/*
 * Pixel Dungeon
 * Copyright (C) 2012-2015 Oleg Dolya
 *
 * Shattered Pixel Dungeon
 * Copyright (C) 2014-2018 Evan Debenham
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

package com.shatteredpixel.shatteredpixeldungeon.levels.features;

import com.shatteredpixel.shatteredpixeldungeon.levels.rooms.Room;
import com.watabou.utils.Random;
import com.watabou.utils.Rect;

public class Maze {
	
	public static boolean EMPTY     = false;
	public static boolean FILLED    = true;
	
	public static boolean[][] generate(Room r){
		boolean[][] maze = new boolean[r.width()][r.height()];
		
		for (int x = 0; x < maze.length; x++) {
			for (int y = 0; y < maze[0].length; y++) {
				if (x == 0 || x == maze.length - 1 ||
						y == 0 || y == maze[0].length - 1) {
					
					maze[x][y] = FILLED;
					
				}
			}
		}
		
		//set spaces where there are doors
		for (Room.Door d : r.connected.values()) {
			maze[d.x - r.left][d.y - r.top] = EMPTY;
		}
		
		return generate(maze);
	}
	
	public static boolean[][] generate(Rect r){
		return generate(r.width()+1, r.height()+1);
	}
	
	public static boolean[][] generate(int width, int height){
		return generate(new boolean[width][height]);
	}
	
	public static boolean[][] generate(boolean[][] maze){
		int fails = 0;
		int x, y, moves;
		int[] mov;
		while (fails < 2500) {
			
			//find a random wall point
			do {
				x = Random.Int(maze.length);
				y = Random.Int(maze[0].length);
			} while (!maze[x][y]);
			
			//decide on how we're going to move
			mov = decideDirection(maze, x, y);
			if (mov == null) {
				fails++;
			} else {
				
				fails = 0;
				moves = 0;
				do {
					x += mov[0];
					y += mov[1];
					maze[x][y] = FILLED;
					moves++;
				} while (Random.Int(moves) == 0 && checkValidMove(maze, x, y, mov));
				
			}
			
		}
		
		return maze;
	}
	
	private static int[] decideDirection(boolean[][] maze, int x, int y){
		
		//attempts to move up
		if (Random.Int(4) == 0 && //1 in 4 chance
				checkValidMove(maze, x, y, new int[]{0, -1})){
			return new int[]{0, -1};
		}
		
		//attempts to move right
		if (Random.Int(3) == 0 && //1 in 3 chance
				checkValidMove(maze, x, y, new int[]{1, 0})){
			return new int[]{1, 0};
		}
		
		//attempts to move down
		if (Random.Int(2) == 0 && //1 in 2 chance
				checkValidMove(maze, x, y, new int[]{0, 1})){
			return new int[]{0, 1};
		}
		
		//attempts to move left
		if (
				checkValidMove(maze, x, y, new int[]{-1, 0})){
			return new int[]{-1, 0};
		}
		
		return null;
	}
	
	private static boolean checkValidMove( boolean[][] maze, int x, int y, int[] mov){
		int sideX = 1 - Math.abs(mov[0]);
		int sideY = 1 - Math.abs(mov[1]);
		
		//checking two tiles forward in the movement, and the tiles to their left/right
		for (int i = 0; i < 2; i ++) {
			x += mov[0];
			y += mov[1];
			//checks if tiles we're examining are valid and open
			if ( x > 0 && x < maze.length-1 && y > 0 && y < maze[0].length-1 &&
					!maze[x][y] && !maze[x + sideX][y+ sideY] && !maze[x - sideX][y - sideY]){
				continue;
			} else {
				return false;
			}
		}
		return true;
	}
}
