Musare/backend/logic/songs.js

import async from "async";
import config from "config";
import mongoose from "mongoose";
import CoreClass from "../core";

let SongsModule;
let CacheModule;
let DBModule;
let UtilsModule;
let YouTubeModule;
let StationsModule;
let PlaylistsModule;

class _SongsModule extends CoreClass {
	// eslint-disable-next-line require-jsdoc
	constructor() {
		super("songs");

		SongsModule = this;
	}

	/**
	 * Initialises the songs module
	 *
	 * @returns {Promise} - returns promise (reject, resolve)
	 */
	async initialize() {
		this.setStage(1);

		CacheModule = this.moduleManager.modules.cache;
		DBModule = this.moduleManager.modules.db;
		UtilsModule = this.moduleManager.modules.utils;
		YouTubeModule = this.moduleManager.modules.youtube;
		StationsModule = this.moduleManager.modules.stations;
		PlaylistsModule = this.moduleManager.modules.playlists;

		this.SongModel = await DBModule.runJob("GET_MODEL", { modelName: "song" });
		this.SongSchemaCache = await CacheModule.runJob("GET_SCHEMA", { schemaName: "song" });

		this.setStage(2);

		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						this.setStage(2);
						CacheModule.runJob("HGETALL", { table: "songs" })
							.then(songs => {
								next(null, songs);
							})
							.catch(next);
					},

					(songs, next) => {
						this.setStage(3);

						if (!songs) return next();

						const youtubeIds = Object.keys(songs);

						return async.each(
							youtubeIds,
							(youtubeId, next) => {
								SongsModule.SongModel.findOne({ youtubeId }, (err, song) => {
									if (err) next(err);
									else if (!song)
										CacheModule.runJob("HDEL", {
											table: "songs",
											key: youtubeId
										})
											.then(() => next())
											.catch(next);
									else next();
								});
							},
							next
						);
					},

					next => {
						this.setStage(4);
						SongsModule.SongModel.find({}, next);
					},

					(songs, next) => {
						this.setStage(5);
						async.each(
							songs,
							(song, next) => {
								CacheModule.runJob("HSET", {
									table: "songs",
									key: song.youtubeId,
									value: SongsModule.SongSchemaCache(song)
								})
									.then(() => next())
									.catch(next);
							},
							next
						);
					}
				],
				async err => {
					if (err) {
						err = await UtilsModule.runJob("GET_ERROR", { error: err });
						reject(new Error(err));
					} else resolve();
				}
			)
		);
	}

	/**
	 * Gets a song by id from the cache or Mongo, and if it isn't in the cache yet, adds it the cache
	 *
	 * @param {object} payload - object containing the payload
	 * @param {string} payload.songId - the id of the song we are trying to get
	 * @returns {Promise} - returns a promise (resolve, reject)
	 */
	GET_SONG(payload) {
		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						if (!mongoose.Types.ObjectId.isValid(payload.songId))
							return next("songId is not a valid ObjectId.");
						return CacheModule.runJob("HGET", { table: "songs", key: payload.songId }, this)
							.then(song => next(null, song))
							.catch(next);
					},

					(song, next) => {
						if (song) return next(true, song);
						return SongsModule.SongModel.findOne({ _id: payload.songId }, next);
					},

					(song, next) => {
						if (song) {
							CacheModule.runJob(
								"HSET",
								{
									table: "songs",
									key: payload.songId,
									value: song
								},
								this
							).then(song => next(null, song));
						} else next("Song not found.");
					}
				],
				(err, song) => {
					if (err && err !== true) return reject(new Error(err));
					return resolve({ song });
				}
			)
		);
	}

