const models = require('../models');
import * as api from '../../client/src/api';

export const CreateSongEndpointHandler = (req: any, res: any) => {
  if (!api.checkCreateSongRequest(req)) {
    console.log('Invalid CreateSong request: ' + JSON.stringify(req.body));
    res.sendStatus(400);
    return;
  }
  const reqObject: api.CreateSongRequest = req.body;

  // Start retrieving the artist instances to link the song to.
  var artistInstancePromises: Promise<any>[] = [];
  reqObject.artistIds?.forEach((artistId: Number) => {
    artistInstancePromises.push(
      models.Artist.findAll({
        where: { id: artistId }
      })
        .then((artist: any[]) => {
          if (artist.length != 1) {
            throw 'There is no artist with id ' + artistId + '.';
          }
          return artist[0];
        })
    );
  });
  var artistInstancesPromise = Promise.all(artistInstancePromises);

  // Start retrieving the album instances to link the song to.
  var albumInstancePromises: Promise<any>[] = [];
  reqObject.albumIds?.forEach((albumId: Number) => {
    albumInstancePromises.push(
      models.Album.findAll({
        where: { id: albumId }
      })
        .then((album: any[]) => {
          if (album.length != 1) {
            throw 'There is no album with id ' + albumId + '.';
          }
          return album[0];
        })
    );
  });
  var albumInstancesPromise = Promise.all(albumInstancePromises);

  // Upon finish retrieving artists and albums, create the song and associate it.
  Promise.all([artistInstancesPromise, albumInstancesPromise])
    .then((values: any) => {
      var [artists, albums] = values;
      models.Song.create({
        title: reqObject.title,
      })
        .then(Promise.all([
          (song: any) => {
            song.addArtists(artists);
          },
          (song: any) => {
            song.addAlbums(albums);
          }
        ]))
        .then((song: any) => {
          const responseObject: api.CreateSongResponse = {
            id: song.id
          };
          res.status(200).send(responseObject);
        })
  });
}