/*
 * Copyright (c) 2011, salesforce.com, inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this list of conditions and the
 * following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
 * the following disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * Neither the name of salesforce.com, inc. nor the names of its contributors may be used to endorse or
 * promote products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/* JavaScript library to wrap REST API on Visualforce. Leverages Ajax Proxy
 * (see http://bit.ly/sforce_ajax_proxy for details).
 *
 * Note that you must add the REST endpoint hostname for your instance (i.e. 
 * https://na1.salesforce.com/ or similar) as a remote site - in the admin
 * console, go to Your Name | Setup | Security Controls | Remote Site Settings
 */

/*jslint browser: true*/
/*global alert, Blob, $, jQuery*/

var forcetk = window.forcetk;

if (forcetk === undefined) {
    forcetk = {};
}

if (forcetk.Client === undefined) {

    /**
     * The Client provides a convenient wrapper for the Force.com REST API, 
     * allowing JavaScript in Visualforce pages to use the API via the Ajax
     * Proxy.
     * @param [clientId=null] 'Consumer Key' in the Remote Access app settings
     * @param [loginUrl='https://login.salesforce.com/'] Login endpoint
     * @param [proxyUrl=null] Proxy URL. Omit if running on Visualforce or 
     *                  PhoneGap etc
     * @constructor
     */
    forcetk.Client = function (clientId, loginUrl, proxyUrl) {
        'use strict';
        this.clientId = clientId;
        this.loginUrl = loginUrl || 'https://login.salesforce.com/';
        if (proxyUrl === undefined || proxyUrl === null) {
            if (location.protocol === 'file:' || location.protocol === 'ms-appx:') {
                // In PhoneGap
                this.proxyUrl = null;
            } else {
                // In Visualforce - still need proxyUrl for Apex REST methods
                this.proxyUrl = location.protocol + "//" + location.hostname
                    + "/services/proxy";
            }
            this.authzHeader = "Authorization";
        } else {
            // On a server outside VF
            this.proxyUrl = proxyUrl;
            this.authzHeader = "X-Authorization";
        }
        this.refreshToken = null;
        this.sessionId = null;
        this.apiVersion = null;
        this.visualforce = false;
        this.instanceUrl = null;
        this.asyncAjax = true;
    };

    /**
     * Set a refresh token in the client.
     * @param refreshToken an OAuth refresh token
     */
    forcetk.Client.prototype.setRefreshToken = function (refreshToken) {
        'use strict';
        this.refreshToken = refreshToken;
    };

    /**
     * Refresh the access token.
     * @param callback function to call on success
     * @param error function to call on failure
     */
    forcetk.Client.prototype.refreshAccessToken = function (callback, error) {
        'use strict';
        var that = this,
            url = this.loginUrl + '/services/oauth2/token';
        return $.ajax({
            type: 'POST',
            url: (this.proxyUrl !== null && !this.visualforce) ? this.proxyUrl : url,
            cache: false,
            processData: false,
            data: 'grant_type=refresh_token&client_id=' + this.clientId + '&refresh_token=' + this.refreshToken,
            success: callback,
            error: error,
            dataType: "json",
            beforeSend: function (xhr) {
                if (that.proxyUrl !== null && !this.visualforce) {
                    xhr.setRequestHeader('SalesforceProxy-Endpoint', url);
                }
            }
        });
    };

    /**
     * Set a session token and the associated metadata in the client.
     * @param sessionId a salesforce.com session ID. In a Visualforce page,
     *                   use '{!$Api.sessionId}' to obtain a session ID.
     * @param [apiVersion="v29.0"] Force.com API version
     * @param [instanceUrl] Omit this if running on Visualforce; otherwise 
     *                   use the value from the OAuth token.
     */
    forcetk.Client.prototype.setSessionToken = function (sessionId, apiVersion, instanceUrl) {
        'use strict';
        this.sessionId = sessionId;
        this.apiVersion = (apiVersion === undefined || apiVersion === null)
            ? 'v29.0' : apiVersion;
        if (instanceUrl === undefined || instanceUrl === null) {
            this.visualforce = true;

