/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * 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 University of Southampton 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.openimaj.audio.samples;

import java.util.Iterator;

import org.apache.commons.lang.NotImplementedException;
import org.openimaj.audio.AudioFormat;
import org.openimaj.audio.SampleChunk;
import org.openimaj.audio.timecode.AudioTimecode;

/**
 * A {@link SampleBuffer} for 8 bit sample chunks.
 *
 * @author David Dupplaw (dpd@ecs.soton.ac.uk)
 * @created 23rd November 2011
 */
public class SampleBuffer8Bit implements SampleBuffer, Iterator<Float> {
        /** Scalar to convert integer to byte */
        private final static int SAMPLE_SCALAR = Integer.MAX_VALUE / Byte.MAX_VALUE;

        /** The byte buffer */
        private byte[] byteBuffer = null;

        /** The audio format of the samples */
        private AudioFormat format = null;

        /** The iterator counter for iterating over the samples */
        private int iteratorCount;

        /** The timecode of this sample buffer */
        private AudioTimecode timecode;

        /**
         * Create a new 8-bit sample buffer using the given samples and the given
         * audio format.
         *
         * @param samples
         *            The samples to buffer.
         * @param af
         *            The audio format.
         */
        public SampleBuffer8Bit(final SampleChunk samples, final AudioFormat af) {
                this.format = af;
                if (this.format == null || this.format.getNBits() != 8)
                        throw new IllegalArgumentException("Number of bits " +
                                        "must be 8 if you're instantiating an 8 bit " +
                                        "sample buffer. However " +
                                        (this.format == null ? "format object was null."
                                                        : "number of bits in format was " + this.format.getNBits()));

                this.byteBuffer = samples.getSamples();
                this.timecode = samples.getStartTimecode();
        }

        /**
         * Create a new sample buffer with the given format and the given number of
         * samples. It does not scale for the number of channels in the audio
         * format, so you must pre-multiply the number of samples by the number of
         * channels if you are only counting samples per channel.
         *
         * @param af
         *            The {@link AudioFormat} of the samples
         * @param nSamples
         *            The number of samples
         */
        public SampleBuffer8Bit(final AudioFormat af, final int nSamples) {
                this.format = af.clone();
                if (this.format == null || this.format.getNBits() != 8)
                        throw new IllegalArgumentException("Number of bits " +
                                        "must be 8 if you're instantiating an 8 bit " +
                                        "sample buffer. However " +
                                        (this.format == null ? "format object was null."
                                                        : "number of bits in format was " + this.format.getNBits()));

                this.byteBuffer = new byte[nSamples];
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#getSampleChunk()
         */
        @Override
        public SampleChunk getSampleChunk() {
                final SampleChunk sc = new SampleChunk(this.byteBuffer, this.format);
                sc.setStartTimecode(this.timecode);
                return sc;
        }

        /**
         * {@inheritDoc}
         *
         * Note that because we cannot use native methods for copying parts of an
         * array, we must use Java methods so this will be considerably slower than
         * {@link #getSampleChunk()}.
         *
         * @see org.openimaj.audio.samples.SampleBuffer#getSampleChunk(int)
         */
        @Override
        public SampleChunk getSampleChunk(final int channel) {
                if (channel > this.format.getNumChannels())
                        throw new IllegalArgumentException("Cannot generate sample chunk " +
                                        "for channel " + channel + " as sample only has " +
                                        this.format.getNumChannels() + " channels.");

                if (channel == 0 && this.format.getNumChannels() == 1)
                        return this.getSampleChunk();

                final byte[] newSamples = new byte[this.size()];
                for (int i = 0; i < this.size(); i++)
                        newSamples[i] = this.byteBuffer[i * this.format.getNumChannels() + channel];

                final AudioFormat af = this.format.clone();
                af.setNumChannels(1);
                return new SampleChunk(newSamples, af);
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#get(int)
         */
        @Override
        public float get(final int index) {
                // Convert the byte to an integer
                return this.byteBuffer[index] * SampleBuffer8Bit.SAMPLE_SCALAR;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#getUnscaled(int)
         */
        @Override
        public float getUnscaled(final int index) {
                return this.byteBuffer[index];
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#set(int, float)
         */
        @Override
        public void set(final int index, float sample) {
                if (sample > Byte.MAX_VALUE)
                        sample = Byte.MAX_VALUE;
                if (sample < Byte.MIN_VALUE)
                        sample = Byte.MIN_VALUE;

                this.byteBuffer[index] = (byte) (sample / SampleBuffer8Bit.SAMPLE_SCALAR);
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#size()
         */
        @Override
        public int size() {
                return this.byteBuffer.length;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#getFormat()
         */
        @Override
        public AudioFormat getFormat() {
                return this.format;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#setFormat(org.openimaj.audio.AudioFormat)
         */
        @Override
        public void setFormat(final AudioFormat af) {
                this.format = af;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#asDoubleArray()
         */
        @Override
        public double[] asDoubleArray() {
                final double[] d = new double[this.size()];
                for (int i = 0; i < this.size(); i++)
                        d[i] = this.get(i);
                return d;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#asDoubleChannelArray()
         */
        @Override
        public double[][] asDoubleChannelArray() {
                final int nc = this.format.getNumChannels();
                final double[][] s = new double[nc][this.size() / nc];
                for (int c = 0; c < nc; c++)
                        for (int sa = 0; sa < this.size() / nc; sa++)
                                s[c][sa] = this.get(sa * nc + c);
                return s;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#asDoubleArray()
         */
        @Override
        public float[] asFloatArray() {
                final float[] d = new float[this.size()];
                for (int i = 0; i < this.size(); i++)
                        d[i] = this.get(i);
                return d;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#asDoubleChannelArray()
         */
        @Override
        public float[][] asFloatChannelArray() {
                final int nc = this.format.getNumChannels();
                final float[][] s = new float[nc][this.size() / nc];
                for (int c = 0; c < nc; c++)
                        for (int sa = 0; sa < this.size() / nc; sa++)
                                s[c][sa] = this.get(sa * nc + c);
                return s;
        }

        /**
         * {@inheritDoc}
         * 
         * @see java.lang.Iterable#iterator()
         */
        @Override
        public Iterator<Float> iterator() {
                this.iteratorCount = 0;
                return this;
        }

        /**
         * {@inheritDoc}
         * 
         * @see java.util.Iterator#hasNext()
         */
        @Override
        public boolean hasNext() {
                return this.iteratorCount < this.size();
        }

        /**
         * {@inheritDoc}
         * 
         * @see java.util.Iterator#next()
         */
        @Override
        public Float next() {
                final float f = this.get(this.iteratorCount);
                this.iteratorCount++;
                return f;
        }

        /**
         * {@inheritDoc}
         * 
         * @see java.util.Iterator#remove()
         */
        @Override
        public void remove() {
                throw new NotImplementedException("Cannot remove from 16bit sample buffer");
        }

        @Override
        public AudioTimecode getStartTimecode() {
                return this.timecode;
        }
}