/**
 *  Doorman entrypoint
 */
const fetch = require('node-fetch');

async function getConfig(context, buzzer) {
  return await fetch(context.DOORMAN_URL + `/api/door/info?buzzer=${buzzer}`)
    .then(res => res.json())
    .catch(err => {
      return undefined;
    });
}

function notifyDiscord(context, msg, u, optionalJsonStr) {
  return fetch(context.DOORMAN_URL + 
    `/api/door/notify?discordUser=${u}&msg=${encodeURIComponent(msg)}&json=${encodeURIComponent(optionalJsonStr)}`,
  ).catch(err => console.log(err))
}

function notifyAllDiscord(context, config, msg, optionalJsonStr) {
  return Promise.all(config.discordUsers.map((u) => 
    notifyDiscord(context, msg, u, optionalJsonStr)
  ));
}

function doorOpenTwiml(twiml, config) {
  twiml.play('https://buzzer-2439-prod.twil.io/buzzing_up_boosted.mp3');
  twiml.play({ digits: config.pressKey }); // configured in doorman what button to click and passed into this function
  twiml.pause({ length: 1 });
  twiml.hangup();
}

function dialFallbackTwiml(twiml, config) {
  let dial = twiml.dial({
    timeLimit: 20, 
    timeout: 20
  });

  config.fallbackNumbers.forEach(number => {
    dial.number(number);
  });
}

exports.handler = async function(context, event, callback) {
  let config = event.config;

  // get by api or parse it out from query
  if (!config) {
    config = await getConfig(context, event.From);
  } else {
    try {
      config = JSON.parse(config);
    } catch(e) {
      config = await getConfig(context, event.From);
    }
  }

  // reject the call if this is not configured
  if (!config || !config.door) {
    let twiml = new Twilio.twiml.VoiceResponse();
    twiml.reject();
    callback(null, twiml);
    return;
  }

  // let users know someone is currently buzzing, and allow unlock by discord user
  let msg = `🔔 Someone is dialing right now @ Door "${config.door}" [Click to unlock](${context.DOORMAN_URL}/api/door/auth?door=${config.door}&key=`;
  
  // TODO: should we await for one delivery?
  Promise.race(config.discordUsers.map((u) => 
    notifyDiscord(context, msg + u + ')', u)
  ));

  let discordLock = false;
  let intervals = [];
  let timeouts = [];

  const unlockPromise = new Promise((resolve, reject) => {
    intervals.push(setInterval(() => {
      fetch(context.DOORMAN_URL + `/api/door/status?door=${config.door}`)
        .then(async res => {
          if (res.status === 200) {
            clearInterval(intervals[0]);
            const body = await res.json();
            const twiml = new Twilio.twiml.VoiceResponse();
            doorOpenTwiml(twiml, config);
            if (!discordLock) {
              discordLock = true;
              console.log(
                "UnlockPromise: I was the fastest, so I will attempt to notify discord users before resolving with unlock"
              );
              await notifyAllDiscord(context, config, `🔓 Doorman buzzed someone up @ Door "${config.door}"`, JSON.stringify(body.fingerprint));
              resolve(twiml);
            } else {
              console.log(
                "UnlockPromise: dropping out of the race, graceful fallback is already notifiying discord users"
              );
            }
          }
        }).catch(err => console.log(err));
    }, 500));
  });

  const gracefulFallbackPromise = new Promise((resolve, reject) => {
    timeouts.push(setTimeout(async () => {
      const twiml = new Twilio.twiml.VoiceResponse();
      dialFallbackTwiml(twiml, config);

      if (!discordLock) {
        discordLock = true;

        console.log(
          "GracefulFallbackPromise: I was the fastest, so I will attempt to notify discord users before resolving with a call"
        );
        await notifyAllDiscord(
          context, 
          config, 
          `📞 Somebody buzzed the door and it dialed through to fallback phone numbers @ Door "${config.door}"`
        );
        resolve(twiml);
      } else {
        console.log(
          "GracefulFallbackPromise: dropping out of the race, unlock is already notifying discord users"
        );
      }
    }, 6000));
  });

  const ungracefulFallbackPromise = new Promise((resolve, reject) => {
    timeouts.push(setTimeout(async () => {
      const twiml = new Twilio.twiml.VoiceResponse();
      dialFallbackTwiml(twiml, config);
      console.error(
        "UngracefulFallbackPromise: Cutting it too close to timeout! Skipping notifying users and calling fallback"
      );
      resolve(twiml);
    }, 8000));
  });

  const twiml = await Promise.race([unlockPromise, gracefulFallbackPromise, ungracefulFallbackPromise]);
  console.log("Race ended, clearing residual timers");
  timeouts.forEach(timeout => clearTimeout(timeout));
  intervals.forEach(interval => clearInterval(interval));
  callback(null, twiml);
};