// Draws a line between two points
var drawLine = function(point1, point2) {
	var lineColor = rgbToHex(hsvToRgb(properties.hue, 1, 1));

	var dist = properties.distance * 3;

	// Create arrow
	var origin = new THREE.Vector3(point1[0], point1[1], point1[2]);
	var terminus  = new THREE.Vector3(point2[0], point2[1], point2[2]);
	var direction = new THREE.Vector3().subVectors(terminus, origin).normalize();
	var arrow = new THREE.ArrowHelper(direction, origin);

	// Create cylinder
	var geometry = new THREE.CylinderGeometry(turtle.state.girth, turtle.state.girth, dist, 20);
	geometry.applyMatrix(new THREE.Matrix4().makeTranslation(0, dist / 2, 0));


	var material = new THREE.MeshLambertMaterial({ color: 0x844400, shading: THREE.SmoothShading });
	var cylinder = new THREE.Mesh(geometry, material);

	// Use arrow properties
	Object.assign(cylinder.position, arrow.position);

	// TODO oneliner
	cylinder.rotation.x = arrow.rotation.x;
	cylinder.rotation.y = arrow.rotation.y;
	cylinder.rotation.z = arrow.rotation.z;
	
	cylinder.castShadow = true;
	cylinder.receiveShadow = false;

	treeparts.add(cylinder);
};

// Draws flower
var drawFlower = function() {
	// Move to current position
	var pos = turtle.state.position;
	
	var geometry = new THREE.SphereGeometry(properties.distance, 32, 32);
	var material = new THREE.MeshLambertMaterial({color: 0x00FF00});
	var sphere = new THREE.Mesh(geometry, material);
	
	sphere.position.set(pos[0], pos[1], pos[2]);
	
	treeparts.add(sphere);
};

// Gets the end point of the line to be drawn based on the turtle's current orientation
var getDestination = function() {

	// Based on the header vector, return the resultant position
	var orientation = turtle.state.orientation;
	var destination = [0, 0, 0];

	for(var i = 0; i < destination.length; i++) {
		for(var j = 0; j < destination.length; j++) {
			destination[i] += orientation[i][0] * properties.distance;
		}
		destination[i] += turtle.state.position[i];
	}
	return destination;
};

// Rotation matrices
var Ru = function(theta) {
	return [
		[Math.cos(theta), Math.sin(theta), 0],
		[-Math.sin(theta), Math.cos(theta), 0],
		[0, 0, 1]
	];
};

var Rl = function(theta) {
	return [
		[Math.cos(theta), 0, -Math.sin(theta)],
		[0, 1, 0],
		[Math.sin(theta), 0, Math.cos(theta)]
	];
};

var Rh = function(theta) {
	return [
		[1, 0, 0],
		[0, Math.cos(theta), -Math.sin(theta)],
		[0, Math.sin(theta), Math.cos(theta)]
	];
};

// Multiply matrices
function multiply(a, b) {
	var aNumRows = a.length, aNumCols = a[0].length,
	bNumRows = b.length, bNumCols = b[0].length,
	m = new Array(aNumRows);
	for (var r = 0; r < aNumRows; ++r) {
		m[r] = new Array(bNumCols);
		for (var c = 0; c < bNumCols; ++c) {
			m[r][c] = 0;
			for (var i = 0; i < aNumCols; ++i) {
			m[r][c] += a[r][i] * b[i][c];
			}
		}
	}
	return m;
}


var interpret = function(char) {
	switch(char) {
		// Turn left by θ
 		case '+':
			turtle.rotate(Ru(turtle.dTheta));
			break;

		// Turn right by θ
		case '-':
			turtle.rotate(Ru(-turtle.dTheta));
			break;

		// Pitch down by θ
		case '&':
			turtle.rotate(Rl(turtle.dTheta));
			break;

		// Pitch up by θ
		case '^':
			turtle.rotate(Rl(-turtle.dTheta));
			break;

		// Roll left by θ
		case '\\':
			turtle.rotate(Rh(turtle.dTheta));
			break;

		// Roll right by θ
		case '/':
			turtle.rotate(Rh(-turtle.dTheta));
			break;

		// Turn around
		case '|':
			turtle.rotate(Ru(Math.PI));
			break;

		// Move forward and draw line
		case 'F':
			var destination = getDestination();
			drawLine(turtle.state.position, destination);
			turtle.state.position = destination;
			break;

		// Increase index in color palette
		case '\'':
			// Todo actually implement color palette
			//properties.hue += .03;
			break;

		// Decrease branch girth
		case '!':
			turtle.state.girth -= 1.3;
			break;

		// Draws flower, or sphere in this case
		case 'A':
			drawFlower();
			break;

		case 'f':
			drawFlower();
			break;
			
		// Save state
		case '[':
			var oldState = {};
			Object.assign(oldState, turtle.state);
			turtle.stack.push(oldState);
			break;
		
		// Read state
		case ']':
			turtle.state = turtle.stack.pop();
			break;

		default:
			//console.log('The character \'' + char + '\' had no affect');
			break;
	}
};

var runSystem = function() {
	// Remove existing branches in case this is an update
	scene.remove(scene.getObjectByName('treeparts'));

	treeparts = new THREE.Group();
	treeparts.name = 'treeparts';

	// Re-initialize turtle
	// ihat, jhat, khat
	var orientation = [
			[1, 0, 0],
			[0, 1, 0],
			[0, 0, 1]
	];
	var position = [0, 0, 0];
	var state = {position: position, orientation: orientation, girth: 8};
	turtle = new Turtle(state);
	turtle.dTheta = guiproperties.rotation * (Math.PI/180);

	properties = {hue: 0, distance: 10};

	turtle.rotate(Ru(-Math.PI/2));

	lsystem.sentence = lsystem.axiom;
	for(var i = 0; i < guiproperties.iterations; i++) {
		lsystem.iterate();
	}

	for(var i = 0; i < lsystem.sentence.length; i++) {
		interpret(lsystem.sentence.charAt(i));
	}

	// Add all of the parts of the tree to the actual scene
	scene.add(treeparts);
}