MusareFork/backend/logic/actions/songs.js

import async from "async";

import { isAdminRequired, isLoginRequired } from "./hooks";

import moduleManager from "../../index";

const DBModule = moduleManager.modules.db;
const UtilsModule = moduleManager.modules.utils;
const IOModule = moduleManager.modules.io;
const CacheModule = moduleManager.modules.cache;
const SongsModule = moduleManager.modules.songs;
const ActivitiesModule = moduleManager.modules.activities;
const PlaylistsModule = moduleManager.modules.playlists;

CacheModule.runJob("SUB", {
	channel: "song.removed",
	cb: songId => {
		IOModule.runJob("EMIT_TO_ROOM", {
			room: "admin.songs",
			args: ["event:admin.song.removed", songId]
		});
	}
});

CacheModule.runJob("SUB", {
	channel: "song.added",
	cb: async songId => {
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" });
		songModel.findOne({ _id: songId }, (err, song) => {
			IOModule.runJob("EMIT_TO_ROOM", {
				room: "admin.songs",
				args: ["event:admin.song.added", song]
			});
		});
	}
});

CacheModule.runJob("SUB", {
	channel: "song.updated",
	cb: async songId => {
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" });
		songModel.findOne({ _id: songId }, (err, song) => {
			IOModule.runJob("EMIT_TO_ROOM", {
				room: "admin.songs",
				args: ["event:admin.song.updated", song]
			});
		});
	}
});

CacheModule.runJob("SUB", {
	channel: "song.like",
	cb: data => {
		IOModule.runJob("EMIT_TO_ROOM", {
			room: `song.${data.songId}`,
			args: [
				"event:song.like",
				{
					songId: data.songId,
					likes: data.likes,
					dislikes: data.dislikes
				}
			]
		});
		IOModule.runJob("SOCKETS_FROM_USER", { userId: data.userId }).then(response => {
			response.sockets.forEach(socket => {
				socket.emit("event:song.newRatings", {
					songId: data.songId,
					liked: true,
					disliked: false
				});
			});
		});
	}
});

CacheModule.runJob("SUB", {
	channel: "song.dislike",
	cb: data => {
		IOModule.runJob("EMIT_TO_ROOM", {
			room: `song.${data.songId}`,
			args: [
				"event:song.dislike",
				{
					songId: data.songId,
					likes: data.likes,
					dislikes: data.dislikes
				}
			]
		});
		IOModule.runJob("SOCKETS_FROM_USER", { userId: data.userId }).then(response => {
			response.sockets.forEach(socket => {
				socket.emit("event:song.newRatings", {
					songId: data.songId,
					liked: false,
					disliked: true
				});
			});
		});
	}
});

CacheModule.runJob("SUB", {
	channel: "song.unlike",
	cb: data => {
		IOModule.runJob("EMIT_TO_ROOM", {
			room: `song.${data.songId}`,
			args: [
				"event:song.unlike",
				{
					songId: data.songId,
					likes: data.likes,
					dislikes: data.dislikes
				}
			]
		});
		IOModule.runJob("SOCKETS_FROM_USER", { userId: data.userId }).then(response => {
			response.sockets.forEach(socket => {
				socket.emit("event:song.newRatings", {
					songId: data.songId,
					liked: false,
					disliked: false
				});
			});
		});
	}
});

CacheModule.runJob("SUB", {
	channel: "song.undislike",
	cb: data => {
		IOModule.runJob("EMIT_TO_ROOM", {
			room: `song.${data.songId}`,
			args: [
				"event:song.undislike",
				{
					songId: data.songId,
					likes: data.likes,
					dislikes: data.dislikes
				}
			]
		});
		IOModule.runJob("SOCKETS_FROM_USER", { userId: data.userId }).then(response => {
			response.sockets.forEach(socket => {
				socket.emit("event:song.newRatings", {
					songId: data.songId,
					liked: false,
					disliked: false
				});
			});
		});
	}
});

export default {
	/**
	 * Returns the length of the songs list
	 *
	 * @param {object} session - the session object automatically added by socket.io
	 * @param cb
	 */
	length: isAdminRequired(async function length(session, cb) {
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);
		async.waterfall(
			[
				next => {
					songModel.countDocuments({}, next);
				}
			],
			async (err, count) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log("ERROR", "SONGS_LENGTH", `Failed to get length from songs. "${err}"`);
					return cb({ status: "failure", message: err });
				}
				this.log("SUCCESS", "SONGS_LENGTH", `Got length from songs successfully.`);
				return cb(count);
			}
		);
	}),

