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 javax.annotation.Nullable;

 import java.io.BufferedInputStream;

 import java.io.BufferedOutputStream;

 import java.io.ByteArrayInputStream;

 import java.io.ByteArrayOutputStream;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.InputStreamReader;

 import java.io.OutputStream;

 import java.io.OutputStreamWriter;

 import java.io.Reader;

 import java.io.StringReader;

 import java.io.StringWriter;

 import java.io.Writer;

 import java.nio.channels.Channel;

 /**

  * General IO Stream manipulation.

  * <p>

  * This class provides static utility methods for input/output operations, particularly buffered

  * copying between sources (<code>InputStream</code>, <code>Reader</code>, <code>String</code> and

  * <code>byte[]</code>) and destinations (<code>OutputStream</code>, <code>Writer</code>,

  * <code>String</code> and <code>byte[]</code>).

  * </p>

  * <p/>

  * <p>Unless otherwise noted, these <code>copy</code> methods do <em>not</em> flush or close the

  * streams. Often, doing so would require making non-portable assumptions about the streams' origin

  * and further use. This means that both streams' <code>close()</code> methods must be called after

  * copying. if one omits this step, then the stream resources (sockets, file descriptors) are

  * released when the associated Stream is garbage-collected. It is not a good idea to rely on this

  * mechanism. For a good overview of the distinction between "memory management" and "resource

  * management", see <a href="http://www.unixreview.com/articles/1998/9804/9804ja/ja.htm">this

  * UnixReview article</a></p>

  * <p/>

  * <p>For each <code>copy</code> method, a variant is provided that allows the caller to specify the

  * buffer size (the default is 4k). As the buffer size can have a fairly large impact on speed, this

  * may be worth tweaking. Often "large buffer -> faster" does not hold, even for large data

  * transfers.</p>

  * <p/>

  * <p>For byte-to-char methods, a <code>copy</code> variant allows the encoding to be selected

  * (otherwise the platform default is used).</p>

  * <p/>

  * <p>The <code>copy</code> methods use an internal buffer when copying. It is therefore advisable

  * <em>not</em> to deliberately wrap the stream arguments to the <code>copy</code> methods in

  * <code>Buffered*</code> streams. For example, don't do the

  * following:</p>

  * <p/>

  * <code>copy( new BufferedInputStream( in ), new BufferedOutputStream( out ) );</code>

  * <p/>

  * <p>The rationale is as follows:</p>

  * <p/>

  * <p>Imagine that an InputStream's read() is a very expensive operation, which would usually suggest

  * wrapping in a BufferedInputStream. The BufferedInputStream works by issuing infrequent

  * {@link java.io.InputStream#read(byte[] b, int off, int len)} requests on the underlying InputStream, to

  * fill an internal buffer, from which further <code>read</code> requests can inexpensively get

  * their data (until the buffer runs out).</p>

  * <p>However, the <code>copy</code> methods do the same thing, keeping an internal buffer,

  * populated by {@link InputStream#read(byte[] b, int off, int len)} requests. Having two buffers

  * (or three if the destination stream is also buffered) is pointless, and the unnecessary buffer

  * management hurts performance slightly (about 3%, according to some simple experiments).</p>

  *

  * @author <a href="mailto:peter@apache.org">Peter Donald</a>

  * @author <a href="mailto:jefft@apache.org">Jeff Turner</a>

  * @version CVS $Revision: 1401872 $ $Date: 2012-10-24 22:45:04 +0200 (on., 24 okt. 2012) $

  * 

  */

 /*

  * Behold, intrepid explorers; a map of this class:

  *

  *       Method      Input               Output          Dependency

  *       ------      -----               ------          -------

  * 1     copy        InputStream         OutputStream    (primitive)

  * 2     copy        Reader              Writer          (primitive)

  *

  * 3     copy        InputStream         Writer          2

  * 4     toString    InputStream         String          3

  * 5     toByteArray InputStream         byte[]          1

  *

  * 6     copy        Reader              OutputStream    2

  * 7     toString    Reader              String          2

  * 8     toByteArray Reader              byte[]          6

  *

  * 9     copy        String              OutputStream    2

  * 10    copy        String              Writer          (trivial)

  * 11    toByteArray String              byte[]          9

  *

  * 12    copy        byte[]              Writer          3

  * 13    toString    byte[]              String          12

  * 14    copy        byte[]              OutputStream    (trivial)

  *

  *

  * Note that only the first two methods shuffle bytes; the rest use these two, or (if possible) copy

  * using native Java copy methods. As there are method variants to specify buffer size and encoding,

  * each row may correspond to up to 4 methods.