            // location.hostname can be of the form 'abc.na1.visual.force.com',
            // 'na1.salesforce.com' or 'abc.my.salesforce.com' (custom domains). 
            // Split on '.', and take the [1] or [0] element as appropriate
            var elements = location.hostname.split("."),
                instance = null;
            if (elements.length === 4 && elements[1] === 'my') {
                instance = elements[0] + '.' + elements[1];
            } else if (elements.length === 3) {
                instance = elements[0];
            } else {
                instance = elements[1];
            }

            this.instanceUrl = "https://" + instance + ".salesforce.com";
        } else {
            this.instanceUrl = instanceUrl;
        }
    };

    /*
     * Low level utility function to call the Salesforce endpoint.
     * @param path resource path relative to /services/data
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     * @param [method="GET"] HTTP method for call
     * @param [payload=null] payload for POST/PATCH etc
     */
    forcetk.Client.prototype.ajax = function (path, callback, error, method, payload, retry) {
        'use strict';
        var that = this,
            url = (this.visualforce ? '' : this.instanceUrl) + '/services/data' + path;

        return $.ajax({
            type: method || "GET",
            async: this.asyncAjax,
            url: (this.proxyUrl !== null && !this.visualforce) ? this.proxyUrl : url,
            contentType: method === "DELETE"  ? null : 'application/json',
            cache: false,
            processData: false,
            data: payload,
            success: callback,
            error: (!this.refreshToken || retry) ? error : function (jqXHR, textStatus, errorThrown) {
                if (jqXHR.status === 401) {
                    that.refreshAccessToken(function (oauthResponse) {
                        that.setSessionToken(oauthResponse.access_token, null,
                            oauthResponse.instance_url);
                        that.ajax(path, callback, error, method, payload, true);
                    },
                        error);
                } else {
                    error(jqXHR, textStatus, errorThrown);
                }
            },
            dataType: "json",
            beforeSend: function (xhr) {
                if (that.proxyUrl !== null && !that.visualforce) {
                    xhr.setRequestHeader('SalesforceProxy-Endpoint', url);
                }
                xhr.setRequestHeader(that.authzHeader, "Bearer " + that.sessionId);
                xhr.setRequestHeader('X-User-Agent', 'salesforce-toolkit-rest-javascript/' + that.apiVersion);
            }
        });
    };

    /**
     * Utility function to query the Chatter API and download a file
     * Note, raw XMLHttpRequest because JQuery mangles the arraybuffer
     * This should work on any browser that supports XMLHttpRequest 2 because arraybuffer is required. 
     * For mobile, that means iOS >= 5 and Android >= Honeycomb
     * @author Tom Gersic
     * @param path resource path relative to /services/data
     * @param mimetype of the file
     * @param callback function to which response will be passed
     * @param [error=null] function to which request will be passed in case of error
     * @param retry true if we've already tried refresh token flow once
     */
    forcetk.Client.prototype.getChatterFile = function (path, mimeType, callback, error, retry) {
        'use strict';
        var that = this,
            url = (this.visualforce ? '' : this.instanceUrl) + path,
            request = new XMLHttpRequest();

        request.open("GET", (this.proxyUrl !== null && !this.visualforce) ? this.proxyUrl : url, true);
        request.responseType = "arraybuffer";

        request.setRequestHeader(this.authzHeader, "Bearer " + this.sessionId);
        request.setRequestHeader('X-User-Agent', 'salesforce-toolkit-rest-javascript/' + this.apiVersion);
        if (this.proxyUrl !== null && !this.visualforce) {
            request.setRequestHeader('SalesforceProxy-Endpoint', url);
        }

        request.onreadystatechange = function () {
            // continue if the process is completed
            if (request.readyState === 4) {
                // continue only if HTTP status is "OK"
                if (request.status === 200) {
                    try {
                        // retrieve the response
                        callback(request.response);
                    } catch (e) {
                        // display error message
                        alert("Error reading the response: " + e.toString());
                    }
                } else if (request.status === 401 && !retry) {
                    //refresh token in 401
                    that.refreshAccessToken(function (oauthResponse) {
                        that.setSessionToken(oauthResponse.access_token, null, oauthResponse.instance_url);
                        that.getChatterFile(path, mimeType, callback, error, true);
                    }, error);
                } else {
                    // display status message
                    error(request, request.statusText, request.response);
                }
            }
        };

        request.send();

    };

