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/*
 Copyright (C) 2000 Andrew Sorensen & Andrew Brown 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

package jm.audio.synth;

import jm.audio.AOException;
import jm.audio.AudioObject;

/**
 * @author Andrew Sorensen
 */
public final class ReSample extends AudioObject {
    //----------------------------------------------
    // Attributes
    //----------------------------------------------
    private double baseFreq = 0.0;
    private double newFreq = 0.0;
    private boolean noteFreq = true;

    //----------------------------------------------
    // Constructors
    //----------------------------------------------
    public ReSample(AudioObject ao, double baseFreq) {
        super(ao, "[ReSample]");
        this.baseFreq = baseFreq;
    }

    //----------------------------------------------
    // Public Methods
    //----------------------------------------------

    /**
     */
    public void build() {
        if (noteFreq) this.newFreq = this.currentNote.getFrequency();
        this.finished = true;
    }

    //----------------------------------------------
    // Protected Methods
    //----------------------------------------------

    /**
     * This is nextWork method simply needs to skip over
     * the right number of samples to cause a shorter
     * wave period. This means that the pitch goes up.
     * The number of samples to skip is calculated by
     * the setPhaseInt() method which is the real
     * nextWork horse of this class.
     *
     * @param input a single Audio Object input.
     */
    public int work(float[] buffer) throws AOException {
        double cfm = newFreq / baseFreq;
        double skip = -1.0 / ((1.0 - cfm) / cfm);
        double remains = 0.0;
        int upSample = 0; //value 0 is upsample
        if (skip < 0) {
            skip = -1.0 / skip;
            upSample = 1;
        }//value 1 is downsample
        if (skip == 0) {
            upSample = 2;
            skip = 1;
        }//value 2 is no resample
        float[] tmpBuf = new float[(int) ((double) (buffer.length * cfm) + 0.5) + 1]; // +1
        int ret = this.previous[0].nextWork(tmpBuf);
        float tmp = 0.0f; //holds previous sample for interpolation
        int count = 0, index = 0;
        for (int i = 0; true; i++) {
            if (upSample == 0) { //Remove Samples
                if (++index >= (int) (skip + remains)) {
                    remains = (skip + remains) % 1.0;
                    index = 0;
                    continue;
                }
                if (count >= buffer.length) break;
                buffer[count++] = tmpBuf[i];
            } else if (upSample == 1) { //Add Samples
                if ((skip + remains) >= 1.0) { //add extra interpolated sample
                    float increment = (tmpBuf[i] - tmp) / (float) (skip + remains);
                    for (int k = 0; k < (int) (skip + remains); k++) {
                        buffer[count++] = tmp + (increment * k);
                        if (count == buffer.length) break;
                    }
                }
                if (count == buffer.length) break;
                buffer[count++] = tmpBuf[i];
                tmp = tmpBuf[i];
                remains = (skip + remains) % 1.0;
            } else { //Do Nothing
                buffer[count++] = tmpBuf[i];
            }
            if (count == buffer.length) break;
        }
        return buffer.length;
    }
}