var max = 3;
var score = 0;
var moves = 0;
var ex = 3;
var ey = 3;

function getElement15(form, name) {
	var k;
	var elements = form.elements;
	for (k = 0; k < elements.length; k++) {
		if (elements[k].name == name) return elements[k];
	}
}

function press15(form, button) {
	name = button.name;
	x = name.substring(0,1);
	y = name.substring(2,3);
	play15(form, (x-1+1), (y-1+1));
}

function shuffle15(form, num) {
	for (i = 0; i < num; i++) {
		x = Math.floor(Math.random(4) * 4);
		if (x == 0) { toggle15(form, ex, ey, ex + 1, ey); }
		else if (x == 1) { toggle15(form, ex, ey, ex - 1, ey); }
		else if (x == 2) { toggle15(form, ex, ey, ex, ey + 1); }
		else if (x == 3) { toggle15(form, ex, ey, ex, ey - 1); }
	}
}

function play15(form, x, y) {			
	if (Math.abs(ex - x) + Math.abs(ey - y) == 1) {
		done = toggle15(form, x, y, x+1, y);
		if (!done) { done = toggle15(form, x, y, x-1, y); }
		if (!done) { done = toggle15(form, x, y, x, y+1); }
		if (!done) { done = toggle15(form, x, y, x, y-1);	}
		moves++;
		if (check15(form)) {
			alert('You win with ' + moves + ' moves!');
			resetboard15(form);
		}
	}
	
}

function showrules15() {
	rules = 'Peeptin by flooble.com \n\n' 
		+ 'The goal of the game is to arrange \n' 
		+ 'the blocks from 1 to 15 in their \n'
		+ 'numeric order. Click a number next to\n'
		+ 'the empty cell to move it into that cell.\n'
		+ 'The game is won when all the numbers\n'
		+ 'are sorted, and the empty square is in the \n'
		+ 'lower-righthand corner.';
	alert(rules);
}

function resetboard15(form) {
	for (i = 0; i < 4; i++) {
		for (j = 0; j < 4; j++) {
			val = 1 + i + (4*j);
			if (val == 16) {
				getElement15(form,i + '_' + j).value = ' ';
			} else {
				getElement15(form,i + '_' + j).value = val;
			}
		}
	}
	score = 0;
	moves = 0;
	ex = 3;
	ey = 3;
}

function toggle15(form, x, y, x1, y1) {
	if (x < 0 || y < 0 || x > max || y > max) {
		return false;
	}
	if (x1 < 0 || y1 < 0 || x1 > max || y1 > max) {
		return false;
	}

	name = x + '_' + y;
	button = getElement15(form,name);
	name = x1 + '_' + y1;
	button1 = getElement15(form,name);
	if (button.value == ' ' || button1.value == ' ') {
		tmp = button.value;
		button.value = button1.value;
		button1.value = tmp;
		if (button.value == ' ') {
			ex = x;
			ey = y;
		} else {
			ex = x1;
			ey = y1;
		}
		return true;
	}
	return false;
}

function check15(form) {
	score = 0;
	for (i = 0; i < 4; i++) {
		for (j = 0; j < 4; j++) {
			val = 1 + i + (4*j);
			if (val < 16) {
				if (getElement15(form,i + '_' + j).value == val) {
					score++;
				}
			}
		}
	}
	return score == 15;
}