util.js

'use strict';

const execSync  = require('child_process').execSync;

// Lodash for some nice stuff
const _ = require('lodash');

const util = {
	// Finds the correct command to start the IPC socket for mpv. It looks at the
	// output of 'mpv --version' and uses Regular Expressions to determine the mpv
	// version.
	// With mpv version 0.17.0 the command changed from "--input-unix-socket" to
	// "--input-ipc-server"
	//
	// @param binary
	// The binary path for the mpv executable
	//
	// @ return
	// The ipc command flag used by mpv
	//
	findIPCCommand: function(options) {
		// if the ipc Command was set by the user, use that
		if(options.ipc_command){
			if(!(options.ipc_command == "--input-ipc-server" || options.ipc_command == "--input-unix-socket")){
				console.log('Warning: ipcCommand was neither "--input-unix-socket" nor "--input-ipc-server", using the up to date "--input-ipc-server"');
			}
			return "--input-ipc-server";
		}
		// determine the ipc command according to the version number
		else{
			// the name of the ipc command was changed in mpv version 0.17.0 to "--input-ipc-server"
			// that's why we have to check which mpv version is running
			// asks for the mpv version
			const output = execSync((options.binary ? '"' + options.binary + '"' + " --version" : "mpv --version"), {encoding: 'utf8'});

			// Version Number found
			if(output.match(/UNKNOWN/) == null){
				// get the version part of the output
				// looking for mpv 0.XX.Y
				const regex_match = output.match(/(mpv) \d+.\d+.\d+/)
				// check if there actually was a match
				if(regex_match){
					const match = regex_match[0];
					// split at the whitespace to get the numbers
					// split at the dot and look at the middle one to check for the
					// critical version number
					const versionNumber = parseInt(match.split(" ")[1].split(".")[1]);
					// Verison 0.17.0 and higher
					if(versionNumber >= 17){
						return "--input-ipc-server";
					}
					// Version 0.16.0 and below
					else{
						return "--input-unix-socket";
					}
				}
				// when MPV is built from source it sometimes has a git hash as
				// the version number
				// In this case assume it's a newer version and use the new command
				else{
					return "--input-ipc-server";
				}
			}
			// when compiling mpv from source the displayed version number is "UNKNOWN"
			// I assume that version that is compiled from source is the latest version
			// and use the new command
			else{
				return "--input-ipc-server";
			}
		}
	},
	// Merges the options input by the user with the default options, giving
	// the user input options priority
	//
	// @param options
	// node-mpv options object input by the user
	//
	// @ return
	// Merged options object (UserInput with DefaultOptions)
	//
	mergeDefaultOptions: function(userInputOptions) {
		// the default options to start the socket with
		let defaultOptions = {
			"debug": false,
			"verbose": false,
			// Windows and UNIX defaults
			"socket": process.platform === "win32" ? "\\\\.\\pipe\\mpvserver" : "/tmp/node-mpv.sock",
			"audio_only": false,
			"time_update": 1,
			"binary": null
		}

		// merge the default options with the one specified by the user
		return _.defaults(userInputOptions || {}, defaultOptions);
	},
	// Determies the properties observed by default
	// If the player is NOT set to audio only, video properties are observed
	// as well
	//
	// @param adioOnlyOption
	// Flag if mpv should be started in audio only mode
	//
	// @return
	// Observed properties object
	//
	observedProperties: function(audioOnlyOption) {
		// basic observed properties
		let basicObserved = {
			"mute": false,
			"pause": false,
			"duration": null,
			"volume": 100,
			"filename": null,
			"path": null,
			"media-title": null,
			"playlist-pos": null,
			"playlist-count": null,
			"loop": "no"
		};

		// video related properties (not required in audio-only mode)
		const observedVideo = {
			"fullscreen": false,
			"sub-visibility": false,
		}

		// add the video properties if not set to audio only
		if(!audioOnlyOption){
			basicObserved = _.merge(basicObserved, observedVideo);
		}

		return basicObserved;
	},
	// Determines the arguments to start mpv with
	// These consist of some default arguments and user input arguments
	// @param options
	// node-mpv options object
	// @param userInputArguments
	// mpv arguments input by the user
	//
	// @return
	// list of arguments for mpv
	mpvArguments: function(options, userInputArguments) {
		// determine the IPC argument
		const ipcCommand = this.findIPCCommand(options);

		// default Arguments
		//  --ipcCommand (--ipc-input-server / --input-unix-socket) IPC socket to communicate with mpv
		//  --idle always run in the background
		//  --really-quite  no console prompts. Buffer might overflow otherwise
		let defaultArgs = [ipcCommand + "=" + options.socket, '--idle', '--really-quiet'];

		//  audio_only option aditional arguments
		// --no-video  no video will be displayed
		// --audio-display  prevents album covers embedded in audio files from being displayed
		if(options.audio_only){
			defaultArgs = _.concat(defaultArgs, ['--no-video', '--no-audio-display']);
		}

		// add the user specified arguments if specified
		if(userInputArguments){
			defaultArgs = _.union(defaultArgs, userInputArguments);
		}

		return defaultArgs;
	},
	// takes an options list consisting of strings of the following pattern
	//      option=value
	//   => ["option1=value1", "option2=value2"]
	// and formats into a JSON object such that the mpv JSON api accepts it
	//   => {"option1": "value1", "option2": "value2"}
	// @param options
	// list of options
	//
	// @return
	// correctly formatted JSON object with the options
	formatOptions: function(options) {
		// JSON Options object
		let optionJSON = {}
		// each options is of the form options=value and has to be splited
		let splitted = []
		// iterate through every options
		for(let i = 0; i < options.length; i++){
			splitted = options[i].split('=')
			optionJSON[splitted[0]] = splitted[1]
		}
		return optionJSON;
	}
}

module.exports = util;