/* CertificateURL.java --
   Copyright (C) 2006  Free Software Foundation, Inc.

This file is a 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 of the License, 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; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, 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.javax.net.ssl.provider;

import gnu.javax.net.ssl.provider.Extension.Value;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.util.List;
import java.util.NoSuchElementException;

/**
 * The CertificateURL extension value.
 * 
 * <pre>
enum {
  individual_certs(0), pkipath(1), (255)
} CertChainType;

enum {
  false(0), true(1)
} Boolean;

struct {
  CertChainType type;
  URLAndOptionalHash url_and_hash_list&lt;1..2^16-1&gt;;
} CertificateURL;

struct {
  opaque url&lt;1..2^16-1&gt;;
  Boolean hash_present;
  select (hash_present) {
    case false: struct {};
    case true: SHA1Hash;
  } hash;
} URLAndOptionalHash;

opaque SHA1Hash[20];</pre>
 *
 * @author csm
 *
 */
public class CertificateURL extends Value implements Iterable<CertificateURL.URLAndOptionalHash>
{
  private ByteBuffer buffer;
  
  public CertificateURL(final ByteBuffer buffer)
  {
    this.buffer = buffer;
  }
  
  public CertificateURL(CertChainType type, List<URLAndOptionalHash> urls)
  {
    int length = 3;
    for (URLAndOptionalHash url : urls)
      length += url.length();
    buffer = ByteBuffer.allocate(length);
    buffer.put((byte) type.getValue());
    buffer.putShort((short) (length - 1));
    for (URLAndOptionalHash url : urls)
      buffer.put(url.buffer());
    buffer.rewind();
  }
  
  public int length()
  {
    return 3 + (buffer.getShort(1) & 0xFFFF);
  }
  
  public ByteBuffer buffer()
  {
    return (ByteBuffer) buffer.duplicate().limit(length());
  }

  public CertChainType type()
  {
    switch (buffer.get(0))
      {
        case 0: return CertChainType.INDIVIDUAL_CERTS;
        case 1: return CertChainType.PKIPATH;
      }
    throw new IllegalArgumentException("unknown certificate URL type");
  }
  
  public int size()
  {
    int len = buffer.getShort(1) & 0xFFFF;
    int n = 0;
    for (int i = 3; i < len; )
      {
        URLAndOptionalHash u
          = new URLAndOptionalHash((ByteBuffer) buffer.duplicate().position(i));
        int l = u.length();
        i += l;
        n++;
      }
    return n;
  }
  
  public URLAndOptionalHash get(int index)
  {
    int len = buffer.getShort(1) & 0xFFFF;
    int n = 0;
    int l = 0;
    int i;
    for (i = 3; i < len && n < index; )
      {
        URLAndOptionalHash u
          = new URLAndOptionalHash((ByteBuffer) buffer.duplicate().position(i));
        l = u.length();
        i += l;
        n++;
      }
    if (n < index)
      throw new IndexOutOfBoundsException();
    return new URLAndOptionalHash(((ByteBuffer) buffer.duplicate().position(i).limit(i+l)).slice());
  }
  
  public void set(int index, URLAndOptionalHash url)
  {
    int len = buffer.getShort(1) & 0xFFFF;
    int n = 0;
    int i;
    for (i = 3; i < len && n < index-1; )
      {
        URLAndOptionalHash u
          = new URLAndOptionalHash((ByteBuffer) buffer.duplicate().position(i));
        int l = u.length();
        i += l;
        n++;
      }
    if (n < index - 1)
      throw new IndexOutOfBoundsException();
    int l = url.urlLength();
    buffer.putShort(i, (short) l);
    ((ByteBuffer) buffer.duplicate().position(i+2)).put(url.urlBuffer());
    buffer.put(i+l+2, (byte) (url.hashPresent() ? 1 : 0));
    if (url.hashPresent())
      ((ByteBuffer) buffer.duplicate().position(i+l+3)).put (url.sha1Hash());
  }
  
  public void setLength(final int length)
  {
    if (length < 0 || length > 65535)
      throw new IllegalArgumentException("length must be between 0 and 65535");
    buffer.putShort(1, (short) length);
  }
  
  public String toString()
  {
    return toString(null);
  }
  
  public String toString(String prefix)
  {
    StringWriter str = new StringWriter();
    PrintWriter out = new PrintWriter(str);
    if (prefix != null) out.print(prefix);
    out.println ("struct {");
    if (prefix != null) out.print(prefix);
    out.print("  type = ");
    out.print(type());
    out.println(";");
    if (prefix != null) out.print(prefix);
    out.println("  url_and_hash_list = {");
    String subprefix = "  ";
    if (prefix != null) subprefix = prefix + subprefix;
    for (URLAndOptionalHash url : this)
      {
        out.println(url.toString(subprefix));
      }
    if (prefix != null) out.print(prefix);
    out.println("  };");
    if (prefix != null) out.print(prefix);
    out.print("} CertificateURL;");
    return str.toString();
  }

