/**
 * @class Icey's Maze generator
 * See http://www.roguebasin.roguelikedevelopment.org/index.php?title=Simple_maze for explanation
 * @augments ROT.Map
 */
ROT.Map.IceyMaze = function(width, height, regularity) {
	ROT.Map.call(this, width, height);
	this._regularity = regularity || 0;
}
ROT.Map.IceyMaze.extend(ROT.Map);

ROT.Map.IceyMaze.prototype.create = function(callback) {
	var width = this._width;
	var height = this._height;
	
	var map = this._fillMap(1);
	
	width -= (width % 2 ? 1 : 2);
	height -= (height % 2 ? 1 : 2);

	var cx = 0;
	var cy = 0;
	var nx = 0;
	var ny = 0;

	var done = 0;
	var blocked = false;
	var dirs = [
		[0, 0],
		[0, 0],
		[0, 0],
		[0, 0]
	];
	do {
		cx = 1 + 2*Math.floor(ROT.RNG.getUniform()*(width-1) / 2);
		cy = 1 + 2*Math.floor(ROT.RNG.getUniform()*(height-1) / 2);

		if (!done) { map[cx][cy] = 0; }
		
		if (!map[cx][cy]) {
			this._randomize(dirs);
			do {
				if (Math.floor(ROT.RNG.getUniform()*(this._regularity+1)) == 0) { this._randomize(dirs); }
				blocked = true;
				for (var i=0;i<4;i++) {
					nx = cx + dirs[i][0]*2;
					ny = cy + dirs[i][1]*2;
					if (this._isFree(map, nx, ny, width, height)) {
						map[nx][ny] = 0;
						map[cx + dirs[i][0]][cy + dirs[i][1]] = 0;
						
						cx = nx;
						cy = ny;
						blocked = false;
						done++;
						break;
					}
				}
			} while (!blocked);
		}
	} while (done+1 < width*height/4);
	
	for (var i=0;i<this._width;i++) {
		for (var j=0;j<this._height;j++) {
			callback(i, j, map[i][j]);
		}
	}
	this._map = null;
	return this;
}

ROT.Map.IceyMaze.prototype._randomize = function(dirs) {
	for (var i=0;i<4;i++) {
		dirs[i][0] = 0;
		dirs[i][1] = 0;
	}
	
	switch (Math.floor(ROT.RNG.getUniform()*4)) {
		case 0:
			dirs[0][0] = -1; dirs[1][0] = 1;
			dirs[2][1] = -1; dirs[3][1] = 1;
		break;
		case 1:
			dirs[3][0] = -1; dirs[2][0] = 1;
			dirs[1][1] = -1; dirs[0][1] = 1;
		break;
		case 2:
			dirs[2][0] = -1; dirs[3][0] = 1;
			dirs[0][1] = -1; dirs[1][1] = 1;
		break;
		case 3:
			dirs[1][0] = -1; dirs[0][0] = 1;
			dirs[3][1] = -1; dirs[2][1] = 1;
		break;
	}
}

ROT.Map.IceyMaze.prototype._isFree = function(map, x, y, width, height) {
	if (x < 1 || y < 1 || x >= width || y >= height) { return false; }
	return map[x][y];
}