//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.start;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.Enumeration;
  import java.util.Map;
  import java.util.Properties;
  import java.util.jar.Attributes;
  import java.util.jar.JarEntry;
  import java.util.jar.JarFile;
  import java.util.jar.Manifest;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Attempt to determine the version of the Jar File based on common version locations.
   */
  public class JarVersion
  {
      private static JarEntry findEntry(JarFile jar, String regex)
      {
          Pattern pattern = Pattern.compile(regex);
          Matcher matcher;
          Enumeration<JarEntry> en = jar.entries();
          while (en.hasMoreElements())
          {
              JarEntry entry = en.nextElement();
              matcher = pattern.matcher(entry.getName());
              if (matcher.matches())
              {
                  return entry;
              }
          }
  
          return null;
      }
  
      private static String getBundleVersion(Manifest manifest)
      {
          Attributes attribs = manifest.getMainAttributes();
          if (attribs == null)
          {
              return null;
          }
  
          String version = attribs.getValue("Bundle-Version");
          if (version == null)
          {
              return null;
          }
  
          return stripV(version);
      }
  
      private static String getMainManifestImplVersion(Manifest manifest)
      {
          Attributes attribs = manifest.getMainAttributes();
          if (attribs == null)
          {
              return null;
          }
  
          String version = attribs.getValue(Attributes.Name.IMPLEMENTATION_VERSION);
          if (version == null)
          {
              return null;
          }
  
          return stripV(version);
      }
  
      private static String getMavenVersion(JarFile jar) throws IOException
      {
          JarEntry pomProp = findEntry(jar,"META-INF/maven/.*/pom\\.properties$");
          if (pomProp == null)
          {
              return null;
          }
  
          InputStream stream = null;
 
         try
         {
             stream = jar.getInputStream(pomProp);
             Properties props = new Properties();
             props.load(stream);
 
             String version = props.getProperty("version");
             if (version == null)
             {
                 return null;
             }
 
             return stripV(version);
         }
         finally
         {
             FS.close(stream);
         }
     }
 
     private static String getSubManifestImplVersion(Manifest manifest)
     {
         Map<String, Attributes> entries = manifest.getEntries();
 
         for (Attributes attribs : entries.values())
         {
             if (attribs == null)
             {
                 continue; // skip entry
             }
 
             String version = attribs.getValue(Attributes.Name.IMPLEMENTATION_VERSION);
             if (version == null)
             {
                 continue; // empty, no value, skip it
             }
 
             return stripV(version);
         }
 
         return null; // no valid impl version entries found
     }
 
     public static String getVersion(File file)
     {
         try (JarFile jar = new JarFile(file))
         {
             String version = null;
 
             Manifest manifest = jar.getManifest();
             
             if (manifest == null)
             {
                 return "(none specified)";
             }
 
             version = getMainManifestImplVersion(manifest);
             if (version != null)
             {
                 return version;
             }
 
             version = getSubManifestImplVersion(manifest);
             if (version != null)
             {
                 return version;
             }
 
             version = getBundleVersion(manifest);
             if (version != null)
             {
                 return version;
             }
 
             version = getMavenVersion(jar);
             if (version != null)
             {
                 return version;
             }
 
             return "(none specified)";
         }
         catch (IOException e)
         {
             return "(error: " + e.getClass().getSimpleName() + " " + e.getMessage() + ")";
         }
     }
 
     private static String stripV(String version)
     {
         if (version.charAt(0) == 'v')
         {
             return version.substring(1);
         }
 
         return version;
     }
 }