  public java.util.Iterator<URLAndOptionalHash> iterator()
  {
    return new Iterator();
  }
  
  public class Iterator implements java.util.Iterator<URLAndOptionalHash>
  {
    private int index;
    
    public Iterator()
    {
      index = 0;
    }
    
    public URLAndOptionalHash next() throws NoSuchElementException
    {
      try
        {
          return get(index++);
        }
      catch (IndexOutOfBoundsException ioobe)
        {
          throw new NoSuchElementException();
        }
    }
    
    public boolean hasNext()
    {
      return index < size();
    }
    
    public void remove()
    {
      throw new UnsupportedOperationException();
    }
  }
  
  public static enum CertChainType
  {
    INDIVIDUAL_CERTS (0), PKIPATH (1);
    
    private final int value;
    
    private CertChainType (final int value)
    {
      this.value = value;
    }
    
    public int getValue()
    {
      return value;
    }
  }
  
  public static class URLAndOptionalHash implements Builder, Constructed
  {
    private ByteBuffer buffer;
    
    public URLAndOptionalHash (final ByteBuffer buffer)
    {
      this.buffer = buffer.duplicate().order(ByteOrder.BIG_ENDIAN);
    }
    
    public URLAndOptionalHash(String url)
    {
      this(url, null);
    }
    
    public URLAndOptionalHash(String url, byte[] hash)
    {
      if (hash != null && hash.length < 20)
        throw new IllegalArgumentException();
      int length = 3 + url.length();
      if (hash != null)
        length += 20;
      buffer = ByteBuffer.allocate(length);
      buffer.putShort((short) url.length());
      Charset cs = Charset.forName("US-ASCII");
      CharsetEncoder ascii = cs.newEncoder();
      ascii.encode(CharBuffer.wrap(url), buffer, true);
      buffer.put((byte) (hash != null ? 1 : 0));
      if (hash != null)
        buffer.put(hash, 0, 20);
      buffer.rewind();
    }
    
    public int length()
    {
      return ((buffer.getShort(0) & 0xFFFF)
              + (hashPresent() ? 23 : 3));
    }
    
    public ByteBuffer buffer()
    {
      return (ByteBuffer) buffer.duplicate().limit(length());
    }
    
    public String url()
    {
      Charset cs = Charset.forName("ASCII");
      return cs.decode(urlBuffer()).toString();
    }
    
    public int urlLength()
    {
      return buffer.getShort(0) & 0xFFFF;
    }
    
    public ByteBuffer urlBuffer()
    {
      int len = urlLength();
      return ((ByteBuffer) buffer.duplicate().position(2).limit(2+len)).slice();
    }
    
    public boolean hashPresent()
    {
      int i = (buffer.getShort(0) & 0xFFFF) + 2;
      byte b = buffer.get(i);
      if (b == 0)
        return false;
      if (b == 1)
        return true;
      throw new IllegalArgumentException("expecting 0 or 1: " + (b & 0xFF));
    }
    
    public byte[] sha1Hash()
    {
      int i = (buffer.getShort(0) & 0xFFFF) + 2;
      byte b = buffer.get(i);
      if (b == 0)
        return null;
      byte[] buf = new byte[20];
      ((ByteBuffer) buffer.duplicate().position(i+1)).get(buf);
      return buf;
    }
    
    public String toString()
    {
      return toString(null);
    }
    
    public String toString(final String prefix)
    {
      StringWriter str = new StringWriter();
      PrintWriter out = new PrintWriter(str);
      if (prefix != null) out.print(prefix);
      out.println("struct {");
      if (prefix != null) out.print(prefix);
      out.print("  url = ");
      out.print(url());
      out.println(";");
      boolean has_hash = hashPresent();
      if (prefix != null) out.print(prefix);
      out.print("  hash_present = ");
      out.print(has_hash);
      out.println(";");
      if (has_hash)
        {
          if (prefix != null) out.print(prefix);
          out.print("  sha1Hash = ");
          out.print(Util.toHexString(sha1Hash(), ':'));
          out.println(";");
        }
      if (prefix != null) out.print(prefix);
      out.print("} URLAndOptionalHash;");
      return str.toString();
    }
  }
}