  *

  */

 public final class IOUtil

 {

     private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

     /**

      * Private constructor to prevent instantiation.

      */

     private IOUtil()

     {

     }

     ///////////////////////////////////////////////////////////////

     // Core copy methods

     ///////////////////////////////////////////////////////////////

     /**

      * Copy bytes from an <code>InputStream</code> to an <code>OutputStream</code>.

      */

     public static void copy( @Nonnull final InputStream input, @Nonnull final OutputStream output )

         throws IOException

     {

         copy( input, output, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Copy bytes from an <code>InputStream</code> to an <code>OutputStream</code>.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public static void copy( @Nonnull final InputStream input, @Nonnull final OutputStream output, final int bufferSize )

         throws IOException

     {

         final byte[] buffer = new byte[bufferSize];

         int n;

         while ( -1 != ( n = input.read( buffer ) ) )

         {

             output.write( buffer, 0, n );

         }

     }

     /**

      * Copy chars from a <code>Reader</code> to a <code>Writer</code>.

      */

     public static void copy( @Nonnull final Reader input, @Nonnull final Writer output )

         throws IOException

     {

         copy( input, output, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Copy chars from a <code>Reader</code> to a <code>Writer</code>.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public static void copy( @Nonnull final Reader input, @Nonnull final Writer output, final int bufferSize )

         throws IOException

     {

         final char[] buffer = new char[bufferSize];

         int n;

         while ( -1 != ( n = input.read( buffer ) ) )

         {

             output.write( buffer, 0, n );

         }

         output.flush();

     }

     ///////////////////////////////////////////////////////////////

     // Derived copy methods

     // InputStream -> *

     ///////////////////////////////////////////////////////////////

     ///////////////////////////////////////////////////////////////

     // InputStream -> Writer

     /**

      * Copy and convert bytes from an <code>InputStream</code> to chars on a

      * <code>Writer</code>.

      * The platform's default encoding is used for the byte-to-char conversion.

      */

     public static void copy( @Nonnull final InputStream input, @Nonnull final Writer output )

         throws IOException

     {

         copy( input, output, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Copy and convert bytes from an <code>InputStream</code> to chars on a

      * <code>Writer</code>.

      * The platform's default encoding is used for the byte-to-char conversion.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public static void copy( @Nonnull final InputStream input, @Nonnull final Writer output, final int bufferSize )

         throws IOException

     {

         final InputStreamReader in = new InputStreamReader( input );

         copy( in, output, bufferSize );

     }

     /**

      * Copy and convert bytes from an <code>InputStream</code> to chars on a

      * <code>Writer</code>, using the specified encoding.

      *

      * @param encoding The name of a supported character encoding. See the

      *                 <a href="http://www.iana.org/assignments/character-sets">IANA

      *                 Charset Registry</a> for a list of valid encoding types.

      */

     public static void copy( @Nonnull final InputStream input, @Nonnull final Writer output, @Nonnull final String encoding )

         throws IOException

     {

         final InputStreamReader in = new InputStreamReader( input, encoding );

         copy( in, output );

     }

     /**

      * Copy and convert bytes from an <code>InputStream</code> to chars on a

      * <code>Writer</code>, using the specified encoding.

      *

      * @param encoding   The name of a supported character encoding. See the

      *                   <a href="http://www.iana.org/assignments/character-sets">IANA

      *                   Charset Registry</a> for a list of valid encoding types.

      * @param bufferSize Size of internal buffer to use.

      */

     public static void copy( @Nonnull final InputStream input, @Nonnull final Writer output, @Nonnull final String encoding, final int bufferSize )

         throws IOException

     {

         final InputStreamReader in = new InputStreamReader( input, encoding );

         copy( in, output, bufferSize );

     }

     ///////////////////////////////////////////////////////////////

     // InputStream -> String

     /**

      * Get the contents of an <code>InputStream</code> as a String.

      * The platform's default encoding is used for the byte-to-char conversion.

      */

     public @Nonnull static String toString( @Nonnull final InputStream input )

         throws IOException

     {

         return toString( input, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Get the contents of an <code>InputStream</code> as a String.