	/**
	 * Makes sure that if a song is not currently in the songs db, to add it
	 *
	 * @param {object} payload - an object containing the payload
	 * @param {string} payload.youtubeId - the youtube song id of the song we are trying to ensure is in the songs db
	 * @param {string} payload.userId - the youtube song id of the song we are trying to ensure is in the songs db
	 * @param {string} payload.automaticallyRequested - whether the song was automatically requested or not
	 * @returns {Promise} - returns a promise (resolve, reject)
	 */
	ENSURE_SONG_EXISTS_BY_YOUTUBE_ID(payload) {
		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						SongsModule.SongModel.findOne({ youtubeId: payload.youtubeId }, next);
					},

					(song, next) => {
						if (song && song.duration > 0) next(true, song);
						else {
							YouTubeModule.runJob("GET_SONG", { youtubeId: payload.youtubeId }, this)
								.then(response => {
									next(null, song, response.song);
								})
								.catch(next);
						}

						// else if (song && song.duration <= 0) {
						// 	YouTubeModule.runJob("GET_SONG", { youtubeId: payload.youtubeId }, this)
						// 		.then(response => next(null, { ...response.song }, false))
						// 		.catch(next);
						// } else {
						// 	YouTubeModule.runJob("GET_SONG", { youtubeId: payload.youtubeId }, this)
						// 		.then(response => next(null, { ...response.song }, false))
						// 		.catch(next);
						// }
					},

					(song, youtubeSong, next) => {
						if (song && song.duration <= 0) {
							song.duration = youtubeSong.duration;
							song.save({ validateBeforeSave: true }, err => {
								if (err) return next(err, song);
								return next(null, song);
							});
						} else {
							const status =
								(!payload.userId && config.get("hideAnonymousSongs")) ||
								(payload.automaticallyRequested && config.get("hideAutomaticallyRequestedSongs"))
									? "hidden"
									: "unverified";

							const song = new SongsModule.SongModel({
								...youtubeSong,
								status,
								requestedBy: payload.userId,
								requestedAt: Date.now()
							});
							song.save({ validateBeforeSave: true }, err => {
								if (err) return next(err, song);
								return next(null, song);
							});
						}
					}
				],
				(err, song) => {
					if (err && err !== true) return reject(new Error(err));
					return resolve({ song });
				}
			)
		);
	}

	/**
	 * Gets a song by youtube id
	 *
	 * @param {object} payload - an object containing the payload
	 * @param {string} payload.youtubeId - the youtube id of the song we are trying to get
	 * @returns {Promise} - returns a promise (resolve, reject)
	 */
	GET_SONG_FROM_YOUTUBE_ID(payload) {
		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						SongsModule.SongModel.findOne({ youtubeId: payload.youtubeId }, next);
					}
				],
				(err, song) => {
					if (err && err !== true) return reject(new Error(err));
					return resolve({ song });
				}
			)
		);
	}

	/**
	 * Gets a song from id from Mongo and updates the cache with it
	 *
	 * @param {object} payload - an object containing the payload
	 * @param {string} payload.songId - the id of the song we are trying to update
	 * @returns {Promise} - returns a promise (resolve, reject)
	 */
	UPDATE_SONG(payload) {
		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						SongsModule.SongModel.findOne({ _id: payload.songId }, next);
					},

					(song, next) => {
						if (!song) {
							CacheModule.runJob("HDEL", {
								table: "songs",
								key: payload.songId
							});
							return next("Song not found.");
						}

						return CacheModule.runJob(
							"HSET",
							{
								table: "songs",
								key: payload.songId,
								value: song
							},
							this
						)
							.then(song => {
								next(null, song);
							})
							.catch(next);
					},

