source: branches/gdl-frontend/src/ajax/javascripts/requests.js

//+-----------------------------------------------------------------------------
//+  Isidorus
//+  (c) 2008-2010 Marc Kuester, Christoph Ludwig, Lukas Georgieff
//+
//+  Isidorus is freely distributable under the LLGPL license.
//+  This ajax module uses the frameworks PrototypeJs and Scriptaculous, both
//+  are distributed under the MIT license.
//+  You can find a detailed description in trunk/docs/LLGPL-LICENSE.txt, and
//+  trunk/docs/LGPL-LICENSE.txt in
//+  trunk/src/ajax/javascripts/external/MIT-LICENSE.txt.
//+-----------------------------------------------------------------------------


// --- replaces every / character that is not prefixed by a \ character
function escapeSlashInJSON(jsonString){
    return jsonString.replace(/([^\\])\//g, '$1\\/').replace(/([^\\])\//g, '$1\\/');
}


// --- Sets a timeout function which alerts a message.
function setAjaxTimeout(time, url)
{
    return setTimeout(function(){
        alert("The AJAX request for \"" + url + "\" timed out. Please check your network connection!");
        hideLoad();
    }, time);
}


// --- Returns a function whihc can be used as an XHR-Handler.
// --- The returned function is the passed handler wrapped in
// --- a lambda-function which additionally clears the passed timeout
// --- function and call onLoad.
function createXHRHandler(handler, timeFun)
{
    function fun(xhr){
        clearTimeout(timeFun);
        hideLoad();
        handler(xhr);
    }
    return fun;
}


// --- Removes all divs with the class ajaxLoader. The inner image with the
// --- class ajaxLoader will be moved to the top of div.content and the
// --- display attribute will be set to none;
function hideLoad()
{
    var img = $$("img." + CLASSES.ajaxLoader());
    if(img.length === 1){
        img[0].setStyle({"display" : "none"})
        $("page").insert({"top" : img[0]});
    }

    var loading = $$("div." + CLASSES.load());
    if(loading.length === 1) loading[0].remove();
    var content = $$("div." + CLASSES.content());
    if(content.length === 1) content[0].show();
}


// --- The hidden image with the class ajaxLoader will be moved to the new created
// --- div with the given message. The div with the class content will be hidden and instaed
// --- of the hidden div there will be shown the new created element.
function onLoad(text)
{
    var div = new Element("div", {"class" : CLASSES.load()}).update(content);
    var content = $$("div." + CLASSES.content());
    if(content.length === 1){
        content[0].hide();
        var load = new Element("div", {"class" : CLASSES.load()}).update("<br/><br/>" + text);
        content[0].insert({"before" : load});
        var img = $$("img." + CLASSES.ajaxLoader());
        if(img.length === 1){
            img[0].setStyle({"display" : "block"})
            load.insert({"top" : img[0]})
        }
    }
}


// --- This is the default error handler of the used ajax.requests.
function defaultFailureHandler(xhr)
{
    window.alert("Something went wrong by calling \"" + xhr.request.url + "\"\n" + xhr.status +
                 ": " + xhr.statusText + "\n" + xhr.responseText);
}


// --- Gets all psis from the server. If typePsis is set to true
// --- there will be requested only TopicType's psis.
function getPsis(onSuccessHandler, onFailureHandler, what)
{
    try{
        var onFailure = onFailureHandler ? onFailureHandler : defaultFailureHandler;
        var timeFun = setAjaxTimeout(TIMEOUT, TYPE_PSIS_URL);
        
        var url = ALL_PSIS_URL;
        var message = "Requesting all type PSIs";
        if(what && what.types && what.types === true) url = TYPE_PSIS_URL;
        else if(what && what.instances && what.instances === true){
            url = INSTANCE_PSIS_URL;
            message = "Requesting all instance PSIs";
        }
        else if(what && what.all && what.all === true){
            url = ALL_PSIS_URL;
            message = "Requesting all PSIs";
        }

        onLoad(message);

        new Ajax.Request(url, {
            "method" : "get",
            "requestHeaders" : INIT_DATE,
            "onSuccess" : createXHRHandler(onSuccessHandler, timeFun),
            "onFailure" : createXHRHandler(onFailure, timeFun)});
    }
    catch(err){
        alert("From getTypePsis(): could not request all type PSIs, please try again!\n\n" + err);
    }
}


// --- Sends a post-request to the server with the passed psis as postBody.
// --- Gets a constraint-object.
function requestConstraints(psis, onSuccessHandler, onFailureHandler, typeConstraints)
{
    try{
        var onFailure = onFailureHandler ? onFailureHandler : defaultFailureHandler;
        var timeFun = setAjaxTimeout(TIMEOUT, TMCL_TYPE_URL);
        onLoad("Requesting all constraints for the psis:\<br/>" + psis.gsub("\\[", "").gsub("\\]", ""));

        url = TMCL_INSTANCE_URL;
        if(typeConstraints === true) url = TMCL_TYPE_URL;

        new Ajax.Request(url, {
            "method" : "post",
            "postBody" : psis,
            "onSuccess" : createXHRHandler(onSuccessHandler, timeFun),
            "onFailure" : createXHRHandler(onFailure, timeFun)});
    }
    catch(err){
        alert("Could not request contraints, please try again!\n\n" + err);
    }
}


