/*
 * Copyright (c) 2013, Slick2D
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name of the Slick2D nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without
 *   specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package org.newdawn.slick.openal;

import java.io.IOException;
import java.io.InputStream;

import javazoom.jl.decoder.Bitstream;
import javazoom.jl.decoder.BitstreamException;
import javazoom.jl.decoder.Decoder;
import javazoom.jl.decoder.DecoderException;
import javazoom.jl.decoder.Header;
import javazoom.jl.decoder.SampleBuffer;

import org.newdawn.slick.util.Log;

/**
 * An input stream that can extract MP3 data.
 *
 * @author fluddokt (https://github.com/fluddokt)
 */
public class Mp3InputStream extends InputStream implements AudioInputStream {
	/** The MPEG audio bitstream. */
	private Bitstream bitstream;

	/** The MPEG decoder. */
	private Decoder decoder;

	/** The frame header extractor. */
	private Header header;

	/** The buffer. */
	private SampleBuffer buf;

	/** The number of channels. */
	private int channels;

	/** The sample rate. */
	private int sampleRate;

	/** The buffer length. */
	private int bufLen = 0;

	/** True if we've reached the end of the available data. */
	private boolean endOfStream = false;

	/** The byte position. */
	private int bpos;

	/**
	 * Create a new stream to decode MP3 data.
	 * @param input the input stream from which to read the MP3 file
	 * @throws IOException failure to read the header from the input stream
	 */
	public Mp3InputStream(InputStream input) throws IOException {
		decoder = new Decoder();
		bitstream = new Bitstream(input);
		try {
			header = bitstream.readFrame();
		} catch (BitstreamException e) {
			Log.error(e);
		}
		if (header == null) {
			close();
			throw new IOException("Failed to read header from MP3 input stream.");
		}

		channels = (header.mode() == Header.SINGLE_CHANNEL) ? 1 : 2;
		sampleRate = header.frequency();

		buf = new SampleBuffer(sampleRate, channels);
		decoder.setOutputBuffer(buf);

		try {
			decoder.decodeFrame(header, bitstream);
		} catch (DecoderException e) {
			Log.error(e);
		}

		bufLen = buf.getBufferLength();
		bitstream.closeFrame();
	}

	@Override
	public int read() throws IOException {
		if (atEnd())
			return -1;
		while (bpos / 2 >= bufLen) {
			try {
				header = bitstream.readFrame();
				if (header == null) {
					buf.clear_buffer();

					endOfStream = true;
					return -1;
				}
				buf.clear_buffer();
				decoder.decodeFrame(header, bitstream);
				bufLen = buf.getBufferLength();
				bitstream.closeFrame();
			} catch (DecoderException | BitstreamException e) {
				Log.error(e);
			}
			bpos = 0;
		}
		int npos = bpos / 2;
		bpos++;

		if (bpos % 2 == 0)
			return (buf.getBuffer()[npos] >> 8) & 0xff;
		else
			return (buf.getBuffer()[npos]) & 0xff;
	}

	@Override
	public boolean atEnd() { return endOfStream; }

	@Override
	public int getChannels() { return channels; }

	@Override
	public int getRate() { return sampleRate; }

	@Override
	public int read(byte[] b, int off, int len) throws IOException {
		for (int i = 0; i < len; i++) {
			try {
				int value = read();
				if (value >= 0)
					b[i] = (byte) value;
				else
					return (i == 0) ? -1 : i;
			} catch (IOException e) {
				Log.error(e);
				return i;
			}
		}

		return len;
	}

	@Override
	public int read(byte[] b) throws IOException { return read(b, 0, b.length); }

	@Override
	public long skip(long length) {
		if (bufLen <= 0)
			Log.warn("Mp3InputStream: skip: bufLen not yet determined.");

		int skipped = 0;
		while (skipped + bufLen * 2 < length) {
			try {
				header = bitstream.readFrame();
				if (header == null) {
//					Log.warn("Mp3InputStream: skip: header is null.");
					endOfStream = true;
					return -1;
				}

				// last frame that won't be skipped so better read it
				if (skipped + bufLen * 2 * 4 >= length || bufLen <= 0) {
					buf.clear_buffer();
					decoder.decodeFrame(header, bitstream);
					bufLen = buf.getBufferLength();
				}
				skipped += bufLen * 2 - bpos;

				bitstream.closeFrame();
				bpos = 0;
			} catch (BitstreamException | DecoderException e) {
				Log.error(e);
			}
		}
		if (bufLen * 2 - bpos > length - skipped) {
			bpos += length - skipped;
			skipped += length - skipped;
		}

		return skipped;
	}

	@Override
	public void close() throws IOException {
		try {
			bitstream.close();
		} catch (BitstreamException e) {
			e.printStackTrace();
		}
	}
}