					(song, next) => {
						next(null, song);
						const { _id, youtubeId, title, artists, thumbnail, duration, status } = song;
						const trimmedSong = {
							_id,
							youtubeId,
							title,
							artists,
							thumbnail,
							duration,
							status
						};
						this.log("INFO", `Going to update playlists and stations now for song ${_id}`);
						DBModule.runJob("GET_MODEL", { modelName: "playlist" }).then(playlistModel => {
							playlistModel.updateMany(
								{ "songs._id": song._id },
								{ $set: { "songs.$": trimmedSong } },
								err => {
									if (err) this.log("ERROR", err);
									else
										playlistModel.find({ "songs._id": song._id }, (err, playlists) => {
											playlists.forEach(playlist => {
												PlaylistsModule.runJob("UPDATE_PLAYLIST", {
													playlistId: playlist._id
												});
											});
										});
								}
							);
						});
						DBModule.runJob("GET_MODEL", { modelName: "station" }).then(stationModel => {
							stationModel.updateMany(
								{ "queue._id": song._id },
								{
									$set: {
										"queue.$.youtubeId": youtubeId,
										"queue.$.title": title,
										"queue.$.artists": artists,
										"queue.$.thumbnail": thumbnail,
										"queue.$.duration": duration,
										"queue.$.status": status
									}
								},
								err => {
									if (err) this.log("ERROR", err);
									else
										stationModel.find({ "queue._id": song._id }, (err, stations) => {
											stations.forEach(station => {
												StationsModule.runJob("UPDATE_STATION", { stationId: station._id });
											});
										});
								}
							);
						});
					},

					(song, next) => {
						async.eachLimit(
							song.genres,
							1,
							(genre, next) => {
								PlaylistsModule.runJob("AUTOFILL_GENRE_PLAYLIST", { genre }, this)
									.then(() => {
										next();
									})
									.catch(err => next(err));
							},
							err => {
								next(err, song);
							}
						);
					}
				],
				(err, song) => {
					if (err && err !== true) return reject(new Error(err));
					return resolve(song);
				}
			)
		);
	}

	/**
	 * Updates all songs
	 *
	 * @returns {Promise} - returns a promise (resolve, reject)
	 */
	UPDATE_ALL_SONGS() {
		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						return next("Currently disabled since it's broken due to the backend memory leak issue.");
						SongsModule.SongModel.find({}, next);
					},

					(songs, next) => {
						let index = 0;
						const { length } = songs;
						async.eachLimit(
							songs,
							10,
							(song, next) => {
								index += 1;
								console.log(`Updating song #${index} out of ${length}: ${song._id}`);
								SongsModule.runJob("UPDATE_SONG", { songId: song._id }, this, 9)
									.then(() => {
										next();
									})
									.catch(err => {
										next(err);
									});
							},
							err => {
								next(err);
							}
						);
					}
				],
				err => {
					if (err && err !== true) return reject(new Error(err));
					return resolve();
				}
			)
		);
	}

	// /**
	//  * Deletes song from id from Mongo and cache
	//  *
	//  * @param {object} payload - returns an object containing the payload
	//  * @param {string} payload.songId - the song id of the song we are trying to delete
	//  * @returns {Promise} - returns a promise (resolve, reject)
	//  */
	// DELETE_SONG(payload) {
	// 	return new Promise((resolve, reject) =>
	// 		async.waterfall(
	// 			[
	// 				next => {
	// 					SongsModule.SongModel.deleteOne({ _id: payload.songId }, next);
	// 				},

	// 				next => {
	// 					CacheModule.runJob(
	// 						"HDEL",
	// 						{
	// 							table: "songs",
	// 							key: payload.songId
	// 						},
	// 						this
	// 					)
	// 						.then(() => next())
	// 						.catch(next);
	// 				},

	// 				next => {
	// 					this.log("INFO", `Going to update playlists and stations now for deleted song ${payload.songId}`);
	// 					DBModule.runJob("GET_MODEL", { modelName: "playlist" }).then(playlistModel => {
	// 						playlistModel.find({ "songs._id": song._id }, (err, playlists) => {
	// 							if (err) this.log("ERROR", err);
	// 							else {
	// 								playlistModel.updateMany(
	// 									{ "songs._id": payload.songId },
	// 									{ $pull: { "songs.$._id": payload.songId} },
	// 									err => {
	// 										if (err) this.log("ERROR", err);
	// 										else {
	// 											playlists.forEach(playlist => {
	// 												PlaylistsModule.runJob("UPDATE_PLAYLIST", {
	// 													playlistId: playlist._id
	// 												});
	// 											});
	// 										}
	// 									}
	// 								);
									
