/*
Copyright (c) 2006, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
Version: 0.11.3
*/

/**
 * The Connection Manager provides a simplified interface to the XMLHttpRequest
 * object.  It handles cross-browser instantiantion of XMLHttpRequest, negotiates the
 * interactive states and server response, returning the results to a pre-defined
 * callback you create.
 * @ class
 */
YAHOO.util.Connect =
{
/**
   * Array of MSFT ActiveX ids for XMLHttpRequest.
   * @private
   * @type array
   */
    _msxml_progid:[
        'MSXML2.XMLHTTP.3.0',
        'MSXML2.XMLHTTP',
        'Microsoft.XMLHTTP'
        ],

  /**
   * Object literal of HTTP header(s)
   * @private
   * @type object
   */
    _http_header:{},

  /**
   * Determines if HTTP headers are set.
   * @private
   * @type boolean
   */
    _has_http_headers:false,

 /**
  * Determines if a default header of
  * Content-Type of 'application/x-www-form-urlencoded'
  * will be added to any client HTTP headers sent for POST
  * transactions.
  * @private
  * @type boolean
  */
    _use_default_post_header:true,

 /**
  * Determines if a default header of
  * Content-Type of 'application/x-www-form-urlencoded'
  * will be added to any client HTTP headers sent for POST
  * transactions.
  * @private
  * @type boolean
  */
    _default_post_header:'application/x-www-form-urlencoded',

 /**
  * Property modified by setForm() to determine if the data
  * should be submitted as an HTML form.
  * @private
  * @type boolean
  */
    _isFormSubmit:false,

 /**
  * Property modified by setForm() to determine if a file(s)
  * upload is expected.
  * @private
  * @type boolean
  */
    _isFileUpload:false,

 /**
  * Property modified by setForm() to set a reference to the HTML
  * form node if the desired action is file upload.
  * @private
  * @type object
  */
    _formNode:null,

 /**
  * Property modified by setForm() to set the HTML form data
  * for each transaction.
  * @private
  * @type string
  */
    _sFormData:null,

 /**
  * Collection of polling references to the polling mechanism in handleReadyState.
  * @private
  * @type object
  */
    _poll:{},

 /**
  * Queue of timeout values for each transaction callback with a defined timeout value.
  * @private
  * @type object
  */
    _timeOut:{},

  /**
   * The polling frequency, in milliseconds, for HandleReadyState.
   * when attempting to determine a transaction's XHR readyState.
   * The default is 50 milliseconds.
   * @private
   * @type int
   */
     _polling_interval:50,

  /**
   * A transaction counter that increments the transaction id for each transaction.
   * @private
   * @type int
   */
     _transaction_id:0,

  /**
   * Member to add an ActiveX id to the existing xml_progid array.
   * In the event(unlikely) a new ActiveX id is introduced, it can be added
   * without internal code modifications.
   * @public
   * @param string id The ActiveX id to be added to initialize the XHR object.
   * @return void
   */
    setProgId:function(id)
    {
        this._msxml_progid.unshift(id);
    },

  /**
   * Member to enable or disable the default POST header.
   * @public
   * @param boolean b Set and use default header - true or false .
   * @return void
   */
    setDefaultPostHeader:function(b)
    {
        this._use_default_post_header = b;
    },

  /**
   * Member to modify the default polling interval.
   * @public
   * @param {int} i The polling interval in milliseconds.
   * @return void
   */
    setPollingInterval:function(i)
    {
        if(typeof i == 'number' && isFinite(i)){
            this._polling_interval = i;
        }
    },

  /**
   * Instantiates a XMLHttpRequest object and returns an object with two properties:
   * the XMLHttpRequest instance and the transaction id.
   * @private
   * @param {int} transactionId Property containing the transaction id for this transaction.
   * @return connection object
   */
    createXhrObject:function(transactionId)
    {
        var obj,http;
        try
        {
            // Instantiates XMLHttpRequest in non-IE browsers and assigns to http.
            http = new XMLHttpRequest();
            //  Object literal with http and tId properties
            obj = { conn:http, tId:transactionId };
        }
        catch(e)
        {
            for(var i=0; i<this._msxml_progid.length; ++i){
                try
                {
                    // Instantiates XMLHttpRequest for IE and assign to http.
                    http = new ActiveXObject(this._msxml_progid[i]);
                    //  Object literal with http and tId properties
                    obj = { conn:http, tId:transactionId };
                    break;
                }
                catch(e){}
            }
        }
        finally
        {
            return obj;
        }
    },

