/**
 * @class Random dungeon generator using human-like digging patterns.
 * Heavily based on Mike Anderson's ideas from the "Tyrant" algo, mentioned at 
 * http://www.roguebasin.roguelikedevelopment.org/index.php?title=Dungeon-Building_Algorithm.
 * @augments ROT.Map.Dungeon
 */
ROT.Map.Digger = function(width, height, options) {
	ROT.Map.Dungeon.call(this, width, height);
	
	this._options = {
		roomWidth: [3, 9], /* room minimum and maximum width */
		roomHeight: [3, 5], /* room minimum and maximum height */
		corridorLength: [3, 10], /* corridor minimum and maximum length */
		dugPercentage: 0.2, /* we stop after this percentage of level area has been dug out */
		timeLimit: 1000 /* we stop after this much time has passed (msec) */
	}
	for (var p in options) { this._options[p] = options[p]; }
	
	this._features = {
		"Room": 4,
		"Corridor": 4
	}
	this._featureAttempts = 20; /* how many times do we try to create a feature on a suitable wall */
	this._walls = {}; /* these are available for digging */
	
	this._digCallback = this._digCallback.bind(this);
	this._canBeDugCallback = this._canBeDugCallback.bind(this);
	this._isWallCallback = this._isWallCallback.bind(this);
	this._priorityWallCallback = this._priorityWallCallback.bind(this);
}
ROT.Map.Digger.extend(ROT.Map.Dungeon);

/**
 * Create a map
 * @see ROT.Map#create
 */
ROT.Map.Digger.prototype.create = function(callback) {
	this._rooms = [];
	this._corridors = [];
	this._map = this._fillMap(1);
	this._walls = {};
	this._dug = 0;
	var area = (this._width-2) * (this._height-2);

	this._firstRoom();
	
	var t1 = Date.now();

	do {
		var t2 = Date.now();
		if (t2 - t1 > this._options.timeLimit) { break; }

		/* find a good wall */
		var wall = this._findWall();
		if (!wall) { break; } /* no more walls */
		
		var parts = wall.split(",");
		var x = parseInt(parts[0]);
		var y = parseInt(parts[1]);
		var dir = this._getDiggingDirection(x, y);
		if (!dir) { continue; } /* this wall is not suitable */
		
//		console.log("wall", x, y);

		/* try adding a feature */
		var featureAttempts = 0;
		do {
			featureAttempts++;
			if (this._tryFeature(x, y, dir[0], dir[1])) { /* feature added */
				if (this._rooms.length + this._corridors.length == 2) { this._rooms[0].addDoor(x, y); } /* first room oficially has doors */
				this._removeSurroundingWalls(x, y);
				this._removeSurroundingWalls(x-dir[0], y-dir[1]);
				break; 
			}
		} while (featureAttempts < this._featureAttempts);
		
		var priorityWalls = 0;
		for (var id in this._walls) { 
			if (this._walls[id] > 1) { priorityWalls++; }
		}

	} while (this._dug/area < this._options.dugPercentage || priorityWalls); /* fixme number of priority walls */

	if (callback) {
		for (var i=0;i<this._width;i++) {
			for (var j=0;j<this._height;j++) {
				callback(i, j, this._map[i][j]);
			}
		}
	}
	
	this._walls = {};
	this._map = null;

	return this;
}

ROT.Map.Digger.prototype._digCallback = function(x, y, value) {
	if (value == 0 || value == 2) { /* empty */
		this._map[x][y] = 0;
		this._dug++;
	} else { /* wall */
		this._walls[x+","+y] = 1;
	}
}

ROT.Map.Digger.prototype._isWallCallback = function(x, y) {
	if (x < 0 || y < 0 || x >= this._width || y >= this._height) { return false; }
	return (this._map[x][y] == 1);
}

ROT.Map.Digger.prototype._canBeDugCallback = function(x, y) {
	if (x < 1 || y < 1 || x+1 >= this._width || y+1 >= this._height) { return false; }
	return (this._map[x][y] == 1);
}

ROT.Map.Digger.prototype._priorityWallCallback = function(x, y) {
	this._walls[x+","+y] = 2;
}

ROT.Map.Digger.prototype._firstRoom = function() {
	var cx = Math.floor(this._width/2);
	var cy = Math.floor(this._height/2);
	var room = ROT.Map.Feature.Room.createRandomCenter(cx, cy, this._options);
	this._rooms.push(room);
	room.create(this._digCallback);
}

/**
 * Get a suitable wall
 */
ROT.Map.Digger.prototype._findWall = function() {
	var prio1 = [];
	var prio2 = [];
	for (var id in this._walls) {
		var prio = this._walls[id];
		if (prio == 2) { 
			prio2.push(id); 
		} else {
			prio1.push(id);
		}
	}
	
	var arr = (prio2.length ? prio2 : prio1);
	if (!arr.length) { return null; } /* no walls :/ */
	
	var id = arr.random();
	delete this._walls[id];

	return id;
}

/**
 * Tries adding a feature
 * @returns {bool} was this a successful try?
 */
ROT.Map.Digger.prototype._tryFeature = function(x, y, dx, dy) {
	var feature = null;
	var total = 0;
	for (var p in this._features) { total += this._features[p]; }
	var random = Math.floor(ROT.RNG.getUniform()*total);
	
	var sub = 0;
	for (var p in this._features) {
		sub += this._features[p];
		if (random < sub) { 
			feature = ROT.Map.Feature[p];
			break; 
		}
	}
	
	feature = feature.createRandomAt(x, y, dx, dy, this._options);
	
	if (!feature.isValid(this._isWallCallback, this._canBeDugCallback)) {
//		console.log("not valid");
//		feature.debug();
		return false;
	}
	
	feature.create(this._digCallback);
//	feature.debug();

	if (feature instanceof ROT.Map.Feature.Room) { this._rooms.push(feature); }
	if (feature instanceof ROT.Map.Feature.Corridor) { 
		feature.createPriorityWalls(this._priorityWallCallback);
		this._corridors.push(feature); 
	}
	
	return true;
}

ROT.Map.Digger.prototype._removeSurroundingWalls = function(cx, cy) {
	var deltas = ROT.DIRS[4];

	for (var i=0;i<deltas.length;i++) {
		var delta = deltas[i];
		var x = cx + delta[0];
		var y = cy + delta[1];
		delete this._walls[x+","+y];
		var x = cx + 2*delta[0];
		var y = cy + 2*delta[1];
		delete this._walls[x+","+y];
	}
}

/**
 * Returns vector in "digging" direction, or false, if this does not exist (or is not unique)
 */
ROT.Map.Digger.prototype._getDiggingDirection = function(cx, cy) {
	var result = null;
	var deltas = ROT.DIRS[4];
	
	for (var i=0;i<deltas.length;i++) {
		var delta = deltas[i];
		var x = cx + delta[0];
		var y = cy + delta[1];
		
		if (x < 0 || y < 0 || x >= this._width || y >= this._width) { return null; }
		
		if (!this._map[x][y]) { /* there already is another empty neighbor! */
			if (result) { return null; }
			result = delta;
		}
	}
	
	/* no empty neighbor */
	if (!result) { return null; }
	
	return [-result[0], -result[1]];
}