	// 							}
	// 						});
	// 					});
	// 					DBModule.runJob("GET_MODEL", { modelName: "station" }).then(stationModel => {
	// 						stationModel.find({ "queue._id": payload.songId }, (err, stations) => {
	// 							stationModel.updateMany(
	// 								{ "queue._id": payload.songId },
	// 								{
	// 									$pull: { "queue._id":  }
	// 								},
	// 								err => {
	// 									if (err) this.log("ERROR", err);
	// 									else {
	// 										stations.forEach(station => {
	// 											StationsModule.runJob("UPDATE_STATION", { stationId: station._id });
	// 										});	
	// 									}
	// 								}
	// 							);
	// 						});
	// 					});
	// 				}
	// 			],
	// 			err => {
	// 				if (err && err !== true) return reject(new Error(err));
	// 				return resolve();
	// 			}
	// 		)
	// 	);
	// }

	/**
	 * Searches through songs
	 *
	 * @param {object} payload - object that contains the payload
	 * @param {string} payload.query - the query
	 * @param {string} payload.includeHidden - include hidden songs
	 * @param {string} payload.includeUnverified - include unverified songs
	 * @param {string} payload.includeVerified - include verified songs
	 * @param {string} payload.trimmed - include trimmed songs
	 * @param {string} payload.page - page (default 1)
	 * @returns {Promise} - returns promise (reject, resolve)
	 */
	SEARCH(payload) {
		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						const statuses = [];
						if (payload.includeHidden) statuses.push("hidden");
						if (payload.includeUnverified) statuses.push("unverified");
						if (payload.includeVerified) statuses.push("verified");
						if (statuses.length === 0) return next("No statuses have been included.");

						const filterArray = [
							{
								title: new RegExp(`${payload.query}`, "i"),
								status: { $in: statuses }
							},
							{
								artists: new RegExp(`${payload.query}`, "i"),
								status: { $in: statuses }
							}
						];

						return next(null, filterArray);
					},

					(filterArray, next) => {
						const page = payload.page ? payload.page : 1;
						const pageSize = 15;
						const skipAmount = pageSize * (page - 1);

						SongsModule.SongModel.find({ $or: filterArray }).count((err, count) => {
							if (err) next(err);
							else {
								SongsModule.SongModel.find({ $or: filterArray })
									.skip(skipAmount)
									.limit(pageSize)
									.exec((err, songs) => {
										if (err) next(err);
										else {
											next(null, {
												songs,
												page,
												pageSize,
												skipAmount,
												count
											});
										}
									});
							}
						});
					},

					(data, next) => {
						if (data.songs.length === 0) next("No songs found");
						else if (payload.trimmed) {
							next(null, {
								songs: data.songs.map(song => {
									const { _id, youtubeId, title, artists, thumbnail, duration, status } = song;
									return {
										_id,
										youtubeId,
										title,
										artists,
										thumbnail,
										duration,
										status
									};
								}),
								...data
							});
						} else next(null, data);
					}
				],
				(err, data) => {
					if (err && err !== true) return reject(new Error(err));
					return resolve(data);
				}
			)
		);
	}

	/**
	 * Recalculates dislikes and likes for a song
	 *
	 * @param {object} payload - returns an object containing the payload
	 * @param {string} payload.youtubeId - the youtube id of the song
	 * @param {string} payload.songId - the song id of the song
	 * @returns {Promise} - returns a promise (resolve, reject)
	 */
	async RECALCULATE_SONG_RATINGS(payload) {
		const playlistModel = await DBModule.runJob("GET_MODEL", { modelName: "playlist" }, this);

		return new Promise((resolve, reject) => {
			async.waterfall(
				[
					next => {
						playlistModel.countDocuments(
							{ songs: { $elemMatch: { youtubeId: payload.youtubeId } }, displayName: "Liked Songs" },
							(err, likes) => {
								if (err) return next(err);
								return next(null, likes);
							}
						);
					},

