use serde::{Deserialize, Serialize};
use sqlx::PgPool;
use sqlx::postgres::PgPoolOptions;
use uuid::Uuid;

/// Generate a short URL-safe slug from a UUID v4.
fn generate_slug() -> String {
    Uuid::new_v4().simple().to_string()[..12].to_owned()
}

pub async fn connect(database_url: &str) -> Result<PgPool, sqlx::Error> {
    PgPoolOptions::new()
        .max_connections(5)
        .connect(database_url)
        .await
}

pub async fn migrate(pool: &PgPool) -> Result<(), sqlx::migrate::MigrateError> {
    sqlx::migrate!("./migrations").run(pool).await
}

// --- Models ---

#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct Artist {
    pub id: i64,
    pub name: String,
}

#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct Album {
    pub id: i64,
    pub artist_id: i64,
    pub name: String,
    pub year: Option<i32>,
}

#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct PendingTrack {
    pub id: Uuid,
    pub status: String,
    pub inbox_path: String,
    pub file_hash: String,
    pub file_size: i64,
    // Raw metadata from file tags
    pub raw_title: Option<String>,
    pub raw_artist: Option<String>,
    pub raw_album: Option<String>,
    pub raw_year: Option<i32>,
    pub raw_track_number: Option<i32>,
    pub raw_genre: Option<String>,
    pub duration_secs: Option<f64>,
    // Path-derived hints
    pub path_artist: Option<String>,
    pub path_album: Option<String>,
    pub path_year: Option<i32>,
    pub path_track_number: Option<i32>,
    pub path_title: Option<String>,
    // Normalized (LLM output)
    pub norm_title: Option<String>,
    pub norm_artist: Option<String>,
    pub norm_album: Option<String>,
    pub norm_year: Option<i32>,
    pub norm_track_number: Option<i32>,
    pub norm_genre: Option<String>,
    pub norm_featured_artists: Option<String>,  // JSON array
    pub confidence: Option<f64>,
    pub llm_notes: Option<String>,
    pub error_message: Option<String>,
    pub created_at: chrono::DateTime<chrono::Utc>,
    pub updated_at: chrono::DateTime<chrono::Utc>,
}


#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct SimilarArtist {
    pub id: i64,
    pub name: String,
    pub similarity: f32,
}

#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct SimilarAlbum {
    pub id: i64,
    pub artist_id: i64,
    pub name: String,
    pub year: Option<i32>,
    pub similarity: f32,
}

#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct AlbumImage {
    pub id: i64,
    pub album_id: i64,
    pub image_type: String,
    pub file_path: String,
    pub file_hash: String,
    pub mime_type: String,
    pub width: Option<i32>,
    pub height: Option<i32>,
    pub file_size: i64,
}

// --- Queries ---

pub async fn file_hash_exists(pool: &PgPool, hash: &str) -> Result<bool, sqlx::Error> {
    let row: (bool,) = sqlx::query_as(
        "SELECT EXISTS(SELECT 1 FROM tracks WHERE file_hash = $1) OR EXISTS(SELECT 1 FROM pending_tracks WHERE file_hash = $1 AND status NOT IN ('rejected', 'error'))"
    )
    .bind(hash)
    .fetch_one(pool)
    .await?;
    Ok(row.0)
}

pub async fn insert_pending(
    pool: &PgPool,
    inbox_path: &str,
    file_hash: &str,
    file_size: i64,
    raw: &RawFields,
    path_hints: &PathHints,
    duration_secs: Option<f64>,
) -> Result<Uuid, sqlx::Error> {
    let row: (Uuid,) = sqlx::query_as(
        r#"INSERT INTO pending_tracks
           (inbox_path, file_hash, file_size,
            raw_title, raw_artist, raw_album, raw_year, raw_track_number, raw_genre,
            path_title, path_artist, path_album, path_year, path_track_number,
            duration_secs, status)
           VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, 'pending')
           RETURNING id"#,
    )
    .bind(inbox_path)
    .bind(file_hash)
    .bind(file_size)
    .bind(&raw.title)
    .bind(&raw.artist)
    .bind(&raw.album)
    .bind(raw.year)
    .bind(raw.track_number)
    .bind(&raw.genre)
    .bind(&path_hints.title)
    .bind(&path_hints.artist)
    .bind(&path_hints.album)
    .bind(path_hints.year)
    .bind(path_hints.track_number)
    .bind(duration_secs)
    .fetch_one(pool)
    .await?;
    Ok(row.0)
}

pub async fn update_pending_normalized(
    pool: &PgPool,
    id: Uuid,
    status: &str,
    norm: &NormalizedFields,
    error_message: Option<&str>,
) -> Result<(), sqlx::Error> {
    let featured_json = if norm.featured_artists.is_empty() {
        None
    } else {
        Some(serde_json::to_string(&norm.featured_artists).unwrap_or_default())
    };

