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

use shanty_data::MetadataFetcher;
use shanty_db::entities::wanted_item::WantedStatus;
use shanty_db::queries;

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

#[derive(Deserialize)]
pub struct PaginationParams {
    #[serde(default = "default_limit")]
    limit: u64,
    #[serde(default)]
    offset: u64,
}
fn default_limit() -> u64 {
    50
}

#[derive(Deserialize)]
pub struct AddAlbumRequest {
    artist: Option<String>,
    album: Option<String>,
    mbid: Option<String>,
}

#[derive(Serialize)]
struct AlbumTrackInfo {
    recording_mbid: String,
    title: String,
    track_number: Option<i32>,
    disc_number: Option<i32>,
    duration_ms: Option<u64>,
    status: Option<String>,
}

pub fn configure(cfg: &mut web::ServiceConfig) {
    cfg.service(
        web::resource("/albums")
            .route(web::get().to(list_albums))
            .route(web::post().to(add_album)),
    )
    .service(web::resource("/albums/{mbid}/watch").route(web::delete().to(unwatch_album)))
    .service(web::resource("/albums/{mbid}").route(web::get().to(get_album)));
}

async fn list_albums(
    state: web::Data<AppState>,
    session: Session,
    query: web::Query<PaginationParams>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let albums = queries::albums::list(state.db.conn(), query.limit, query.offset).await?;
    Ok(HttpResponse::Ok().json(albums))
}

/// Get album by MBID. Accepts either a release MBID or a release-group MBID.
/// Tries as a release first; if that fails (404), treats it as a release-group
/// and browses for its first release.
async fn get_album(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<String>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let mbid = path.into_inner();

    // Try fetching as a release first
    let (mb_tracks, _release_mbid) = match state.mb_client.get_release_tracks(&mbid).await {
        Ok(tracks) => (tracks, mbid.clone()),
        Err(_) => {
            // Probably a release-group MBID. Browse releases for this group.
            let resolved = resolve_release_from_group(&state, &mbid).await?;
            let tracks = state
                .mb_client
                .get_release_tracks(&resolved)
                .await
                .map_err(|e| ApiError::Internal(format!("MusicBrainz error: {e}")))?;
            (tracks, resolved)
        }
    };

    // Get the album artist from the release's recording credits
    let album_artist = if let Some(first_track) = mb_tracks.first() {
        state
            .mb_client
            .get_recording(&first_track.recording_mbid)
            .await
            .ok()
            .map(|r| r.artist)
    } else {
        None
    };

    // Get all wanted items to check local status
    let all_wanted = queries::wanted::list(state.db.conn(), None, None).await?;

    let tracks: Vec<AlbumTrackInfo> = mb_tracks
        .into_iter()
        .map(|t| {
            let status = all_wanted
                .iter()
                .find(|w| w.musicbrainz_id.as_deref() == Some(&t.recording_mbid))
                .map(|w| match w.status {
                    WantedStatus::Owned => "owned",
                    WantedStatus::Downloaded => "downloaded",
                    WantedStatus::Wanted => "wanted",
                    WantedStatus::Available => "available",
                })
                .map(String::from);

            AlbumTrackInfo {
                recording_mbid: t.recording_mbid,
                title: t.title,
                track_number: t.track_number,
                disc_number: t.disc_number,
                duration_ms: t.duration_ms,
                status,
            }
        })
        .collect();

    Ok(HttpResponse::Ok().json(serde_json::json!({
        "mbid": mbid,
        "artist": album_artist,
        "tracks": tracks,
    })))
}

/// Given a release-group MBID, find the first release MBID via the shared MB client.
async fn resolve_release_from_group(
    state: &web::Data<AppState>,
    release_group_mbid: &str,
) -> Result<String, ApiError> {
    state
        .mb_client
        .resolve_release_from_group(release_group_mbid)
        .await
        .map_err(|e| {
            ApiError::NotFound(format!(
                "no releases found for release group {release_group_mbid}: {e}"
            ))
        })
}

async fn add_album(
    state: web::Data<AppState>,
    session: Session,
    body: web::Json<AddAlbumRequest>,
) -> Result<HttpResponse, ApiError> {
    let (user_id, _, _) = auth::require_auth(&session)?;
    if body.artist.is_none() && body.album.is_none() && body.mbid.is_none() {
        return Err(ApiError::BadRequest("provide artist+album or mbid".into()));
    }

    // Try adding with the given MBID first. If it fails (e.g., the MBID is a release-group,
    // not a release), resolve it to an actual release MBID and retry.
    let mut mbid = body.mbid.clone();
    let result = shanty_watch::add_album(
        state.db.conn(),
        body.artist.as_deref(),
        body.album.as_deref(),
        mbid.as_deref(),
        &state.mb_client,
        Some(user_id),
    )
    .await;

    let summary = match result {
        Ok(s) => s,
        Err(_) if mbid.is_some() => {
            let rg_mbid = mbid.as_deref().unwrap();
            let release_mbid = resolve_release_from_group(&state, rg_mbid).await?;
            mbid = Some(release_mbid);
            shanty_watch::add_album(
                state.db.conn(),
                body.artist.as_deref(),
                body.album.as_deref(),
                mbid.as_deref(),
                &state.mb_client,
                Some(user_id),
            )
            .await?
        }
        Err(e) => return Err(e.into()),
    };

    Ok(HttpResponse::Ok().json(serde_json::json!({
        "tracks_added": summary.tracks_added,
        "tracks_already_owned": summary.tracks_already_owned,
        "errors": summary.errors,
    })))
}

async fn unwatch_album(
    state: web::Data<AppState>,
    session: Session,
    path: web::Path<String>,
) -> Result<HttpResponse, ApiError> {
    auth::require_auth(&session)?;
    let mbid = path.into_inner();
    let conn = state.db.conn();

    // Get the album's tracks from MB to find their recording MBIDs
    let tracks = match state.mb_client.get_release_tracks(&mbid).await {
        Ok(t) => t,
        Err(_) => {
            // Try as release-group
            let release_mbid = resolve_release_from_group(&state, &mbid).await?;
            state
                .mb_client
                .get_release_tracks(&release_mbid)
                .await
                .map_err(|e| ApiError::Internal(format!("MusicBrainz error: {e}")))?
        }
    };

    let mut removed = 0u64;
    for track in &tracks {
        removed += queries::wanted::remove_by_mbid(conn, &track.recording_mbid).await?;
    }

    Ok(HttpResponse::Ok().json(serde_json::json!({"removed": removed})))
}