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/*
*      _______                       _____   _____ _____  
*     |__   __|                     |  __ \ / ____|  __ \ 
*        | | __ _ _ __ ___  ___  ___| |  | | (___ | |__) |
*        | |/ _` | '__/ __|/ _ \/ __| |  | |\___ \|  ___/ 
*        | | (_| | |  \__ \ (_) \__ \ |__| |____) | |     
*        |_|\__,_|_|  |___/\___/|___/_____/|_____/|_|     
*                                                         
* -------------------------------------------------------------
*
* TarsosDSP is developed by Joren Six at IPEM, University Ghent
*  
* -------------------------------------------------------------
*
*  Info: http://0110.be/tag/TarsosDSP
*  Github: https://github.com/JorenSix/TarsosDSP
*  Releases: http://0110.be/releases/TarsosDSP/
*  
*  TarsosDSP includes modified source code by various authors,
*  for credits and info, see README.
* 
*/


package be.tarsos.dsp.pitch;

import be.tarsos.dsp.AudioEvent;
import be.tarsos.dsp.AudioProcessor;

/**
 * Contains an implementation of the Goertzel algorithm. It can be used to
 * detect if one or more predefined frequencies are present in a signal. E.g. to
 * do DTMF decoding.
 * 
 * @author Joren Six
 */
public class Goertzel implements AudioProcessor {

	/**
	 * If the power in dB is higher than this threshold, the frequency is
	 * present in the signal.
	 */
	private static final double POWER_THRESHOLD = 35;// in dB

	/**
	 * A list of frequencies to detect.
	 */
	private final double[] frequenciesToDetect;
	/**
	 * Cached cosine calculations for each frequency to detect.
	 */
	private final double[] precalculatedCosines;
	/**
	 * Cached wnk calculations for each frequency to detect.
	 */
	private final double[] precalculatedWnk;
	/**
	 * A calculated power for each frequency to detect. This array is reused for
	 * performance reasons.
	 */
	private final double[] calculatedPowers;

	private final FrequenciesDetectedHandler handler;

	public Goertzel(final float audioSampleRate, final int bufferSize,
			double[] frequencies, FrequenciesDetectedHandler handler) {

		frequenciesToDetect = frequencies;
		precalculatedCosines = new double[frequencies.length];
		precalculatedWnk = new double[frequencies.length];
		this.handler = handler;

		calculatedPowers = new double[frequencies.length];

		for (int i = 0; i < frequenciesToDetect.length; i++) {
			precalculatedCosines[i] = 2 * Math.cos(2 * Math.PI
					* frequenciesToDetect[i] / audioSampleRate);
			precalculatedWnk[i] = Math.exp(-2 * Math.PI
					* frequenciesToDetect[i] / audioSampleRate);
		}
	}

	/**
	 * An interface used to react on detected frequencies.
	 * 
	 * @author Joren Six
	 */
	public static interface FrequenciesDetectedHandler {
		/**
		 * React on detected frequencies.
		 * 
		 * @param frequencies
		 *            A list of detected frequencies.
		 * @param powers
		 *            A list of powers of the detected frequencies.
		 * @param allFrequencies
		 *            A list of all frequencies that were checked.
		 * @param allPowers
		 *            A list of powers of all frequencies that were checked.
		 */
		void handleDetectedFrequencies(final double timestamp,final double[] frequencies,
				final double[] powers, final double[] allFrequencies,
				final double allPowers[]);
	}

	@Override
	public boolean process(AudioEvent audioEvent) {
		float[] audioFloatBuffer = audioEvent.getFloatBuffer();
		double skn0, skn1, skn2;
		int numberOfDetectedFrequencies = 0;
		for (int j = 0; j < frequenciesToDetect.length; j++) {
			skn0 = skn1 = skn2 = 0;
			for (int i = 0; i < audioFloatBuffer.length; i++) {
				skn2 = skn1;
				skn1 = skn0;
				skn0 = precalculatedCosines[j] * skn1 - skn2
						+ audioFloatBuffer[i];
			}
			double wnk = precalculatedWnk[j];
			calculatedPowers[j] = 20 * Math.log10(Math.abs(skn0 - wnk * skn1));
			if (calculatedPowers[j] > POWER_THRESHOLD) {
				numberOfDetectedFrequencies++;
			}
		}

		if (numberOfDetectedFrequencies > 0) {
			double[] frequencies = new double[numberOfDetectedFrequencies];
			double[] powers = new double[numberOfDetectedFrequencies];
			int index = 0;
			for (int j = 0; j < frequenciesToDetect.length; j++) {
				if (calculatedPowers[j] > POWER_THRESHOLD) {
					frequencies[index] = frequenciesToDetect[j];
					powers[index] = calculatedPowers[j];
					index++;
				}
			}
			handler.handleDetectedFrequencies(audioEvent.getTimeStamp(),frequencies, powers,
					frequenciesToDetect.clone(), calculatedPowers.clone());
		}

		return true;
	}



	@Override
	public void processingFinished() {
	}

}