/**
 * 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 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;
        }
}