/*
 * TrackChunk.java
 * Copyright 2001 Michael Castleman, mlc67@columbia.edu
 *
 * This program 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. 
 *
 * This program 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 program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/**
 * Reperesentation of a MTrk chunk, which encodes a MIDI track
 * @see CMidi
 */
final class TrackChunk {
    /**
     * Magic 4 bytes that identify a track chunk
     * @see CMidi#writeChunk(String,byte[])
     */
    public static final String TRACK_TYPE = "MTrk";

    private byte [] bytes;
    private int chunklen;
    private int arySize;

    private boolean haveSpace = false;
    private boolean haveNL = false;

    /** Creates a new TrackChunk
     * <p>
     * The TrackChunk is basically a {@link java.util.Vector} for <code>byte</code>s.
     * It's got a buffer, which will grow automatically as things are
     * added to it.
     * @param initialSize Initial bufffersize.
     */
    public TrackChunk(int initialSize) {
        chunklen = 0;
        arySize = initialSize;
        bytes = new byte[arySize];
    }

    /** Creates a new TrackChunk
     * <p>
     * The intial buffer size will be 32
     * @see TrackChunk(int)
     */
    public TrackChunk() {
        this(32);
    }

    /**
     * Gets the bytes in a form suitable for passing to
     * {@link CMidi#writeChunk(String,byte[])}
     * @return an array of bytes
     */
    public byte [] getBytes() {
        byte [] ret = new byte[chunklen];
        System.arraycopy(bytes, 0, ret, 0, chunklen);
        return ret;
    }

    /**
     * Adds bytes to the chunk
     * @param bytes the bytes to add
     */
    public void addBytes(byte[] data) {
        if (chunklen + data.length > arySize) {
            int newSize = Math.max(chunklen + data.length, arySize * 2);
            byte [] newAry = new byte[newSize];
            System.arraycopy(bytes, 0, newAry, 0, chunklen);
            arySize = newSize;
            bytes = newAry;
        }
        System.arraycopy(data, 0, bytes, chunklen, data.length);
        chunklen += data.length;
    }

    /**
     * Adds a single byte to the buffer.
     * @param data the byte
     */
    public void addByte(byte data) {
        if (chunklen + 1 > arySize) {
            int newSize = arySize * 2;
            byte [] newAry = new byte[newSize];
            System.arraycopy(bytes, 0, newAry, 0, chunklen);
            arySize = newSize;
            bytes = newAry;
        }
        bytes[chunklen++] = data;
    }

    /**
     * Adds a funky varlen.
     * <p>
     * This is a datatype used by MIDI files which
     * can hold values from 0-0x0FFFFFFF and takes between 1 and 4 bytes.
     * @param value The varlen to add.
     */
    public void addVarLen(int value) {
        int buffer = (value & 0x7F);

        while((value >>= 7) != 0) {
            buffer <<= 8;
            buffer |= ((value & 0x7F) | 0x80);
        }

        while(true) {
            addByte((byte)(buffer & 0xFF));
            if ((buffer & 0x80) != 0)
                buffer >>= 8;
            else
                break;
        }
    }

    /**
     * Adds a text tag.
     * @param text The text to add.
     */
    public void addText(String text) {
        addByte((byte)(0xFF));
        addByte((byte)(0x03));
        addVarLen(text.length());
        addBytes(text.getBytes());
    }

    /**
     * Ends the track.
     */
    public void endTrack() {
        final byte[] data = {(byte)(0x00), (byte)(0xFF),
            (byte)(0x2f), (byte)(0x00)};
        addBytes(data);
    }

    private void realWriteData(byte b) {
        addVarLen(0);
        addByte((byte)0x90); // note on
        addByte(b);
        addByte((byte)(127));
        int timing;
        if (haveNL)
            timing = 48;
        else if (haveSpace)
            timing = 24;
        else
            timing = 12;
        addVarLen(timing);
        addByte((byte)0x80); // note off
        addByte(b);
        addByte((byte)(127));
        haveSpace = haveNL = false;
    }

    /**
     * Adds a note representing a byte from the input file.
     * @param b The character to add.
     * @trows IllegalArgumentException if <code>b > 127</code>
     */
    public void writeDataByte(byte b) {
        if (b > 127)
            throw new IllegalArgumentException("Notes must be between 0 and 127");
        switch(b) {
        case ' ':
        case '\t':
            haveSpace = true;
            break;
        case '\n':
        case '\r':
            haveNL = true;
            break;
        default:
            realWriteData(b);
            break;
        }
    }
}