	/**
	 * Gets a set of songs
	 *
	 * @param {object} session - the session object automatically added by socket.io
	 * @param set - the set number to return
	 * @param cb
	 */
	getSet: isAdminRequired(async function getSet(session, set, cb) {
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);
		async.waterfall(
			[
				next => {
					songModel
						.find({})
						.skip(15 * (set - 1))
						.limit(15)
						.exec(next);
				}
			],
			async (err, songs) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log("ERROR", "SONGS_GET_SET", `Failed to get set from songs. "${err}"`);
					return cb({ status: "failure", message: err });
				}
				this.log("SUCCESS", "SONGS_GET_SET", `Got set from songs successfully.`);
				return cb(songs);
			}
		);
	}),

	/**
	 * Gets a song from the YouTube song id
	 *
	 * @param {object} session - the session object automatically added by socket.io
	 * @param {string} songId - the YouTube song id
	 * @param {Function} cb
	 */
	getSong: isAdminRequired(function getSong(session, songId, cb) {
		async.waterfall(
			[
				next => {
					SongsModule.runJob("GET_SONG_FROM_ID", { songId }, this)
						.then(song => {
							next(null, song);
						})
						.catch(err => {
							next(err);
						});
				}
			],
			async (err, song) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log("ERROR", "SONGS_GET_SONG", `Failed to get song ${songId}. "${err}"`);
					return cb({ status: "failure", message: err });
				}
				this.log("SUCCESS", "SONGS_GET_SONG", `Got song ${songId} successfully.`);
				return cb({ status: "success", data: song });
			}
		);
	}),

	/**
	 * Gets a song from the Musare song id
	 *
	 * @param {object} session - the session object automatically added by socket.io
	 * @param {string} songId - the Musare song id
	 * @param {Function} cb
	 */
	getSongFromMusareId: isAdminRequired(function getSong(session, songId, cb) {
		async.waterfall(
			[
				next => {
					SongsModule.runJob("GET_SONG", { id: songId }, this)
						.then(response => {
							next(null, response.song);
						})
						.catch(err => {
							next(err);
						});
				}
			],
			async (err, song) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log("ERROR", "SONGS_GET_SONG_FROM_MUSARE_ID", `Failed to get song ${songId}. "${err}"`);
					return cb({ status: "failure", message: err });
				}
				this.log("SUCCESS", "SONGS_GET_SONG_FROM_MUSARE_ID", `Got song ${songId} successfully.`);
				return cb({ status: "success", data: { song } });
			}
		);
	}),

	/**
	 * Obtains basic metadata of a song in order to format an activity
	 *
	 * @param {object} session - the session object automatically added by socket.io
	 * @param {string} songId - the song id
	 * @param {Function} cb - callback
	 */
	getSongForActivity(session, songId, cb) {
		async.waterfall(
			[
				next => {
					SongsModule.runJob("GET_SONG_FROM_ID", { songId }, this)
						.then(response => next(null, response.song))
						.catch(next);
				}
			],
			async (err, song) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);

					this.log(
						"ERROR",
						"SONGS_GET_SONG_FOR_ACTIVITY",
						`Failed to obtain metadata of song ${songId} for activity formatting. "${err}"`
					);

					return cb({ status: "failure", message: err });
				}

				if (song) {
					this.log(
						"SUCCESS",
						"SONGS_GET_SONG_FOR_ACTIVITY",
						`Obtained metadata of song ${songId} for activity formatting successfully.`
					);