  /**
   * This method is called by asyncRequest to create a
   * valid connection object for the transaction.  It also passes a
   * transaction id and increments the transaction id counter.
   * @private
   * @return object
   */
    getConnectionObject:function()
    {
        var o;
        var tId = this._transaction_id;

        try
        {
            o = this.createXhrObject(tId);
            if(o){
                this._transaction_id++;
            }
        }
        catch(e){}
        finally
        {
            return o;
        }
    },

  /**
   * Method for initiating an asynchronous request via the XHR object.
   * @public
   * @param {string} method HTTP transaction method
   * @param {string} uri Fully qualified path of resource
   * @param callback User-defined callback function or object
   * @param {string} postData POST body
   * @return {object} Returns the connection object
   */
    asyncRequest:function(method, uri, callback, postData)
    {
        var o = this.getConnectionObject();

        if(!o){
            return null;
        }
        else{
            if(this._isFormSubmit){
                if(this._isFileUpload){
                    this.uploadFile(o.tId, callback, uri);
                    this.releaseObject(o);
                    return;
                }

                //If the specified HTTP method is GET, setForm() will return an
                //encoded string that is concatenated to the uri to
                //create a querystring.
                if(method == 'GET'){
                    uri += "?" +  this._sFormData;
                }
                else if(method == 'POST'){
                    //If POST data exists in addition to the HTML form data,
                    //it will be concatenated to the form data.
                    postData = (postData?this._sFormData + "&" + postData:this._sFormData);
                }
                this._sFormData = '';
            }

            o.conn.open(method, uri, true);

            if(this._isFormSubmit || (postData && this._use_default_post_header)){
                this.initHeader('Content-Type', this._default_post_header);
                if(this._isFormSubmit){
                    this._isFormSubmit = false;
                }
            }

            if(this._has_http_headers){
                this.setHeader(o);
            }

            this.handleReadyState(o, callback);
            o.conn.send(postData?postData:null);

            return o;
        }
    },

  /**
   * This method serves as a timer that polls the XHR object's readyState
   * property during a transaction, instead of binding a callback to the
   * onreadystatechange event.  Upon readyState 4, handleTransactionResponse
   * will process the response, and the timer will be cleared.
   *
   * @private
   * @param {object} o The connection object
   * @param callback User-defined callback object
   * @return void
   */
    handleReadyState:function(o, callback)
    {

        var oConn = this;

        if(callback && callback.timeout){
            this._timeOut[o.tId] = window.setTimeout(function(){ oConn.abort(o, callback, true); }, callback.timeout);
        }

        this._poll[o.tId] = window.setInterval(
            function(){
                if(o.conn && o.conn.readyState == 4){
                    window.clearInterval(oConn._poll[o.tId]);
                    delete oConn._poll[o.tId];

                    if(callback && callback.timeout){
                        delete oConn._timeOut[o.tId];
                    }

                    oConn.handleTransactionResponse(o, callback);
                }
            }
        ,this._polling_interval);
    },

  /**
   * This method attempts to interpret the server response and
   * determine whether the transaction was successful, or if an error or
   * exception was encountered.
   *
   * @private
   * @param {object} o The connection object
   * @param {object} callback - User-defined callback object
   * @param {boolean} determines if the transaction was aborted.
   * @return void
   */
    handleTransactionResponse:function(o, callback, isAbort)
    {
        // If no valid callback is provided, then do not process any callback handling.
        if(!callback){
            this.releaseObject(o);
            return;
        }

        var httpStatus, responseObject;

        try
        {
            if(o.conn.status !== undefined && o.conn.status != 0){
                httpStatus = o.conn.status;
            }
            else{
                httpStatus = 13030;
            }
        }
        catch(e){
            // 13030 is the custom code to indicate the condition -- in Mozilla/FF --
            // when the o object's status and statusText properties are
            // unavailable, and a query attempt throws an exception.
            httpStatus = 13030;
        }