    // Local utility to create a random string for multipart boundary
    var randomString = function () {
        'use strict';
        var str = '',
            i;
        for (i = 0; i < 4; i += 1) {
            str += (Math.random().toString(16) + "000000000").substr(2, 8);
        }
        return str;
    };

    /* Low level function to create/update records with blob data
     * @param path resource path relative to /services/data
     * @param fields an object containing initial field names and values for 
     *               the record, e.g. {ContentDocumentId: "069D00000000so2", 
     *               PathOnClient: "Q1 Sales Brochure.pdf"}
     * @param filename filename for blob data; e.g. "Q1 Sales Brochure.pdf"
     * @param payloadField 'VersionData' for ContentVersion, 'Body' for Document
     * @param payload Blob, File, ArrayBuffer (Typed Array), or String payload
     * @param callback function to which response will be passed
     * @param [error=null] function to which response will be passed in case of error
     * @param retry true if we've already tried refresh token flow once
     */
    forcetk.Client.prototype.blob = function (path, fields, filename, payloadField, payload, callback, error, retry) {
        'use strict';
        var that = this,
            url = (this.visualforce ? '' : this.instanceUrl) + '/services/data' + path,
            boundary = randomString(),
            blob = new Blob([
                "--boundary_" + boundary + '\n'
                    + "Content-Disposition: form-data; name=\"entity_content\";" + "\n"
                    + "Content-Type: application/json" + "\n\n"
                    + JSON.stringify(fields)
                    + "\n\n"
                    + "--boundary_" + boundary + "\n"
                    + "Content-Type: application/octet-stream" + "\n"
                    + "Content-Disposition: form-data; name=\"" + payloadField
                    + "\"; filename=\"" + filename + "\"\n\n",
                payload,
                "\n\n"
                    + "--boundary_" + boundary + "--"
            ], {type : 'multipart/form-data; boundary=\"boundary_' + boundary + '\"'}),
            request = new XMLHttpRequest();

        request.open("POST", (this.proxyUrl !== null && !this.visualforce) ? this.proxyUrl : url, this.asyncAjax);

        request.setRequestHeader('Accept', 'application/json');
        request.setRequestHeader(this.authzHeader, "Bearer " + this.sessionId);
        request.setRequestHeader('X-User-Agent', 'salesforce-toolkit-rest-javascript/' + this.apiVersion);
        request.setRequestHeader('Content-Type', 'multipart/form-data; boundary=\"boundary_' + boundary + '\"');
        if (this.proxyUrl !== null && !this.visualforce) {
            request.setRequestHeader('SalesforceProxy-Endpoint', url);
        }

        if (this.asyncAjax) {
            request.onreadystatechange = function () {
                // continue if the process is completed
                if (request.readyState === 4) {
                    // continue only if HTTP status is good
                    if (request.status >= 200 && request.status < 300) {
                        // retrieve the response
                        callback(request.response ? JSON.parse(request.response) : null);
                    } else if (request.status === 401 && !retry) {
                        that.refreshAccessToken(function (oauthResponse) {
                            that.setSessionToken(oauthResponse.access_token, null, oauthResponse.instance_url);
                            that.blob(path, fields, filename, payloadField, payload, callback, error, true);
                        }, error);
                    } else {
                        // return status message
                        error(request, request.statusText, request.response);
                    }
                }
            };
        }

        request.send(blob);

        return this.asyncAjax ? null : JSON.parse(request.response);
    };

    /*
     * Create a record with blob data
     * @param objtype object type; e.g. "ContentVersion"
     * @param fields an object containing initial field names and values for 
     *               the record, e.g. {ContentDocumentId: "069D00000000so2", 
     *               PathOnClient: "Q1 Sales Brochure.pdf"}
     * @param filename filename for blob data; e.g. "Q1 Sales Brochure.pdf"
     * @param payloadField 'VersionData' for ContentVersion, 'Body' for Document
     * @param payload Blob, File, ArrayBuffer (Typed Array), or String payload
     * @param callback function to which response will be passed
     * @param [error=null] function to which response will be passed in case of error
     * @param retry true if we've already tried refresh token flow once
     */
    forcetk.Client.prototype.createBlob = function (objtype, fields, filename,
                                                   payloadField, payload, callback,
                                                   error, retry) {
        'use strict';
        return this.blob('/' + this.apiVersion + '/sobjects/' + objtype + '/',
                         fields, filename, payloadField, payload, callback, error, retry);
    };

