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/* ChunkedInputStream.java --

   Copyright (C) 2004, 2006 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package gnu.java.net.protocol.http;

import gnu.java.lang.CPStringBuilder;

import java.io.IOException;

import java.io.InputStream;

import java.net.ProtocolException;

//

// Note that we rely on the implemtation of skip() in the super class

// (InputStream) calling our read methods to account for chunk headers

// while skipping.

//

/**

 * Input stream wrapper for the "chunked" transfer-coding.

 *

 * @author Chris Burdess (dog@gnu.org)

 */

public class ChunkedInputStream

  extends InputStream

{

  Headers headers;

  /** The underlying stream. */

  private InputStream in;

  /** Size of the chunk we're reading.  */

  int size;

  /** Number of bytes we've read in this chunk.  */

  int count;

  /**

   * True when we should read meta-information, false when we should

   * read data.

   */

  boolean meta;

  /** True when we've hit EOF.  */

  boolean eof;

  /**

   * Constructor.

   * @param in the response socket input stream

   * @param headers the headers to receive additional header lines

   */

  public ChunkedInputStream(InputStream in, Headers headers)

  {

    this.in = in;

    this.headers = headers;

    size = -1;

    count = 0;

    meta = true;

  }

  public int read()

    throws IOException

  {

    byte[] buf = new byte[1];

    int len = read(buf, 0, 1);

    if (len == -1)

      {

        return -1;

      }

    return 0xff & buf[0];

  }

  public synchronized int read(byte[] buffer, int offset, int length)

    throws IOException

  {

    if (eof)

      {

        return -1;

      }

    if (meta)

      {

        // Read chunk header

        int c, last = 0;

        boolean seenSemi = false;

        CPStringBuilder buf = new CPStringBuilder();

        do

          {

            c = in.read();

            if (c == 0x3b) // ;

              {

                seenSemi = true;

              }

            else if (c == 0x0a && last == 0x0d) // CRLF

              {

                try

                  {

                    size = Integer.parseInt(buf.toString(), 16);

                  }

                catch (NumberFormatException nfe)

                  {

                    IOException ioe = new IOException("Bad chunk header");

                    ioe.initCause(nfe);

                    // Unrecoverable.  Don't try to read more.

                    in.close();

                    throw ioe;

                  }

                break;

              }

            else if (!seenSemi && c >= 0x30)

              {

                buf.append ((char) c);

              }

            last = c;

          }

        while(c != -1);

        count = 0;

        meta = false;

      }

    if (size == 0)

      {

        // Read trailer

        headers.parse(in);

        eof = true;

        return -1;

      }

    else

      {

        int canRead = Math.min(size - count, length);

        int len = in.read(buffer, offset, canRead);

        if (len == -1)

          {

            // This is an error condition but it isn't clear what we

            // should do with it.

            eof = true;

            return -1;

          }

        count += len;

        if (count == size)

          {

            // Read CRLF

            int c1 = in.read();

            int c2 = in.read();

            if (c1 == -1 || c2 == -1)

              {

                // EOF before CRLF: bad, but ignore

                eof = true;

                return -1;

              }

            if (c1 != 0x0d || c2 != 0x0a)

              {

                throw new ProtocolException("expecting CRLF: " + c1 + "," + c2);

              }

            meta = true;

          }

        return len;

      }

  }

  /**

   * This method returns the number of bytes that can be read from

   * this stream before a read might block.  Even if the underlying

   * InputStream has data available past the end of the current chunk,

   * we have no way of knowing how large the next chunk header will

   * be. So we cannot report available data past the current chunk.

   *

   * @return The number of bytes that can be read before a read might

   * block

   *

   * @exception IOException If an error occurs

   */

  public int available() throws IOException

  {

    if (meta)

      return 0;

    return Math.min(in.available(), size - count);

  }

  /**

   * This method closes the ChunkedInputStream by closing the underlying

   * InputStream.

   *

   * @exception IOException If an error occurs

   */

  public void close() throws IOException

  {

    in.close();

  }

}