      * The platform's default encoding is used for the byte-to-char conversion.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public @Nonnull static String toString( @Nonnull final InputStream input, final int bufferSize )

         throws IOException

     {

         final StringWriter sw = new StringWriter();

         copy( input, sw, bufferSize );

         return sw.toString();

     }

     /**

      * Get the contents of an <code>InputStream</code> as a String.

      *

      * @param encoding The name of a supported character encoding. See the

      *                 <a href="http://www.iana.org/assignments/character-sets">IANA

      *                 Charset Registry</a> for a list of valid encoding types.

      */

     public @Nonnull static String toString( @Nonnull final InputStream input, @Nonnull final String encoding )

         throws IOException

     {

         return toString( input, encoding, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Get the contents of an <code>InputStream</code> as a String.

      *

      * @param encoding   The name of a supported character encoding. See the

      *                   <a href="http://www.iana.org/assignments/character-sets">IANA

      *                   Charset Registry</a> for a list of valid encoding types.

      * @param bufferSize Size of internal buffer to use.

      */

     public @Nonnull static String toString( @Nonnull final InputStream input, @Nonnull final String encoding, final int bufferSize )

         throws IOException

     {

         final StringWriter sw = new StringWriter();

         copy( input, sw, encoding, bufferSize );

         return sw.toString();

     }

     ///////////////////////////////////////////////////////////////

     // InputStream -> byte[]

     /**

      * Get the contents of an <code>InputStream</code> as a <code>byte[]</code>.

      */

     public @Nonnull static byte[] toByteArray( @Nonnull final InputStream input )

         throws IOException

     {

         return toByteArray( input, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Get the contents of an <code>InputStream</code> as a <code>byte[]</code>.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public @Nonnull static byte[] toByteArray( @Nonnull final InputStream input, final int bufferSize )

         throws IOException

     {

         final ByteArrayOutputStream output = new ByteArrayOutputStream();

         copy( input, output, bufferSize );

         return output.toByteArray();

     }

     ///////////////////////////////////////////////////////////////

     // Derived copy methods

     // Reader -> *

     ///////////////////////////////////////////////////////////////

     ///////////////////////////////////////////////////////////////

     // Reader -> OutputStream

     /**

      * Serialize chars from a <code>Reader</code> to bytes on an <code>OutputStream</code>, and

      * flush the <code>OutputStream</code>.

      */

     public static void copy( @Nonnull final Reader input, @Nonnull final OutputStream output )

         throws IOException

     {

         copy( input, output, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Serialize chars from a <code>Reader</code> to bytes on an <code>OutputStream</code>, and

      * flush the <code>OutputStream</code>.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public static void copy( @Nonnull final Reader input, @Nonnull final OutputStream output, final int bufferSize )

         throws IOException

     {

         final OutputStreamWriter out = new OutputStreamWriter( output );

         copy( input, out, bufferSize );

         // NOTE: Unless anyone is planning on rewriting OutputStreamWriter, we have to flush

         // here.

         out.flush();

     }

     ///////////////////////////////////////////////////////////////

     // Reader -> String

     /**

      * Get the contents of a <code>Reader</code> as a String.

      */

     public @Nonnull static String toString( @Nonnull final Reader input )

         throws IOException

     {

         return toString( input, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Get the contents of a <code>Reader</code> as a String.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public @Nonnull static String toString( @Nonnull final Reader input, final int bufferSize )

         throws IOException

     {

         final StringWriter sw = new StringWriter();

         copy( input, sw, bufferSize );

         return sw.toString();

     }

     ///////////////////////////////////////////////////////////////

     // Reader -> byte[]

     /**

      * Get the contents of a <code>Reader</code> as a <code>byte[]</code>.

      */

     public @Nonnull static byte[] toByteArray( @Nonnull final Reader input )

         throws IOException

     {

         return toByteArray( input, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Get the contents of a <code>Reader</code> as a <code>byte[]</code>.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public @Nonnull static byte[] toByteArray( @Nonnull final Reader input, final int bufferSize )

         throws IOException

     {

         ByteArrayOutputStream output = new ByteArrayOutputStream();

         copy( input, output, bufferSize );

         return output.toByteArray();

     }

     ///////////////////////////////////////////////////////////////

     // Derived copy methods

     // String -> *

     ///////////////////////////////////////////////////////////////

     ///////////////////////////////////////////////////////////////

     // String -> OutputStream

     /**

      * Serialize chars from a <code>String</code> to bytes on an <code>OutputStream</code>, and

      * flush the <code>OutputStream</code>.

