core.js

const log = require('fancy-log'),
    jsdom = require('jsdom'),
    { 
        ignoreBrackets, 
        ignoreFiletype, 
        replaceUnderscore, 
        showRemainingTime,  
        replaceDots,
    } = require('./config'),
    { JSDOM } = jsdom;

// Discord Rich Presence has a string length limit of 128 characters.
// This little plugin (based on https://stackoverflow.com/a/43006978/7090367)
// helps by trimming strings up to a given length.
String.prototype.trimStr = function (length) {
    return this.length > length ? this.substring(0, length - 3) + "..." : this;
};

// Defines playback data fetched from MPC.
let playback = {
    filename: '',
    position: '',
    duration: '',
    fileSize: '',
    state: '',
    prevState: '',
    prevPosition: '',
};

// Defines strings and image keys according to the 'state' string
// provided by MPC.
const states = {
    '-1': {
        string: 'Idling',
        stateKey: 'stop_small'
    },
    '0': {
        string: 'Stopped',
        stateKey: 'stop_small'
    },
    '1': {
        string: 'Paused',
        stateKey: 'pause_small'
    },
    '2': {
        string: 'Playing',
        stateKey: 'play_small'
    }
};

/**
 * Sends Rich Presence updates to Discord client.
 * @param {AxiosResponse} res Response from MPC Web Interface variables page
 * @param {RPCClient} rpc Discord Client RPC connection instance
 */
const updatePresence = (res, rpc) => {
    // Identifies which MPC fork is running.
    const mpcFork = res.headers.server.replace(' WebServer', '');

    // Gets a DOM object based on MPC Web Interface variables page.
    const { document } = new JSDOM(res.data).window;

    // Gets relevant info from the DOM object.
    let filename = playback.filename = document.getElementById('filepath').textContent.split("\\").pop().trimStr(128);
    playback.state = document.getElementById('state').textContent;
    playback.duration = sanitizeTime(document.getElementById('durationstring').textContent);
    playback.position = sanitizeTime(document.getElementById('positionstring').textContent);

    // Replaces underscore characters to space characters
    if (replaceUnderscore) playback.filename = playback.filename.replace(/_/g, " ");

	// Removes brackets and its content from filename if `ignoreBrackets` option
	// is set to true
    if (ignoreBrackets) {
        playback.filename = playback.filename.replace(/ *\[[^\]]*\]/g, "").trimStr(128);
        if (playback.filename.substr(0, playback.filename.lastIndexOf(".")).length == 0) playback.filename = filename;
    }
	
    // Replaces dots in filenames to space characters
    // Solution found at https://stackoverflow.com/a/28673744
    if (replaceDots) {
        playback.filename = playback.filename.replace(/[.](?=.*[.])/g, " ");
    }

	// Removes filetype from displaying
	if (ignoreFiletype) playback.filename = playback.filename.substr(0, playback.filename.lastIndexOf("."));

    // Prepares playback data for Discord Rich Presence.
    let payload = {
        state: playback.duration + ' total',
        startTimestamp: undefined,
        endTimestamp: undefined,
        details: playback.filename,
        largeImageKey: mpcFork === 'MPC-BE' ? 'mpcbe_logo' : 'default',
        largeImageText: mpcFork,
        smallImageKey: states[playback.state].stateKey,
        smallImageText: states[playback.state].string
    };

    // Makes changes to payload data according to playback state.
    switch (playback.state) {
        case '-1': // Idling
            payload.state = states[playback.state].string;
            payload.details = undefined;
            break;
        case '1': // Paused
            payload.state = playback.position + ' / ' + playback.duration;
            break;
        case '2': // Playing
            if (showRemainingTime) {
                payload.endTimestamp = Date.now() + (convert(playback.duration) - convert(playback.position));
            } else {
                payload.startTimestamp = Date.now() - convert(playback.position);
            }
            break;
    }

    // Only sends presence updates if playback state changes or if playback position
    // changes while playing.
    if ((playback.state !== playback.prevState) || (
        playback.state === '2' &&
        convert(playback.position) !== convert(playback.prevPosition) + 5000
    )) {
        rpc.setActivity(payload)
            .catch((err) => {
                log.error('ERROR: ' + err);
            });
        log.info('INFO: Presence update sent: ' +
            `${states[playback.state].string} - ${playback.position} / ${playback.duration} - ${playback.filename}`
        );
    }

    // Replaces previous playback state and position for later comparison.
    playback.prevState = playback.state;
    playback.prevPosition = playback.position;
    return true;
};

/**
 * Simple and quick utility to convert time from 'hh:mm:ss' format to milliseconds.
 * @param {string} time Time string formatted as 'hh:mm:ss'
 * @returns {number} Number of milliseconds converted from the given time string
 */
const convert = time => {
    let parts = time.split(':'),
        seconds = parseInt(parts[parts.length - 1]),
        minutes = parseInt(parts[parts.length - 2]),
        hours = (parts.length > 2) ? parseInt(parts[0]) : 0;
    return ((hours * 60 * 60) + (minutes * 60) + seconds) * 1000;
};

/**
 * In case the given 'hh:mm:ss' formatted time string is less than 1 hour, 
 * removes the '00' hours from it.
 * @param {string} time Time string formatted as 'hh:mm:ss'
 * @returns {string} Time string without '00' hours
 */
const sanitizeTime = time => {
    if (time.split(':')[0] === '00') {
        return time.substr(3, time.length - 1);
    }
    return time;
};

module.exports = updatePresence;