					(likes, next) => {
						playlistModel.countDocuments(
							{ songs: { $elemMatch: { youtubeId: payload.youtubeId } }, displayName: "Disliked Songs" },
							(err, dislikes) => {
								if (err) return next(err);
								return next(err, { likes, dislikes });
							}
						);
					},

					({ likes, dislikes }, next) => {
						SongsModule.SongModel.updateOne(
							{ _id: payload.songId },
							{
								$set: {
									likes,
									dislikes
								}
							},
							err => next(err, { likes, dislikes })
						);
					}
				],
				(err, { likes, dislikes }) => {
					if (err) return reject(new Error(err));
					return resolve({ likes, dislikes });
				}
			);
		});
	}

	/**
	 * Gets an array of all genres
	 *
	 * @returns {Promise} - returns a promise (resolve, reject)
	 */
	GET_ALL_GENRES() {
		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						SongsModule.SongModel.find({ status: "verified" }, { genres: 1, _id: false }, next);
					},

					(songs, next) => {
						let allGenres = [];
						songs.forEach(song => {
							allGenres = allGenres.concat(song.genres);
						});

						const lowerCaseGenres = allGenres.map(genre => genre.toLowerCase());
						const uniqueGenres = lowerCaseGenres.filter(
							(value, index, self) => self.indexOf(value) === index
						);

						next(null, uniqueGenres);
					}
				],
				(err, genres) => {
					if (err && err !== true) return reject(new Error(err));
					return resolve({ genres });
				}
			)
		);
	}

	/**
	 * Gets an array of all songs with a specific genre
	 *
	 * @param {object} payload - returns an object containing the payload
	 * @param {string} payload.genre - the genre
	 * @returns {Promise} - returns a promise (resolve, reject)
	 */
	GET_ALL_SONGS_WITH_GENRE(payload) {
		return new Promise((resolve, reject) =>
			async.waterfall(
				[
					next => {
						SongsModule.SongModel.find(
							{
								status: "verified",
								genres: { $regex: new RegExp(`^${payload.genre.toLowerCase()}$`, "i") }
							},
							next
						);
					}
				],
				(err, songs) => {
					if (err && err !== true) return reject(new Error(err));
					return resolve({ songs });
				}
			)
		);
	}

	// runjob songs GET_ORPHANED_PLAYLIST_SONGS {}

	/**
	 * Gets a orphaned playlist songs
	 *
	 * @returns {Promise} - returns promise (reject, resolve)
	 */
	GET_ORPHANED_PLAYLIST_SONGS() {
		return new Promise((resolve, reject) => {
			DBModule.runJob("GET_MODEL", { modelName: "playlist" }, this).then(playlistModel => {
				playlistModel.find({}, (err, playlists) => {
					if (err) reject(new Error(err));
					else {
						SongsModule.SongModel.find({}, { _id: true, youtubeId: true }, (err, songs) => {
							if (err) reject(new Error(err));
							else {
								const songIds = songs.map(song => song._id.toString());
								const orphanedYoutubeIds = new Set();
								async.eachLimit(
									playlists,
									1,
									(playlist, next) => {
										playlist.songs.forEach(song => {
											if (
												(!song._id || songIds.indexOf(song._id.toString() === -1)) &&
												!orphanedYoutubeIds.has(song.youtubeId)
											) {
												orphanedYoutubeIds.add(song.youtubeId);
											}
										});
										next();
									},
									() => {
										resolve({ youtubeIds: Array.from(orphanedYoutubeIds) });
									}
								);
							}
						});
					}
				});
			});
		});
	}

