function trackInventory() {
  var report = ''; // Email Report

  // Find Apple Product that are to be tracked
  var items = SpreadsheetApp.getActiveSheet().getRange('B6:D121').getValues();

  // Check inventory of Apple Stores near this zip code
  var zip = UserProperties.getProperty('zip');

  for (var i = 0; i < items.length; i++) {
    if (items[i][2] === 'Y') {
      // Check product availability at the given zip code
      var url =
        'http://store.apple.com/us/retail/availabilitySearch?parts.0=' +
        encodeURIComponent(items[i][1]) +
        '&zip=' +
        zip;

      var locations = '';

      try {
        var response = UrlFetchApp.fetch(url);
        var json = Utilities.jsonParse(response.getContentText());

        for (var j = 0; j < json.body.stores.length; j++) {
          // Is the product (Apple Part) listed as "available" in that Apple Store
          var store = json.body.stores[j];
          if (store['partsAvailability'][items[i][1]]['pickupSearchQuote'] != 'Unavailable for Pickup') {
            locations +=
              "<li><small><a href='" +
              store['directionsUrl'] +
              "'>" +
              store['storeDisplayName'] +
              '</a> ' +
              store['address']['address2'] +
              ', ' +
              store['city'] +
              ' ' +
              store['address']['postalCode'] +
              ' ' +
              store['state'] +
              ' (' +
              store['phoneNumber'] +
              ')</small></li>';
          }
        }

        if (locations.length) {
          report +=
            "<p><strong><a href='" +
            storeURL(items[i][0]) +
            "'>" +
            items[i][0] +
            '</a></strong> is currently available at: </p><ul>';
          report += locations + '</ul>';
        }
      } catch (e) {
        Logger.log(e.toString());
      }
    }
  }

  // Send HTML Mail with the product availability details
  if (report.length) {
    MailApp.sendEmail(UserProperties.getProperty('email'), 'Apple Tracker', report, { htmlBody: report });
  }
}

function onOpen() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var menu = [
    { name: 'Step 1: Initialize', functionName: 'OpenWizard' },
    { name: 'Step 2: Start Tracking', functionName: 'OpenWizard' },
  ];

  ss.addMenu('Apple Store Tracker', menu);
  ss.toast('Please click the Apple Tracker menu above to continue..', '', 5);
}

// Create UI to get email address and zip code from the user
function OpenWizard() {
  var app = UiApp.createApplication().setTitle('Apple Inventory Tracker').setHeight(160).setWidth(300);
  var top_panel = app.createFlowPanel();
  top_panel.add(app.createLabel('').setHeight(10));

  top_panel.add(app.createLabel('Please enter your ZIP code'));
  var zip = app.createTextBox().setName('zip').setWidth(250).setValue(UserProperties.getProperty('zip'));
  top_panel.add(zip);

  top_panel.add(app.createLabel('').setHeight(10));
  top_panel.add(app.createLabel('Please enter your Email Address'));
  var email = app.createTextBox().setName('email').setWidth(250).setValue(UserProperties.getProperty('email'));
  top_panel.add(email);

  top_panel.add(app.createLabel('').setHeight(5));
  var btn = app.createButton('Start Tracking');
  top_panel.add(btn);

  var handler = app.createServerHandler('storeDB').addCallbackElement(zip).addCallbackElement(email);
  btn.addClickHandler(handler);

  app.add(top_panel);
  SpreadsheetApp.getActiveSpreadsheet().show(app);
}

// Get the Apple Store URL based on the Part Name
function storeURL(partName) {
  var storeURL;

  if (partName.search('iPad Air') != -1) storeURL = 'http://store.apple.com/us/buy-ipad/ipad-air';
  else if (partName.search('iPad Mini Retina') != -1) storeURL = 'http://store.apple.com/us/buy-ipad/ipad-mini-retina';
  else storeURL = 'http://store.apple.com/us/buy-iphone/iphone5s';

  return storeURL;
}

// Store the Zip and Email address in User Properties
function storeDB(e) {
  var ss = SpreadsheetApp.getActiveSpreadsheet();

  UserProperties.setProperty('email', e.parameter.email);
  UserProperties.setProperty('zip', e.parameter.zip);

  var app = UiApp.getActiveApplication();
  app.close();
  return app;
}