/**

  * Copyright 2010 The Kuali 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.osedu.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 org.kuali.student.common.util;

 import java.io.IOException;

 import java.io.InputStream;

 import java.util.jar.Attributes;

 import java.util.jar.Manifest;

 import javax.servlet.ServletContext;

 import static org.apache.commons.io.IOUtils.*;

 import static org.apache.commons.lang.StringUtils.*;

 /**

  * Obtains version information about the application from the META-INF/MANIFEST.MF file contained inside a .war file

  */

 public class ManifestInspector {

         /**

          * Location of the MANIFEST.MF file

          */

         public static final String MANIFEST_LOCATION = "/META-INF/MANIFEST.MF";

         public static final String BUNDLE_NAME = "Bundle-Name";

         public static final String BUNDLE_VERSION = "Bundle-Version";

         public static final String BUNDLE_TIMESTAMP = "Bundle-Timestamp";

         public static final String BUNDLE_BUILD_NUMBER = "Bundle-BuildNumber";

         public static final String NO_BUILD_INFORMATION_AVAILABLE = "No build information available";

         /**

          * Return a Manifest object

          */

         protected Manifest getManifest(ServletContext servletContext) throws IOException {

                 InputStream in = null;

                 try {

                         in = servletContext.getResourceAsStream(MANIFEST_LOCATION);

                         if (in == null) {

                                 return null;

                         } else {

                                 return new Manifest(in);

                         }

                 } catch (IOException e) {

                         throw e;

                 } finally {

                         closeQuietly(in);

                 }

         }

         /**

          * Examine the manifest provided for build information. Returns null if manifest is null

          */

         protected BuildInformation getBuildInformation(Manifest manifest) {

                 // No Manifest is available

                 if (manifest == null) {

                         return null;

                 }

                 // Extract the attributes

                 Attributes attributes = manifest.getMainAttributes();

                 // Manifest attributes containing the build information

                 String name = attributes.getValue(BUNDLE_NAME);

                 String version = attributes.getValue(BUNDLE_VERSION);

                 String buildNumber = attributes.getValue(BUNDLE_BUILD_NUMBER);

                 String timestamp = attributes.getValue(BUNDLE_TIMESTAMP);

                 // Create and populate a BuildInformation object

                 BuildInformation bi = new BuildInformation();

                 bi.setName(name);

                 bi.setVersion(version);

                 bi.setBuildNumber(buildNumber);

                 bi.setTimestamp(timestamp);

                 return bi;

         }

         /**

          * Obtain version information from MANIFEST.MF

          */

         public String getBuildInformationString(ServletContext context) throws IOException {

                 // Get a handle to a Manifest object

                 Manifest manifest = getManifest(context);

                 // Store build information attributes from the manifest into a POJO

                 BuildInformation buildInformation = getBuildInformation(manifest);

                 // Convert the POJO to a string

                 return toString(buildInformation);

         }

         /**

          * Return true if BuildInformation is null or does not contain any meaningful information.

          */

         protected boolean isNullOrEmpty(BuildInformation bi) {

                 if (bi == null) {

                         return true;

                 }

                 if (!isEmpty(bi.getName())) {

                         return false;

                 }

                 if (!isEmpty(bi.getVersion())) {

                         return false;

                 }

                 if (!isEmpty(bi.getBuildNumber())) {

                         return false;

                 }

                 if (!isEmpty(bi.getTimestamp())) {

                         return false;

                 }

                 return true;

         }

         /**

          * Convert the build information POJO to a display String

          */

         public String toString(BuildInformation bi) {

                 /**

                  * For developers pointed at a local build, MANIFEST.MF may not be present

                  * 

                  * Since we overlay the Rice war file, the MANIFEST.MF from Rice may be present but doesn't contain build

                  * information

                  */

                 if (isNullOrEmpty(bi)) {

                         return NO_BUILD_INFORMATION_AVAILABLE;

                 }

                 /**

                  * Build number is only present if Hudson has done the build

                  */

                 if (!isEmpty(bi.getBuildNumber())) {

                         bi.setBuildNumber("#" + bi.getBuildNumber());

                 }

                 /**

                  * Build a string out of the build information

                  */

                 StringBuffer sb = new StringBuffer();

                 if (!isEmpty(bi.getName())) {

                         sb.append(bi.getName());

                         sb.append(" :: ");

                 }

                 if (!isEmpty(bi.getVersion())) {

                         sb.append(bi.getVersion());

                         sb.append(" :: ");

                 }

                 if (!isEmpty(bi.getBuildNumber())) {

                         sb.append(bi.getBuildNumber());

                         sb.append(" :: ");

                 }

                 if (!isEmpty(bi.getTimestamp())) {

                         sb.append(bi.getTimestamp());

                 }

                 return sb.toString();

         }

 }