    sqlx::query(
        r#"UPDATE pending_tracks SET
           status = $2,
           norm_title = $3, norm_artist = $4, norm_album = $5,
           norm_year = $6, norm_track_number = $7, norm_genre = $8,
           norm_featured_artists = $9,
           confidence = $10, llm_notes = $11, error_message = $12,
           updated_at = NOW()
           WHERE id = $1"#,
    )
    .bind(id)
    .bind(status)
    .bind(&norm.title)
    .bind(&norm.artist)
    .bind(&norm.album)
    .bind(norm.year)
    .bind(norm.track_number)
    .bind(&norm.genre)
    .bind(&featured_json)
    .bind(norm.confidence)
    .bind(&norm.notes)
    .bind(error_message)
    .execute(pool)
    .await?;
    Ok(())
}

pub async fn update_pending_status(
    pool: &PgPool,
    id: Uuid,
    status: &str,
    error_message: Option<&str>,
) -> Result<(), sqlx::Error> {
    sqlx::query("UPDATE pending_tracks SET status = $2, error_message = $3, updated_at = NOW() WHERE id = $1")
        .bind(id)
        .bind(status)
        .bind(error_message)
        .execute(pool)
        .await?;
    Ok(())
}

pub async fn find_similar_artists(pool: &PgPool, name: &str, limit: i32) -> Result<Vec<SimilarArtist>, sqlx::Error> {
    // pg_trgm needs at least 3 chars to produce trigrams; for shorter queries use ILIKE prefix
    if name.chars().count() < 3 {
        sqlx::query_as::<_, SimilarArtist>(
            "SELECT id, name, 1.0::real AS similarity FROM artists WHERE name ILIKE $1 || '%' ORDER BY name LIMIT $2"
        )
        .bind(name)
        .bind(limit)
        .fetch_all(pool)
        .await
    } else {
        sqlx::query_as::<_, SimilarArtist>(
            r#"SELECT id, name, MAX(sim) AS similarity FROM (
                SELECT id, name, similarity(name, $1) AS sim FROM artists WHERE name % $1
                UNION ALL
                SELECT id, name, 0.01::real AS sim FROM artists WHERE name ILIKE '%' || $1 || '%'
            ) sub GROUP BY id, name ORDER BY similarity DESC LIMIT $2"#
        )
        .bind(name)
        .bind(limit)
        .fetch_all(pool)
        .await
    }
}

pub async fn find_similar_albums(pool: &PgPool, name: &str, limit: i32) -> Result<Vec<SimilarAlbum>, sqlx::Error> {
    sqlx::query_as::<_, SimilarAlbum>(
        "SELECT id, artist_id, name, year, similarity(name, $1) AS similarity FROM albums WHERE name % $1 ORDER BY similarity DESC LIMIT $2"
    )
    .bind(name)
    .bind(limit)
    .fetch_all(pool)
    .await
}

pub async fn upsert_artist(pool: &PgPool, name: &str) -> Result<i64, sqlx::Error> {
    let slug = generate_slug();
    let row: (i64,) = sqlx::query_as(
        "INSERT INTO artists (name, slug) VALUES ($1, $2) ON CONFLICT (name) DO UPDATE SET name = EXCLUDED.name RETURNING id"
    )
    .bind(name)
    .bind(&slug)
    .fetch_one(pool)
    .await?;
    Ok(row.0)
}

pub async fn upsert_album(pool: &PgPool, artist_id: i64, name: &str, year: Option<i32>) -> Result<i64, sqlx::Error> {
    let slug = generate_slug();
    let row: (i64,) = sqlx::query_as(
        r#"INSERT INTO albums (artist_id, name, year, slug)
           VALUES ($1, $2, $3, $4)
           ON CONFLICT (artist_id, name) DO UPDATE SET year = COALESCE(EXCLUDED.year, albums.year)
           RETURNING id"#
    )
    .bind(artist_id)
    .bind(name)
    .bind(year)
    .bind(&slug)
    .fetch_one(pool)
    .await?;
    Ok(row.0)
}

pub async fn insert_track(
    pool: &PgPool,
    artist_id: i64,
    album_id: Option<i64>,
    title: &str,
    track_number: Option<i32>,
    genre: Option<&str>,
    duration_secs: Option<f64>,
    file_hash: &str,
    file_size: i64,
    storage_path: &str,
) -> Result<i64, sqlx::Error> {
    let slug = generate_slug();
    let row: (i64,) = sqlx::query_as(
        r#"INSERT INTO tracks
           (artist_id, album_id, title, track_number, genre, duration_secs, file_hash, file_size, storage_path, slug)
           VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
           RETURNING id"#
    )
    .bind(artist_id)
    .bind(album_id)
    .bind(title)
    .bind(track_number)
    .bind(genre)
    .bind(duration_secs)
    .bind(file_hash)
    .bind(file_size)
    .bind(storage_path)
    .bind(&slug)
    .fetch_one(pool)
    .await?;
    Ok(row.0)
}

