/**
 * 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.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.ShortBuffer;
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 16-bit sample chunks.
 *
 * @author David Dupplaw (dpd@ecs.soton.ac.uk)
 * @created 23rd November 2011
 */
public class SampleBuffer16Bit implements SampleBuffer, Iterator<Float> {
        /** The underlying byte array we're wrapping */
        private byte[] samples = null;

        /** The short buffer that we're wrapping */
        private ShortBuffer shortBuffer = null;

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

        /** A counter used for iterating over the samples */
        private int iteratorCount;

        /** The timecode of this buffer */
        private AudioTimecode timecode = null;

        /**
         * Create a new 16-bit sample buffer using the given samples and the given
         * audio format.
         *
         * @param samples
         *            The samples to buffer.
         * @param af
         *            The audio format.
         */
        public SampleBuffer16Bit(final SampleChunk samples, final AudioFormat af) {
                this.format = af;
                this.shortBuffer = samples.getSamplesAsByteBuffer().asShortBuffer();
                this.samples = samples.getSamples();
                this.setStartTimecode(samples.getStartTimecode());
        }

        /**
         * Create a new 16-bit sample buffer using the given sample format at the
         * given size. 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 audio format of the samples
         * @param nSamples
         *            The number of samples
         */
        public SampleBuffer16Bit(final AudioFormat af, final int nSamples) {
                this.format = af.clone();
                this.samples = new byte[nSamples * 2];
                this.shortBuffer = new SampleChunk(this.samples, this.format)
                                .getSamplesAsByteBuffer().asShortBuffer();
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.audio.samples.SampleBuffer#getSampleChunk()
         */
        @Override
        public SampleChunk getSampleChunk() {
                final SampleChunk sc = new SampleChunk(this.samples, 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() * 2];
                final ShortBuffer sb = ByteBuffer.wrap(newSamples).order(
                                this.format.isBigEndian() ? ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN).asShortBuffer();
                for (int i = 0; i < this.size() / this.format.getNumChannels(); i++)
                        sb.put(i, this.shortBuffer.get(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) {
                if (index >= this.shortBuffer.limit())
                        return 0;

                // Convert the short to an integer
                return (float) this.shortBuffer.get(index) * Integer.MAX_VALUE / Short.MAX_VALUE;
        }

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

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

                this.shortBuffer.put(index, (short) (sample * Short.MAX_VALUE / Integer.MAX_VALUE));
        }

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

        /**
         * {@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) / Integer.MAX_VALUE;
                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) / Integer.MAX_VALUE;
                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) / Integer.MAX_VALUE;
                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) / Integer.MAX_VALUE;
                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;
        }

        /**
         * Set the timecode for this buffer.
         * 
         * @param timecode
         *            The timecode
         */
        public void setStartTimecode(final AudioTimecode timecode) {
                this.timecode = timecode;
        }
}