k3kc stock monitor - Google Apps Script

k3.js

var max_errors = 5;
var EMAIL = Session.getActiveUser().getEmail();
var scriptProperties = PropertiesService.getScriptProperties();
//scriptProperties.deleteAllProperties();
function myFunction() {

  var current_stock = {};
  var shop_url = 'http://www.k3kc.com/shop/';
  var links = new Array();
  
  var html = getXMLRequest(shop_url);
  
  // determine number of shop pages to fetch and parse
  var page_nums = getElementsByTagName(getElementsByClassName(html, 'page-numbers')[0], 'li').length;
  
  for (var p = 1; p <= page_nums; p++) {    
   html = getXMLRequest(shop_url + 'page/' + p);
  // parse a page for product links
    var product_links = getElementsByTagName(html, 'table');
    for (i in product_links) {
      links.push(getElementsByTagName(product_links[i], 'a')[0].getAttribute('href').getValue());
    }
  }
  // check stock for each link
  var name_re = new RegExp(/shop\/(.+)\/$/);
  var stock_re = new RegExp(/Only (\d+)/);
  for (var j = 0; j < links.length; j++) {
  
    var name = name_re.exec(links[j])[1];
    var html = getHTMLRequest(links[j]);
    if (!html) {
      Logger.log('FAILED: ' + links[j]);
      continue;
    }
    if (html.match('in-stock')) {
      
      var stock = stock_re.exec(html);
      if (stock){
//        Logger.log(links[j] + ' ' + stock[1]);
        current_stock[name] = stock[1];
      }
      else {
//        Logger.log(links[j] + " In stock");
        current_stock[name] = "in stock";
      }
    }
    else {
//      Logger.log(links[j] + " Out of stock");
      current_stock[name] = "out of stock";
    }
  }
  Logger.log(current_stock);
  var num_changed = 0;
  var body = '';
  for (var key in current_stock) {
    var curr = current_stock[key];
    var prev = scriptProperties[key];
    
    if (curr != prev) {
      Logger.log(key + ' changed from: ' + prev + ' to: ' + curr);
      body += key + ' changed from: ' + prev + ' to: ' + curr + "\n";
      scriptProperties.setProperty(key, curr);
    }
  }
  if (num_changed > 0) {
    var title = num_changed + ' updated items';
    MailApp.sendEmail(EMAIL, title, body, {name: 'K3 Stock'});
    Logger.log('email sent');
  }
  else {
    Logger.log('no changes detected');
  }
}

function getHTMLRequest(url) {
var errors = 0;
  Utilities.sleep(1000);
  var page;
  try {
   page = UrlFetchApp.fetch(url).getContentText();
  }
  catch (e) {
    if (errors++ > max_errors) {
      Logger.log("could not fetch HTML URL: " + url);
      throw Error("too many attempts: " + url);
    }
    Utilities.sleep(5000);
  }
  return page;
}

function getXMLRequest(url) {
  var errors = 0;
  Utilities.sleep(1000);
  var page;
  try {
   page = UrlFetchApp.fetch(url);
  }
  catch (e) {
    if (errors++ > max_errors) {
      Logger.log("could not fetch XML URL: " + url);
      throw Error("too many attempts: " + url);
    }
    Utilities.sleep(5000);
  }
  var doc = Xml.parse(page, true);
  var bodyHtml = doc.html.body.toXmlString();
  doc = XmlService.parse(bodyHtml);
  var html = doc.getRootElement();
  return html;
}

function getElementsByClassName(element, classToFind) {  
  var data = [];
  var descendants = element.getDescendants();
  descendants.push(element);  
  for(i in descendants) {
    var elt = descendants[i].asElement();
    if(elt != null) {
      var classes = elt.getAttribute('class');
      if(classes != null) {
        classes = classes.getValue();
        if(classes == classToFind) data.push(elt);
        else {
          classes = classes.split(' ');
          for(j in classes) {
            if(classes[j] == classToFind) {
              data.push(elt);
              break;
            }
          }
        }
      }
    }
  }
  return data;
}

function getElementsByTagName(element, tagName) {  
  var data = [];
  var descendants = element.getDescendants();  
  for(i in descendants) {
    var elt = descendants[i].asElement();     
    if( elt !=null && elt.getName()== tagName) data.push(elt);      
  }
  return data;
}

function getElementById(element, idToFind) {  
  var descendants = element.getDescendants();  
  for(i in descendants) {
    var elt = descendants[i].asElement();
    if( elt !=null) {
      var id = elt.getAttribute('id');
      if( id !=null && id.getValue()== idToFind) return elt;    
    }
  }
}