/*
  Ajax bootstrapping code

*/

// bound in sjs-ajax-bootstrap.js
// var Ajax = {};

//----------------------------------------------------------------------
// helpers

// implemented in sjs-ajax-bootstrap.js (pending SJS implementation of for-in)
//Ajax.constructURI = function(baseuri, properties) 
  

//----------------------------------------------------------------------
// loading scripts

Ajax._pendingScripts = {};
Ajax._loadedScripts = {};

Ajax.loadScript = function(url) {
  if (this._loadedScripts[url])
    return;
  var hook = this._pendingScripts[url];
  
  if (hook != null) {
    suspend {
      hook.push(resume);
    }
    //    retract {
    // XXX could remove resume function from hook here
    //    }
    
  }
  else {
    // we're the inital requester
    var THIS=this; // XXX bug workaround; see http://www.croczilla.com/stratified
    
    suspend {
      var elem = document.createElement("script");
      var hook = [];
      THIS._pendingScripts[url] = hook;
      
      function listener(e) {
        resume();
      }
      
      function listenerIE(e) {
        if (e.srcElement.readyState == "loaded" ||
            e.srcElement.readyState == "complete")
          resume();
      }
      
      if (elem.addEventListener)
        elem.addEventListener("load", listener, false);
      else // IE
        elem.attachEvent("onreadystatechange", listenerIE);
      
      // kick off the load:
      elem.src = url;
      document.getElementsByTagName("head")[0].appendChild(elem);
    }
    retract {
      THIS._pendingScripts[url] = null;
    }
    finally {
      if (elem.removeEventListener)
        elem.removeEventListener("load", listener, false);
      else
        elem.detachEvent("onreadystatechange", listenerIE);
    }
    
    this._pendingScripts[url] = null;
    this._loadedScripts[url] = true;
    for (var i=0; i<hook.length; ++i)
      hook[i]();
  }
};

Ajax.loadSJS = function(url) {
  Ajax.loadScript("http://uk.croczilla.com/proxy/compile?script=" + url);
};

//----------------------------------------------------------------------
// requests

Ajax.requestJSONP = function(url, params, callback_parameter) {
  var cbparam = {};
  cbparam[callback_parameter ? callback_parameter : "callback"] = "R";  
  url = Ajax.constructURI(url, cbparam, params);
  
  var iframe = document.createElement("iframe");
  document.getElementsByTagName("head")[0].appendChild(iframe);
  var rv;
  suspend {
    var doc = iframe.contentWindow.document;
    doc.open();
    iframe.contentWindow.R = function(data) { rv = data; resume(); };
    doc.write("\x3Cscript type='text/javascript' src='"+url+"'>\x3C/script>");
    doc.close();
  }
  finally {
    iframe.parentNode.removeChild(iframe);
  }
  
  return rv;
};

//----------------------------------------------------------------------
// DOM helpers:

Ajax.DOM = {};

Ajax.DOM.waitForEvent = function(event, elem) {
  if (typeof elem == "string")
    elem = document.getElementById(elem);
  
  suspend {
    var rv;
    var listener_func = function(e) { rv = e; resume(); }
    if (elem.addEventListener)
      elem.addEventListener(event, listener_func, false);
    else // IE
      elem.attachEvent("on"+event, listener_func);
  }
  finally {
    if (elem.removeEventListener)
      elem.removeEventListener(event, listener_func, false);
    else // IE
      elem.detachEvent("on"+event, listener_func);
  }

  return rv;
};

  
//----------------------------------------------------------------------
// Google API wrapper:

Ajax.google = {};

// ensure that the google ajax api is loaded. Only used internally.
Ajax.google._ensureAPI = function() {
  Ajax.loadScript("http://www.google.com/jsapi");
};

// load a particular module through the google api loader
Ajax.google.loadModule = function(moduleName, moduleVersion) {
  Ajax.google._ensureAPI();
  suspend {
    google.load(moduleName, moduleVersion, { callback: resume });
  }
};

// low-level wrapper of google search api
// see http://code.google.com/apis/ajaxsearch/documentation/reference.html#_restUrlBase
// type parameter: web (default) | local | video | blogs | news | books | images | patent
Ajax.google.search = function(query, /*[opt] */ type, /* [opt] */ extra_params) {
  var params = { q : query,
                 v : "1.0"
               };
  if (!type) type = "web";
  var url = Ajax.constructURI("http://ajax.googleapis.com/ajax/services/search/" + type,
                              params, extra_params);
  return Ajax.requestJSONP(url);
};

Ajax.google.feed = {};

// low-level wrappers of google feed api
// see http://code.google.com/apis/ajaxfeeds/documentation/reference.html#_restUrlBase
Ajax.google.feed.load = function(query, /* [opt] */ extra_params) {
  var params = { q : query,
                 v : "1.0"
               };
  var url = Ajax.constructURI("http://ajax.googleapis.com/ajax/services/feed/load",
                              params, extra_params);
  return Ajax.requestJSONP(url);
};
Ajax.google.feed.find = function(query, /* [opt] */ extra_params) {
  var params = { q : query,
                 v : "1.0"
               };
  var url = Ajax.constructURI("http://ajax.googleapis.com/ajax/services/feed/find",
                              params, extra_params);
  return Ajax.requestJSONP(url);
};
Ajax.google.feed.lookup = function(query, /* [opt] */ extra_params) {
  var params = { q : query,
                 v : "1.0"
               };
  var url = Ajax.constructURI("http://ajax.googleapis.com/ajax/services/feed/lookup",
                              params, extra_params);
  return Ajax.requestJSONP(url);
};

// deprecated method that loads feeds through the google API
Ajax.google.feed.loadFeed = function(url, numEntries) {
  Ajax.google.loadModule("feeds", "1");
  var feed = new google.feeds.Feed(url);
  feed.setNumEntries(numEntries ? numEntries : 20);
  var result;
  suspend {
    feed.load(function(res) { result = res; resume(); });
  }
  
  return result;
};

Ajax.google.language = {};

// low-level wrappers of google language api
// see http://code.google.com/apis/ajaxlanguage/documentation/reference.html#_intro_fonje

// src_lang can be null or "", in which case the src language will be
// autodetected
Ajax.google.language.translate = function(text, dest_lang, src_lang, /* [opt] */ extra_params) {
  if (src_lang == null) src_lang = "";
  var params = { q : text,
                 v : "1.0",
                 langpair : src_lang + "|" + dest_lang
               };
  var url = Ajax.constructURI("http://ajax.googleapis.com/ajax/services/language/translate",
                              params, extra_params);
  return Ajax.requestJSONP(url);
};

Ajax.google.language.detect = function(text, /* [opt] */ extra_params) {
  var params = { q : text,
                 v : "1.0"
               };
  var url = Ajax.constructURI("http://ajax.googleapis.com/ajax/services/language/detect",
                              params, extra_params);
  return Ajax.requestJSONP(url);
};