// JSONscriptRequest -- a simple class for accessing Yahoo! Web Services
// using dynamically generated script tags and JSON
//
// Author: Jason Levitt
// Date: December 7th, 2005
//
// A SECURITY WARNING FROM DOUGLAS CROCKFORD:
// "The dynamic <script> tag hack suffers from a problem. It allows a page 
// to access data from any server in the web, which is really useful. 
// Unfortunately, the data is returned in the form of a script. That script 
// can deliver the data, but it runs with the same authority as scripts on 
// the base page, so it is able to steal cookies or misuse the authorization 
// of the user with the server. A rogue script can do destructive things to 
// the relationship between the user and the base server."
//
// So, be extremely cautious in your use of this script.
//

// Constructor -- pass a REST request URL to the constructor
//
function JSONscriptRequest(fullUrl) {
    // REST request path
    this.fullUrl = fullUrl; 
    // Keep IE from caching requests
    if (fullUrl.indexOf('?') > -1)
    {
        this.noCacheIE = '&noCacheIE=' + (new Date()).getTime();
    }
    else{
        this.noCacheIE = '?noCacheIE=' + (new Date()).getTime();
    }
    // Get the DOM location to put the script tag
    this.headLoc = document.getElementsByTagName("head").item(0);
    // Generate a unique script tag id
    this.scriptId = 'YJscriptId' + JSONscriptRequest.scriptCounter++;
}



// Static script ID counter
JSONscriptRequest.scriptCounter = 1;

// buildScriptTag method
//
JSONscriptRequest.prototype.buildScriptTag = function () {

    // Create the script tag
    this.scriptObj = document.createElement("script");
    
    // Add script object attributes
    this.scriptObj.setAttribute("type", "text/javascript");
    this.scriptObj.setAttribute("src", this.fullUrl + this.noCacheIE);
    this.scriptObj.setAttribute("id", this.scriptId);
}
 
// removeScriptTag method
// 
JSONscriptRequest.prototype.removeScriptTag = function () {
    // Destroy the script tag
    this.headLoc.removeChild(this.scriptObj);  
}

// addScriptTag method
//
JSONscriptRequest.prototype.addScriptTag = function () {
    // Create the script tag    
    this.headLoc.appendChild(this.scriptObj);
}

/************* BEGIN JSON Callback functions  ********/

  function makeCall(requestURL){  
  try
  {  
     aObj = new JSONscriptRequest(requestURL);
    // Build the script tag
    aObj.buildScriptTag();
 
    // Execute (add) the script tag
    aObj.addScriptTag();
    } 
  catch (e) 
    {
        handleException("Error making call : " + requestURL);        
    }    
  }
  
  
  
  
//  twitterbadgeOperaSafe = function(){
//          function show(result){
//            alert(result);
//          };
//          var restURL = 'http://twitter.com/statuses/user_timeline/' +   
//                        'codepo8.json?callback=twitterbadgeOperaSafe.show' + 
//                        '&amp;count=10';
//          var s = document.createElement('script');
//          s.setAttribute('src',restURL);
//          return {
//            show:show,
//            init:function(){
//              document.getElementsByTagName('head')[0].appendChild(s);
//            }
//          };
//        }();
//        twitterbadgeOperaSafe.init();
//  
   
 /************* END JSON Callback functions  ********/
 
 /************* START Helper function  ********/
 function handleException (message)
 {
    alert (message);
 }

    
 
 /************* END Helper function  ********/