use std::sync::Arc;

use axum::{
    body::Body,
    extract::{Path, Query, State},
    http::{HeaderMap, StatusCode, header},
    response::{IntoResponse, Json, Response},
};
use serde::Deserialize;
use tokio::io::{AsyncReadExt, AsyncSeekExt};

use crate::db;
use super::AppState;

type S = Arc<AppState>;

// --- Library browsing ---

pub async fn list_artists(State(state): State<S>) -> impl IntoResponse {
    match db::list_artists(&state.pool).await {
        Ok(artists) => (StatusCode::OK, Json(serde_json::to_value(artists).unwrap())).into_response(),
        Err(e) => error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    }
}

pub async fn get_artist(State(state): State<S>, Path(slug): Path<String>) -> impl IntoResponse {
    match db::get_artist(&state.pool, &slug).await {
        Ok(Some(artist)) => (StatusCode::OK, Json(serde_json::to_value(artist).unwrap())).into_response(),
        Ok(None) => error_json(StatusCode::NOT_FOUND, "artist not found"),
        Err(e) => error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    }
}

pub async fn list_artist_albums(State(state): State<S>, Path(slug): Path<String>) -> impl IntoResponse {
    match db::list_albums_by_artist(&state.pool, &slug).await {
        Ok(albums) => (StatusCode::OK, Json(serde_json::to_value(albums).unwrap())).into_response(),
        Err(e) => error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    }
}

pub async fn list_artist_all_tracks(State(state): State<S>, Path(slug): Path<String>) -> impl IntoResponse {
    match db::list_all_tracks_by_artist(&state.pool, &slug).await {
        Ok(tracks) => (StatusCode::OK, Json(serde_json::to_value(tracks).unwrap())).into_response(),
        Err(e) => error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    }
}

pub async fn get_track_detail(State(state): State<S>, Path(slug): Path<String>) -> impl IntoResponse {
    match db::get_track(&state.pool, &slug).await {
        Ok(Some(track)) => (StatusCode::OK, Json(serde_json::to_value(track).unwrap())).into_response(),
        Ok(None) => error_json(StatusCode::NOT_FOUND, "track not found"),
        Err(e) => error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    }
}

pub async fn get_album_tracks(State(state): State<S>, Path(slug): Path<String>) -> impl IntoResponse {
    match db::list_tracks_by_album(&state.pool, &slug).await {
        Ok(tracks) => (StatusCode::OK, Json(serde_json::to_value(tracks).unwrap())).into_response(),
        Err(e) => error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    }
}

// --- Stream ---

pub async fn stream_track(
    State(state): State<S>,
    Path(slug): Path<String>,
    headers: HeaderMap,
) -> impl IntoResponse {
    let track = match db::get_track(&state.pool, &slug).await {
        Ok(Some(t)) => t,
        Ok(None) => return error_json(StatusCode::NOT_FOUND, "track not found"),
        Err(e) => return error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    };

    let file_path = std::path::Path::new(&track.storage_path);
    if !file_path.exists() {
        return error_json(StatusCode::NOT_FOUND, "file not found on disk");
    }

    let file_size = match tokio::fs::metadata(file_path).await {
        Ok(m) => m.len(),
        Err(e) => return error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    };

    let content_type = mime_guess::from_path(file_path)
        .first_or_octet_stream()
        .to_string();

    // Parse Range header
    let range = headers.get(header::RANGE).and_then(|v| v.to_str().ok());

    if let Some(range_str) = range {
        stream_range(file_path, file_size, &content_type, range_str).await
    } else {
        stream_full(file_path, file_size, &content_type).await
    }
}

async fn stream_full(path: &std::path::Path, size: u64, content_type: &str) -> Response {
    let file = match tokio::fs::File::open(path).await {
        Ok(f) => f,
        Err(e) => return error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    };

    let stream = tokio_util::io::ReaderStream::new(file);
    let body = Body::from_stream(stream);

    Response::builder()
        .status(StatusCode::OK)
        .header(header::CONTENT_TYPE, content_type)
        .header(header::CONTENT_LENGTH, size)
        .header(header::ACCEPT_RANGES, "bytes")
        .body(body)
        .unwrap()
}

async fn stream_range(path: &std::path::Path, size: u64, content_type: &str, range_str: &str) -> Response {
    // Parse "bytes=START-END"
    let range = range_str.strip_prefix("bytes=").unwrap_or("");
    let parts: Vec<&str> = range.split('-').collect();

    let start: u64 = parts.first().and_then(|s| s.parse().ok()).unwrap_or(0);
    let end: u64 = parts.get(1).and_then(|s| if s.is_empty() { None } else { s.parse().ok() }).unwrap_or(size - 1);

    if start >= size || end >= size || start > end {
        return Response::builder()
            .status(StatusCode::RANGE_NOT_SATISFIABLE)
            .header(header::CONTENT_RANGE, format!("bytes */{}", size))
            .body(Body::empty())
            .unwrap();
    }

    let length = end - start + 1;

    let mut file = match tokio::fs::File::open(path).await {
        Ok(f) => f,
        Err(e) => return error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    };

    if start > 0 {
        if let Err(e) = file.seek(std::io::SeekFrom::Start(start)).await {
            return error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string());
        }
    }

    let limited = file.take(length);
    let stream = tokio_util::io::ReaderStream::new(limited);
    let body = Body::from_stream(stream);

