/*
original : https://gist.github.com/BinaryMuse/2378993
Changes :
-Shares an instance of phantomJS for all requests instead of creating a new one for each
-Sends the created file as a response
-Uses good old JavaScript
-Coffee version below
*/

var phantom = require('phantom'),
_ = require('underscore'),//if you dont want underscore, do a foreach instead of _.each
phantomInstance = false,
phantomCallbacks = [];

console.log("Opening a new phantomJS instance");
phantom.create(function(ph) {
  console.log("PhantomJS loaded");
  phantomInstance = ph;
  _.each(phantomCallbacks, function(cb){
    cb();
  });
});

exports.takeSnapshot = function(folder, filename, url,  res) {

  var DEST_ROOT = "../../";
  var filepath = folder + "/" + filename;
  var previewPath = DEST_ROOT + filepath;

  function snapShot(){
    return phantomInstance.createPage(function(page) {
      page.set('viewportSize', {
        width: 640,
        height: 800
      });
      page.set('clipRect', {
        top: 0,
        left: 0,
        width: 640,
        height: 800
      });
      console.log("Opening " + url + " ...");
      return page.open(url, function(status) {
        console.log("Rendering screenshot ...");
        return setTimeout((function() {
          return page.render(previewPath, function() {
            page.close();
            setTimeout(function(){
                  res.sendfile(filepath, {root: __dirname+DEST_ROOT});
              }, 10);
          });
        }), 500);
      });
    });
  }
  if(phantomInstance){
    snapShot();
  }
  else{
    phantomCallbacks.push(snapShot);
  }
}