	/**
	 * Requests a song, adding it to the DB
	 *
	 * @param {object} payload - The payload
	 * @param {string} payload.youtubeId - The YouTube song id of the song
	 * @param {string} payload.userId - The user id of the person requesting the song
	 * @returns {Promise} - returns promise (reject, resolve)
	 */
	REQUEST_SONG(payload) {
		return new Promise((resolve, reject) => {
			const { youtubeId, userId } = payload;
			const requestedAt = Date.now();

			async.waterfall(
				[
					next => {
						DBModule.runJob("GET_MODEL", { modelName: "user" }, this)
							.then(UserModel => {
								UserModel.findOne({ _id: userId }, { "preferences.anonymousSongRequests": 1 }, next);
							})
							.catch(next);
					},

					(user, next) => {
						SongsModule.SongModel.findOne({ youtubeId }, (err, song) => next(err, user, song));
					},

					// Get YouTube data from id
					(user, song, next) => {
						if (song) return next("This song is already in the database.");
						// TODO Add err object as first param of callback

						const requestedBy = user.preferences.anonymousSongRequests ? null : userId;
						const status = !requestedBy && config.get("hideAnonymousSongs") ? "hidden" : "unverified";

						return YouTubeModule.runJob("GET_SONG", { youtubeId }, this)
							.then(response => {
								const { song } = response;
								song.artists = [];
								song.genres = [];
								song.skipDuration = 0;
								song.explicit = false;
								song.requestedBy = user.preferences.anonymousSongRequests ? null : userId;
								song.requestedAt = requestedAt;
								song.status = status;
								next(null, song);
							})
							.catch(next);
					},
					(newSong, next) => {
						const song = new SongsModule.SongModel(newSong);
						song.save({ validateBeforeSave: false }, err => {
							if (err) return next(err, song);
							return next(null, song);
						});
					},
					(song, next) => {
						DBModule.runJob("GET_MODEL", { modelName: "user" }, this)
							.then(UserModel => {
								UserModel.findOne({ _id: userId }, (err, user) => {
									if (err) return next(err);
									if (!user) return next(null, song);

									user.statistics.songsRequested += 1;

									return user.save(err => {
										if (err) return next(err);
										return next(null, song);
									});
								});
							})
							.catch(next);
					}
				],
				async (err, song) => {
					if (err) reject(err);

					SongsModule.runJob("UPDATE_SONG", { songId: song._id });

					CacheModule.runJob("PUB", {
						channel: "song.newUnverifiedSong",
						value: song._id
					});

					resolve();
				}
			);
		});
	}

	/**
	 * Hides a song
	 *
	 * @param {object} payload - The payload
	 * @param {string} payload.songId - The song id of the song
	 * @returns {Promise} - returns promise (reject, resolve)
	 */
	HIDE_SONG(payload) {
		return new Promise((resolve, reject) => {
			const { songId } = payload;

			async.waterfall(
				[
					next => {
						SongsModule.SongModel.findOne({ _id: songId }, next);
					},

					// Get YouTube data from id
					(song, next) => {
						if (!song) return next("This song does not exist.");
						if (song.status === "hidden") return next("This song is already hidden.");
						if (song.status === "verified") return next("Verified songs cannot be hidden.");
						// TODO Add err object as first param of callback
						return next();
					},

					next => {
						SongsModule.SongModel.updateOne({ _id: songId }, { status: "hidden" }, next);
					},

					(res, next) => {
						SongsModule.runJob("UPDATE_SONG", { songId });
						next();
					}
				],
				async err => {
					if (err) reject(err);

					CacheModule.runJob("PUB", {
						channel: "song.newHiddenSong",
						value: songId
					});