      */

     public static void copy( @Nonnull final String input, @Nonnull final OutputStream output )

         throws IOException

     {

         copy( input, output, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Serialize chars from a <code>String</code> to bytes on an <code>OutputStream</code>, and

      * flush the <code>OutputStream</code>.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public static void copy( @Nonnull final String input, @Nonnull final OutputStream output, final int bufferSize )

         throws IOException

     {

         final StringReader in = new StringReader( input );

         final OutputStreamWriter out = new OutputStreamWriter( output );

         copy( in, out, bufferSize );

         // NOTE: Unless anyone is planning on rewriting OutputStreamWriter, we have to flush

         // here.

         out.flush();

     }

     ///////////////////////////////////////////////////////////////

     // String -> Writer

     /**

      * Copy chars from a <code>String</code> to a <code>Writer</code>.

      */

     public static void copy( @Nonnull final String input, @Nonnull final Writer output )

         throws IOException

     {

         output.write( input );

     }

     ///////////////////////////////////////////////////////////////

     // String -> byte[]

     /**

      * Get the contents of a <code>String</code> as a <code>byte[]</code>.

      */

     public @Nonnull static byte[] toByteArray( @Nonnull final String input )

         throws IOException

     {

         return toByteArray( input, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Get the contents of a <code>String</code> as a <code>byte[]</code>.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public @Nonnull static byte[] toByteArray( @Nonnull final String input, final int bufferSize )

         throws IOException

     {

         ByteArrayOutputStream output = new ByteArrayOutputStream();

         copy( input, output, bufferSize );

         return output.toByteArray();

     }

     ///////////////////////////////////////////////////////////////

     // Derived copy methods

     // byte[] -> *

     ///////////////////////////////////////////////////////////////

     ///////////////////////////////////////////////////////////////

     // byte[] -> Writer

     /**

      * Copy and convert bytes from a <code>byte[]</code> to chars on a

      * <code>Writer</code>.

      * The platform's default encoding is used for the byte-to-char conversion.

      */

     public static void copy( @Nonnull final byte[] input, @Nonnull final Writer output )

         throws IOException

     {

         copy( input, output, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Copy and convert bytes from a <code>byte[]</code> to chars on a

      * <code>Writer</code>.

      * The platform's default encoding is used for the byte-to-char conversion.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public static void copy( @Nonnull final byte[] input, @Nonnull final Writer output, final int bufferSize )

         throws IOException

     {

         final ByteArrayInputStream in = new ByteArrayInputStream( input );

         copy( in, output, bufferSize );

     }

     /**

      * Copy and convert bytes from a <code>byte[]</code> to chars on a

      * <code>Writer</code>, using the specified encoding.

      *

      * @param encoding The name of a supported character encoding. See the

      *                 <a href="http://www.iana.org/assignments/character-sets">IANA

      *                 Charset Registry</a> for a list of valid encoding types.

      */

     public static void copy( @Nonnull final byte[] input, @Nonnull final Writer output, final String encoding )

         throws IOException

     {

         final ByteArrayInputStream in = new ByteArrayInputStream( input );

         copy( in, output, encoding );

     }

     /**

      * Copy and convert bytes from a <code>byte[]</code> to chars on a

      * <code>Writer</code>, using the specified encoding.

      *

      * @param encoding   The name of a supported character encoding. See the

      *                   <a href="http://www.iana.org/assignments/character-sets">IANA

      *                   Charset Registry</a> for a list of valid encoding types.

      * @param bufferSize Size of internal buffer to use.

      */

     public static void copy( @Nonnull final byte[] input, @Nonnull final Writer output, @Nonnull final String encoding, final int bufferSize )

         throws IOException

     {

         final ByteArrayInputStream in = new ByteArrayInputStream( input );

         copy( in, output, encoding, bufferSize );

     }

     ///////////////////////////////////////////////////////////////

     // byte[] -> String

     /**

      * Get the contents of a <code>byte[]</code> as a String.

      * The platform's default encoding is used for the byte-to-char conversion.

      */

     public @Nonnull static String toString( @Nonnull final byte[] input )

         throws IOException

     {

         return toString( input, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Get the contents of a <code>byte[]</code> as a String.

      * The platform's default encoding is used for the byte-to-char conversion.