    /*
     * Update a record with blob data
     * @param objtype object type; e.g. "ContentVersion"
     * @param id the record's object ID
     * @param fields an object containing initial field names and values for 
     *               the record, e.g. {ContentDocumentId: "069D00000000so2", 
     *               PathOnClient: "Q1 Sales Brochure.pdf"}
     * @param filename filename for blob data; e.g. "Q1 Sales Brochure.pdf"
     * @param payloadField 'VersionData' for ContentVersion, 'Body' for Document
     * @param payload Blob, File, ArrayBuffer (Typed Array), or String payload
     * @param callback function to which response will be passed
     * @param [error=null] function to which response will be passed in case of error
     * @param retry true if we've already tried refresh token flow once
     */
    forcetk.Client.prototype.updateBlob = function (objtype, id, fields, filename,
                                                   payloadField, payload, callback,
                                                   error, retry) {
        'use strict';
        return this.blob('/' + this.apiVersion + '/sobjects/' + objtype + '/' + id +
                         '?_HttpMethod=PATCH', fields, filename, payloadField, payload, callback, error, retry);
    };

    /*
     * Low level utility function to call the Salesforce endpoint specific for Apex REST API.
     * @param path resource path relative to /services/apexrest
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     * @param [method="GET"] HTTP method for call
     * @param [payload=null] string or object with payload for POST/PATCH etc or params for GET
     * @param [paramMap={}] parameters to send as header values for POST/PATCH etc
     * @param [retry] specifies whether to retry on error
     */
    forcetk.Client.prototype.apexrest = function (path, callback, error, method, payload, paramMap, retry) {
        'use strict';
        var that = this,
            url = this.instanceUrl + '/services/apexrest' + path;

        method = method || "GET";

        if (method === "GET") {
            // Handle proxied query params correctly
            if (this.proxyUrl && payload) {
                if (typeof payload !== 'string') {
                    payload = $.param(payload);
                }
                url += "?" + payload;
                payload = null;
            }
        } else {
            // Allow object payload for POST etc
            if (payload && typeof payload !== 'string') {
                payload = JSON.stringify(payload);
            }
        }

        return $.ajax({
            type: method,
            async: this.asyncAjax,
            url: this.proxyUrl || url,
            contentType: 'application/json',
            cache: false,
            processData: false,
            data: payload,
            success: callback,
            error: (!this.refreshToken || retry) ? error : function (jqXHR, textStatus, errorThrown) {
                if (jqXHR.status === 401) {
                    that.refreshAccessToken(function (oauthResponse) {
                        that.setSessionToken(oauthResponse.access_token, null,
                            oauthResponse.instance_url);
                        that.apexrest(path, callback, error, method, payload, paramMap, true);
                    }, error);
                } else {
                    error(jqXHR, textStatus, errorThrown);
                }
            },
            dataType: "json",
            beforeSend: function (xhr) {
                var paramName;
                if (that.proxyUrl !== null) {
                    xhr.setRequestHeader('SalesforceProxy-Endpoint', url);
                }
                //Add any custom headers
                if (paramMap === null) {
                    paramMap = {};
                }
                for (paramName in paramMap) {
                    if (paramMap.hasOwnProperty(paramName)) {
                        xhr.setRequestHeader(paramName, paramMap[paramName]);
                    }
                }
                xhr.setRequestHeader(that.authzHeader, "Bearer " + that.sessionId);
                xhr.setRequestHeader('X-User-Agent', 'salesforce-toolkit-rest-javascript/' + that.apiVersion);
            }
        });
    };

    /*
     * Lists summary information about each Salesforce.com version currently 
     * available, including the version, label, and a link to each version's
     * root.
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.versions = function (callback, error) {
        'use strict';
        return this.ajax('/', callback, error);
    };

    /*
     * Lists available resources for the client's API version, including 
     * resource name and URI.
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.resources = function (callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/', callback, error);
    };

    /*
     * Lists the available objects and their metadata for your organization's 
     * data.
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.describeGlobal = function (callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/sobjects/', callback, error);
    };

    /*
     * Describes the individual metadata for the specified object.
     * @param objtype object type; e.g. "Account"
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.metadata = function (objtype, callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/sobjects/' + objtype + '/',
            callback, error);
    };