        if(httpStatus >= 200 && httpStatus < 300){
            try
            {
                responseObject = this.createResponseObject(o, callback.argument);
                if(callback.success){
                    if(!callback.scope){
                        callback.success(responseObject);
                    }
                    else{
                        // If a scope property is defined, the callback will be fired from
                        // the context of the object.
                        callback.success.apply(callback.scope, [responseObject]);
                    }
                }
            }
            catch(e){}
        }
        else{
            try
            {
                switch(httpStatus){
                    // The following case labels are wininet.dll error codes that may be encountered.
                    case 12002: // Server timeout
                    case 12029: // 12029 to 12031 correspond to dropped connections.
                    case 12030:
                    case 12031:
                    case 12152: // Connection closed by server.
                    case 13030: // See above comments for variable status.
                        responseObject = this.createExceptionObject(o.tId, callback.argument, (isAbort?isAbort:false));
                        if(callback.failure){
                            if(!callback.scope){
                                callback.failure(responseObject);
                            }
                            else{
                                callback.failure.apply(callback.scope, [responseObject]);
                            }
                        }
                        break;
                    default:
                        responseObject = this.createResponseObject(o, callback.argument);
                        if(callback.failure){
                            if(!callback.scope){
                                callback.failure(responseObject);
                            }
                            else{
                                callback.failure.apply(callback.scope, [responseObject]);
                            }
                        }
                }
            }
            catch(e){}
        }

        this.releaseObject(o);
        responseObject = null;
    },

  /**
   * This method evaluates the server response, creates and returns the results via
   * its properties.  Success and failure cases will differ in the response
   * object's property values.
   * @private
   * @param {object} o The connection object
   * @param {} callbackArg User-defined argument or arguments to be passed to the callback
   * @return object
   */
    createResponseObject:function(o, callbackArg)
    {
        var obj = {};
        var headerObj = {};

        try
        {
            var headerStr = o.conn.getAllResponseHeaders();
            var header = headerStr.split('\n');
            for(var i=0; i < header.length; i++){
                var delimitPos = header[i].indexOf(':');
                if(delimitPos != -1){
                    headerObj[header[i].substring(0,delimitPos)] = header[i].substring(delimitPos + 2);
                }
            }
        }
        catch(e){}

        obj.tId = o.tId;
        obj.status = o.conn.status;
        obj.statusText = o.conn.statusText;
        obj.getResponseHeader = headerObj;
        obj.getAllResponseHeaders = headerStr;
        obj.responseText = o.conn.responseText;
        obj.responseXML = o.conn.responseXML;

        if(typeof callbackArg !== undefined){
            obj.argument = callbackArg;
        }

        return obj;
    },

  /**
   * If a transaction cannot be completed due to dropped or closed connections,
   * there may be not be enough information to build a full response object.
   * The failure callback will be fired and this specific condition can be identified
   * by a status property value of 0.
   *
   * If an abort was successful, the status property will report a value of -1.
   *
   * @private
   * @param {int} tId Transaction Id
   * @param callbackArg The user-defined arguments
   * @param isAbort Determines if the exception is an abort.
   * @return object
   */
    createExceptionObject:function(tId, callbackArg, isAbort)
    {
        var COMM_CODE = 0;
        var COMM_ERROR = 'communication failure';
        var ABORT_CODE = -1;
        var ABORT_ERROR = 'transaction aborted';

        var obj = {};

        obj.tId = tId;
        if(isAbort){
            obj.status = ABORT_CODE;
            obj.statusText = ABORT_ERROR;
        }
        else{
            obj.status = COMM_CODE;
            obj.statusText = COMM_ERROR;
        }

        if(callbackArg){
            obj.argument = callbackArg;
        }

        return obj;
    },

  /**
   * Public method that stores the custom HTTP headers for each transaction.
   * @public
   * @param {string} label The HTTP header label
   * @param {string} value The HTTP header value
   * @return void
   */
    initHeader:function(label,value)
    {
        if(this._http_header[label] === undefined){
            this._http_header[label] = value;
        }
        else{
            // Concatenate multiple values, comma-delimited,
            // for the same header label,
            this._http_header[label] =  value + "," + this._http_header[label];
        }

