Checks for Pi Zero availability on Adafruit, Pimoroni, and Pi Hut, sends alerts to Pushbullet

pihut_pi_zero_in_stock.js

var requestjson = require('request-json');
var request = require('request');
var PushBullet = require('pushbullet');
var pusher = new PushBullet('PUSHBULLET_API_KEY');
var cheerio = require('cheerio');

var stores = [
{name:"The Pi Hut",url:'http://thepihut.com/products/raspberry-pi-zero',in_stock:check_pihut_inventory
},
{name:"Adafruit",url:'https://www.adafruit.com/products/2816',in_stock:check_adafruit_inventory
},
{name:"Adafruit",url:'https://www.adafruit.com/products/2817',in_stock:check_adafruit_inventory
},
{name:"Adafruit",url:'https://www.adafruit.com/products/2885',in_stock:check_adafruit_inventory
},
{name:"Pimoroni",url:'https://shop.pimoroni.com/products/raspberry-pi-zero',in_stock:check_pimoroni_inventory
}];

function check_pihut_inventory(callback) {
  var client = requestjson.createClient("http://thepihut.com/");
  var ret = [];
  client.get("products/raspberry-pi-zero.js", function(err, res, body) {
    if(body) {
      for (var i = body.variants.length - 1; i >= 0; i--) {
        sku_map[body.variants[i].sku + "pihut"] = body.variants[i].option1;
        ret[body.variants[i].sku + "pihut"] = body.variants[i].available
      };
    }
    callback(ret);
  });
}

function check_adafruit_inventory(callback) {
  var ret = [];
  request(this.url,function(err,response,body) {
    if(!err) {
      var $ = cheerio.load(body);
      var twitter_metas = $("meta[name^='twitter']");
      var product_name;
      var in_stock;
      for (ind in twitter_metas) {
        if(twitter_metas[ind].attribs) {
          if(twitter_metas[ind].attribs.name == "twitter:title") {
            product_name = twitter_metas[ind].attribs.content;
          } else if(twitter_metas[ind].attribs.name == "twitter:data2") {
            in_stock = (twitter_metas[ind].attribs.content == "IN STOCK");
          }
        }
      };
      if(typeof(product_name) != 'undefined' && typeof(in_stock) != 'undefined') {
        ret[product_name+"ada"] = in_stock;
        sku_map[product_name+"ada"] = product_name;
        callback(ret);
        return;
      }
    }
    callback([]);
  });
}

function check_pimoroni_inventory(callback) {
  var ret = [];
  request(this.url,function(err,response,body) {
    if(!err) {
      var $ = cheerio.load(body);
      var schema_elements = $("div[itemtype='http://schema.org/Product']");
      for (ind in schema_elements) {
        if(schema_elements[ind].type != "tag") {
          continue;
        }
        var schema_avaialbility = $(schema_elements[ind]).find('meta[itemprop="availability"]');
        var schema_name = $(schema_elements[ind]).find('meta[itemprop="name"]');

        if(schema_avaialbility && schema_name) {
          availability = (schema_avaialbility.attr('content') == "http://schema.org/InStock");
          prod_name = schema_name.attr('content').replace("Raspberry Pi Zero - Max 1 Pi Zero Per Order! - ","");
          sku_map[prod_name+"pim"] = prod_name;
          ret[prod_name+"pim"] = availability;
        }

      }
      callback(ret);
      return;
    }
    callback([]);
  });
}

function notify_stock(name,url,status,product_name) {
/*  console.log(product_name);
  console.log(status);
  return;*/
  if(status) {
    notify_in_stock(url,name,product_name);
  } else {
    notify_out_of_stock(name,product_name);
  }
}

function notify_in_stock(url,shop_name,product_name) {
  pusher.link({channel_tag:'pizeroinstock'}, "In Stock! Pi Zero ("+product_name+") @ " + shop_name, url, function(error, response) {
    //cool
  });
}

function notify_out_of_stock(shop_name,product_name) {
  pusher.note({channel_tag:'pizeroinstock'}, "Out of Stock: Pi Zero ("+product_name+") @ " + shop_name, shop_name + " is out of stock of "+product_name+".", function(error, response) {
    //cool
  });
}

function product_name(sku) {
  return !(sku in sku_map) ? "Pi Zero" : sku_map[sku];
}

var sku_map = [];
var in_stock_statuses = [];

function check_availability() {

  var stores_checked = 0;
  for (var i = stores.length - 1; i >= 0; i--) {
    (function() {
      var index = i;
      var avaialbilities = stores[index].in_stock(function(statuses) {
        if(statuses && typeof(statuses) == "object") {
          for(var sku in statuses) {
            if(!(sku in in_stock_statuses)) {
              in_stock_statuses[sku] = statuses[sku];
              //notify_stock(stores[index].name,stores[index].url,in_stock_statuses[sku],product_name(sku));
            } else if(in_stock_statuses[sku] != statuses[sku]) {
              in_stock_statuses[sku] = statuses[sku];
              notify_stock(stores[index].name,stores[index].url,in_stock_statuses[sku],product_name(sku));
            }
          }
        }
        stores_checked++;
        if (stores_checked >= stores.length) {
          setTimeout(check_availability,1000);
        };
      });
    })();

  };
  

}

check_availability();