✨ Add back method

Closes #133

src/Player.js

@@ -478,6 +478,23 @@ class Player extends EventEmitter {
         return queue
     }
 
+    /**
+     * Play back the previous song.
+     * @param {Discord.Message} message
+     * @returns {Queue}
+     */
+    back (message) {
+        // Get guild queue
+        const queue = this.queues.get(message.guild.id)
+        if (!queue) return this.emit('error', 'NotPlaying', message)
+        queue.tracks.splice(1, 0, queue.previousTracks.shift())
+        // End the dispatcher
+        queue.voiceConnection.dispatcher.end()
+        queue.lastSkipped = true
+        // Return the queue
+        return queue
+    }
+
     /**
      * Get the played song in the server.
      * @param {Discord.Message} message

src/Queue.js

@@ -35,6 +35,11 @@ class Queue extends EventEmitter {
          * @type {Track[]}
          */
         this.tracks = []
+        /**
+         * The previous tracks in this queue.
+         * @type {Track[]}
+         */
+        this.previousTracks = []
         /**
          * Whether the stream is currently stopped.
          * @type {boolean}

typings/index.d.ts

@@ -33,6 +33,7 @@ declare module 'discord-player' {
         public getQueue(message: Message): Queue;
         public clearQueue(message: Message): void;
         public skip(message: Message): void;
+        public back(message: Message): void;
         public nowPlaying(message: Message): Track;
         public setRepeatMode(message: Message): boolean;
         public setLoopMode(message: Message, enabled: boolean): boolean
@@ -90,6 +91,7 @@ declare module 'discord-player' {
         public voiceConnection?: VoiceConnection;
         public stream: Stream;
         public tracks: Track[];
+        public previousTracks: Track[];
         public stopped: boolean;
         public lastSkipped: boolean;
         public volume: number;