Discord.js Music Bot

const Discord = require("discord.js");

const bot = new Discord.Client();

const config = require("./config.json");
const ytdl = require("ytdl-core");

const prefix  = config.prefix;

var queue = new Map();

bot.on("ready", () => {
    console.log(`I am ready! I am in ${bot.guilds.size} guilds`);

    bot.user.setActivity(`Hello!`);
});

bot.on("message", async message => {
    if(message.author.bot) return;
    if(message.content.indexOf(prefix) !== 0) return;

    const args = message.content.slice(prefix.length).trim().split(/ +/g);
    const command = args.shift().toLowerCase();

    const serverQueue = queue.get(message.guild.id);

    if(command === 'hello') {
        message.reply('Hello!');
    }

    if(command === 'ping') {
        const msg = await message.channel.send("Pinging...");
        msg.edit(`Pong! Latency is ${msg.createdTimestamp - message.createdTimestamp}ms. API Latency is ${Math.round(bot.ping)}ms`);
    }

    if(command === 'kick') {
        if(!message.member.hasPermission("ADMINISTRATOR")) return message.reply('Sorry you do not have permission!');
        let member = message.mentions.members.first() || message.guild.members.get(args[0]);
        if(!member) return message.reply("Please mention a valid user");
        if(!member.kickable) return message.channel.send("Sorry I cannot kick that person! Do they have a higher role?");

        let reason = args.slice(1).join(' ');
        if(!reason) reason = "No reason provided";

        await member.kick(reason)
            .catch(e => message.reply(`Sorry I couldn't kick them! Error: ${e}`));
        message.reply(`:white_check_mark: User kicked!`);
    }

    if(command === 'ban') {
        if(!message.member.hasPermission("ADMINISTRATOR")) return message.reply('Sorry you do not have permission!');
        let member = message.mentions.members.first() || message.guild.members.get(args[0]);
        if(!member) return message.reply("Please mention a valid user");
        if(!member.bannable) return message.channel.send("Sorry I cannot ban that person! Do they have a higher role?");

        let reason = args.slice(1).join(' ');
        if(!reason) reason = "No reason provided";

        await member.ban(reason)
            .catch(e => message.reply(`Sorry I couldn't ban them! Error: ${e}`));
        message.reply(`:white_check_mark: User banned!`);
    }

    if(command === 'play') {
        // !play url

        play(message, serverQueue);
    }

});

async function play(message, serverQueue) {
    const args = message.content.split(" ");

    const voiceChannel = message.member.voiceChannel;
    if(!voiceChannel) return message.reply("You must be in a voice channel!");
    const permission = voiceChannel.permissionsFor(message.client.user);
    if(!permission.has('CONNECT') || !permission.has("SPEAK")) {
        return message.channel.send("I need permission to join and speak in your voice channel!")
    }

    const songInfo = await ytdl.getInfo(args[1]);
    const song = {
        title: songInfo.title,
        url: songInfo.video_url,
    };

    if(!serverQueue) {
        const queueConstruct = {
            textChannel: message.channel,
            voiceChannel: voiceChannel,
            connection: null,
            songs: [],
            volume: 5,
            playing: true,
        };
        queue.set(message.guild.id, queueConstruct);

        queueConstruct.songs.push(song);

        try{
            var connection = await voiceChannel.join();
            queueConstruct.connection = connection;
            playSong(message.guild, queueConstruct.songs[0]);
        } catch (err) {
            console.log(err);
            queue.delete(message.guild.id)
            return message.channel.send("There was an error playing! " + err);
        }
    } else {
        serverQueue.songs.push(song);
        return message.channel.send(`${song.title} has been added to the queue!`);
    }
}

function playSong(guild, song) {
    const serverQueue = queue.get(guild.id);

    if(!song) {
        serverQueue.voiceChannel.leave();
        queue.delete(guild.id);
        return;
    }

    const dispatcher = serverQueue.connection.playStream(ytdl(song.url))
        .on('end', () => {
            serverQueue.songs.shift();
            playSong(guild, serverQueue.songs[0]);
        })
        .on('error', error => {
            console.log(error);
        })
    dispatcher.setVolumeLogarithmic(serverQueue.volume / 5);
}


bot.login(config.token);