					return cb({
						status: "success",
						data: {
							title: song.title,
							thumbnail: song.thumbnail
						}
					});
				}

				this.log(
					"ERROR",
					"SONGS_GET_SONG_FOR_ACTIVITY",
					`Song ${songId} does not exist so failed to obtain for activity formatting.`
				);

				return cb({ status: "failure" });
			}
		);
	},

	/**
	 * Updates a song
	 *
	 * @param {object} session - the session object automatically added by socket.io
	 * @param {string} songId - the song id
	 * @param {object} song - the updated song object
	 * @param {Function} cb
	 */
	update: isAdminRequired(async function update(session, songId, song, cb) {
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);
		let existingSong = null;
		async.waterfall(
			[
				next => {
					songModel.findOne({ _id: songId }, next);
				},

				(_existingSong, next) => {
					existingSong = _existingSong;
					songModel.updateOne({ _id: songId }, song, { runValidators: true }, next);
				},

				(res, next) => {
					SongsModule.runJob("UPDATE_SONG", { songId }, this)
						.then(song => {
							existingSong.genres
								.concat(song.genres)
								.filter((value, index, self) => self.indexOf(value) === index)
								.forEach(genre => {
									PlaylistsModule.runJob("AUTOFILL_GENRE_PLAYLIST", { genre })
										.then(() => {})
										.catch(() => {});
								});

							next(null, song);
						})
						.catch(next);
				}
			],
			async (err, song) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);

					this.log("ERROR", "SONGS_UPDATE", `Failed to update song "${songId}". "${err}"`);

					return cb({ status: "failure", message: err });
				}

				this.log("SUCCESS", "SONGS_UPDATE", `Successfully updated song "${songId}".`);

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

				return cb({
					status: "success",
					message: "Song has been successfully updated",
					data: song
				});
			}
		);
	}),

	/**
	 * Removes a song
	 *
	 * @param session
	 * @param songId - the song id
	 * @param cb
	 */
	remove: isAdminRequired(async function remove(session, songId, cb) {
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);
		let song = null;
		async.waterfall(
			[
				next => {
					songModel.findOne({ _id: songId }, next);
				},

				(_song, next) => {
					song = _song;
					songModel.deleteOne({ _id: songId }, next);
				},

				(res, next) => {
					// TODO Check if res gets returned from above
					CacheModule.runJob("HDEL", { table: "songs", key: songId }, this)
						.then(() => {
							next();
						})
						.catch(next)
						.finally(() => {
							song.genres.forEach(genre => {
								PlaylistsModule.runJob("AUTOFILL_GENRE_PLAYLIST", { genre })
									.then(() => {})
									.catch(() => {});
							});
						});
				}
			],
			async err => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);

					this.log("ERROR", "SONGS_UPDATE", `Failed to remove song "${songId}". "${err}"`);

					return cb({ status: "failure", message: err });
				}

				this.log("SUCCESS", "SONGS_UPDATE", `Successfully remove song "${songId}".`);

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

				return cb({
					status: "success",
					message: "Song has been successfully updated"
				});
			}
		);
	}),

	/**
	 * Adds a song
	 *
	 * @param session
	 * @param song - the song object
	 * @param cb
	 */
	add: isAdminRequired(async function add(session, song, cb) {
		const SongModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);
		async.waterfall(
			[
				next => {
					SongModel.findOne({ songId: song.songId }, next);
				},

				(existingSong, next) => {
					if (existingSong) return next("Song is already in rotation.");
					return next();
				},

				next => {
					const newSong = new SongModel(song);
					newSong.acceptedBy = session.userId;
					newSong.acceptedAt = Date.now();
					newSong.save(next);
				},

				(res, next) => {
					this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "queueSongs",
								action: "remove",
								args: [song._id]
							},
							this
						)
						.finally(() => {
							song.genres.forEach(genre => {
								PlaylistsModule.runJob("AUTOFILL_GENRE_PLAYLIST", { genre })
									.then(() => {})
									.catch(() => {});
							});

							next();
						});
				}
			],
			async err => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);

					this.log("ERROR", "SONGS_ADD", `User "${session.userId}" failed to add song. "${err}"`);

					return cb({ status: "failure", message: err });
				}

				this.log("SUCCESS", "SONGS_ADD", `User "${session.userId}" successfully added song "${song.songId}".`);