        this._has_http_headers = true;
    },

  /**
   * Accessor that sets the HTTP headers for each transaction.
   * @private
   * @param {object} o The connection object for the transaction.
   * @return void
   */
    setHeader:function(o)
    {
        for(var prop in this._http_header){
            if(this._http_header.hasOwnProperty(prop)){
                o.conn.setRequestHeader(prop, this._http_header[prop]);
            }
        }
        delete this._http_header;

        this._http_header = {};
        this._has_http_headers = false;
    },

  /**
   * This method assembles the form label and value pairs and
   * constructs an encoded string.
   * asyncRequest() will automatically initialize the
   * transaction with a HTTP header Content-Type of
   * application/x-www-form-urlencoded.
   * @public
   * @param {string || object} form id or name attribute, or form object.
   * @param {string} optional boolean to indicate SSL environment.
   * @param {string || boolean} optional qualified path of iframe resource for SSL in IE.
   * @return void
   */
    setForm:function(formId, isUpload, secureUri)
    {
        this._sFormData = '';
        if(typeof formId == 'string'){
            // Determine if the argument is a form id or a form name.
            // Note form name usage is deprecated by supported
            // here for legacy reasons.
            var oForm = (document.getElementById(formId) || document.forms[formId]);
        }
        else if(typeof formId == 'object'){
            // Treat argument as an HTML form object.
            var oForm = formId;
        }
        else{
            return;
        }

        // If the isUpload argument is true, setForm will call createFrame to initialize
        // an iframe as the form target.
        //
        // The argument secureURI is also required by IE in SSL environments
        // where the secureURI string is a fully qualified HTTP path, used to set the source
        // of the iframe, to a stub resource in the same domain.
        if(isUpload){
            this.createFrame(secureUri?secureUri:null);
            this._isFormSubmit = true;
            this._isFileUpload = true;
            this._formNode = oForm;

            return;
        }

        var oElement, oName, oValue, oDisabled;
        var hasSubmit = false;

        // Iterate over the form elements collection to construct the
        // label-value pairs.
        for (var i=0; i<oForm.elements.length; i++){
            oElement = oForm.elements[i];
            oDisabled = oForm.elements[i].disabled;
            oName = oForm.elements[i].name;
            oValue = oForm.elements[i].value;

            // Do not submit fields that are disabled or
            // do not have a name attribute value.
            if(!oDisabled && oName)
            {
                switch (oElement.type)
                {
                    case 'select-one':
                    case 'select-multiple':
                        for(var j=0; j<oElement.options.length; j++){
                            if(oElement.options[j].selected){
                                if(window.ActiveXObject){
                                    this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oElement.options[j].attributes['value'].specified?oElement.options[j].value:oElement.options[j].text) + '&';
                                }
                                else{
                                    this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oElement.options[j].hasAttribute('value')?oElement.options[j].value:oElement.options[j].text) + '&';
                                }

                            }
                        }
                        break;
                    case 'radio':
                    case 'checkbox':
                        if(oElement.checked){
                            this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
                        }
                        break;
                    case 'file':
                        // stub case as XMLHttpRequest will only send the file path as a string.
                    case undefined:
                        // stub case for fieldset element which returns undefined.
                    case 'reset':
                        // stub case for input type reset button.
                    case 'button':
                        // stub case for input type button elements.
                        break;
                    case 'submit':
                        if(hasSubmit == false){
                            this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
                            hasSubmit = true;
                        }
                        break;
                    default:
                        this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
                        break;
                }
            }
        }

        this._isFormSubmit = true;
        this._sFormData = this._sFormData.substr(0, this._sFormData.length - 1);
    },

  /**
   * Creates an iframe to be used for form file uploads.  It is remove from the
   * document upon completion of the upload transaction.
   *
   * @private
   * @param {string} optional qualified path of iframe resource for SSL in IE.
   * @return void
   */
    createFrame:function(secureUri){

