/* 
    XmlHttpRequest Wrapper
    Version 1.2.2
    29 Jul 2005 
    adamv.com/dev/
*/

var Http = {
    ReadyState: {
        Uninitialized: 0,
        Loading: 1,
        Loaded:2,
        Interactive:3,
        Complete: 4
    },
        
    Status: {
        OK: 200,
        
        Created: 201,
        Accepted: 202,
        NoContent: 204,
        
        BadRequest: 400,
        Forbidden: 403,
        NotFound: 404,
        Gone: 410,
        
        ServerError: 500
    },
        
    Cache: {
        Get: 1,
        GetCache: 2,
        GetNoCache: 3,
        FromCache: 4
    },
    
    Method: {Get: "GET", Post: "POST", Put: "PUT", Delete: "DELETE"},
    
    enabled: false,
    logging: false,
    _get: null,    // Reference to the XmlHttpRequest object
    _cache: new Object(),
    
    Init: function(){
        Http._get = Http._getXmlHttp()
        Http.enabled = (Http._get != null)
        Http.logging = (window.Logging != null);
    },
    
    _getXmlHttp: function(){
    /*@cc_on @*//*@if (@_jscript_version >= 5)
        try { return new ActiveXObject("Msxml2.XMLHTTP"); } 
        catch (e) {} 
        try { return new ActiveXObject("Microsoft.XMLHTTP"); } 
        catch (e) {} 
    @end @*/
        try { return new XMLHttpRequest();}
        catch (e) {}

        return null;
    },

/*
    Params:
        url: The URL to request. Required.
        cache: Cache control. Defaults to Cache.Get.
        callback: onreadystatechange function, called when request is completed. Optional.
        method: HTTP method. Defaults to Method.Get.
*/
    get: function(params, callback_args){    
        if (!Http.enabled) throw "Http: XmlHttpRequest not available.";
        
        var url = params.url;
        if (!url) throw "Http: A URL must be specified";
                
        var cache = params.cache || Http.Cache.Get;
        var method = params.method || Http.Method.Get;
        var callback = params.callback;
        
        if ((cache == Http.Cache.FromCache) || (cache == Http.Cache.GetCache))
        {
            var in_cache = Http.from_cache(url, callback, callback_args)

            if (Http.logging){
                Logging.log(["Http: URL in cache: " + in_cache]);
            }

            if (in_cache || (cache == Http.Cache.FromCache)) return in_cache;
        }
        
        if (cache == Http.Cache.GetNoCache)
        {
            var sep = (-1 < url.indexOf("?")) ? "&" : "?"    
            url = url + sep + "__=" + encodeURIComponent((new Date()).getTime());
        }
    
        // Only one request at a time, please
        if ((Http._get.readyState != Http.ReadyState.Uninitialized) && 
            (Http._get.readyState != Http.ReadyState.Complete)){
            this._get.abort();
            
            if (Http.logging){
                Logging.log(["Http: Aborted request in progress."]);
            }
        }
        
        Http._get.open(method, url, true);

        Http._get.onreadystatechange =  function() {
            if (Http._get.readyState != Http.ReadyState.Complete) return;
            
            if (Http.logging){
                Logging.log(["Http: Returned, status: " + Http._get.status]);
            }

            if ((cache == Http.Cache.GetCache) && (Http._get.status == Http.Status.OK)){
                Http._cache[url] = Http._get.responseText;
            }
            
            if (callback_args == null) callback_args = new Array();

            var cb_params = new Array();
            cb_params.push(Http._get);
            for(var i=0;i<callback_args.length;i++)
                cb_params.push(callback_args[i]);
                
            callback.apply(null, cb_params);
        }
        
        if(Http.logging){
            Logging.log(["Http: Started\n\tURL: " + url + "\n\tMethod: " + method + "; Cache: " + Hash.keyName(Http.Cache,cache)])
        }
        
        Http._get.send(params.body || null);
    },
    
    from_cache: function(url, callback, callback_args){
        var result = Http._cache[url];
        
        if (result != null) {
            var response = new Http.CachedResponse(result)
            
            var cb_params = new Array();
            cb_params.push(response);
            for(var i=0;i<callback_args.length;i++)
                cb_params.push(callback_args[i]);
                            
            callback.apply(null, cb_params);
                
            return true
        }
        else
            return false
    },
    
    clear_cache: function(){
        Http._cache = new Object();
    },
    
    is_cached: function(url){
        return Http._cache[url]!=null;
    },
    
    CachedResponse: function(response) {
        this.readyState = Http.ReadyState.Complete
        this.status = Http.Status.OK
        this.responseText = response
    }    
}

Http.Init()

function json_response(response){
    var js = response.responseText;
    try{
        return eval(js); 
    } catch(e){
        if (Http.logging){
            Logging.logError(["json_response: " + e]);
        }
        else{
            alert("Error: " + e + "\n" + js);
        }
        return null;
    }
}

function getResponseProps(response, header){
    try {
        var s = response.getResponseHeader(header || 'X-Ajax-Props');
        if (s==null || s=="")
            return new Object()
        else
            return eval("o="+s)
    } catch (e) { return new Object() }
}