/**
 * @file
 *
 * Rewrites XMLHttpRequest to automatically send CSRF token with it. In theory
 * plays nice with other JavaScript libraries, needs testing though.
 */

// Here are the basic overloaded method definitions
// The wrapper must be set BEFORE onreadystatechange is written to, since
// a bug in ActiveXObject prevents us from properly testing for it.
CsrfMagic = function(real) {
    // try to make it ourselves, if you didn't pass it
    if (!real) try { real = new XMLHttpRequest; } catch (e) {;}
    if (!real) try { real = new ActiveXObject('Msxml2.XMLHTTP'); } catch (e) {;}
    if (!real) try { real = new ActiveXObject('Microsoft.XMLHTTP'); } catch (e) {;}
    if (!real) try { real = new ActiveXObject('Msxml2.XMLHTTP.4.0'); } catch (e) {;}
    this.csrf = real;
    // properties
    var csrfMagic = this;
    real.onreadystatechange = function() {
        csrfMagic._updateProps();
        return csrfMagic.onreadystatechange ? csrfMagic.onreadystatechange() : null;
    };
    csrfMagic._updateProps();
}

CsrfMagic.prototype = {

    open: function(method, url, async, username, password) {
        if (method == 'POST') this.csrf_isPost = true;
        // deal with Opera bug, thanks jQuery
        if (username) return this.csrf_open(method, url, async, username, password);
        else return this.csrf_open(method, url, async);
    },
    csrf_open: function(method, url, async, username, password) {
        if (username) return this.csrf.open(method, url, async, username, password);
        else return this.csrf.open(method, url, async);
    },

    send: function(data) {
        if (!this.csrf_isPost) return this.csrf_send(data);
        prepend = csrfMagicName + '=' + csrfMagicToken + '&';
        if (this.csrf_purportedLength === undefined) {
            this.csrf_setRequestHeader("Content-length", this.csrf_purportedLength + prepend.length);
            delete this.csrf_purportedLength;
        }
        delete this.csrf_isPost;
        return this.csrf_send(prepend + data);
    },
    csrf_send: function(data) {
        return this.csrf.send(data);
    },

    setRequestHeader: function(header, value) {
        // We have to auto-set this at the end, since we don't know how long the
        // nonce is when added to the data.
        if (this.csrf_isPost && header == "Content-length") {
            this.csrf_purportedLength = value;
            return;
        }
        return this.csrf_setRequestHeader(header, value);
    },
    csrf_setRequestHeader: function(header, value) {
        return this.csrf.setRequestHeader(header, value);
    },

    abort: function() {
        return this.csrf.abort();
    },
    getAllResponseHeaders: function() {
        return this.csrf.getAllResponseHeaders();
    },
    getResponseHeader: function(header) {
        return this.csrf.getResponseHeader(header);
    } // ,
}

// proprietary
CsrfMagic.prototype._updateProps = function() {
    this.readyState = this.csrf.readyState;
    if (this.readyState == 4) {
        this.responseText = this.csrf.responseText;
        this.responseXML  = this.csrf.responseXML;
        this.status       = this.csrf.status;
        this.statusText   = this.csrf.statusText;
    }
}
CsrfMagic.process = function(base) {
    var prepend = csrfMagicName + '=' + csrfMagicToken;
    if (base) return prepend + '&' + base;
    return prepend;
}
// callback function for when everything on the page has loaded
CsrfMagic.end = function() {
    // This rewrites forms AGAIN, so in case buffering didn't work this
    // certainly will.
    forms = document.getElementsByTagName('form');
    for (var i = 0; i < forms.length; i++) {
        form = forms[i];
        if (form.method.toUpperCase() !== 'POST') continue;
        if (form.elements[csrfMagicName]) continue;
        var input = document.createElement('input');
        input.setAttribute('name',  csrfMagicName);
        input.setAttribute('value', csrfMagicToken);
        input.setAttribute('type',  'hidden');
        form.appendChild(input);
    }
}

// Sets things up for Mozilla/Opera/nice browsers
if (window.XMLHttpRequest && window.XMLHttpRequest.prototype) {
    var x = XMLHttpRequest.prototype;
    var c = CsrfMagic.prototype;

    // Save the original functions
    x.csrf_open = x.open;
    x.csrf_send = x.send;
    x.csrf_setRequestHeader = x.setRequestHeader;

    // Notice that CsrfMagic is itself an instantiatable object, but only
    // open, send and setRequestHeader are necessary as decorators.
    x.open = c.open;
    x.send = c.send;
    x.setRequestHeader = c.setRequestHeader;
} else {
    // The only way we can do this is by modifying a library you have been
    // using. We support YUI, script.aculo.us, prototype, MooTools,
    // jQuery, Ext and Dojo.
    if (window.jQuery) {
        // jQuery didn't implement a new XMLHttpRequest function, so we have
        // to do this the hard way.
        jQuery.csrf_ajax = jQuery.ajax;
        jQuery.ajax = function( s ) {
            if (s.type && s.type.toUpperCase() == 'POST') {
                s = jQuery.extend(true, s, jQuery.extend(true, {}, jQuery.ajaxSettings, s));
                if ( s.data && s.processData && typeof s.data != "string" ) {
                    s.data = jQuery.param(s.data);
                }
                s.data = CsrfMagic.process(s.data);
            }
            return jQuery.csrf_ajax( s );
        }
    } else if (window.Prototype) {
        // This works for script.aculo.us too
        Ajax.csrf_getTransport = Ajax.getTransport;
        Ajax.getTransport = function() {
            return new CsrfMagic(Ajax.csrf_getTransport());
        }
    } else if (window.MooTools) {
        Browser.csrf_Request = Browser.Request;
        Browser.Request = function () {
            return new CsrfMagic(Browser.csrf_Request());
        }
    } else if (window.YAHOO) {
        YAHOO.util.Connect.csrf_createXhrObject = YAHOO.util.Connect.createXhrObject;
        YAHOO.util.Connect.createXhrObject = function (transaction) {
            obj = YAHOO.util.Connect.csrf_createXhrObject(transaction);
            obj.conn = new CsrfMagic(obj.conn);
            return obj;
        }
    } else if (window.Ext) {
        // Ext can use other js libraries as loaders, so it has to come last
        // Ext's implementation is pretty identical to Yahoo's, but we duplicate
        // it for comprehensiveness's sake.
        Ext.lib.Ajax.csrf_createXhrObject = Ext.lib.Ajax.createXhrObject;
        Ext.lib.Ajax.createXhrObject = function (transaction) {
            obj = Ext.lib.Ajax.csrf_createXhrObject(transaction);
            obj.conn = new CsrfMagic(obj.conn);
            return obj;
        }
    } else if (window.dojo) {
        dojo.csrf__xhrObj = dojo._xhrObj;
        dojo._xhrObj = function () {
            return new CsrfMagic(dojo.csrf__xhrObj());
        }
    }
}
