use actix_session::Session;
use actix_web::{HttpResponse, web};
use serde::{Deserialize, Serialize};

use shanty_db::queries;
use shanty_playlist::{self, PlaylistRequest};

use crate::auth;
use crate::error::ApiError;
use crate::state::AppState;

pub fn configure(cfg: &mut web::ServiceConfig) {
    cfg.service(web::resource("/playlists/generate").route(web::post().to(generate_playlist)))
        .service(
            web::resource("/playlists")
                .route(web::get().to(list_playlists))
                .route(web::post().to(save_playlist)),
        )
        .service(
            web::resource("/playlists/{id}")
                .route(web::get().to(get_playlist))
                .route(web::put().to(update_playlist))
                .route(web::delete().to(delete_playlist)),
        )
        .service(web::resource("/playlists/{id}/m3u").route(web::get().to(export_m3u)))
        .service(
            web::resource("/playlists/{id}/tracks")
                .route(web::post().to(add_track))
                .route(web::put().to(reorder_tracks)),
        )
        .service(
            web::resource("/playlists/{id}/tracks/{track_id}")
                .route(web::delete().to(remove_track)),
        );
}

/// POST /api/playlists/generate — generate a playlist without saving.
async fn generate_playlist(
    state: web::Data<AppState>,
    session: Session,
    body: web::Json<PlaylistRequest>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let req = body.into_inner();
    let conn = state.db.conn();

    let config = state.config.read().await;
    let lastfm_key = config.metadata.lastfm_api_key.clone();
    drop(config);

    let result = match req.strategy.as_str() {
        "similar" => {
            let api_key = lastfm_key.unwrap_or_default();
            if api_key.is_empty() {
                return Err(ApiError::BadRequest(
                    "SHANTY_LASTFM_API_KEY is required for similar-artist playlists".into(),
                ));
            }
            let fetcher = shanty_data::LastFmSimilarFetcher::new(api_key)
                .map_err(|e| ApiError::Internal(e.to_string()))?;
            shanty_playlist::similar_artists(
                conn,
                &fetcher,
                req.seed_artists,
                req.count,
                req.popularity_bias,
                &req.ordering,
            )
            .await
            .map_err(|e| ApiError::Internal(e.to_string()))?
        }
        "genre" => shanty_playlist::genre_based(conn, req.genres, req.count, &req.ordering)
            .await
            .map_err(|e| ApiError::Internal(e.to_string()))?,
        "random" => shanty_playlist::random(conn, req.count, req.ordering != "random")
            .await
            .map_err(|e| ApiError::Internal(e.to_string()))?,
        "smart" => {
            let rules = req.rules.unwrap_or_default();
            shanty_playlist::smart(conn, rules, req.count)
                .await
                .map_err(|e| ApiError::Internal(e.to_string()))?
        }
        other => {
            return Err(ApiError::BadRequest(format!("unknown strategy: {other}")));
        }
    };

    Ok(HttpResponse::Ok().json(result))
}

#[derive(Deserialize)]
struct SavePlaylistRequest {
    name: String,
    description: Option<String>,
    track_ids: Vec<i32>,
}

/// POST /api/playlists — save a generated playlist.
async fn save_playlist(
    state: web::Data<AppState>,
    session: Session,
    body: web::Json<SavePlaylistRequest>,
) -> Result<HttpResponse, ApiError> {
    let (user_id, _, _) = auth::require_auth(&session)?;
    let req = body.into_inner();
    let playlist = queries::playlists::create(
        state.db.conn(),
        &req.name,
        req.description.as_deref(),
        Some(user_id),
        &req.track_ids,
    )
    .await?;

    Ok(HttpResponse::Created().json(playlist))
}

/// GET /api/playlists — list saved playlists.
async fn list_playlists(
    state: web::Data<AppState>,
    session: Session,
) -> Result<HttpResponse, ApiError> {
    let (user_id, _, _) = auth::require_auth(&session)?;
    let playlists = queries::playlists::list(state.db.conn(), Some(user_id)).await?;

