#include <iostream>
using namespace std;
void clear(char board[3][3]);
void display(const char board[3][3]);
void takeTurn(char board[3][3], char &nextPlayer);
char winner(char board[3][3]);

void clear(char board[3][3]){

  for(int i = 0; i <= 2; i++)
    for(int j = 0; j <= 2; j++)
       board[i][j] = ' ';
}

void display(const char board[3][3]){


  for(int i = 0; i <= 2; i++) {
    for(int j = 0; j <= 2; j++) {
       cout << board[i][j];
         if (j < 2)
           cout << "|";

     }
    if(i < 2)
    cout << endl << "-----" ;
    cout << endl;
   }


}

void takeTurn(char board[3][3], char &nextPlayer) {
   int row, column;

   //if the data that is entered is valid then this variable will be 1
   //otherwise if the row or column is out of range it's 0
   //otherwise if it already contain something it's 0
   int is_valid = 0;

   while (is_valid != 1) {

     cout << "It is now " << nextPlayer << "'s turn." << endl;
     cout << "Please enter your move in the form row column" << endl;
     cout << "So 0 0 would be the top left, and 0 2 would be the top right" << endl;

     cin >> row >> column;

     is_valid = 1;

     // check to see if the input is in the valid range
     if ( (row < 0) || (row > 2) || (column < 0) || (column > 2) ) {
       cout << "Invalid entry: row and column must both be between 0 and 2 (inclusive)." << endl;
       cout << "Please try again." << endl;
       is_valid = 0;
     }

     // then check to see if there is something already there
     if ( board[row][column] != ' ') {
       cout << "Invalid entry: Row " << row << "at Column " << column << " already contains: " << board[row][column] << endl;
       is_valid = 0;
     }


   }

   board[row][column] = nextPlayer;

   if (nextPlayer == 'X') {  nextPlayer = 'O'; return; }
   if (nextPlayer == 'O') {  nextPlayer = 'X' ; return;}
}

char winner(char board[3][3]) {


    //check to see if any rows are all X
    for (int i=0; i <=2; i++) {
       if (board[i][0] == 'X' && board[i][1] == 'X' && board[i][2] == 'X') {
           display(board);
           cout << "Congratulations, X YOU WON!" << endl;
           return 'X';
       }
    }

    // check to see if any columns are all X
    for (int i=0; i <=2; i++) {
       if (board[0][i] == 'X' && board[1][i] == 'X' && board[2][i] == 'X') {
           display(board);
           cout << "Congratulations, X YOU WON!" << endl;
           return 'X';
       }
    }



    //check to see if any rows are all O
    for (int i=0; i <=2; i++) {
       if (board[i][0] == 'O' && board[i][1] == 'O' && board[i][2] == 'O') {
           display(board);
           cout << "Congratulations, O YOU WON!" << endl;
           return 'O';
        }
    }

    // check to see if any columns are all X
    for (int i=0; i <=2; i++) {
       if (board[0][i] == 'O' && board[1][i] == 'O' && board[2][i] == 'O') {
           display(board);
           cout << "Congratulations, O YOU WON!" << endl;
           return 'O';
       }
    }

   //check the left to right diagonal to see if there is a winner
   if (board[0][0] == 'X' && board[1][1] == 'X' && board [2][2] == 'X') {
          display(board);
          cout << "Congratulations, X YOU WON!" << endl;
          return 'X';
   }

   if (board[0][0] == 'O' && board[1][1] == 'O' && board [2][2] == 'O') {
          display(board);
          cout << "Congratulations, O YOU WON!" << endl;
          return 'O';
   }

  //check to see if the right to left diagonal is a winner
  if (board[0][2] == 'X' && board[1][1] == 'X' && board[2][0] == 'X') {
       display(board);
       cout << "Congratulations, X YOU WON!" << endl;
       return 'X';
  }

   if (board[0][2] == 'O' && board[1][1] == 'O' && board[2][0] == 'O') {
       display(board);
       cout << "Congratulations, O YOU WON!" << endl;
       return 'O';
  }

  //now check to see if we have filled all the board positions
  //since we have checked for all the possible wining combinations
  //at this point, if the board is filled, it must be a tie
  int is_tie = 1;
  for (int i = 0; i <=2; i++) {
    for (int j = 0; j <=2; j++) {
       if (board[i][j] == ' ') {  is_tie = 0; }
    }
  }
  if (is_tie == 1) {
     display(board);
     cout << "Nobody won.  Please play again.";
     return '?';
  }

  //Finally, if there is no winner, and there is no tie, then we will return a ' ' meaning that the game is still
  // active and we will play another round
  return ' ';

}

int main()
{

  char board[3][3];
  char nextPlayer;
  char winningPlayer;

  clear(board);

  //winningPlayer can be:
  //' ' no winner yet
  //?  tie
  //X  X wins
  //O  O wins
  winningPlayer = ' ';
  nextPlayer = 'X';

  /*
  board[0][0] = 'X';
  board[2][1] = 'O';
  board[1][2] = 'X';
  board[1][1] = 'O';
  board[2][0] = 'X';
  board[0][1] = 'O';*/

  while (winningPlayer == ' '){
     display(board);
     takeTurn(board, nextPlayer);
     winningPlayer = winner(board);
  }

  return 0;
}