var HTTP = {};

HTTP.debug = {};
HTTP.debug.on = false;
HTTP.debug.gen = function(response){
	var debug = window.open("","smallwin",
    "width=400,height=350,status=yes,resizable=yes");
	debug.document.write(response+"<br />");
}


// This is a list of XMLHttpRequest-creation factory functions to try
HTTP._factories = [
    function() { return new XMLHttpRequest(); },
    function() { return new ActiveXObject("Msxml2.XMLHTTP"); },
    function() { return new ActiveXObject("Microsoft.XMLHTTP"); }
];

// When we find a factory that works, store it here.
HTTP._factory = null;

// Create and return a new XMLHttpRequest object.
//
// The first time we're called, try the list of factory functions until
// we find one that returns a non-null value and does not throw an
// exception. Once we find a working factory, remember it for later use.
//
HTTP.newRequest = function() {
    if (HTTP._factory != null) return HTTP._factory();

    for(var i = 0; i < HTTP._factories.length; i++) {
        try {
            var factory = HTTP._factories[i];
            var request = factory();
            if (request != null) {
                HTTP._factory = factory;
                return request;
            }
        }
        catch(e) {
            continue;
        }
    }
    // If we get here, none of the factory candidates succeeded,
    // so throw an exception now and for all future calls.
    HTTP._factory  = function() 
	{
        throw new Error("XMLHttpRequest not supported");
    }
    HTTP._factory(); // Throw an error
}

//Simple get request
HTTP.getText = function(url, callback) {	
    var request = HTTP.newRequest();
    request.onreadystatechange = function() {
        if (request.readyState == 4 && request.status == 200)
		{
			if(HTTP.debug.on){					
					HTTP.debug.gen(HTTP._getResponse(request));
			}
			
            callback(HTTP._getResponse(request));
		}
    }
    request.open("GET", url);
    request.send(null);
};

//XML Request
HTTP.getXML = function(url, callback) {
    var request = HTTP.newRequest();
    request.onreadystatechange = function() {
        if (request.readyState == 4 && request.status == 200)
            callback(request.responseXML);
    }
    request.open("GET", url);
    request.send(null);
};

/**
 * Use an HTTP HEAD request to obtain the headers for the specified URL.
 * When the headers arrive, parse them with HTTP.parseHeaders() and pass the
 * resulting object to the specified callback function. If the server returns
* an error code, invoke the specified errorHandler function instead. If no
 * error handler is specified, pass null to the callback function.
 */
HTTP.getHeaders = function(url, callback, errorHandler) {
    var request = HTTP.newRequest();
    request.onreadystatechange = function() {
        if (request.readyState == 4) {
            if (request.status == 200) {
                callback(HTTP.parseHeaders(request));
            }
            else {
                if (errorHandler) errorHandler(request.status,
                                               request.statusText);
                else callback(null);
            }
        }
    }
    request.open("HEAD", url);
    request.send(null);
};

// Parse the response headers from an XMLHttpRequest object and return
// the header names and values as property names and values of a new object.
HTTP.parseHeaders = function(request) {
    var headerText = request.getAllResponseHeaders();  // Text from the server
    var headers = {}; // This will be our return value
    var ls = /^\s*/;  // Leading space regular expression
    var ts = /\s*$/;  // Trailing space regular expression

    // Break the headers into lines
    var lines = headerText.split("\n");
    // Loop through the lines
    for(var i = 0; i < lines.length; i++) {
        var line = lines[i];
        if (line.length == 0) continue;  // Skip empty lines
        // Split each line at first colon, and trim whitespace away
        var pos = line.indexOf(':');
        var name = line.substring(0, pos).replace(ls, "").replace(ts, "");
        var value = line.substring(pos+1).replace(ls, "").replace(ts, "");
        // Store the header name/value pair in a JavaScript object
        headers[name] = value;
    }
    return headers;
};

/**
 * Send an HTTP POST request to the specified URL, using the names and values
 * of the properties of the values object as the body of the request.
 * Parse the server's response according to its content type and pass
 * the resulting value to the callback function. If an HTTP error occurs,
 * call the specified errorHandler function, or pass null to the callback
 * if no error handler is specified.
 **/
HTTP.post = function(url, values, callback, errorHandler) {
    var request = HTTP.newRequest();
    request.onreadystatechange = function() {
        if (request.readyState == 4) {
            if (request.status == 200) {
				if(HTTP.debug.on){					
					HTTP.debug.gen(HTTP._getResponse(request));
				}
                callback(HTTP._getResponse(request));
            }
            else {
                if (errorHandler) errorHandler(request.status,
                                               request.statusText);
                else callback(null);
            }
        }
    }

    request.open("POST", url);
    // This header tells the server how to interpret the body of the request.
    request.setRequestHeader("Content-Type",
                             "application/x-www-form-urlencoded");
    // Encode the properties of the values object and send them as
    // the body of the request.
    request.send(HTTP.encodeFormData(values));
};

/**
 * Encode the property name/value pairs of an object as if they were from
 * an HTML form, using application/x-www-form-urlencoded format
 */
HTTP.encodeFormData = function(data) {
    var pairs = [];
    var regexp = /%20/g; // A regular expression to match an encoded space

    for(var name in data) {
        var value = data[name].toString();
        // Create a name/value pair, but encode name and value first
        // The global function encodeURIComponent does almost what we want,
        // but it encodes spaces as %20 instead of as "+". We have to
        // fix that with String.replace()
        var pair = encodeURIComponent(name).replace(regexp,"+") + '=' +
            encodeURIComponent(value).replace(regexp,"+");
        pairs.push(pair);
    }

    // Concatenate all the name/value pairs, separating them with &
    return pairs.join('&');
};


HTTP._getResponse = function(request) {
    // Check the content type returned by the server
    switch(request.getResponseHeader("Content-Type")) {
    case "text/xml":
        // If it is an XML document, use the parsed Document object.
        return request.responseXML;

    case "text/json":
    case "text/javascript":
    case "application/javascript":
    case "application/x-javascript":
        // If the response is JavaScript code, or a JSON-encoded value,
        // call eval() on the text to "parse" it to a JavaScript value.
        // Note: only do this if the JavaScript code is from a trusted server!
        return eval(request.responseText);

    default:
        // Otherwise, treat the response as plain text and return as a string.
        return request.responseText;
    }
};