Add shuffle command

src/commands/shuffle.ts

@@ -0,0 +1,29 @@
+import {Message} from 'discord.js';
+import {TYPES} from '../types';
+import {inject, injectable} from 'inversify';
+import Queue from '../services/queue';
+import Command from '.';
+
+@injectable()
+export default class implements Command {
+  public name = 'shuffle';
+  public description = 'shuffle current queue';
+  private readonly queue: Queue;
+
+  constructor(@inject(TYPES.Services.Queue) queue: Queue) {
+    this.queue = queue;
+  }
+
+  public async execute(msg: Message, _: string []): Promise<void> {
+    const queue = this.queue.get(msg.guild!.id);
+
+    if (queue.length <= 2) {
+      await msg.channel.send('error: not enough songs to shuffle');
+      return;
+    }
+
+    this.queue.shuffle(msg.guild!.id);
+
+    await msg.channel.send('`' + JSON.stringify(this.queue.get(msg.guild!.id).slice(0, 10)) + '`');
+  }
+}