        // IE does not allow the setting of id and name attributes as object
        // properties via createElement().  A different iframe creation
        // pattern is required for IE.
        var frameId = 'yuiIO' + this._transaction_id;
        if(window.ActiveXObject){
            var io = document.createElement('<IFRAME id="' + frameId + '" name="' + frameId + '">');

            // IE will throw a security exception in an SSL environment if the
            // iframe source isn't set.
            if(typeof secureUri == 'boolean'){
                io.src = 'javascript:false';
            }
            else{
                io.src = secureUri;
            }
        }
        else{
            var io = document.createElement('IFRAME');
            io.id = frameId;
            io.name = frameId;
        }

        io.style.position = 'absolute';
        io.style.top = '-1000px';
        io.style.left = '-1000px';

        document.body.appendChild(io);
    },

  /**
   * Uploads HTML form, including files/attachments,  targeting the
   * iframe created in createFrame.
   *
   * @private
   * @param {int} id The transaction id.
   * @param {object} callback - User-defined callback object.
   * @param {string} uri Fully qualified path of resource.
   * @return void
   */
    uploadFile:function(id, callback, uri){

        var frameId = 'yuiIO' + id;
        var io = document.getElementById(frameId);

        // Initialize the HTML form properties in case they are
        // not defined in the HTML form.
        this._formNode.action = uri;
        this._formNode.enctype = 'multipart/form-data';
        this._formNode.method = 'POST';
        this._formNode.target = frameId;
        this._formNode.submit();

        // Reset form status properties.
        this._formNode = null;
        this._isFileUpload = false;
        this._isFormSubmit = false;

        // Create the upload callback handler that fires when the iframe
        // receives the load event.  Subsequently, the event handler is detached
        // and the iframe removed from the document.

        var uploadCallback = function()
        {
            var obj = {};

            obj.tId = id;
            obj.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;
            obj.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;
            obj.argument = callback.argument;

            if(callback.upload){
                if(!callback.scope){
                    callback.upload(obj);
                }
                else{
                    callback.upload.apply(callback.scope, [obj]);
                }
            }

            if(YAHOO.util.Event){
                YAHOO.util.Event.removeListener(io, "load", uploadCallback);
            }
            else if(window.ActiveXObject){
                io.detachEvent('onload', uploadCallback);
            }
            else{
                io.removeEventListener('load', uploadCallback, false);
            }
            setTimeout(function(){ document.body.removeChild(io); }, 100);
        };


        // Bind the onload handler to the iframe to detect the file upload response.
        if(YAHOO.util.Event){
            YAHOO.util.Event.addListener(io, "load", uploadCallback);
        }
        else if(window.ActiveXObject){
            io.attachEvent('onload', uploadCallback);
        }
        else{
            io.addEventListener('load', uploadCallback, false);
        }
    },

  /**
   * Public method to terminate a transaction, if it has not reached readyState 4.
   * @public
   * @param {object} o The connection object returned by asyncRequest.
   * @param {object} callback  User-defined callback object.
   * @param {string} isTimeout boolean to indicate if abort was a timeout.
   * @return void
   */
    abort:function(o, callback, isTimeout)
    {
        if(this.isCallInProgress(o)){
            o.conn.abort();
            window.clearInterval(this._poll[o.tId]);
            delete this._poll[o.tId];
            if(isTimeout){
                delete this._timeOut[o.tId];
            }

            this.handleTransactionResponse(o, callback, true);

            return true;
        }
        else{
            return false;
        }
    },

  /**
   * Public method to check if the transaction is still being processed.
   * @public
   * @param {object} o The connection object returned by asyncRequest
   * @return boolean
   */
    isCallInProgress:function(o)
    {
        // if the XHR object assigned to the transaction has not been dereferenced,
        // then check its readyState status.  Otherwise, return false.
        if(o.conn){
            return o.conn.readyState != 4 && o.conn.readyState != 0;
        }
        else{
            //The XHR object has been destroyed.
            return false;
        }
    },

  /**
   * Dereference the XHR instance and the connection object after the transaction is completed.
   * @private
   * @param {object} o The connection object
   * @return void
   */
    releaseObject:function(o)
    {
        //dereference the XHR instance.
        o.conn = null;
        //dereference the connection object.
        o = null;
    }
};