    /*
     * Completely describes the individual metadata at all levels for the 
     * specified object.
     * @param objtype object type; e.g. "Account"
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.describe = function (objtype, callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/sobjects/' + objtype
            + '/describe/', callback, error);
    };

    /*
     * Creates a new record of the given type.
     * @param objtype object type; e.g. "Account"
     * @param fields an object containing initial field names and values for 
     *               the record, e.g. {:Name "salesforce.com", :TickerSymbol 
     *               "CRM"}
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.create = function (objtype, fields, callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/sobjects/' + objtype + '/',
            callback, error, "POST", JSON.stringify(fields));
    };

    /*
     * Retrieves field values for a record of the given type.
     * @param objtype object type; e.g. "Account"
     * @param id the record's object ID
     * @param [fields=null] optional comma-separated list of fields for which 
     *               to return values; e.g. Name,Industry,TickerSymbol
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.retrieve = function (objtype, id, fieldlist, callback, error) {
        'use strict';
        if (arguments.length === 4) {
            error = callback;
            callback = fieldlist;
            fieldlist = null;
        }
        var fields = fieldlist ? '?fields=' + fieldlist : '';
        return this.ajax('/' + this.apiVersion + '/sobjects/' + objtype + '/' + id
            + fields, callback, error);
    };

    /*
     * Upsert - creates or updates record of the given type, based on the 
     * given external Id.
     * @param objtype object type; e.g. "Account"
     * @param externalIdField external ID field name; e.g. "accountMaster__c"
     * @param externalId the record's external ID value
     * @param fields an object containing field names and values for 
     *               the record, e.g. {:Name "salesforce.com", :TickerSymbol 
     *               "CRM"}
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.upsert = function (objtype, externalIdField, externalId, fields, callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/sobjects/' + objtype + '/' + externalIdField + '/' + externalId
            + '?_HttpMethod=PATCH', callback, error, "POST", JSON.stringify(fields));
    };

    /*
     * Updates field values on a record of the given type.
     * @param objtype object type; e.g. "Account"
     * @param id the record's object ID
     * @param fields an object containing initial field names and values for 
     *               the record, e.g. {:Name "salesforce.com", :TickerSymbol 
     *               "CRM"}
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.update = function (objtype, id, fields, callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/sobjects/' + objtype + '/' + id
            + '?_HttpMethod=PATCH', callback, error, "POST", JSON.stringify(fields));
    };

    /*
     * Deletes a record of the given type. Unfortunately, 'delete' is a 
     * reserved word in JavaScript.
     * @param objtype object type; e.g. "Account"
     * @param id the record's object ID
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.del = function (objtype, id, callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/sobjects/' + objtype + '/' + id,
            callback, error, "DELETE");
    };

    /*
     * Executes the specified SOQL query.
     * @param soql a string containing the query to execute - e.g. "SELECT Id, 
     *             Name from Account ORDER BY Name LIMIT 20"
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.query = function (soql, callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/query?q=' + encodeURIComponent(soql),
            callback, error);
    };

    /*
     * Queries the next set of records based on pagination.
     * <p>This should be used if performing a query that retrieves more than can be returned
     * in accordance with http://www.salesforce.com/us/developer/docs/api_rest/Content/dome_query.htm</p>
     * <p>Ex: forcetkClient.queryMore( successResponse.nextRecordsUrl, successHandler, failureHandler )</p>
     * 
     * @param url - the url retrieved from nextRecordsUrl or prevRecordsUrl
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.queryMore = function (url, callback, error) {
        'use strict';
        //-- ajax call adds on services/data to the url call, so only send the url after
        var serviceData = "services/data",
            index = url.indexOf(serviceData);

        if (index > -1) {
            url = url.substr(index + serviceData.length);
        }

        return this.ajax(url, callback, error);
    };

    /*
     * Executes the specified SOSL search.
     * @param sosl a string containing the search to execute - e.g. "FIND 
     *             {needle}"
     * @param callback function to which response will be passed
     * @param [error=null] function to which jqXHR will be passed in case of error
     */
    forcetk.Client.prototype.search = function (sosl, callback, error) {
        'use strict';
        return this.ajax('/' + this.apiVersion + '/search?q=' + encodeURIComponent(sosl),
            callback, error);
    };
}