    Response::builder()
        .status(StatusCode::PARTIAL_CONTENT)
        .header(header::CONTENT_TYPE, content_type)
        .header(header::CONTENT_LENGTH, length)
        .header(header::CONTENT_RANGE, format!("bytes {}-{}/{}", start, end, size))
        .header(header::ACCEPT_RANGES, "bytes")
        .body(body)
        .unwrap()
}

// --- Cover art ---

pub async fn album_cover(State(state): State<S>, Path(slug): Path<String>) -> impl IntoResponse {
    serve_album_cover_by_slug(&state, &slug).await
}

/// Cover for a specific track: album_images → embedded in file → 404
pub async fn track_cover(State(state): State<S>, Path(slug): Path<String>) -> impl IntoResponse {
    let lookup = match db::get_track_cover_lookup(&state.pool, &slug).await {
        Ok(Some(l)) => l,
        Ok(None) => return error_json(StatusCode::NOT_FOUND, "track not found"),
        Err(e) => return error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    };

    // 1) Try album cover from DB
    if let Some(album_id) = lookup.album_id {
        if let Ok(Some(cover)) = db::get_album_cover_by_id(&state.pool, album_id).await {
            let path = std::path::Path::new(&cover.file_path);
            if path.exists() {
                if let Ok(data) = tokio::fs::read(path).await {
                    return Response::builder()
                        .status(StatusCode::OK)
                        .header(header::CONTENT_TYPE, &cover.mime_type)
                        .header(header::CACHE_CONTROL, "public, max-age=86400")
                        .body(Body::from(data))
                        .unwrap();
                }
            }
        }
    }

    // 2) Try extracting embedded cover from the audio file
    let file_path = std::path::PathBuf::from(&lookup.storage_path);
    if file_path.exists() {
        let result = tokio::task::spawn_blocking(move || extract_embedded_cover(&file_path)).await;
        if let Ok(Some((data, mime))) = result {
            return Response::builder()
                .status(StatusCode::OK)
                .header(header::CONTENT_TYPE, mime)
                .header(header::CACHE_CONTROL, "public, max-age=86400")
                .body(Body::from(data))
                .unwrap();
        }
    }

    error_json(StatusCode::NOT_FOUND, "no cover art available")
}

/// Extract embedded cover art from an audio file using Symphonia.
fn extract_embedded_cover(path: &std::path::Path) -> Option<(Vec<u8>, String)> {
    use symphonia::core::{
        formats::FormatOptions,
        io::MediaSourceStream,
        meta::MetadataOptions,
        probe::Hint,
    };

    let file = std::fs::File::open(path).ok()?;
    let mss = MediaSourceStream::new(Box::new(file), Default::default());

    let mut hint = Hint::new();
    if let Some(ext) = path.extension().and_then(|e| e.to_str()) {
        hint.with_extension(ext);
    }

    let mut probed = symphonia::default::get_probe().format(
        &hint,
        mss,
        &FormatOptions { enable_gapless: false, ..Default::default() },
        &MetadataOptions::default(),
    ).ok()?;

    // Check metadata side-data
    if let Some(rev) = probed.metadata.get().as_ref().and_then(|m| m.current()) {
        if let Some(visual) = rev.visuals().first() {
            return Some((visual.data.to_vec(), visual.media_type.clone()));
        }
    }

    // Check format-embedded metadata
    if let Some(rev) = probed.format.metadata().current() {
        if let Some(visual) = rev.visuals().first() {
            return Some((visual.data.to_vec(), visual.media_type.clone()));
        }
    }

    None
}

async fn serve_album_cover_by_slug(state: &AppState, slug: &str) -> Response {
    let cover = match db::get_album_cover(&state.pool, slug).await {
        Ok(Some(c)) => c,
        Ok(None) => return error_json(StatusCode::NOT_FOUND, "no cover"),
        Err(e) => return error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    };

    let path = std::path::Path::new(&cover.file_path);
    if !path.exists() {
        return error_json(StatusCode::NOT_FOUND, "cover file missing");
    }

    match tokio::fs::read(path).await {
        Ok(data) => Response::builder()
            .status(StatusCode::OK)
            .header(header::CONTENT_TYPE, &cover.mime_type)
            .header(header::CACHE_CONTROL, "public, max-age=86400")
            .body(Body::from(data))
            .unwrap(),
        Err(e) => error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    }
}

// --- Search ---

#[derive(Deserialize)]
pub struct SearchQuery {
    pub q: String,
    #[serde(default = "default_limit")]
    pub limit: i32,
}

fn default_limit() -> i32 { 20 }

pub async fn search(State(state): State<S>, Query(q): Query<SearchQuery>) -> impl IntoResponse {
    if q.q.is_empty() {
        return (StatusCode::OK, Json(serde_json::json!([]))).into_response();
    }
    match db::search(&state.pool, &q.q, q.limit).await {
        Ok(results) => (StatusCode::OK, Json(serde_json::to_value(results).unwrap())).into_response(),
        Err(e) => error_json(StatusCode::INTERNAL_SERVER_ERROR, &e.to_string()),
    }
}

// --- Helpers ---

fn error_json(status: StatusCode, message: &str) -> Response {
    (status, Json(serde_json::json!({"error": message}))).into_response()
}