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

				return cb({
					status: "success",
					message: "Song has been moved from the queue successfully."
				});
			}
		);
		// TODO Check if video is in queue and Add the song to the appropriate stations
	}),

	/**
	 * Likes a song
	 *
	 * @param session
	 * @param musareSongId - the song id
	 * @param cb
	 */
	like: isLoginRequired(async function like(session, musareSongId, cb) {
		const userModel = await DBModule.runJob("GET_MODEL", { modelName: "user" }, this);
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);

		async.waterfall(
			[
				next => {
					songModel.findOne({ songId: musareSongId }, next);
				},

				(song, next) => {
					if (!song) return next("No song found with that id.");
					return next(null, song._id);
				},

				(songId, next) => userModel.findOne({ _id: session.userId }, (err, user) => next(err, songId, user)),

				(songId, user, next) => {
					if (!user) return next("User does not exist.");

					return this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "playlists",
								action: "addSongToPlaylist",
								args: [false, musareSongId, user.likedSongsPlaylist]
							},
							this
						)
						.then(res => {
							if (res.status === "failure")
								return next("Unable to add song to the 'Liked Songs' playlist.");
							return next(null, songId, user.dislikedSongsPlaylist);
						})
						.catch(err => next(err));
				},

				(songId, dislikedSongsPlaylist, next) => {
					this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "playlists",
								action: "removeSongFromPlaylist",
								args: [musareSongId, dislikedSongsPlaylist]
							},
							this
						)
						.then(res => {
							if (res.status === "failure")
								return next("Unable to remove song from the 'Disliked Songs' playlist.");
							return next(null, songId);
						})
						.catch(err => next(err));
				},

				(songId, next) => {
					SongsModule.runJob("RECALCULATE_SONG_RATINGS", { songId, musareSongId })
						.then(ratings => next(null, songId, ratings))
						.catch(err => next(err));
				}
			],
			async (err, songId, { likes, dislikes }) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log(
						"ERROR",
						"SONGS_LIKE",
						`User "${session.userId}" failed to like song ${musareSongId}. "${err}"`
					);
					return cb({ status: "failure", message: err });
				}

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

				CacheModule.runJob("PUB", {
					channel: "song.like",
					value: JSON.stringify({
						songId: musareSongId,
						userId: session.userId,
						likes,
						dislikes
					})
				});

				ActivitiesModule.runJob("ADD_ACTIVITY", {
					userId: session.userId,
					activityType: "liked_song",
					payload: [songId]
				});

				return cb({
					status: "success",
					message: "You have successfully liked this song."
				});
			}
		);
	}),

	// TODO: ALready liked/disliked etc.

	/**
	 * Dislikes a song
	 *
	 * @param session
	 * @param musareSongId - the song id
	 * @param cb
	 */
	dislike: isLoginRequired(async function dislike(session, musareSongId, cb) {
		const userModel = await DBModule.runJob("GET_MODEL", { modelName: "user" }, this);
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);

		async.waterfall(
			[
				next => {
					songModel.findOne({ songId: musareSongId }, next);
				},

				(song, next) => {
					if (!song) return next("No song found with that id.");
					return next(null, song._id);
				},

				(songId, next) => userModel.findOne({ _id: session.userId }, (err, user) => next(err, songId, user)),

				(songId, user, next) => {
					if (!user) return next("User does not exist.");

					return this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "playlists",
								action: "addSongToPlaylist",
								args: [false, musareSongId, user.dislikedSongsPlaylist]
							},
							this
						)
						.then(res => {
							if (res.status === "failure")
								return next("Unable to add song to the 'Disliked Songs' playlist.");
							return next(null, songId, user.likedSongsPlaylist);
						})
						.catch(err => next(err));
				},

