node-mpv-2/lib/mpv/_controls.js

A Node module for MPV

'use strict';

const net = require('net');

const controls = {
	// toggles pause
	togglePause: function() {
		return this.cycleProperty('pause');
	},
	// pause
	pause: function() {
		return this.setProperty('pause', true);
	},
	// resume
	resume: function() {
		return this.setProperty('pause', false);
	},
	// play
	play: async function() {
		const idle = await this.getProperty('idle-active')
		const playlist_size = await this.getPlaylistSize();
		// if mpv is idle but has a playlist, set playlist-pos to 0,
		// which starts the playback
		if(idle && playlist_size > 0){
			return new Promise(async (resolve, reject) => {
				// get the filename of the first item in the playlist for error handling purposes
				const fname = await this.getProperty('playlist/0/filename');

				let started = false;
				// socket to observe if the file is being played back
				const observeSocket = new net.Socket();
				observeSocket.connect({path: this.options.socket}, async () => {
					// this starts the playback when mpv is idle but songs are queued in the playlist
					await this.setProperty('playlist-pos', 0);
				}).on('data', (data) => {
					// parse the messages from the socket
					const messages = data.toString('utf-8').split('\n');
					// check every message
					messages.forEach((message) => {
						// ignore empty messages
						if(message.length > 0){
							message = JSON.parse(message);
							// look for the file-loaded event to see if the file was loaded and is played 
							if('event' in message){
								if(message.event === 'start-file'){
									started = true;
								}
								// when the file has successfully been loaded resolve the promise
								else if(message.event === 'file-loaded' && started){
									observeSocket.destroy();
									// resolve the promise
									return resolve();
								}
								// when the track has changed we don't need a seek event
								else if (message.event === 'end-file' && started){
									observeSocket.destroy();
									return reject(this.errorHandler.errorMessage(0, 'play()', [fname]));
								}
							}
						}
					});
				});
			});
		}
		// if mpv is not idle and has files queued just set the pause state to false
		else{
			return this.setProperty('pause', false);
		} 
	},
	// stop
	stop: function() {
		return this.command('stop', []);
	},
	// quit
	quit: function() {
		// unbind the event listeners
		this.mpvPlayer.removeAllListeners('close');
		this.mpvPlayer.removeAllListeners('error');
		this.mpvPlayer.removeAllListeners('message');
		clearInterval(this.timepositionListenerId);
		// send the quit command to mpv
		this.socket.command("quit");
		// quit the socket connection
		this.socket.quit();
	},
	// volume control values 0-100
	volume: function(value) {
		return this.setProperty('volume', value);
	},
	adjustVolume: function(value) {
		return this.addProperty('volume', value);
	},
	// mute
	// bool set 
	// 	true mutes
	// 	false unmutes
	// 	Not setting set toggles the mute state
	mute: function(set) {
		return  set!=null ? this.setProperty('mute', set) : this.cycleProperty('mute');
	},
	//  relative search
	seek: async function(seconds, mode = 'relative') {
		// reject the promise if the mode is not correct
		if(!['relative', 'absolute', 'append-play'].includes(mode)){
			throw ( this.errorHandler.errorMessage(1, 'seek()', mode, null, {
					'relative': 'Searches x seconds from the current position',
					'absolute': 'Goes to position x seconds of the current track',
				}));
		}
		// perform a seek operation	
		return new Promise((resolve, reject) => {
			// tracks if the seek event has been emitted
			let seek_event_started = false;
			const observeSocket = new net.Socket();
			observeSocket.connect({path: this.options.socket}, async () => {
				try {
					await this.command('seek', [seconds, mode, 'exact']);
				}
				catch (err) {
					reject(err);
				}
			}).on('data', (data) => {
				// parse the messages from the socket
				const messages = data.toString('utf-8').split('\n');
				// check every message
				messages.forEach((message) => {
					// ignore empty messages
					if(message.length > 0){
						message = JSON.parse(message);
						if('event' in message){
							// if the seek event was found set the flag variable to true
							if(message.event === 'seek') seek_event_started = true;
							// resolve the promise if the playback-restart event was fired
							else if (seek_event_started && message.event === 'playback-restart') {
								observeSocket.destroy();
								resolve();
							}
						}
					}
				});
			});
		});
	},
	// go to position of the song
	goToPosition: async function(seconds) {
		return this.seek(seconds, 'absolute');
	},
	// loop
	// int/string times
	// 	number n - loop n times
	// 	'inf' 	 - loop infinitely often
	// 	'no'	 - switch loop to off
	// 
	// if times is not set, this method will toggle the loop state, if any looping is set, either 'inf' or a fixed number it will be switched off
	loop: async function(times) {
		// if times was set, use it. Times can be any number > 0, 'inf' and 'no'
 		if (times!=null) {
			return this.setProperty('loop', times);
		}
		// if times was not set, net loop toggle the mute property
		else {
			// get the loop status
			// if any loop status was set, either 'inf' or a fixed number, switch loop to off
			// if no loop status was set, switch it on to 'inf'
			const loop_status = await this.getProperty('loop');			
			return !loop_status ? this.setProperty('loop', 'inf') : this.setProperty('loop', 'no');
		}
	}
}

module.exports = controls;