// --- gets all topicStubs information for the passed psis and
// --- executes the onSuccessHandler or the on FailureHandler
// --- if all stubs are requested or one request fails.
function getTopicStubs(psis, onSuccessHandler, onFailureHandler)
{
    if(!onSuccessHandler || !onFailureHandler) throw "From getTopicStubs(): onsuccessHandler and onFailureHandler must be set!";
    try{
        var topicStubs = new Array();

        if(psis && psis.length !== 0){
            onLoad("Requesting topicStubs information for<br/>" + psis);
            for(var i = 0; i !== psis.length; ++i){
                var url = GET_STUB_PREFIX + psis[i].gsub("#", "%23");
                new Ajax.Request(url, {
                    "method" : "get",
                    "requestHeaders" : INIT_DATE,
                    "onSuccess" : function(xhr){
                        if(xhr.responseText.length === 0 || xhr.responseText.isJSON() === false) errorHandler("Got bad JSON-Data for \"" + psis[i] + "\"!");
                        else topicStubs.push(xhr.responseText);
                    },
                    "onFailure" : function(xhr){
                        alert("From getTopicStubs(): Could not request topicStub information for \"" + xhr.request.url + "\"!!!");
                        onFailureHandler();
                    }});
            }
        }

        // --- Checks the requested value. If there are all values requested, there will be called the
        // --- onSuccessHandler - otherwise (after the maximum time out or an faild request) there will
        // --- be called the onErrorHandler.
        var maxTimeout = psis.length * TIMEOUT;
        var neededTime = 0;
        function checkRequests(){
            var delta = 100;
            neededTime += delta;
            if(delta > maxTimeout && psis && psis.length !== 0){
                alert("From getTopicStubs(): Please check your network-connection - the request timed out!!!");
                hideLoad();
                onFailureHandler();
                return;
            }

            if(topicStubs.length === psis.length){
                hideLoad();
                onSuccessHandler(topicStubs);
                
            }
            else setTimeout(checkRequests, delta);
        }

        checkRequests();
    }
    catch(err){
        alert("From getTopicStubs(): Could not request topicStubs information for: " + psis + "\n\n" + err);
    }
}


// --- Sends a POST-Message to the server with the fragment data which hast to be committed.
function commitFragment(json, onSuccessHandler, onFailureHandler)
{
    if(!json || !onSuccessHandler) throw "From commitFragment(): json and onSuccessHandler must be set!";
    try{
        var onFailure = onFailureHandler ? onFailureHandler : defaultFailureHandler;
        var timeFun = setAjaxTimeout(TIMEOUT, COMMIT_URL);
        onLoad("Committing current fragment to " + COMMIT_URL);
        
        new Ajax.Request(COMMIT_URL, {
            "method" : "post",
            "postBody" : escapeSlashInJSON(json),
            "onSuccess" : createXHRHandler(onSuccessHandler, timeFun),
            "onFailure" : createXHRHandler(onFailure, timeFun)});
    }
    catch(err){
        alert("From commitFragment(): " + err);
    }
}


// --- Sends a DELETE-Message to the server. The sent message enables the server
// --- to find the spcified object and mark it as deleted
function commitDeletedObject(json, onSuccessHandler, onFailureHandler)
{
    if(!json || !onSuccessHandler) throw "From commitDeletedObject(): json and onSuccessHandler must be set!";
    try{
        var onFailure = onFailureHandler ? onFailureHandler : defaultFailureHandler;
        var timeFun = setAjaxTimeout(TIMEOUT, COMMIT_URL);
        new Ajax.Request(MARK_AS_DELETED_URL, {
            "method" : "delete",
            "postBody" : escapeSlashInJSON(json),
            "onSuccess" : createXHRHandler(onSuccessHandler, timeFun),
            "onFailure" : createXHRHandler(onFailure, timeFun)});
    }
    catch(err){
        alert("From commitDeletedObject(): " + err);
    }
}


// --- Requests a JSON-Fragment for the passed psi and calls the onSuccessHandler function
// --- after a succeeded request.
function requestFragment(psi, onSuccessHandler, onFailureHandler)
{
    if(!psi || !onSuccessHandler) throw "From requestFragment(): psi and onSuccessHandler must be set!";

    try{
        var onFailure = onFailureHandler ? onFailureHandler : defaultFailureHandler;
        var timeFun = setAjaxTimeout(TIMEOUT, COMMIT_URL);
        onLoad("Requesting fragment for the topic " + psi);
        
        var url = GET_PREFIX + psi.gsub("#", "%23");

        new Ajax.Request(url, {
            "method" : "get",
            "requestHeaders" : INIT_DATE,
            "onSuccess" : createXHRHandler(onSuccessHandler, timeFun),
            "onFailure" : createXHRHandler(onFailure, timeFun)});
    }
    catch(err){
        alert("From requestFragment(): " + err);
    }
}


// --- Request a topic map overview object from the server and calls
// --- onSuccessHandler or OnFailureHandler.
function requestTreeView(onSuccessHandler, onFailureHandler)
{
    if(!onSuccessHandler) throw "From requestTreeView(): onSuccessHandler must be set!";

    try{
        var onFailure = onFailureHandler ? onFailureHandler : defaultFailureHandler;
        var timeFun = setAjaxTimeout(6 * TIMEOUT, COMMIT_URL);
        onLoad("Requesting a topic map overview from " + TM_OVERVIEW);
        
        new Ajax.Request(TM_OVERVIEW, {
            "method" : "get",
            "requestHeaders" : INIT_DATE,
            "onSuccess" : createXHRHandler(onSuccessHandler, timeFun),
            "onFailure" : createXHRHandler(onFailure, timeFun)});
    }
    catch(err){
        alert("From requestFragment(): " + err);
    }
}