function playNote(id) //id format: distortion_atari note index
{
	activeKeyID = id;
	var dist = activeKeyID.substring(0,activeKeyID.indexOf("_"));
	var atariIndex = activeKeyID.substring(activeKeyID.indexOf("_")+1);

	if (atariIndex != "nil")
	{
		if (dist == "square")		dist = 0;
		else if (dist == "lead")	dist = 1;
		else if (dist == "saw")		dist = 2;
		else if (dist == "bass")	dist = 3;

		const audio = document.getElementById('sound');
		audio.src = "midi/"+noteArray[dist][atariIndex][0];
		audio.play();
		writeNoteData(dist,atariIndex);
	}
}

function writeNoteData(dist,atariIndex)
{
	var nv = noteValue;
	if (dotted)
	{
		nv = 2*noteValue/3;
		nv = nv.toString().substring(0,nv.toString().indexOf(".")+3);
	}

	if (channel == 1)
		document.createMidiForm.c1_display.value += noteArray[dist][atariIndex][1]+" "+dist+" "+atariIndex+" "+nv+"\n";
	else if (channel == 2)
		document.createMidiForm.c2_display.value += noteArray[dist][atariIndex][1]+" "+dist+" "+atariIndex+" "+nv+"\n";

	updateBufferArray();
}

function writeRestData(restVal)
{
	if (dotted)
	{
		restVal = 2*restVal/3;
		restVal = restVal.toString().substring(0,restVal.toString().indexOf(".")+3);
	}
	if (channel == 1)
		document.createMidiForm.c1_display.value += "x x x "+restVal+"\n";
	else if (channel == 2)
		document.createMidiForm.c2_display.value += "x x x "+restVal+"\n";

	updateBufferArray();
}

function disableNils()
{
	var x = document.getElementsByTagName("button");
	for (i = 0; i < x.length; i++)
	{
		if (x[i].id.match(/nil/))
		{
			x[i].disabled = "disabled";
			x[i].style.backgroundColor = "#CCCCCC";
			x[i].style.cursor = "default";
		}
	}
}

function selectNote(val)
{
	var x = document.getElementsByName("note-select");
	for (i = 0; i < x.length; i++)
	{
		if (Math.pow(2,i) == val)
		{
			x[i].disabled = "disabled";
			x[i].style.cursor = "default";
		}
		else
		{
			x[i].disabled = "";
			x[i].style.cursor = "pointer";
		}
	}
	noteValue = val;
}

function validateForm()
{
	var x = document.createMidiForm;

	if (isNaN(Number(x.tempo.value)) || isNaN(parseInt(x.tempo.value)) || x.tempo.value == "0")
	{
		x.tempo.value = "";
		alert("Invalid tempo");
		x.tempo.focus();
	}
	else if (isNaN(Number(x.timesig_num.value)) || isNaN(parseInt(x.timesig_num.value)) || x.timesig_num.value == "0")
	{
		x.timesig_num.value = "";
		alert("Invalid time signature");
		x.timesig_num.focus();
	}
}

function toggleColor()
{
	showColor = !showColor;
	var x = document.getElementsByName('key');

	if (showColor)
	{
		for (i = 0; i < x.length; i++)
		{
			var dist = x[i].id.substring(0,x[i].id.indexOf("_"));
			var atariIndex = x[i].id.substring(x[i].id.indexOf("_")+1);

			if (atariIndex != "nil")
			{
				if (dist == "square")		dist = 0;
				else if (dist == "lead")	dist = 1;
				else if (dist == "saw")		dist = 2;
				else if (dist == "bass")	dist = 3;

				x[i].style.backgroundColor = noteArray[dist][atariIndex][8];
			}
		}
	}
	else
	{
		for (i = 0; i < x.length; i++)
		{
			var dist = x[i].id.substring(0,x[i].id.indexOf("_"));
			var atariIndex = x[i].id.substring(x[i].id.indexOf("_")+1);

			if (atariIndex != "nil")
			{
				if (dist == "square")		dist = 0;
				else if (dist == "lead")	dist = 1;
				else if (dist == "saw")		dist = 2;
				else if (dist == "bass")	dist = 3;

				if (x[i].className.match("wkey"))	x[i].style.backgroundColor = "#FFFFFF";
				else											x[i].style.backgroundColor = "#000000";
			}
		}
	}
}

function showFloatingDiv(keyID,e)
{
	activeKeyID = keyID;
	mouseX = e.clientX-50;
	mouseY = e.clientY+10;
	if (mouseX > screen.width-125)	mouseX = screen.width-130;
	else if (mouseX < 5)					mouseX = 5;
	var dist = activeKeyID.substring(0,activeKeyID.indexOf("_"));
	var atariIndex = activeKeyID.substring(activeKeyID.indexOf("_")+1);

