy2.mp4", 100.0, 1920, 1080),
        ];

        let groups = find_metadata_duplicates(&metadata_list, 0.8);

        assert_eq!(groups.len(), 1); // One group of duplicates
        assert!(groups[0].len() >= 2); // At least two files in the group
    }

    // ---- Media-aware filename comparison tests ----

    #[test]
    fn test_filename_comparison_strips_codec_tags() {
        // Same movie, different encoding parameters
        let score = compare_filenames(
            "The.Movie.2024.1080p.x264.mkv",
            "The.Movie.2024.720p.x265.mp4",
        );
        assert!(
            score > 0.8,
            "Same movie with different codecs/resolutions should score > 0.8, got {score}"
        );
    }

    #[test]
    fn test_filename_comparison_strips_release_markers() {
        let score = compare_filenames(
            "Movie.Title.2024.BluRay.REMUX.mkv",
            "Movie.Title.2024.WEB-DL.mp4",
        );
        assert!(
            score > 0.8,
            "Same movie with different release types should score > 0.8, got {score}"
        );
    }

    #[test]
    fn test_filename_comparison_different_content() {
        // Completely different movies should score low
        let score = compare_filenames("Inception.2010.1080p.mkv", "Interstellar.2014.720p.mp4");
        assert!(
            score < 0.8,
            "Different movies should score < 0.8, got {score}"
        );
    }

    #[test]
    fn test_filename_comparison_uhd_vs_hd() {
        let score = compare_filenames(
            "Documentary.2024.2160p.HDR.mkv",
            "Documentary.2024.1080p.SDR.mp4",
        );
        assert!(
            score > 0.7,
            "Same content at different quality tiers should be similar, got {score}"
        );
    }

    #[test]
    fn test_filename_comparison_audio_codecs_stripped() {
        let score = compare_filenames("Concert.2024.FLAC.mkv", "Concert.2024.AAC.mp4");
        assert!(
            score > 0.8,
            "Same content with different audio codecs should match, got {score}"
        );
    }

    #[test]
    fn test_metadata_comparison_uses_fuzzy_filename() {
        let mut meta1 = create_test_metadata("Movie.2024.1080p.x264.BluRay.mkv", 100.0, 1920, 1080);
        meta1.video_codec = Some("h264".to_string());
        meta1.audio_codec = Some("aac".to_string());

        let mut meta2 = create_test_metadata("Movie.2024.720p.x265.WEB-DL.mp4", 100.0, 1280, 720);
        meta2.video_codec = Some("h265".to_string());
        meta2.audio_codec = Some("opus".to_string());

        let sim = compare_metadata(&meta1, &meta2);
        // filename_similarity should be high due to media-aware stripping
        assert!(
            sim.filename_similarity > 0.7,
            "Media-aware filename comparison should score > 0.7, got {}",
            sim.filename_similarity
        );
    }

    // ---- title_fuzzy_score tests ----

    #[test]
    fn test_metadata_fuzzy_similar_titles() {
        let mut meta1 = create_test_metadata("video_a.mp4", 100.0, 1920, 1080);
        meta1.title = Some("The Great Documentary 2024".to_string());

        let mut meta2 = create_test_metadata("video_b.mp4", 100.0, 1920, 1080);
        meta2.title = Some("the great documentary 2024".to_string());

        let sim = compare_metadata(&meta1, &meta2);
        // Identical-modulo-case titles should yield title_fuzzy_score == 1.0
        assert!(
            sim.title_fuzzy_score >= 0.9,
            "Near-identical titles (case difference) should score >= 0.9, got {}",
            sim.title_fuzzy_score
        );
        // And the overall_score uses the maximum of filename and title signals
        assert!(
            sim.overall_score() >= 0.5,
            "Overall score should be raised by the high title signal, got {}",
            sim.overall_score()
        );
    }

    #[test]
    fn test_metadata_fuzzy_different_titles() {
        let mut meta1 = create_test_metadata("video_a.mp4", 100.0, 1920, 1080);
        meta1.title = Some("Inception".to_string());

        let mut meta2 = create_test_metadata("video_b.mp4", 100.0, 1920, 1080);
        meta2.title = Some("Interstellar".to_string());

        let sim = compare_metadata(&meta1, &meta2);
        assert!(
            sim.title_fuzzy_score < 0.7,
            "Clearly different titles should score < 0.7, got {}",
            sim.title_fuzzy_score
        );
    }

    #[test]
    fn test_metadata_no_title_title_score_is_zero() {
        let meta1 = create_test_metadata("video_a.mp4", 100.0, 1920, 1080);
        let meta2 = create_test_metadata("video_b.mp4", 100.0, 1920, 1080);
        let sim = compare_metadata(&meta1, &meta2);
        assert_eq!(
            sim.title_fuzzy_score, 0.0,
            "Missing title tags should produce title_fuzzy_score of 0.0"
        );
    }

    #[test]
    fn test_compare_titles_identical_case_insensitive() {
        assert_eq!(
            compare_titles(Some("Hello World"), Some("hello world")),
            1.0
        );
    }

    #[test]
    fn test_compare_titles_none_returns_zero() {
        assert_eq!(compare_titles(None, Some("title")), 0.0);
        assert_eq!(compare_titles(Some("title"), None), 0.0);
        assert_eq!(compare_titles(None, None), 0.0);
    }

    #[test]
    fn test_compare_titles_similar_strips_noise() {
        // "Movie 1080p" vs "Movie 720p" — differ only in resolution tag
        let score = compare_titles(Some("The Movie 1080p"), Some("The Movie 720p"));
        assert!(
            score > 0.7,
            "Title comparison should strip resolution noise, got {score}"
        );
    }
}