				(songId, likedSongsPlaylist, next) => {
					this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "playlists",
								action: "removeSongFromPlaylist",
								args: [musareSongId, likedSongsPlaylist]
							},
							this
						)
						.then(res => {
							if (res.status === "failure")
								return next("Unable to remove song from the 'Liked Songs' playlist.");
							return next(null, songId);
						})
						.catch(err => next(err));
				},

				(songId, next) => {
					SongsModule.runJob("RECALCULATE_SONG_RATINGS", { songId, musareSongId })
						.then(ratings => next(null, songId, ratings))
						.catch(err => next(err));
				}
			],
			async (err, songId, { likes, dislikes }) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log(
						"ERROR",
						"SONGS_DISLIKE",
						`User "${session.userId}" failed to dislike song ${musareSongId}. "${err}"`
					);
					return cb({ status: "failure", message: err });
				}

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

				CacheModule.runJob("PUB", {
					channel: "song.dislike",
					value: JSON.stringify({
						songId: musareSongId,
						userId: session.userId,
						likes,
						dislikes
					})
				});

				return cb({
					status: "success",
					message: "You have successfully disliked this song."
				});
			}
		);
	}),

	/**
	 * Undislikes a song
	 *
	 * @param session
	 * @param musareSongId - the song id
	 * @param cb
	 */
	undislike: isLoginRequired(async function undislike(session, musareSongId, cb) {
		const userModel = await DBModule.runJob("GET_MODEL", { modelName: "user" }, this);
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);

		async.waterfall(
			[
				next => {
					songModel.findOne({ songId: musareSongId }, next);
				},

				(song, next) => {
					if (!song) return next("No song found with that id.");
					return next(null, song._id);
				},

				(songId, next) => userModel.findOne({ _id: session.userId }, (err, user) => next(err, songId, user)),

				(songId, user, next) => {
					if (!user) return next("User does not exist.");

					return this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "playlists",
								action: "removeSongFromPlaylist",
								args: [musareSongId, user.dislikedSongsPlaylist]
							},
							this
						)
						.then(res => {
							if (res.status === "failure")
								return next("Unable to remove song from the 'Disliked Songs' playlist.");
							return next(null, songId, user.likedSongsPlaylist);
						})
						.catch(err => next(err));
				},

				(songId, likedSongsPlaylist, next) => {
					this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "playlists",
								action: "removeSongFromPlaylist",
								args: [musareSongId, likedSongsPlaylist]
							},
							this
						)
						.then(res => {
							if (res.status === "failure")
								return next("Unable to remove song from the 'Liked Songs' playlist.");
							return next(null, songId);
						})
						.catch(err => next(err));
				},

				(songId, next) => {
					SongsModule.runJob("RECALCULATE_SONG_RATINGS", { songId, musareSongId })
						.then(ratings => next(null, songId, ratings))
						.catch(err => next(err));
				}
			],
			async (err, songId, { likes, dislikes }) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log(
						"ERROR",
						"SONGS_UNDISLIKE",
						`User "${session.userId}" failed to undislike song ${musareSongId}. "${err}"`
					);
					return cb({ status: "failure", message: err });
				}

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

				CacheModule.runJob("PUB", {
					channel: "song.undislike",
					value: JSON.stringify({
						songId: musareSongId,
						userId: session.userId,
						likes,
						dislikes
					})
				});

				return cb({
					status: "success",
					message: "You have successfully undisliked this song."
				});
			}
		);
	}),

	/**
	 * Unlikes a song
	 *
	 * @param session
	 * @param musareSongId - the song id
	 * @param cb
	 */
	unlike: isLoginRequired(async function unlike(session, musareSongId, cb) {
		const userModel = await DBModule.runJob("GET_MODEL", { modelName: "user" }, this);
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);

		async.waterfall(
			[
				next => {
					songModel.findOne({ songId: musareSongId }, next);
				},

				(song, next) => {
					if (!song) return next("No song found with that id.");
					return next(null, song._id);
				},

