/* update_html.js:  Provide functions to update content on page with background responses from Umlaut. Used by Umlaut itself, as well as by third party callers.*/
(function($) {
   
    function SectionTarget(config) {
       //Add properties from config to ourself
       $.extend(this, config);
       
       //Defaults
       if (this.selector == undefined)
         this.selector = "#" + this.umlaut_section_id;
       if (this.position == undefined)
         this.position = "html";
              
    }
    //Callback default to no-op function please.    
    var noop = function() {};
    SectionTarget.prototype.before_update = noop;
    SectionTarget.prototype.after_update = noop;
    SectionTarget.prototype.complete = noop;
    
    SectionTarget.prototype.ensure_placement_destination = function() {
        if ( this.selector == undefined) {
          return null; 
        }
        
        //Already have it cached?
        if ( this.host_div_element ) {
          return this.host_div_element;
        }                        
        
        var new_div = $('<div class="umlaut" style="display:none"></div>');        
        // Find the first thing matched by selector, and call the
        // method specified in "action" string on it, giving it our
        // HTML to replace. This works because our actions are
        // all arguments that will take one method: html, before, after, append,
        // prepend.                       
        $(this.selector).eq(0)[ this.position  ]( new_div );
        
        //Cache for later
        this.host_div_element = new_div;
        return this.host_div_element;
      };
    

  // Define an object constructor on the global window object
  // For our UmlautHtmlUpdater object. 
  function HtmlUpdater(umlaut_base, context_object) {
    if (context_object == undefined)
      context_object = "";      
    
    umlaut_base = umlaut_base.replace(/\/$/,'');
    this.umlaut_uri =  umlaut_base + '/resolve/partial_html_sections?umlaut.response_format=json&' + context_object;
        
    this.section_targets = [];
           
    this.add_section_target = function(config) {
      this.section_targets.push( new SectionTarget(config) ); 
    };
    
    //default no-op call-backs
    this.complete = function() {};
    
    //Code for seeing if a URI is same origin or not borrowed from jQuery
    this.is_remote_url = function(url) {
      var regexp = /^(\w+:)?\/\/([^\/?#]+)/;
      var parts = regexp.exec( url );
      return (parts && (parts[1] && parts[1] !== location.protocol || parts[2] !== location.host));
    }
    
    this.update = function() {
      // Need to capture because we won't have 'this' inside the ajax
      // success handler. 
      var myself = this;       
      var dataType = this.is_remote_url( this.umlaut_uri ) ? "jsonp" : "json";
       $.ajax({
             url: myself.umlaut_uri,
             dataType: dataType,
             jsonp: "umlaut.jsonp",
             error: function() {
               $.error("Problem loading background elements.");
             },
             success: function(umlaut_response) {
              for (var i = 0; i < myself.section_targets.length; i++) {
                  var section_target = myself.section_targets[i];                                
                 
                  var umlaut_html_section = myself.find_umlaut_response_section(umlaut_response, section_target.umlaut_section_id);
                                    
                  if (umlaut_html_section == undefined) {
                    continue;
                  }                  
                  var count = null;
                  if (typeof umlaut_html_section.response_count != "undefined") { 
                    count = parseInt(umlaut_html_section.response_count.value);
                  }
                  var existing_element = section_target.ensure_placement_destination();
                  var new_element = $('<div class="umlaut" style="display:none" class="' + section_target.umlaut_section_id +'"></div>');
                  new_element.html(umlaut_html_section.html_content);

                  
                  var should_continue = section_target.before_update(new_element, count, section_target);
                                    
                  if (should_continue != false) {                    
                    existing_element.replaceWith(new_element);
                    
                    section_target.host_div_element = new_element;

                    new_element.show();
                  
                    section_target.after_update(new_element, count, section_target)                                        
                    
                  }
               }
               
               //Do we need to update again?
               if (umlaut_response.partial_html_sections.in_progress) {   
                  //Fix our update URI to be the one umlaut suggests
                  //Except strip out the umlaut.jsonp parameter, jquery is
                  //going to add that back in as desired. 
                  myself.umlaut_uri = 
                    umlaut_response.partial_html_sections.in_progress.refresh_url.replace(/[?;&]umlaut\.jsonp=[^;&]+/, '');
                  
                  
                  var refresh_seconds = 
                    umlaut_response.partial_html_sections.in_progress.requested_wait_seconds;
                  window.setTimeout(function() { myself.update();  }, refresh_seconds * 1000); 
                  
               } else {
                 myself.complete();
                 for (var i = 0; i < myself.section_targets.length; i++) {
                   var section_target = myself.section_targets[i];
                   section_target.complete(section_target);
                 }
               }
               
             }
       });
    };
    this.find_umlaut_response_section = function(response, id) {
      return $.grep(response.partial_html_sections.html_section, function(section) {
        return section.id == id;
      })[0];
    };
    
  };
  
  //Put it in a global object, leave space for other things in "Umlaut" later.
  if (window.Umlaut == undefined)
    window.Umlaut = new Object();
  window.Umlaut.HtmlUpdater = HtmlUpdater; 
  
})(jQuery);