const models = require('../models');
import * as api from '../../client/src/api';
import { EndpointError, EndpointHandler, catchUnhandledErrors } from './types';
const { Op } = require("sequelize");

export const CreateSongEndpointHandler: EndpointHandler = async (req: any, res: any) => {
  if (!api.checkCreateSongRequest(req)) {
    const e: EndpointError = {
      internalMessage: 'Invalid CreateSong request: ' + JSON.stringify(req.body),
      httpStatus: 400
    };
    throw e;
  }
  const reqObject: api.CreateSongRequest = req.body;

  // Start retrieving the artist instances to link the song to.
  var artistInstancesPromise = reqObject.artistIds && models.Artist.findAll({
    where: {
      id: {
        [Op.in]: reqObject.artistIds
      }
    }
  });

  // Start retrieving the album instances to link the song to.
  var albumInstancesPromise = reqObject.albumIds && models.Album.findAll({
    where: {
      id: {
        [Op.in]: reqObject.albumIds
      }
    }
  });

  // Upon finish retrieving artists and albums, create the song and associate it.
  await Promise.all([artistInstancesPromise, albumInstancesPromise])
    .then((values: any) => {
      var [artists, albums] = values;

      if ((reqObject.artistIds && artists.length !== reqObject.artistIds.length) ||
        (reqObject.albumIds && albums.length !== reqObject.albumIds.length)) {
        const e: EndpointError = {
          internalMessage: 'Not all albums and/or artists exist for CreateSong request: ' + JSON.stringify(req.body),
          httpStatus: 400
        };
        throw e;
      }

      var song = models.Song.build({
        title: reqObject.title,
        storeLinks: reqObject.storeLinks || [],
      });
      artists && song.addArtists(artists);
      albums && song.addAlbums(albums);
      return song.save();
    })
    .then((song: any) => {
      const responseObject: api.CreateSongResponse = {
        id: song.id
      };
      res.status(200).send(responseObject);
    })
    .catch(catchUnhandledErrors);
}