'use strict';

var maze = [
    ['*', '*', '*', '*', '*', '*', '*', '*', '*', '*', '*', '*'],
    ['*', '*', '*', '*', '*', '*', '*', '*', '*', '*', '*', '*'],
    ['*', '*', '*', '*', '*', '*', '*', '*', '*', '*', '*', '*'],
    ['*', '*', '*', '*',  0 , ' ', ' ', '*', '*', '*', '*', '*'],
    ['*', '*', '*', '*', ' ', '*', '*', '*', '*', '*', ' ', ' '],
    ['*', '*', '*', '*', ' ', '*', '*', '*', '*', '*', ' ', '*'],
    ['*', '*', '*', '*', ' ', '*', '*', '*', '*', '*', ' ', '*'],
    ['*', '*', '*', '*', ' ', '*', '*', '*', ' ', ' ', ' ', '*'],
    [' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', '*', '*', '*'],
    ['*', ' ', '*', '*', '*', '*', '*', '*', ' ', '*', '*', '*'],
    ['*', ' ', '*', '*', '*', '*', '*', '*', ' ', '*', '*', '*'],
    ['*', ' ', ' ', ' ', ' ', '*', '*', '*', ' ', '*', '*', '*'],
    ['*', '*', '*', '*', ' ', '*', '*', '*', ' ', '*', '*', '*'],
    ['*', '*', '*', '*', ' ', '*', '*', '*', ' ', ' ', ' ', '*'],
    ['*', '*', '*', '*', ' ', '*', '*', '*', '*', '*', ' ', '*']
];

var queue;
var exit_found;

solve_maze(maze);

function solve_maze(maze) {
    exit_found = false;
    queue = find_start(maze)
    while(queue.length != 0) {
        let position = queue.shift();

        try_move_position({row:position.row+1, column:position.column, path:position.path});
        try_move_position({row:position.row-1, column:position.column, path:position.path});
        try_move_position({row:position.row, column:position.column+1, path:position.path});
        try_move_position({row:position.row, column:position.column-1, path:position.path});
    }
    if(!exit_found) {
        console.log("No exit found.");
    }
}

function try_move_position(position) {
    if(!is_inside_maze(position)) {
        exit_found = true;
        print_path(position);
        return;
    }
    if(maze[position.row][position.column] === ' ') {
        let new_path = position.path.slice();
        new_path.push({row:position.row, column:position.column});
        queue.push({row:position.row, column:position.column, path:new_path});
        maze[position.row][position.column] = 'x';
    }
}

function is_inside_maze(position) {
    if(position.row     >= 0 && position.row    < maze.length &&
       position.column  >= 0 && position.column < maze[0].length)
       return true;
}

function print_path(position) {
    let path = position.path;
    path.forEach(step => {
        console.log(step);
    });
    console.log("exit");
}

function find_start(maze) {
    let start = {row: 0, column: 0, path: []};
    for (let row = 0; row < maze.length; row++) {
        for (let column = 0; column < maze[0].length; column++) {
            if(maze[row][column] === 0) {
                start.row = row;
                start.column = column;
            }
        }
    }
    return [start];
}