edu.umich.its.lti.google.GoogleConfigJsonWriter.java Source code

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Here is the source code for edu.umich.its.lti.google.GoogleConfigJsonWriter.java

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/**********************************************************************************
 * $URL$
 * $Id$
 ***********************************************************************************
 *
 * Copyright (c) 2013 The Sakai Foundation
 *
 * Licensed under the Educational Community License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.opensource.org/licenses/ECL-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 **********************************************************************************/
package edu.umich.its.lti.google;

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import edu.umich.its.lti.TcSessionData;
import edu.umich.its.lti.TcSiteToGoogleStorage;

/**
 * This generates JSON object sent to the browser containing user name & roles,
 * and linked folder
 * 
 * <pre>
 *    googleDriveConfig = {
 *         "tp_id" : ""
 *       , "course" : { "id" : "", title: "" }
 *       , "user" : { "name" : "", "roles" : [ "", "" ]}
 *       , "linkedFolders" : [ "" ]
 * 
 *    }
 * </pre>
 * 
 * @author Raymond Naseef
 * 
 */
public class GoogleConfigJsonWriter {

    private static final Log M_log = LogFactory.getLog(GoogleConfigJsonWriter.class);

    /**
     * This creates JSON with configuration of Google Drive, for use by the
     * browser to manage the site's Google Resources.
     */
    static public String getGoogleDriveConfigJson(TcSessionData tcSessionData, HttpServletRequest request)
            throws IOException {
        StringBuilder result = new StringBuilder("{");
        String courseId = tcSessionData.getContextId();
        if ((courseId == null) || courseId.trim().equals("")) {
            M_log.error("Google Drive LTI request made without context_id!");
        }
        result.append("\"tp_id\" : \"").append(escapeQuotesForJson(tcSessionData.getId())).append("\"");
        result.append(", \"course\" : ");
        appendCourseJson(tcSessionData, result);
        result.append(", \"linkedFolders\" : ");
        appendLinkedFolders(tcSessionData, result, request);
        result.append(", \"user\" : ");
        appendUserJson(tcSessionData, result);
        // End the JSON object
        result.append("}");
        return result.toString();
    }

    /**
     * Returns JavaScript setting the JSON configuration object to global
     * variable "googleDriveConfig".
     */
    static public String getGoogleDriveConfigJsonScript(TcSessionData tcSessionData, HttpServletRequest request)
            throws IOException {
        return "googleDriveConfig = " + getGoogleDriveConfigJson(tcSessionData, request);
    }

    // Static private methods ---------------------------------------

    static private void appendCourseJson(TcSessionData tcSessionData, StringBuilder result) {
        // 2 - Begin Adding the folder
        result.append("{ \"id\" : \"").append(escapeQuotesForJson(tcSessionData.getContextId())).append("\"");
        // 2a - Folder's title
        result.append(", \"title\" : \"").append(escapeQuotesForJson(tcSessionData.getContextTitle())).append("\"");
        // 2 - End Adding the folder
        result.append("}");
    }

    /**
     *  Getting the shared folder id from the Session instead of setting service as call to Setting service intermittently not fetching correct value.
     * @param tcSessionData
     * @param result
     * @param request
     */
    static private void appendLinkedFolders(TcSessionData tcSessionData, StringBuilder result,
            HttpServletRequest request) {
        // setting mapping
        result.append("[");
        try {
            String link = (String) request.getSession()
                    .getAttribute(GoogleLtiServlet.SETTING_SERVICE_VALUE_IN_SESSION);
            if (link != null) {
                result.append("\"").append(escapeQuotesForJson(TcSiteToGoogleStorage.parseLink(link).getFolderId()))
                        .append("\"");
            }
        } catch (Exception e) {
            M_log.error("Failed to load the string that has the Shared folder information", e);
        }
        result.append("]");
    }

    static private void appendUserJson(TcSessionData tcSessionData, StringBuilder result) {
        // 1 - Begin Adding User
        result.append("{");
        // 1a - full name
        result.append(" \"name\" : \"").append(escapeQuotesForJson(tcSessionData.getUserNameFull())).append("\"");
        // 1b - roles
        String[] roleArray = tcSessionData.getUserRoleArray();
        result.append(", \"roles\" : [ ");
        for (int idx = 0; idx < roleArray.length; idx++) {
            if (idx > 0) {
                result.append(",");
            }
            result.append("\"").append(escapeQuotesForJson(roleArray[idx])).append("\"");
        }
        result.append("]");
        // 1 - End Adding User
        result.append("}");
    }

    /**
     * Returns the value escaped properly for placement as value in JSON; null
     * is returned as ''
     */
    static private String escapeQuotesForJson(String value) {
        return (value == null) ? "" : value.replace("\"", "\\\"");
    }
}