/*
 * $Id: Headers.java,v 1.4 2004/08/02 17:43:16 dog Exp $
 * Copyright (C) 2004 The Free Software Foundation
 * 
 * This file is part of GNU inetlib, a library.
 * 
 * GNU inetlib 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 inetlib 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 this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License.
 */

package gnu.inet.http;

import java.io.InputStream;
import java.io.IOException;
import java.text.DateFormat;
import java.text.ParseException;
import java.util.Collection;
import java.util.Date;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

import gnu.inet.util.LineInputStream;

/**
 * A collection of HTTP header names and associated values.
 * Retrieval of values is case insensitive. An iteration over the keys
 * returns the header names in the order they were received.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 */
public class Headers implements Map
{

  static final DateFormat dateFormat = new HTTPDateFormat ();

  static class Header
  {

    final String name;

    Header (String name)
    {
      if (name == null || name.length () == 0)
        {
          throw new IllegalArgumentException (name);
        }
      this.name = name;
    }

    public int hashCode ()
    {
      return name.toLowerCase ().hashCode ();
    }

    public boolean equals (Object other)
    {
      if (other instanceof Header)
        {
          return ((Header)other).name.equalsIgnoreCase (name);
        }
      return false;
    }

    public String toString ()
    {
      return name;
    }
    
  }

  static class HeaderEntry implements Map.Entry
  {

    final Map.Entry entry;

    HeaderEntry (Map.Entry entry)
    {
      this.entry = entry;
    }

    public Object getKey ()
    {
      return ((Header) entry.getKey ()).name;
    }

    public Object getValue ()
    {
      return entry.getValue ();
    }

    public Object setValue (Object value)
    {
      return entry.setValue (value);
    }

    public int hashCode ()
    {
      return entry.hashCode ();
    }

    public boolean equals (Object other)
    {
      return entry.equals (other);
    }
    
  }

  private LinkedHashMap headers;

  public Headers ()
  {
    headers = new LinkedHashMap ();
  }

  public int size ()
  {
    return headers.size ();
  }

  public boolean isEmpty ()
  {
    return headers.isEmpty ();
  }

  public boolean containsKey (Object key)
  {
    return headers.containsKey (new Header ((String) key));
  }

  public boolean containsValue (Object value)
  {
    return headers.containsValue (value);
  }

  public Object get (Object key)
  {
    return headers.get (new Header ((String) key));
  }

  /**
   * Returns the value of the specified header as a string.
   */
  public String getValue (String header)
  {
    return (String) headers.get (new Header (header));
  }

  /**
   * Returns the value of the specified header as an integer,
   * or -1 if the header is not present or not an integer.
   */
  public int getIntValue (String header)
  {
    String val = getValue (header);
    if (val == null)
      {
        return -1;
      }
    try
      {
        return Integer.parseInt (val);
      }
    catch (NumberFormatException e)
      {
      }
    return -1;
  }

  /**
   * Returns the value of the specified header as a date,
   * or <code>null</code> if the header is not present or not a date.
   */
  public Date getDateValue (String header)
  {
    String val = getValue (header);
    if (val == null)
      {
        return null;
      }
    try
      {
        return dateFormat.parse (val);
      }
    catch (ParseException e)
      {
        return null;
      }
  }

  public Object put (Object key, Object value)
  {
    return headers.put (new Header ((String) key), value);
  }

  public Object remove (Object key)
  {
    return headers.remove (new Header ((String) key));
  }

  public void putAll (Map t)
  {
    for (Iterator i = t.keySet ().iterator (); i.hasNext (); )
      {
        String key = (String) i.next ();
        String value = (String) t.get (key);
        headers.put (new Header (key), value);
      }
  }
  
  public void clear ()
  {
    headers.clear ();
  }

  public Set keySet ()
  {
    Set keys = headers.keySet ();
    Set ret = new HashSet ();
    for (Iterator i = keys.iterator (); i.hasNext (); )
      {
        ret.add (((Header) i.next()).name);
      }
    return ret;
  }

  public Collection values ()
  {
    return headers.values ();
  }

  public Set entrySet ()
  {
    Set entries = headers.entrySet ();
    Set ret = new HashSet ();
    for (Iterator i = entries.iterator (); i.hasNext (); )
      {
        Map.Entry entry = (Map.Entry) i.next ();
        ret.add (new HeaderEntry (entry));
      }
    return ret;
  }

  public boolean equals (Object other)
  {
    return headers.equals (other);
  }

  public int hashCode ()
  {
    return headers.hashCode ();
  }

  /**
   * Parse the specified input stream, adding headers to this collection.
   */
  public void parse (InputStream in)
    throws IOException
  {
    LineInputStream lin = (in instanceof LineInputStream) ?
      (LineInputStream) in : new LineInputStream (in);
    
    String name = null;
    StringBuffer value = new StringBuffer ();
    while (true)
      {
        String line = lin.readLine ();
        if (line == null)
          {
            if (name != null)
              {
                addValue (name, value.toString ());
              }
            break;
          }
        int len = line.length ();
        if (len < 2)
          {
            if (name != null)
              {
                addValue (name, value.toString ());
              }
            break;
          }
        char c1 = line.charAt (0);
        if (c1 == ' ' || c1 == '\t')
          {
            // Continuation
            value.append (line.substring (0, len - 1));
          }
        else
          {
            if (name != null)
              {
                addValue (name, value.toString ());
              }
            
            int di = line.indexOf (':');
            name = line.substring (0, di);
            value.setLength (0);
            do
              {
                di++;
              }
            while (di < len && line.charAt (di) == ' ');
            value.append (line.substring (di, len - 1));
          }
      }
  }
  
  private void addValue (String name, String value)
  {
    Header key = new Header (name);
    String old = (String) headers.get (key);
    if (old == null)
      {
        headers.put (key, value);
      }
    else
      {
        headers.put (key, old + ", " + value);
      }
  }
  
}