/* XmlHttpRequest library */

function _getXmlHttp() {
    /*@cc_on@*/
    /*@if (@_jscript_version >= 5)
    var progids = ["Msxml2.XMLHTTP", "Microsoft.XMLHTTP"]
    for (i in progids) {
        try { return new ActiveXObject(progids[i]) }
        catch (e) { }
    }
    @end@*/
    try { return new XMLHttpRequest(); }
    catch (e2) { return null; }
}

function CachedResponse(response) {
    this.readyState = ReadyState.Complete
    this.status = HttpStatus.OK
    this.responseText = response
}

ReadyState = {
    Uninitialized: 0,
    Loading: 1,
    Loaded: 2,
    Interactive: 3,
    Complete: 4
}

HttpStatus = {
    OK: 200,
    NotFound: 404
}

function Request_from_cache(url, f_change) {
    var result = this._cache[url];

    if (result != null) {
        var response = new CachedResponse(result)
        f_change(response)
        return true
    }
    else
        return false
}

function Request_cached_get(url, f_change) {
    if (!this.FromCache(url, f_change)) {
        var request = this
        this.Get(url,
        /* Cache results if request completed */
			function(x) {
			    if ((x.readyState == ReadyState.Complete) && (x.status == HttpStatus.OK))
			    { request._cache[url] = x.responseText }
			    f_change(x)
			},
			"GET")
    }
}

function Request_get(url, f_change, method) {
    if (!this._get) return;

    if (method == null) method = "GET"
    if (this._get.readyState != ReadyState.Uninitialized)
        this._get.abort()

    this._get.open(method, url, true);

    if (f_change != null) {
        var _get = this._get;
        this._get.onreadystatechange = function() { f_change(_get); }
    }
    this._get.send(null);
}

function Request_get_no_cache(url, f_change, method) {
    var sep = (-1 < url.indexOf("?")) ? "&" : "?"
    var newurl = url + sep + "__=" + encodeURIComponent((new Date()).toString());
    return this.Get(newurl, f_change, method);
}

function Request() {
    this.Get = Request_get
    this.GetNoCache = Request_get_no_cache
    this.CachedGet = Request_cached_get
    this.FromCache = Request_from_cache

    this.Use = function() { return this._get != null }
    this.Cancel = function() { if (this._get) this._get.abort(); }
    this._cache = new Object();

    this._get = _getXmlHttp();
    if (this._get == null) return;
}