background.js

// globals for easy access by interval'ed callback
var LastIcon = 'default',
  notifer,
  icon = 'default',
  within = '',
  group = 'group_1';

function swapIcon() {
  var schedule = JSON.parse(localStorage.loshinCache || '[0]')[0],
    newDate = new Date(),
    today = 'sunday monday tuesday wednesday thursday friday saturday'.split(' ')[newDate.getDay()],
    alertThreshold = localStorage.loshinAlertBefore * 1 || 15,
    minutes = [],
    blackOut, minute = newDate.getHours() * 60 + newDate.getMinutes(),
    group = localStorage.loshinMyGroup || 'group_1';

  if (!schedule) {
    chrome.browserAction.setIcon({
      path: 'icons/default.png'
    });
    chrome.browserAction.setTitle({
      title: 'loshin: Could not fetch data, Click to reload'
    });
    return;
  }

  blackOut = schedule[group][today];
  ['morning', 'evening'].forEach(function(shift) {
    blackOut[shift].split('-').forEach(function(tym) {
      var tyms = tym.split(':');
      minutes.push((tyms[0] < 1 ? 24 : tyms[0]) * 60 + tyms[1] * 1);
    });
  });

  // quick fix:
  if (minutes[0] > minutes[1]) minutes[1] += 1440;
  if (minutes[2] > minutes[3]) minutes[3] += 1440;

  if (((diff1 = minutes[0] - minute) >= 0 && diff1 < alertThreshold) ||
    ((diff1 = minutes[2] - minute) >= 0 && diff1 < alertThreshold)
  ) icon = 'going';
  else if (((diff2 = minutes[1] - minute) >= 0 && diff2 < alertThreshold) ||
    ((diff2 = minutes[3] - minute) >= 0 && diff2 < alertThreshold)
  ) icon = 'coming';
  else if (minute < minutes[0] || minute > minutes[3] || (minute > minutes[1] && minute < minutes[2]))
    icon = 'on';
  else icon = 'off';

  if (icon == 'going') within = ' within ' + diff1 + ' minute(s)';
  else if (icon == 'coming') within = ' within ' + diff2 + ' minute(s)';
  else within = '';

  chrome.browserAction.setIcon({
    path: 'icons/' + icon + '.png'
  });
  chrome.browserAction.setTitle({
    title: 'loshin: Light is ' + icon + within
  });

  if (icon !== LastIcon) {
    clearInterval(notifer);
    notifer = null;
    notify();
  }

  function notify() {
    LastIcon = icon;
    // revoke as per https://developer.mozilla.org/en/docs/Web/API/notification
    var notif = new Notification(
      new Date().toLocaleTimeString().replace(/:\d+ /, ' '), {
        icon: 'icons/' + icon + '.png',
        body: 'loshin: Light is ' + icon + within
      }
    );
  }

  if (!notifer) {
    var inter = localStorage.loshinNoticeInterval;
    notifer = setInterval(
      function() {
        notify();
      }, (inter || 30) * 60000
    );
  }
}

function ping() {
  var tymr = setInterval(swapIcon, 10000);
  swapIcon();
}

ping();