4. Control playback

import { player } from './player.ts';

/** Builds a command that needs an existing queue and replies with its result. */
function queueCommand(
  name: string,
  description: string,
  action: (queue: NonNullable<ReturnType<typeof player.getQueue>>) => Promise<string> | string,
): Command {
  return {
    data: { name, description },

    async run(interaction) {
      const queue = player.getQueue(interaction.guildId);

      if (!queue?.currentTrack) {
        return interaction.reply({ content: 'Nothing is playing.', flags: MessageFlags.Ephemeral });
      }

      return interaction.reply(await action(queue));
    },
  };
}

const pause = queueCommand('pause', 'Pause playback', async (queue) => {
  await queue.node.pause();

  return 'Paused.';
});

const resume = queueCommand('resume', 'Resume playback', async (queue) => {
  await queue.node.resume();

  return 'Resumed.';
});

const skip = queueCommand('skip', 'Skip the current track', async (queue) => {
  const next = await queue.skip();

  return next ? `Skipped. Now playing **${next.title}**.` : 'Skipped. The queue is empty.';
});

const stop = queueCommand('stop', 'Stop playback and keep the queue', async (queue) => {
  await queue.stop();

  return 'Stopped.';
});

const nowPlaying = queueCommand('queue', 'Show what is playing', (queue) => {
  const upcoming = queue.tracks
    .toArray()
    .slice(0, 10)
    .map((track, index) => `${index + 1}. ${track.title}`);

  return [`Now playing: **${queue.currentTrack?.title}**`, ...upcoming].join('\n');
});

export const commands: Command[] = [play, pause, resume, skip, stop, nowPlaying];