	if (dist == "square")		dist = 0;
	else if (dist == "lead")	dist = 1;
	else if (dist == "saw")		dist = 2;
	else if (dist == "bass")	dist = 3;

	var x = document.getElementById('floatDiv');
	x.style.top = mouseY+"px";
	x.style.left = mouseX+"px";
	x.style.visibility = "visible";
	x.innerHTML = "<a style='float: right; border: 1px dotted #000000; padding: 1px;' href='javascript:void(0)' onclick='hideFloatingDiv()' title='close'><b>X</b></a>";
	x.innerHTML += "<b>"+noteArray[dist][atariIndex][1]+"</b><br />Pitch: <code>"+atariIndex+"</code><br />";
	x.innerHTML += "Freq: <code>"+noteArray[dist][atariIndex][3]+" Hz</code><br />";
	if (noteArray[dist][atariIndex][4] > 0)
		x.innerHTML += "Error: <code>+"+noteArray[dist][atariIndex][4]+"</code>";
	else
		x.innerHTML += "Error: <code>"+noteArray[dist][atariIndex][4]+"</code>";

	for (i = 0; i < 32; i++)
	{
		if (i != atariIndex)
			if (noteArray[dist][atariIndex][1] == noteArray[dist][i][1]) //two pitches with same note name
			{
				x.innerHTML += "<br /><a href='javascript:exchange()'>Exchange</a>";
				break;
			}
	}
}

function exchange()
{
	var dist = activeKeyID.substring(0,activeKeyID.indexOf("_"));
	var atariIndex = activeKeyID.substring(activeKeyID.indexOf("_")+1);

	if (dist == "square")		dist = 0;
	else if (dist == "lead")	dist = 1;
	else if (dist == "saw")		dist = 2;
	else if (dist == "bass")	dist = 3;

	for (j = 0; j < 32; j++)
		if (j != atariIndex && noteArray[dist][atariIndex][1] == noteArray[dist][j][1])
		{
			document.getElementById(activeKeyID).id = dist+"_"+j;
			activeKeyID = dist+"_"+j;
			atariIndex = j;
			break;
		}

	//update floating div
	var x = document.getElementById('floatDiv');
	x.style.top = mouseY+"px";
	x.style.left = mouseX+"px";
	x.style.visibility = "visible";
	x.innerHTML = "<a style='float: right; padding: 1px; border: 1px dotted #000000;' href='javascript:void(0)' onclick='hideFloatingDiv()' title='close'><b>X</b></a>";
	x.innerHTML += "<b>"+noteArray[dist][atariIndex][1]+"</b><br />Pitch: <code>"+atariIndex+"</code><br />";
	x.innerHTML += "Freq: <code>"+noteArray[dist][atariIndex][3]+" Hz</code><br />";
	if (noteArray[dist][atariIndex][4] > 0)
		x.innerHTML += "Error: <code>+"+noteArray[dist][atariIndex][4];
	else
		x.innerHTML += "Error: <code>"+noteArray[dist][atariIndex][4];
	x.innerHTML += "</code><br /><a href='javascript:exchange()'>Exchange</a>";

	//change color, if necessary
	if (showColor)
	{
		showColor = !showColor;
		toggleColor();
	}
}

function showFAQ()
{
	document.getElementById('faq').style.visibility = "visible";
	document.getElementById('faq').style.top = "50px";
	document.getElementById('faq').style.left = "50px";
	document.getElementById('faq').style.width = "910px";
	document.getElementById('faq').style.height = "500px";
}

function updateBufferArray()
{
	bufferArray[0][bufferCount] = document.getElementById('c1_display').value;
	bufferArray[1][bufferCount] = document.getElementById('c2_display').value;
	bufferCount++;
}

function undoLastKeypress()
{
	if (bufferCount >= bufferMin)
	{
		document.getElementById('c1_display').value = bufferArray[0][bufferCount-2].toString();
		document.getElementById('c2_display').value = bufferArray[1][bufferCount-2].toString();
		bufferCount--;
	}
}

function hideFAQ()				{document.getElementById('faq').style.visibility = "hidden";}
function clearChannelData(x)	{document.getElementById("c"+x.toString()+"_display").value = "";}
function setDotted()				{dotted = !dotted;}
function toggleChannel(c)		{channel = c;}
function hideFloatingDiv()		{document.getElementById('floatDiv').style.visibility = "hidden";}