pub async fn link_track_artist(pool: &PgPool, track_id: i64, artist_id: i64, role: &str) -> Result<(), sqlx::Error> {
    sqlx::query(
        "INSERT INTO track_artists (track_id, artist_id, role) VALUES ($1, $2, $3) ON CONFLICT DO NOTHING"
    )
    .bind(track_id)
    .bind(artist_id)
    .bind(role)
    .execute(pool)
    .await?;
    Ok(())
}

pub async fn approve_and_finalize(
    pool: &PgPool,
    pending_id: Uuid,
    storage_path: &str,
) -> Result<i64, sqlx::Error> {
    let pt: PendingTrack = sqlx::query_as("SELECT * FROM pending_tracks WHERE id = $1")
        .bind(pending_id)
        .fetch_one(pool)
        .await?;

    let artist_name = pt.norm_artist.as_deref().unwrap_or("Unknown Artist");
    let artist_id = upsert_artist(pool, artist_name).await?;

    let album_id = match pt.norm_album.as_deref() {
        Some(album_name) => Some(upsert_album(pool, artist_id, album_name, pt.norm_year).await?),
        None => None,
    };

    let title = pt.norm_title.as_deref().unwrap_or("Unknown Title");

    let track_id = insert_track(
        pool,
        artist_id,
        album_id,
        title,
        pt.norm_track_number,
        pt.norm_genre.as_deref(),
        pt.duration_secs,
        &pt.file_hash,
        pt.file_size,
        storage_path,
    )
    .await?;

    // Link primary artist
    link_track_artist(pool, track_id, artist_id, "primary").await?;

    // Link featured artists
    if let Some(featured_json) = &pt.norm_featured_artists {
        if let Ok(featured) = serde_json::from_str::<Vec<String>>(featured_json) {
            for feat_name in &featured {
                let feat_id = upsert_artist(pool, feat_name).await?;
                link_track_artist(pool, track_id, feat_id, "featured").await?;
            }
        }
    }

    update_pending_status(pool, pending_id, "approved", None).await?;

    Ok(track_id)
}

// --- Album images ---

pub async fn image_hash_exists(pool: &PgPool, hash: &str) -> Result<bool, sqlx::Error> {
    let row: (bool,) = sqlx::query_as("SELECT EXISTS(SELECT 1 FROM album_images WHERE file_hash = $1)")
        .bind(hash)
        .fetch_one(pool)
        .await?;
    Ok(row.0)
}

pub async fn insert_album_image(
    pool: &PgPool,
    album_id: i64,
    image_type: &str,
    file_path: &str,
    file_hash: &str,
    mime_type: &str,
    file_size: i64,
) -> Result<i64, sqlx::Error> {
    let row: (i64,) = sqlx::query_as(
        r#"INSERT INTO album_images (album_id, image_type, file_path, file_hash, mime_type, file_size)
           VALUES ($1, $2, $3, $4, $5, $6)
           ON CONFLICT (file_hash) DO NOTHING
           RETURNING id"#
    )
    .bind(album_id)
    .bind(image_type)
    .bind(file_path)
    .bind(file_hash)
    .bind(mime_type)
    .bind(file_size)
    .fetch_one(pool)
    .await?;
    Ok(row.0)
}

pub async fn get_album_images(pool: &PgPool, album_id: i64) -> Result<Vec<AlbumImage>, sqlx::Error> {
    sqlx::query_as::<_, AlbumImage>("SELECT * FROM album_images WHERE album_id = $1 ORDER BY image_type")
        .bind(album_id)
        .fetch_all(pool)
        .await
}

/// Find album_id by artist+album name (used when linking covers to already-finalized albums)
pub async fn find_album_id(pool: &PgPool, artist_name: &str, album_name: &str) -> Result<Option<i64>, sqlx::Error> {
    let row: Option<(i64,)> = sqlx::query_as(
        r#"SELECT a.id FROM albums a
           JOIN artists ar ON a.artist_id = ar.id
           WHERE ar.name = $1 AND a.name = $2"#
    )
    .bind(artist_name)
    .bind(album_name)
    .fetch_optional(pool)
    .await?;
    Ok(row.map(|r| r.0))
}

// --- DTOs for insert helpers ---

#[derive(Debug, Default)]
pub struct RawFields {
    pub title: Option<String>,
    pub artist: Option<String>,
    pub album: Option<String>,
    pub year: Option<i32>,
    pub track_number: Option<i32>,
    pub genre: Option<String>,
}

