M3U Writer Class

m3uWriter.js

/**
 * Constantes used for constructing.
 */
const EXTGRP = 'EXTGRP';
const EXTPLS = 'PLAYLIST';
const GROUPTITLE = 'group-title';

/**
 * M3U Writer Class
 */
 export class m3uWriter {

    // New Line Character(s)
    #newLine = '\n';

    // Use group-title directives?
    #groupDirectives = false;

    // Excluded attributes
    #attributes = [];
    // Excluded directives
    #directives = [];

    // Class constructor
    constructor(options) {
        const vm = this;
        // Set newline character(s)
        if (options && options.newLine && options.newLine.length) {
            vm.#newLine = `${options.newLine}`;
        }
        // Set use group-title directives
        if (options && options.groupDirectives && options.groupDirectives === true) {
            vm.#groupDirectives = options.groupDirectives;
        }
        // Set attributes
        if (options && options.attributes && Array.isArray(options.attributes)) {
            vm.#attributes = [...options.attributes];
        }
        // Set directives
        if (options && options.directives && Array.isArray(options.directives)) {
            vm.#directives = [...options.directives];
        }
    }

    // Format attribute
    formatAttribute(attribute, value) {
        return `${attribute.toLowerCase()}="${value}"`;
    }

    // Format directive
    formatDirective(directive, value) {
        return `#${directive.toUpperCase()}:${value}`;
    }
    
    // Format #EXTINF line from stream
    formatStream(stream, group) {
        const vm = this;
        let res = `#EXTINF:${stream.length}`;
        // Add attributes
        stream.attributes.forEach((attribute) => {
            if (!vm.#attributes.includes(attribute.attribute)) {
                res += ` ${vm.formatAttribute(attribute.attribute, attribute.value)}`;
            }
        });
        // Add group-title?
        if (group && vm.#groupDirectives !== true) {
            res += ` ${vm.formatAttribute(GROUPTITLE, group)}`;
        }
        // Add title
        res += `,${stream.title}`
        return res;
    }

    write(m3u) {
        const vm = this;
        // Return a promise (Async)
        return new Promise((resolve, reject) => {

            // Playlist output
            let playlist = '#EXTM3U';
            if (m3u.attributes && m3u.attributes.length) {
                m3u.attributes.forEach((attribute) => {
                    playlist += ` ${vm.formatAttribute(attribute.attribute, attribute.value)}`;
                });
            }

            // Function: Add line to playlist
            const addLine = (line) => {
                playlist += vm.#newLine;
                playlist += line;
            }

            // Add playlist title
            if (m3u.title && m3u.title.length) {
                addLine(vm.formatDirective(EXTPLS, m3u.title));
            }

            // Add streams
            if (m3u.groups && Array.isArray(m3u.groups)) {
                // Loop over groups
                m3u.groups.forEach((group) => {
                    // Loop over streams in group
                    group.streams.forEach((stream) => {
                        // Add stream #EXTINF
                        addLine(vm.formatStream(stream, group.title));
                        // Add group directive?
                        if (vm.#groupDirectives === true) {
                            addLine(vm.formatDirective(EXTGRP, group.title));
                        }
                        // Add directives
                        stream.directives.forEach((directive) => {
                            if (!vm.#directives.includes(directive.directive)) {
                                addLine(vm.formatDirective(directive.directive, directive.value));
                            }
                        });
                        // Add stream URL/Filename
                        addLine(stream.url);
                    });
                });
            } else {
                reject('error.no-groups-defined');
                return;
            }

            // Finished constructing M3U playlist
            resolve(playlist);
        });
    }

}