const { DeviceDiscovery } = require('sonos');
const ease = require('eases/quad-in-out');

// How long to let the SONOS device play for once playing is detected.
// The longer you leave it the less likely that your co-worker will
// notice that you've turned it off and won't restart it.
const PLAY_DELAY = 120000; // 2 minutes.

// How long it takes to fade the volume down to zero.
const FADE_DELAY = 60000; // 60 seconds.

// Easing period, you shouldn't need to change this. Just don't make it
// longer than the FADE_DELAY.
const FADE_STEP = 500; // 0.5 seconds.

// How often to check if the device is playing.
const POLL_DELAY = 10000; // 10 seconds.

let fadeDown = function(device) {
  device.getVolume().then((volume) => {
    console.log(`Device ${device.host} volume ${volume}`);
    let start = new Date().valueOf();
    let lastVolume = volume;
    let timer = setInterval(() => {
      let elapsed = (new Date().valueOf()) - start;
      if (elapsed > FADE_DELAY) {
        console.log(`Stopping ${device.host}`);
        if (device.stop()) {
          console.log(`Resetting ${device.host} volume back to ${volume}`);
          device.setVolume(volume)
          clearInterval(timer);
          setTimeout(pollState, POLL_DELAY, device);
        }
      } else {
        let newVolume = parseInt(ease(1 - (elapsed / FADE_DELAY)) * volume);
        if (newVolume != lastVolume) {
          console.log(`Setting ${device.host} volume to ${newVolume}`);
          device.setVolume(newVolume);
          lastVolume = newVolume;
        }
      }
    }, FADE_STEP);
  });
}

let pollState = function(device) {
  device.getCurrentState().then((state) => {
    if (state === 'playing') {
      console.log(`Device ${device.host} is playing, queuing fade out`);
      setTimeout(fadeDown, PLAY_DELAY, device);
    } else {
      setTimeout(pollState, POLL_DELAY, device);
    }
  });
};

DeviceDiscovery((device) => {
  console.log(`Found device at ${device.host}`);
  pollState(device);
})