/* Huffman Coder.

 Copyright (c) 2004-2006 The Regents of the University of California.
 All rights reserved.
 Permission is hereby granted, without written agreement and without
 license or royalty fees, to use, copy, modify, and distribute this
 software and its documentation for any purpose, provided that the above
 copyright notice and the following two paragraphs appear in all copies
 of this software.

 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
 ENHANCEMENTS, OR MODIFICATIONS.

 PT_COPYRIGHT_VERSION_2
 COPYRIGHTENDKEY

 */
package ptolemy.actor.lib.comm;

import ptolemy.data.ArrayToken;
import ptolemy.data.BooleanToken;
import ptolemy.data.Token;
import ptolemy.data.type.ArrayType;
import ptolemy.data.type.BaseType;
import ptolemy.kernel.CompositeEntity;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.InternalErrorException;
import ptolemy.kernel.util.NameDuplicationException;
import ptolemy.kernel.util.Workspace;

//////////////////////////////////////////////////////////////////////////
//// HuffmanCoder

/**
 Given a probability distribution and alphabet, encode the input using
 Huffman code and send the result in booleans to the output port.
 Its base class HuffmanBasic generates the code book.
 The HuffmanCoder actor simply encode the input into the corresponding
 booleans in the code book.
 @see HuffmanBasic

 @author Ye Zhou
 @version $Id$
 @since Ptolemy II 4.1
 @Pt.ProposedRating Red (zhouye)
 @Pt.AcceptedRating Red (cxh)
 */
public class HuffmanCoder extends HuffmanBasic {
    /** Construct an actor with the given container and name.
     *  The output and trigger ports are also constructed.
     *  @param container The container.
     *  @param name The name of this actor.
     *  @exception IllegalActionException If the entity cannot be contained
     *   by the proposed container.
     *  @exception NameDuplicationException If the container already has an
     *   actor with this name.
     */
    public HuffmanCoder(CompositeEntity container, String name)
            throws NameDuplicationException, IllegalActionException {
        super(container, name);

        // Declare type constraints.
        alphabet.setTypeAtLeast(ArrayType.arrayOf(input));
        output.setTypeEquals(BaseType.BOOLEAN);
    }

    ///////////////////////////////////////////////////////////////////
    ////                         public methods                    ////

    /** Clone the actor into the specified workspace. This calls the
     *  base class and then creates new ports and parameters.
     *  @param workspace The workspace for the new object.
     *  @return A new actor.
     *  @exception CloneNotSupportedException If a derived class contains
     *   an attribute that cannot be cloned.
     */
    public Object clone(Workspace workspace) throws CloneNotSupportedException {
        HuffmanCoder newObject = (HuffmanCoder) super.clone(workspace);
        try {
            newObject.alphabet.setTypeAtLeast(ArrayType
                    .arrayOf(newObject.input));
        } catch (IllegalActionException e) {
            // Should have been caught before.
            throw new InternalErrorException(e);
        }
        return newObject;
    }

    /** Generate the Huffman codebook for the given <i>pmf</i>, and
     *  encode the input into booleans and send them to the output port.
     */
    public void fire() throws IllegalActionException {
        super.fire();

        ArrayToken alphabetArrayToken = (ArrayToken) alphabet.getToken();
        Token[] alphabetTokens = new Token[_pmf.length];

        for (int i = 0; i < _pmf.length; i++) {
            alphabetTokens[i] = alphabetArrayToken.getElement(i);
        }

        // Get the input token. Ready for output.
        Token inputToken = input.get(0);

        // Find the token in the alphabet;
        //boolean validInput = false;

        for (int i = 0; i < _pmf.length; i++) {
            if (inputToken.equals(alphabetTokens[i])) {
                //validInput = true;
                _sendBooleans(_codeBook[i]);
                break;
            }
        }

        // FIXME: If the input is not found in the alphabet,
        // which means it's probability of occurrence is zero,
        // we might want to ignore it (or give a warning message.)
        //if (!validInput) {
        //  throw new IllegalActionException(this,
        //    "Input is not matched to the alphabet");
        //}
    }

    ///////////////////////////////////////////////////////////////////
    ////                         private methods                   ////

    /** Given a codeword, which should be a string of '0' and '1',
     *  converted it to a sequence of booleans and send them to the
     *  output port.
     * @param codeword The string of codeword.
     * @exception IllegalActionException If the output receiver throws it.
     */
    private void _sendBooleans(String codeword) throws IllegalActionException {
        for (int i = 0; i < codeword.length(); i++) {
            if (codeword.charAt(i) == '1') {
                output.send(0, new BooleanToken(true));
            } else {
                output.send(0, new BooleanToken(false));
            }
        }
    }
}