    #[derive(Serialize)]
    struct PlaylistSummary {
        id: i32,
        name: String,
        description: Option<String>,
        track_count: u64,
        created_at: String,
    }

    let mut summaries = Vec::new();
    for p in playlists {
        let count = queries::playlists::get_track_count(state.db.conn(), p.id).await?;
        summaries.push(PlaylistSummary {
            id: p.id,
            name: p.name,
            description: p.description,
            track_count: count,
            created_at: p.created_at.format("%Y-%m-%d %H:%M").to_string(),
        });
    }

    Ok(HttpResponse::Ok().json(summaries))
}

/// GET /api/playlists/{id} — get playlist with tracks.
async fn get_playlist(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<i32>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let id = path.into_inner();
    let playlist = queries::playlists::get_by_id(state.db.conn(), id).await?;
    let tracks = queries::playlists::get_tracks(state.db.conn(), id).await?;

    Ok(HttpResponse::Ok().json(serde_json::json!({
        "playlist": playlist,
        "tracks": tracks,
    })))
}

#[derive(Deserialize)]
struct UpdatePlaylistRequest {
    name: Option<String>,
    description: Option<String>,
}

/// PUT /api/playlists/{id} — update playlist name/description.
async fn update_playlist(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<i32>,
    body: web::Json<UpdatePlaylistRequest>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let id = path.into_inner();
    let req = body.into_inner();
    let playlist = queries::playlists::update(
        state.db.conn(),
        id,
        req.name.as_deref(),
        req.description.as_deref(),
    )
    .await?;
    Ok(HttpResponse::Ok().json(playlist))
}

/// DELETE /api/playlists/{id} — delete a playlist.
async fn delete_playlist(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<i32>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let id = path.into_inner();
    queries::playlists::delete(state.db.conn(), id).await?;
    Ok(HttpResponse::NoContent().finish())
}

#[derive(Deserialize)]
struct AddTrackRequest {
    track_id: i32,
}

/// POST /api/playlists/{id}/tracks — add a track to playlist.
async fn add_track(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<i32>,
    body: web::Json<AddTrackRequest>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let id = path.into_inner();
    let req = body.into_inner();
    queries::playlists::add_track(state.db.conn(), id, req.track_id).await?;
    Ok(HttpResponse::Ok().json(serde_json::json!({"ok": true})))
}

#[derive(Deserialize)]
struct ReorderTracksRequest {
    track_ids: Vec<i32>,
}

/// PUT /api/playlists/{id}/tracks — reorder tracks in playlist.
async fn reorder_tracks(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<i32>,
    body: web::Json<ReorderTracksRequest>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let id = path.into_inner();
    let req = body.into_inner();
    queries::playlists::reorder_tracks(state.db.conn(), id, req.track_ids).await?;
    Ok(HttpResponse::Ok().json(serde_json::json!({"ok": true})))
}

/// DELETE /api/playlists/{id}/tracks/{track_id} — remove a track from playlist.
async fn remove_track(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<(i32, i32)>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let (id, track_id) = path.into_inner();
    queries::playlists::remove_track(state.db.conn(), id, track_id).await?;
    Ok(HttpResponse::NoContent().finish())
}

/// GET /api/playlists/{id}/m3u — export as M3U file.
async fn export_m3u(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<i32>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let id = path.into_inner();
    let playlist = queries::playlists::get_by_id(state.db.conn(), id).await?;
    let tracks = queries::playlists::get_tracks(state.db.conn(), id).await?;

    // Convert DB tracks to PlaylistTracks for M3U generation
    let playlist_tracks: Vec<shanty_playlist::PlaylistTrack> = tracks
        .into_iter()
        .map(|t| shanty_playlist::PlaylistTrack {
            track_id: t.id,
            file_path: t.file_path,
            title: t.title,
            artist: t.artist,
            album: t.album,
            score: 0.0,
            duration: t.duration,
        })
        .collect();

    let m3u = shanty_playlist::to_m3u(&playlist_tracks);
    let filename = format!("{}.m3u", playlist.name.replace(' ', "_"));

    Ok(HttpResponse::Ok()
        .insert_header(("Content-Type", "audio/x-mpegurl"))
        .insert_header((
            "Content-Disposition",
            format!("attachment; filename=\"{filename}\""),
        ))
        .body(m3u))
}