#include <iostream>
#include <fstream>
using namespace std;

/**********************************************************************
 * This function asks the user for a filename with a sudoku board on it.
 ***********************************************************************/
void getFileName(char fileName[])
{
   cout << "Where is your board located? ";
   cin >> fileName;
}

/**********************************************************************
 * This function reads in the sudoku board.
 ***********************************************************************/
int readFile(char fileName[], char game[][9])
{
   int i = 0;
   ifstream input;
   input.open(fileName);
   if (input.fail())
      return -1;

   for (int i = 0; i < 9; i++)
      for (int j = 0; j < 9; j++)
         input >> game[i][j];

   input.close();
   return i;
}
void display(char game[][9])
{
   cout << "   A B C D E F G H I\n";
   for (int i = 0; i < 9; i++)
   {
      cout << i + 1 << "  ";
      for (int j = 0; j < 9; j++)
         if (game[i][j] == '0')
         {
            cout << " ";
            if (j == 2 || j == 5)
               cout << "|";
            else if (j == 8)
               cout << "";
            else
               cout << " ";
         }
         else if (j == 2 || j == 5)
            cout << game[i][j] << "|";
         else if (j == 8)
            cout << game[i][j];
         else
            cout << game[i][j] << " ";

      if (i == 2 || i == 5)
            cout << "\n   -----+-----+-----" << endl;
      else
         cout << endl;

   }
}
bool checkSquare(int row, int col, char board[][9], int value)
{
   for (int i = 0; i < 9; i++)
      if (board[row][i] == value)
         return false;
   for (int i = 0; i < 9; i++)
      if (board[i][col] == value)
         return false;
   int startX = row/3 * 3;
   int startY = col/3 * 3;

   for (int i = startX; i < startX + 3; i++)
      for (int j = startY; j < startY + 3; j++)
         if (board[i][j] == value)
            return false;
   return true;

}
void editSquare(char game[][9])
{
   bool a = 0;
   int x;
   int y;
   char input[3];
   char value;
   cout << "What are the coordinates of the square: ";
   cin >> input;
   x = input[1] - '1';
   y = input[0] - 'A';


   if (game[x][y] != '0')
   {
      cout << "ERROR: Square '" << input << "' is filled\n";
      //     cout << endl;
   }
   else
   {
      cout << "What is the value at '" << input << "': ";
      cin >> value;
      // cout0 << endl;
      int i = value;
      if (checkSquare(y, x, game, i))
            game[x][y] = value;
         else
         {

            while(bool a = 0)
               cout << "ERROR: Value '" << value << "' in square '" << input[0] << input[1] << "' is invalid\n";
            bool a = 1;
         }
         }
   cout << endl;

}
void showValues(char board[][9])
{
   int x;
   int y;
   int count = 0;
   char input[3];
   cout << "What are the coordinates of the square: ";
   cin >> input;
   x = input[1] - '1';
   y = input[0] - 'A';

   if (board[x][y] != '0')
      cout << "Error at coord " << y + 'A' << x + '1' << "is already filled.\n";
   else
   {
      cout << "Possible values are: ";
      for (int i = 0; i < 9; i++)
         if (checkSquare(x, y, board, i + '0'))
         {
            if (count == 0)
               cout << i;
            else
               cout << ", " << i;
            count++;
                           }
      cout << endl;
   }

}

void gameLoop(char data[][9])
{
  cout << endl;
   char input;
    do
    {
       cout << "> ";
       cin >> input;
       switch (input)
       {
          case '?':
             cout << "Options:\n";
             cout << "   ?  Show these instructions\n";
             cout << "   D  Display the board\n";
             cout << "   E  Edit one square\n";
             cout << "   S  Show the possible values for a square\n";
             cout << "   Q  Save and Quit\n";
             cout << endl << endl;
             break;
          case 'D':
             display(data);
             cout << endl;
             break;
          case 'E':
             editSquare(data);
             break;
          case 'Q':
             break;
          case 'S':
             showValues(data);
             break;
          default:
             cout << "Incorrect input\n";
             break;
       }
    }
    while (input != 'Q');

}

void getFileName2(char fileName[])
{
   cout << "What file would you like to write your board to: ";
   cin >> fileName;
}
int writeFile(char fileName[], char game[][9])
{
   int i = 0;
   ofstream output;
   output.open(fileName);
   if (output.fail())
      return -1;

   for (int i = 0; i < 9; i++)
      for (int j = 0; j < 9; j++)
         output << game[i][j];

   output.close();
   return i;
}
int main()
{

   char fileName[256];
   char data[9][9];
   char input;

   getFileName(fileName);
   int size = readFile(fileName, data);
   if (size == -1)
      cout << "Bad file " << fileName << endl;
   else
   {
      cout << "Options:\n";
      cout << "   ?  Show these instructions\n";
      cout << "   D  Display the board\n";
      cout << "   E  Edit one square\n";
      cout << "   S  Show the possible values for a square\n";
      cout << "   Q  Save and Quit\n";
      cout << endl;

      display(data);
   }
   gameLoop(data);

   getFileName2(fileName);
   writeFile(fileName, data);
   cout << "Board written successfully\n";
   return 0;
}