using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace Random100.TraceRay

{

    class TraceRay

    {

        public static void Main(string[] args)

        {

            var h = 0;

            do

            {

                var arr = new string[20, 20];

                var coord = new int[4];

                createArray(arr);

                displayArray(arr);

                Console.WriteLine("\r \n Choose 2 sets of coordinates (x y x1 y1, each number betwee 1 and 18");

                chooseCoord(coord, arr);

                var x = coord[0];

                var y = coord[1];

                var x1 = coord[2];

                var y1 = coord[3];

                decimal _x = x;

                decimal _y = y;

                decimal _x1 = x1;

                decimal _y1 = y1;

                var k = 0;

                bool isLonger = Math.Abs((_x1 - _x) - 1) > Math.Abs((_y1 - _y) - 1);

                var xCheck = Math.Abs(_x1 - _x) - 1;

                var height = Math.Abs((y1 - y));

                if (y == y1)

                {

                    height++;

                }

                for (int i = 0; Math.Abs(i) <Math.Abs( xCheck);)

​

                {

                    while (Math.Abs(k) < height)

                    {

                        var l = new decimal();

                        if (isLonger)

                        {

                            l = Math.Round((Math.Abs(_x1 - _x) - 1 )/ (Math.Abs(_y1 - _y) - 1) * Math.Abs(k));

                            if (Math.Abs(i) == l && y != y1)

                            {

                                k++;

                            }

                        }

                        else

                        {

                            l = Math.Round((Math.Abs(_y1 - _y) - 1) / (Math.Abs(_x1 - _x) - 1) * Math.Abs(i));

                            if (Math.Abs(k) == l && x != x1)

                            {

                                i++;

                            }

                        }

                        if (isLonger)

                        {

                            if(k == 1 && y == y1)

                            {

                                break;

                            }

                            if (x <= x1 && y <= y1)

                            {

                                arr[y + k, x + (i + 1)] = " O ";

                            }

                            else if (x <= x1 && y >= y1)

                            {

                                arr[y - k, x + (i + 1)] = " O ";

                            }

                            else if (x >= x1 && y <= y1)

                            {

                                arr[y + k, x - (i + 1)] = " O ";

                            }

                            else if (x >= x1 && y >= y1)

                            {

                                arr[y - k, x - (i + 1)] = " O ";

                            }

                            i++;

                            break;

                        }

                        else

                        {

                            if (i == xCheck + 1 && x != x1)

                            {

                                break;

                            }

                            else if (x == x1 && k == Math.Abs((y1 - y))-1)

                            {

                                i++;

                                break;

                            }

                            if (x <= x1 && y <= y1)

                            {

                                arr[y +( k + 1) , x + i ] = " O ";

                            }

                            else if (x <= x1 && y >= y1)

                            {

                                arr[y - (k + 1), x + i ] = " O ";

                            }

                            else if (x >= x1 && y <= y1)

                            {

                                arr[y + (k + 1), x - i ] = " O ";

                            }

                            else if (x >= x1 && y >= y1)

                            {

                                arr[y - (k + 1), x - i ] = " O ";

                            }

                            k++;

                        }

                    }

                    if (x == x1 && k == Math.Abs((y1 - y))-1)

                    {

                        break;

                    }

                }

                displayArray(arr);

                Console.ReadLine();

            } while (h == 0) ;

        }

        public static void createArray(string[,] arr)

        {

            //string[,] arr = new string[10, 10];

​

​

            for (int j = 0; j < 20; j++)

            {

                arr[0, j] = " # ";

                arr[19, j] = " # ";

​

            }

            for (int i = 0; i < 20; i++)

            {

                arr[i, 0] = " # ";

                arr[i, 19] = " # ";

            }

            for (int i = 1; i < 19; i++)

            {

                for (int j = 1; j < 19; j++)

                {

                    arr[i, j] = " . ";

​

                }

            }

​

        }

        public static void displayArray(string[,] arr)

        {

​

            for (int i = 0; i < 20; i++)

            {

                for (int j = 0; j < 20; j++)

                {

                    Console.Write(arr[i, j]);

​

                }

                Console.WriteLine();

            }

​

        }

        public static void chooseCoord(int[] carr, string[,] arr)

        {

            string[] input = Console.ReadLine().Split(' ');

            for (int i = 0; i < 4; i++)

            {

                carr[i] = int.Parse(input[i]);

            }

            arr[carr[1], carr[0]] = " X ";

            arr[carr[3], carr[2]] = " X ";

​

        }

    }

}