					CacheModule.runJob("PUB", {
						channel: "song.removedUnverifiedSong",
						value: songId
					});

					resolve();
				}
			);
		});
	}

	/**
	 * Unhides a song
	 *
	 * @param {object} payload - The payload
	 * @param {string} payload.songId - The song id of the song
	 * @returns {Promise} - returns promise (reject, resolve)
	 */
	UNHIDE_SONG(payload) {
		return new Promise((resolve, reject) => {
			const { songId } = payload;

			async.waterfall(
				[
					next => {
						SongsModule.SongModel.findOne({ _id: songId }, next);
					},

					// Get YouTube data from id
					(song, next) => {
						if (!song) return next("This song does not exist.");
						if (song.status !== "hidden") return next("This song is not hidden.");
						// TODO Add err object as first param of callback
						return next();
					},

					next => {
						SongsModule.SongModel.updateOne({ _id: songId }, { status: "unverified" }, next);
					},

					(res, next) => {
						SongsModule.runJob("UPDATE_SONG", { songId });
						next();
					}
				],
				async err => {
					if (err) reject(err);

					CacheModule.runJob("PUB", {
						channel: "song.newUnverifiedSong",
						value: songId
					});

					CacheModule.runJob("PUB", {
						channel: "song.removedHiddenSong",
						value: songId
					});

					resolve();
				}
			);
		});
	}

	// runjob songs REQUEST_ORPHANED_PLAYLIST_SONGS {}

	/**
	 * Requests all orphaned playlist songs, adding them to the database
	 *
	 * @returns {Promise} - returns promise (reject, resolve)
	 */
	REQUEST_ORPHANED_PLAYLIST_SONGS() {
		return new Promise((resolve, reject) => {
			DBModule.runJob("GET_MODEL", { modelName: "playlist" })
				.then(playlistModel => {
					SongsModule.runJob("GET_ORPHANED_PLAYLIST_SONGS", {}, this).then(response => {
						const { youtubeIds } = response;
						const playlistsToUpdate = new Set();

						async.eachLimit(
							youtubeIds,
							1,
							(youtubeId, next) => {
								async.waterfall(
									[
										next => {
											console.log(
												youtubeId,
												`this is song ${youtubeIds.indexOf(youtubeId) + 1}/${youtubeIds.length}`
											);
											setTimeout(next, 150);
										},

										next => {
											SongsModule.runJob(
												"ENSURE_SONG_EXISTS_BY_SONG_ID",
												{ youtubeId, automaticallyRequested: true },
												this
											)
												.then(() => next())
												.catch(next);
											// SongsModule.runJob("REQUEST_SONG", { youtubeId, userId: null }, this)
											// 	.then(() => {
											// 		next();
											// 	})
											// 	.catch(next);
										},

										next => {
											console.log(444, youtubeId);

											SongsModule.SongModel.findOne({ youtubeId }, next);
										},

										(song, next) => {
											const { _id, title, artists, thumbnail, duration, status } = song;
											const trimmedSong = {
												_id,
												youtubeId,
												title,
												artists,
												thumbnail,
												duration,
												status
											};
											playlistModel.updateMany(
												{ "songs.youtubeId": song.youtubeId },
												{ $set: { "songs.$": trimmedSong } },
												err => {
													next(err, song);
												}
											);
										},

										(song, next) => {
											playlistModel.find({ "songs._id": song._id }, next);
										},

										(playlists, next) => {
											playlists.forEach(playlist => {
												playlistsToUpdate.add(playlist._id.toString());
											});

											next();
										}
									],
									next
								);
							},
							err => {
								if (err) reject(err);
								else {
									async.eachLimit(
										Array.from(playlistsToUpdate),
										1,
										(playlistId, next) => {
											PlaylistsModule.runJob(
												"UPDATE_PLAYLIST",
												{
													playlistId
												},
												this
											)
												.then(() => {
													next();
												})
												.catch(next);
										},
										err => {
											if (err) reject(err);
											else resolve();
										}
									);
								}
							}
						);
					});
				})
				.catch(reject);
		});
	}
}

export default new _SongsModule();