/* global mozIntl */
define(function(require, exports) {
'use strict';

var calc = require('common/calc');
var co = require('ext/co');
var core = require('core');
var debug = require('common/debug')('controllers/notifications');
var messageHandler = require('message_handler');
var notification = require('notification');

exports.observe = function() {
  debug('Will start notifications controller...');
  messageHandler.responder.on('alarm', exports.onAlarm);
};

exports.unobserve = function() {
  messageHandler.responder.off('alarm', exports.onAlarm);
};

exports.onAlarm = co.wrap(function *(alarm) {
  var storeFactory = core.storeFactory;
  var alarmStore = storeFactory.get('Alarm');
  // Fetch our copy of the alarm since this alarm may
  // have come from the alarms api and therefore would
  // not be up-to-date wrt whether or not it had
  // previously been fired.
  alarm = yield alarmStore.get(alarm._id);
  // The event may have been deleted or rescheduled after mozAlarms queued it.
  if (!alarm || alarm.fired) {
    return;
  }

  debug('Will request cpu wake lock...');
  var lock = navigator.requestWakeLock('cpu');
  debug('Received cpu lock. Will issue notification...');
  try {
    yield issueNotification(alarm);
  } catch (err) {
    console.error('[controllers/notifications]', err.toString());
    return;
  } finally {
    // release cpu lock with or without errors
    debug('Will release cpu wake lock...');
    lock.unlock();
  }

  // Save that we've fired this alarm.
  alarm.fired = true;
  yield alarmStore.persist(alarm);
});

var issueNotification = co.wrap(function *(alarm) {
  if (alarm.fired) {
    // Don't send notification if we've already delivered this alarm
    return;
  }

  var storeFactory = core.storeFactory;
  var eventStore = storeFactory.get('Event');
  var busytimeStore = storeFactory.get('Busytime');

  var trans = core.db.transaction(['busytimes', 'events']);

  // Find the event and busytime associated with this alarm.
  var [event, busytime] = yield Promise.all([
    eventStore.get(alarm.eventId, trans),
    busytimeStore.get(alarm.busytimeId, trans)
  ]);

  // just a safeguard on the very unlikely case that busytime or event
  // doesn't exist anymore (should be really hard to happen)
  if (!event) {
    throw new Error(`can't find event with ID: ${alarm.eventId}`);
  }
  if (!busytime) {
    throw new Error(`can't find busytime with ID: ${alarm.busytimeId}`);
  }

  var begins = calc.dateFromTransport(busytime.start);
  var formatter = mozIntl._gaia.RelativeDate(navigator.languages);
  var distance = yield formatter.format(begins);
  var now = new Date();

  var alarmType = begins > now ?
    'alarm-start-notice' :
    'alarm-started-notice';

  var titleL10n = {
    id: alarmType,
    args: {
      title: event.remote.title,
      distance: distance
    }
  };

  var bodyL10n = { raw: event.remote.description || '' };
  debug('Will send event notification with title', titleL10n,
        'body:', bodyL10n);
  return notification.sendNotification(
    titleL10n,
    bodyL10n,
    `/alarm-display/${busytime._id}`,
    { id: event.remote.id }
  );
});

});