package org.apache.maven.shared.utils.io;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache 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.apache.org/licenses/LICENSE-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.
   */
  
  import javax.annotation.Nonnull;
  import java.io.File;
  import java.io.IOException;
  import java.lang.reflect.Array;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  
  /**
   * Java7 feature detection
   *
   * @author Kristian Rosenvold
   */
  public class Java7Support
  {
  
      private static final boolean IS_JAVA7;
  
      private static Method isSymbolicLink;
  
      private static Method delete;
  
      private static Method toPath;
  
      private static Method exists;
  
      private static Method toFile;
  
      private static Method readSymlink;
  
      private static Method createSymlink;
  
      private static Object emptyLinkOpts;
  
      private static Object emptyFileAttributes;
  
      static
      {
          boolean isJava7x = true;
          try
          {
              ClassLoader cl = Thread.currentThread().getContextClassLoader();
              Class<?> files = cl.loadClass( "java.nio.file.Files" );
              Class<?> path = cl.loadClass( "java.nio.file.Path" );
              Class<?> fa = cl.loadClass( "java.nio.file.attribute.FileAttribute" );
              Class<?> linkOption = cl.loadClass( "java.nio.file.LinkOption" );
              isSymbolicLink = files.getMethod( "isSymbolicLink", path );
              delete = files.getMethod( "delete", path );
              readSymlink = files.getMethod( "readSymbolicLink", path );
  
              emptyFileAttributes = Array.newInstance( fa, 0 );
              final Object o = emptyFileAttributes;
              createSymlink = files.getMethod( "createSymbolicLink", path, path, o.getClass() );
              emptyLinkOpts = Array.newInstance( linkOption, 0 );
              exists = files.getMethod( "exists", path, emptyLinkOpts.getClass() );
              toPath = File.class.getMethod( "toPath" );
              toFile = path.getMethod( "toFile" );
          }
          catch ( ClassNotFoundException e )
          {
              isJava7x = false;
          }
          catch ( NoSuchMethodException e )
          {
              isJava7x = false;
          }
          IS_JAVA7 = isJava7x;
      }
  
      /**
       * @param file The file to check for being a symbolic link.
       * @return true if the file is a symlink false otherwise.
       */
      public static boolean isSymLink( @Nonnull File file )
      {
          try
          {
              Object path = toPath.invoke( file );
              return (Boolean) isSymbolicLink.invoke( null, path );
         }
         catch ( IllegalAccessException e )
         {
             throw new RuntimeException( e );
         }
         catch ( InvocationTargetException e )
         {
             throw new RuntimeException( e );
         }
     }
 
 
     /**
      * @param symlink The sym link.
      * @return The file.
      * @throws IOException in case of error.
      */
     @Nonnull public static File readSymbolicLink( @Nonnull File symlink )
         throws IOException
     {
         try
         {
             Object path = toPath.invoke( symlink );
             Object resultPath =  readSymlink.invoke( null, path );
             return (File) toFile.invoke( resultPath );
         }
         catch ( IllegalAccessException e )
         {
             throw new RuntimeException( e );
         }
         catch ( InvocationTargetException e )
         {
             throw new RuntimeException( e );
         }
     }
 
 
     /**
      * @param file The file to check.
      * @return true if exist false otherwise.
      * @throws IOException in case of failure.
      */
     public static boolean exists( @Nonnull File file )
         throws IOException
     {
         try
         {
             Object path = toPath.invoke( file );
             final Object invoke = exists.invoke( null, path, emptyLinkOpts );
             return (Boolean) invoke;
         }
         catch ( IllegalAccessException e )
         {
             throw new RuntimeException( e );
         }
         catch ( InvocationTargetException e )
         {
             throw (RuntimeException) e.getTargetException();
         }
 
     }
 
     /**
      * @param symlink The link name.
      * @param target The target.
      * @return The linked file.
      * @throws IOException in case of an error.
      */
     @Nonnull public static File createSymbolicLink( @Nonnull File symlink,  @Nonnull File target )
         throws IOException
     {
         try
         {
             if ( !exists( symlink ) )
             {
                 Object link = toPath.invoke( symlink );
                 Object path = createSymlink.invoke( null, link, toPath.invoke( target ), emptyFileAttributes );
                 return (File) toFile.invoke( path );
             }
             return symlink;
         }
         catch ( IllegalAccessException e )
         {
             throw new RuntimeException( e );
         }
         catch ( InvocationTargetException e )
         {
             final Throwable targetException = e.getTargetException();
             if ( targetException instanceof IOException )
             {
                 throw (IOException) targetException;
             }
             else if ( targetException instanceof RuntimeException )
             {
                 // java.lang.UnsupportedOperationException: Symbolic links not supported on this operating system
                 // java.lang.SecurityException: denies certain permissions see Javadoc
                 throw ( RuntimeException ) targetException;
             }
             else
             {
                 throw new IOException( targetException.getClass() + ": " + targetException.getLocalizedMessage() );
             }
         }
 
     }
     /**
      * Performs a nio delete
      * @param file the file to delete
      * @throws IOException in case of error.
      */
     public static void delete( @Nonnull File file )
         throws IOException
     {
         try
         {
             Object path = toPath.invoke( file );
             delete.invoke( null, path );
         }
         catch ( IllegalAccessException e )
         {
             throw new RuntimeException( e );
         }
         catch ( InvocationTargetException e )
         {
             throw (IOException) e.getTargetException();
         }
     }
 
     /**
      * @return true in case of Java 7.
      */
     public static boolean isJava7()
     {
         return IS_JAVA7;
     }
 
     /**
      * @return true in case of Java7 or greater.
      */
     public static boolean isAtLeastJava7()
     {
         return IS_JAVA7;
     }
 
 }