				(songId, next) => userModel.findOne({ _id: session.userId }, (err, user) => next(err, songId, user)),

				(songId, user, next) => {
					if (!user) return next("User does not exist.");

					return this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "playlists",
								action: "removeSongFromPlaylist",
								args: [musareSongId, user.dislikedSongsPlaylist]
							},
							this
						)
						.then(res => {
							if (res.status === "failure")
								return next("Unable to remove song from the 'Disliked Songs' playlist.");
							return next(null, songId, user.likedSongsPlaylist);
						})
						.catch(err => next(err));
				},

				(songId, likedSongsPlaylist, next) => {
					this.module
						.runJob(
							"RUN_ACTION2",
							{
								session,
								namespace: "playlists",
								action: "removeSongFromPlaylist",
								args: [musareSongId, likedSongsPlaylist]
							},
							this
						)
						.then(res => {
							if (res.status === "failure")
								return next("Unable to remove song from the 'Liked Songs' playlist.");
							return next(null, songId);
						})
						.catch(err => next(err));
				},

				(songId, next) => {
					SongsModule.runJob("RECALCULATE_SONG_RATINGS", { songId, musareSongId })
						.then(ratings => next(null, songId, ratings))
						.catch(err => next(err));
				}
			],
			async (err, songId, { likes, dislikes }) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log(
						"ERROR",
						"SONGS_UNLIKE",
						`User "${session.userId}" failed to unlike song ${musareSongId}. "${err}"`
					);
					return cb({ status: "failure", message: err });
				}

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

				CacheModule.runJob("PUB", {
					channel: "song.unlike",
					value: JSON.stringify({
						songId: musareSongId,
						userId: session.userId,
						likes,
						dislikes
					})
				});

				return cb({
					status: "success",
					message: "You have successfully unliked this song."
				});
			}
		);
	}),

	/**
	 * Gets user's own song ratings
	 *
	 * @param session
	 * @param musareSongId - the song id
	 * @param cb
	 */

	getOwnSongRatings: isLoginRequired(async function getOwnSongRatings(session, musareSongId, cb) {
		const playlistModel = await DBModule.runJob("GET_MODEL", { modelName: "playlist" }, this);
		const songModel = await DBModule.runJob("GET_MODEL", { modelName: "song" }, this);

		async.waterfall(
			[
				next => {
					songModel.findOne({ songId: musareSongId }, next);
				},

				(song, next) => {
					if (!song) return next("No song found with that id.");
					return next(null);
				},

				next =>
					playlistModel.findOne(
						{ createdBy: session.userId, displayName: "Liked Songs" },
						(err, playlist) => {
							if (err) return next(err);
							if (!playlist) return next("'Liked Songs' playlist does not exist.");

							let isLiked = false;

							Object.values(playlist.songs).forEach(song => {
								// song is found in 'liked songs' playlist
								if (song.songId === musareSongId) isLiked = true;
							});

							return next(null, isLiked);
						}
					),

				(isLiked, next) =>
					playlistModel.findOne(
						{ createdBy: session.userId, displayName: "Disliked Songs" },
						(err, playlist) => {
							if (err) return next(err);
							if (!playlist) return next("'Disliked Songs' playlist does not exist.");

							const ratings = { isLiked, isDisliked: false };

							Object.values(playlist.songs).forEach(song => {
								// song is found in 'disliked songs' playlist
								if (song.songId === musareSongId) ratings.isDisliked = true;
							});

							return next(null, ratings);
						}
					)
			],
			async (err, ratings) => {
				if (err) {
					err = await UtilsModule.runJob("GET_ERROR", { error: err }, this);
					this.log(
						"ERROR",
						"SONGS_GET_OWN_RATINGS",
						`User "${session.userId}" failed to get ratings for ${musareSongId}. "${err}"`
					);
					return cb({ status: "failure", message: err });
				}

				const { isLiked, isDisliked } = ratings;

				return cb({
					status: "success",
					songId: musareSongId,
					liked: isLiked,
					disliked: isDisliked
				});
			}
		);
	})
};