      *

      * @param bufferSize Size of internal buffer to use.

      */

     public @Nonnull static String toString( @Nonnull final byte[] input, final int bufferSize )

         throws IOException

     {

         final StringWriter sw = new StringWriter();

         copy( input, sw, bufferSize );

         return sw.toString();

     }

     /**

      * Get the contents of a <code>byte[]</code> as a String.

      *

      * @param encoding The name of a supported character encoding. See the

      *                 <a href="http://www.iana.org/assignments/character-sets">IANA

      *                 Charset Registry</a> for a list of valid encoding types.

      */

     public @Nonnull static String toString( @Nonnull final byte[] input, @Nonnull final String encoding )

         throws IOException

     {

         return toString( input, encoding, DEFAULT_BUFFER_SIZE );

     }

     /**

      * Get the contents of a <code>byte[]</code> as a String.

      *

      * @param encoding   The name of a supported character encoding. See the

      *                   <a href="http://www.iana.org/assignments/character-sets">IANA

      *                   Charset Registry</a> for a list of valid encoding types.

      * @param bufferSize Size of internal buffer to use.

      */

     public @Nonnull static String toString( @Nonnull final byte[] input, @Nonnull final String encoding, final int bufferSize )

         throws IOException

     {

         final StringWriter sw = new StringWriter();

         copy( input, sw, encoding, bufferSize );

         return sw.toString();

     }

     ///////////////////////////////////////////////////////////////

     // byte[] -> OutputStream

     /**

      * Copy bytes from a <code>byte[]</code> to an <code>OutputStream</code>.

      */

     public static void copy( @Nonnull final byte[] input, @Nonnull final OutputStream output )

         throws IOException

     {

         output.write( input );

     }

     /**

      * Compare the contents of two Streams to determine if they are equal or not.

      *

      * @param input1 the first stream

      * @param input2 the second stream

      * @return true if the content of the streams are equal or they both don't exist, false otherwise

      */

     public static boolean contentEquals( @Nonnull final InputStream input1, @Nonnull final InputStream input2 )

         throws IOException

     {

         final InputStream bufferedInput1 = new BufferedInputStream( input1 );

         final InputStream bufferedInput2 = new BufferedInputStream( input2 );

         int ch = bufferedInput1.read();

         while ( -1 != ch )

         {

             final int ch2 = bufferedInput2.read();

             if ( ch != ch2 )

             {

                 return false;

             }

             ch = bufferedInput1.read();

         }

         final int ch2 = bufferedInput2.read();

         return -1 == ch2;

     }

     // ----------------------------------------------------------------------

     // closeXXX()

     // ----------------------------------------------------------------------

     /**

      * Closes a channel. Channel can be null and any IOException's will be swallowed.

      *

      * @param channel The stream to close.

      */

     public static void close( @Nullable Channel channel )

     {

         if ( channel == null )

         {

             return;

         }

         try

         {

             channel.close();

         }

         catch ( IOException ex )

         {

             // ignore

         }

     }

     /**

      * Closes the input stream. The input stream can be null and any IOException's will be swallowed.

      *

      * @param inputStream The stream to close.

      */

     public static void close( @Nullable InputStream inputStream )

     {

         if ( inputStream == null )

         {

             return;

         }

         try

         {

             inputStream.close();

         }

         catch ( IOException ex )

         {

             // ignore

         }

     }

     /**

      * Closes the output stream. The output stream can be null and any IOException's will be swallowed.

      *

      * @param outputStream The stream to close.

      */

     public static void close( @Nullable OutputStream outputStream )

     {

         if ( outputStream == null )

         {

             return;

         }

         try

         {

             outputStream.close();

         }

         catch ( IOException ex )

         {

             // ignore

         }

     }

     /**

      * Closes the reader. The reader can be null and any IOException's will be swallowed.

      *

      * @param reader The reader to close.

      */

     public static void close( @Nullable Reader reader )

     {

         if ( reader == null )

         {

             return;

         }

         try

         {

             reader.close();

         }

         catch ( IOException ex )

         {

             // ignore

         }

     }

     /**

      * Closes the writer. The writer can be null and any IOException's will be swallowed.

      *

      * @param writer The writer to close.

      */

     public static void close( @Nullable Writer writer )

     {

         if ( writer == null )

         {

             return;

         }

         try

         {

             writer.close();

         }

         catch ( IOException ex )

         {

             // ignore

         }

     }

 }