#[derive(Debug, Default)]
pub struct PathHints {
    pub title: Option<String>,
    pub artist: Option<String>,
    pub album: Option<String>,
    pub year: Option<i32>,
    pub track_number: Option<i32>,
}

#[derive(Debug, Default, Serialize, Deserialize)]
pub struct NormalizedFields {
    pub title: Option<String>,
    pub artist: Option<String>,
    pub album: Option<String>,
    pub year: Option<i32>,
    pub track_number: Option<i32>,
    pub genre: Option<String>,
    #[serde(default)]
    pub featured_artists: Vec<String>,
    pub confidence: Option<f64>,
    pub notes: Option<String>,
}

// --- Admin queries ---

pub async fn list_pending(pool: &PgPool, status_filter: Option<&str>, limit: i64, offset: i64) -> Result<Vec<PendingTrack>, sqlx::Error> {
    match status_filter {
        Some(status) => {
            sqlx::query_as::<_, PendingTrack>(
                "SELECT * FROM pending_tracks WHERE status = $1 ORDER BY created_at DESC LIMIT $2 OFFSET $3"
            )
            .bind(status)
            .bind(limit)
            .bind(offset)
            .fetch_all(pool)
            .await
        }
        None => {
            sqlx::query_as::<_, PendingTrack>(
                "SELECT * FROM pending_tracks ORDER BY created_at DESC LIMIT $1 OFFSET $2"
            )
            .bind(limit)
            .bind(offset)
            .fetch_all(pool)
            .await
        }
    }
}

pub async fn get_pending(pool: &PgPool, id: Uuid) -> Result<Option<PendingTrack>, sqlx::Error> {
    sqlx::query_as::<_, PendingTrack>("SELECT * FROM pending_tracks WHERE id = $1")
        .bind(id)
        .fetch_optional(pool)
        .await
}

pub async fn delete_pending(pool: &PgPool, id: Uuid) -> Result<bool, sqlx::Error> {
    let result = sqlx::query("DELETE FROM pending_tracks WHERE id = $1")
        .bind(id)
        .execute(pool)
        .await?;
    Ok(result.rows_affected() > 0)
}

pub async fn list_artists_all(pool: &PgPool) -> Result<Vec<Artist>, sqlx::Error> {
    sqlx::query_as::<_, Artist>("SELECT id, name FROM artists ORDER BY name")
        .fetch_all(pool)
        .await
}

pub async fn list_albums_by_artist(pool: &PgPool, artist_id: i64) -> Result<Vec<Album>, sqlx::Error> {
    sqlx::query_as::<_, Album>("SELECT id, artist_id, name, year FROM albums WHERE artist_id = $1 ORDER BY year, name")
        .bind(artist_id)
        .fetch_all(pool)
        .await
}

pub async fn update_artist_name(pool: &PgPool, id: i64, name: &str) -> Result<bool, sqlx::Error> {
    let result = sqlx::query("UPDATE artists SET name = $2 WHERE id = $1")
        .bind(id)
        .bind(name)
        .execute(pool)
        .await?;
    Ok(result.rows_affected() > 0)
}

pub async fn update_album(pool: &PgPool, id: i64, name: &str, year: Option<i32>) -> Result<bool, sqlx::Error> {
    let result = sqlx::query("UPDATE albums SET name = $2, year = $3 WHERE id = $1")
        .bind(id)
        .bind(name)
        .bind(year)
        .execute(pool)
        .await?;
    Ok(result.rows_affected() > 0)
}

#[derive(Debug, Serialize)]
pub struct Stats {
    pub total_tracks: i64,
    pub total_artists: i64,
    pub total_albums: i64,
    pub pending_count: i64,
    pub review_count: i64,
    pub error_count: i64,
}

pub async fn get_stats(pool: &PgPool) -> Result<Stats, sqlx::Error> {
    let (total_tracks,): (i64,) = sqlx::query_as("SELECT COUNT(*) FROM tracks").fetch_one(pool).await?;
    let (total_artists,): (i64,) = sqlx::query_as("SELECT COUNT(*) FROM artists").fetch_one(pool).await?;
    let (total_albums,): (i64,) = sqlx::query_as("SELECT COUNT(*) FROM albums").fetch_one(pool).await?;
    let (pending_count,): (i64,) = sqlx::query_as("SELECT COUNT(*) FROM pending_tracks WHERE status = 'pending'").fetch_one(pool).await?;
    let (review_count,): (i64,) = sqlx::query_as("SELECT COUNT(*) FROM pending_tracks WHERE status = 'review'").fetch_one(pool).await?;
    let (error_count,): (i64,) = sqlx::query_as("SELECT COUNT(*) FROM pending_tracks WHERE status = 'error'").fetch_one(pool).await?;
    Ok(Stats { total_tracks, total_artists, total_albums, pending_count, review_count, error_count })
}