package edu.msoe.taylor.audio;

/**
 * The Note class describes a note.  Each note must have duration and either a
 * pitch specified in scientific pitch notation or a frequency.  If scientific
 * pitch is specified, the frequency is calculated.
 * 
 * @see <a href="http://en.wikipedia.org/wiki/Scientific_pitch_notation">Scientific Pitch Notation</a>
 * 
 * @author t a y l o r@msoe.edu
 * @version 2014.04.11
 */
public class Note {
	/**
	 * Name of note in scientific pitch notation.
	 */
	private final String name;
	/** 
	 * Frequency of note in cycles per second. 
	 */
	private final float frequency;
	
	/**
	 *  Duration of note in milliseconds.
	 */
	private final float duration;
	
	/** 
	 * Frequency for A0 
	 */
	private static final float A0 = 27.5f;

	/**
	 * Constructs a new Note object with the specified pitch and duration.
	 * @param name	Scientific pitch notation for the note
	 * @param duration Duration of the note in milliseconds
	 */
	public Note(String name, float duration) {
		this.name = name;
		frequency = getFrequency(name);
		if(duration<0) {
			throw new IllegalArgumentException("Invalid duration (cannot be negative).");
		}
		this.duration = duration;
	}
	
	/**
	 * Constructs a new Note object with the specified frequency and duration.
	 * @param frequency Frequency in hertz
	 * @param duration Duration in milliseconds
	 */
	public Note(float frequency, float duration) {
		this.name = null;
		if(frequency<0) {
			throw new IllegalArgumentException("Invalid frequency (cannot be negative).");
		}
		this.frequency = frequency;
		if(duration<0) {
			throw new IllegalArgumentException("Invalid duration (cannot be negative).");
		}
		this.duration = duration;
	}
	
	/**
	 * Returns the frequency of the specified scientific pitch
	 * For example: ("C4") specifies middle C on a standard piano (~262Hz)
	 * @param scientificPitch	Note from A-G, including sharps (#) with octave
     *                          specified as "A4", "A#4", "B4", ...
	 * @return			The frequency of the specified note.
	 * @see <a href="http://en.wikipedia.org/wiki/Note">wikipedia Note entry</a>
	 */
	private float getFrequency(String scientificPitch) {
		String note = "";
		int octave;
		if(scientificPitch.charAt(1)=='#') {
			note = scientificPitch.substring(0,2);
			octave = Integer.parseInt(scientificPitch.substring(2));
		} else {
			note = scientificPitch.substring(0,1);
			octave = Integer.parseInt(scientificPitch.substring(1));
		}
		double power = 0;
		note = note.toUpperCase();
		if(note.equals("C")) {
			power = (12.0*octave-9)/12;
		} else if(note.equals("C#")) {
			power = (12.0*octave-8)/12;
		} else if(note.equals("D")) {
			power = (12.0*octave-7)/12;
		} else if(note.equals("D#")) {
			power = (12.0*octave-6)/12;
		} else if(note.equals("E")) {
			power = (12.0*octave-5)/12;
		} else if(note.equals("F")) {
			power = (12.0*octave-4)/12;
		} else if(note.equals("F#")) {
			power = (12.0*octave-3)/12;
		} else if(note.equals("G")) {
			power = (12.0*octave-2)/12;
		} else if(note.equals("G#")) {
			power = (12.0*octave-1)/12;
		} else if(note.equals("A")) {
			power = octave;
		} else if(note.equals("A#")) {
			power = (12.0*octave+1)/12;
		} else if(note.equals("B")) {
			power = (12.0*octave+2)/12;
		} else {
			throw new IllegalArgumentException("Note note in scientific pitch notation: " + note);
		}
		return A0*(float)Math.pow(2,power);
	}

	/**
	 * Returns the frequency (in Hz) of this note.
	 * @return	frequency in hertz
	 */
	public float getFrequency() {
		return frequency;
	}
	
	/**
	 * Returns the duration of this note.
	 * @return	duration in milliseconds
	 */
	public float getDuration() {
		return duration;
	}
	
	/**
	 * Returns a string representation of the note.
	 */
	public String toString() {
		return "" + (name==null ? frequency : name) + duration;
	}
}