//=============================================================================
//  MuseScore
//  Linux Music Score Editor
//  $Id:$
//
//  Plugin for gernerating random scores for sight reading practise.
//	Copyright (c) Chris Wilkinson, 2014
//
//	This file is a derivative of createscore.js, one of MuseScore's
//  factory-included plugins.  Original file Copyright (C)2008-2010 
//  Werner Schweer and others
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License version 2.
//
//  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.
//=============================================================================

//
//    This is ECMAScript code (ECMA-262 aka "Java Script")
//

//---------------------------------------------------------
//    init
//    this function will be called on startup of
//    mscore
//---------------------------------------------------------

function init()
      {
      // print("test script init");
      };


function addNote(cursor, pitch, duration, goNextMeasure)
      {
      var chord     = new Chord();
      chord.tickLen = duration;
      var note      = new Note();
      note.pitch    = pitch;
      note.velocity = 127;

      chord.addNote(note);
      cursor.add(chord);
      if (goNextMeasure) 
		cursor.nextMeasure();
      else
		cursor.next();
      };

function run()
	{
	var score   = new Score();
	score.name  = "Random Practise";
	score.title = "Random Practise";
	score.appendPart("Piano");    // create two staff piano part
	score.appendMeasures(32);      // append empty measures
	var cursor = new Cursor(score);

	//  Generate a right-hand part
	cursor.staff = 0;
	cursor.voice = 0;
	var pitches = [60, 62, 64, 65, 67, 69, 71, 72, 74, 76];
	addLevel1 (cursor, score, pitches);

	// Generate left-hand part
	cursor.staff = 1;
	cursor.voice = 0;
	var pitches = [45, 47, 48, 50, 52, 53, 55, 57, 59, 60];
	addLevel1 (cursor, score, pitches);
	};

//  ____________________________________________________________
//  Generate level 1.
function addLevel1(cursor, score, pitches)
	{
	cursor.rewind();
	var phrases =  [[0, 1, 0],
			[0, 1, 2],
			[0, 1, -1],
			[0, 1, 2, 0], 
			[0, 1, -1, 0],
			[0, 1, 2, 3],
			[0, 1, 0, -1],
			[0, 1, -1, -2],
			[0, 1, 0, 1, 0],
			[0, 1, 2, 1, 0],
			[0, 1, 0, 1, 2],
			[0, 1, 0, -1, 0],
			[0, 1, 0, 1, 2],
			[0, 1, 2, 0, 1],
			[0, 1, -2, -1, 0]];
	while (true)
		{
		var phraseNum = Math.floor (Math.random() * phrases.length);  // Choose a phrase at random from the list above.
		var phrase = phrases [phraseNum];
		var invertPhrase = Math.floor( Math.random() * 2);  // 50% chance of playing the phrase upside-down.
		if (invertPhrase)
			phrase = invertArray (phrase);
		var reversePhrase = Math.floor( Math.random() * 2);  // 50% chance of playing the phrase backwards.
		if (reversePhrase)
			phrase = reverseArray (phrase);
		var phraseStartPitchMin = -minElement (phrase);  // No negative indeces.
		var phraseStartPitchMax = pitches.length - maxElement (phrase) - 1;  // No too-high indeces
		var phraseStartPitch = phraseStartPitchMin + Math.floor (Math.random() * (phraseStartPitchMax - phraseStartPitchMin + 1));  // Randomly shift the phrase up or down the keyboard.
		phrase = rearraynge (pitches, phrase, phraseStartPitch);  // Convert from 0s, 1s and 2s to MIDI note numbers
		////  Debug information		
		//var debugInfo = "PhraseNum=" + phraseNum + ", phraseStartPitch=" + phraseStartPitch;
		//if (invertPhrase)
		//	debugInfo = debugInfo + ", inv";
		//if (reversePhrase)
		//	debugInfo = debugInfo + ", rev";
		//var debugText = new Text (score);
		//debugText.text = debugInfo;
		//cursor.putStaffText (debugText);
		//  Now, draw the phrase on the score and leave rests until the beginning of a new bar is reached.
		for (var i=0;  i<phrase.length;  i++)
			{
				addNote (cursor, phrase[i], 480, i == phrase.length-1);
				if (cursor.eos())
					return;
			}
		}
	};

//---------------------------------------------------------
//    menu:  defines were the function will be placed
//           in the menu structure
//---------------------------------------------------------

var mscorePlugin = {
      menu: 'Plugins.Random Practise',
      init: init,
      run:  run
      };

mscorePlugin;

//  ________________________________________________________
//  Array operations needed by other functions

//  Returns the value of the lowest element in a array
function minElement (array)
	{
	var lowestValue = array[0];
	for (var i=0;  i<array.length;  i++)
		{
		if (array[i] < lowestValue)
			lowestValue = array[i];
		}
	return lowestValue;
	};

//  Returns the value of the greatest element in a array
function maxElement (array)
	{
	var greatestValue = array[0];
	for (var i=0;  i<array.length;  i++)
		{
		if (array[i] > greatestValue)
			greatestValue = array[i];
		}
	return greatestValue;
	};

//  Returns an array whose elements are the inverse of those of the arugument
function invertArray (array)
	{
	var r = [];	
	for (var i=0;  i<array.length;  i++) 
		r[i] = -array[i];
	return r;
	};

//  Returns an array whose elements are those of the argument in reverse order
function reverseArray (array)
	{
	var r = [];
	for (var i=0;  i<array.length;  i++) 
		r[i] = array[array.length - i - 1];
	return r;
	};

//  Use one array as indeces for another one
//  Returns r, containing elements of a indexed by elements of b with index offset c.
//  Note that r.length == b.length.
function rearraynge (a, b, c)
	{
	var r = [];
	for (var i=0;  i<b.length;  i++)
		r[i] = a[b[i]+c];
	return r;
	};