package sudokupak;

public class MySudokuModel implements SudokuModel {

    private int board [][] = new int [9][9];


    // put zeros aka 0s in all the squares
    @Override
    public void clear() {
//      System.out.println("inside clear");
        for (int row = 0; row < 9; row++) {
            for (int col = 0; col < 9; col++) {
                board [row][col] = 0;
        }

        }
        // TODO Auto-generated method stub

    }

    // return the sudoku board with a 2D array
    @Override
    public int[][] getBoard() {
//      System.out.println("inside getBoard");

        // TODO Auto-generated method stub
        return board;
    }

    // receives the sudoku board, each row ends with \n
    // checks that the board is "valid" (numbers are placed properly) and that the board is 9x9
    // if something is wrong it should throw a IllegalArgumentException

    //like so:
    //(9 rows x 9 columns)
    // 3...8....
    // .........
    // .........
    // .........
    // .........
    // ......8..

    @Override
    public void setBoard(String input) {
//      System.out.println("inside setBoard");
        // TODO Auto-generated method stub
        String[] rows = input.split("[\r\n]+");
        if (rows.length != 9) {
            throw new IllegalArgumentException();
        }
        //rows
        for (int row = 0; row < rows.length; row++) {

            String r = rows[row];
            if (r.length() != 9) {
                throw new IllegalArgumentException();
            }
            //columns
            for (int col = 0; col < r.length(); col++) {
                String s = String.valueOf(r.charAt(col));
                if (!s.matches("[0-9]")) {
                    s = "0";
                }
                int nr = Integer.valueOf(s);
                board[row][col] = nr;
            }
        }
    }

    // returns the board like so: return board [row][col]
    @Override
    public int getSquare(int row, int col) {
        return board[row][col];
    }


    // check that its allowed to put the number in the square
    // if yes, make the necessary changes and return true
    // else do nothing and return false
    @Override
    public boolean setSquare(int row, int col, int val) {
//      System.out.println("inside setSquare");
        int r = row - row%3;
        int c = col - col%3;
        for(int i = r ; i< r+3 ; i++)
        {
            for(int j = c; j < c+3 ; j++)
            {
                if(board[i][j]==val)
                {
//                  System.out.println("setSquare wtf");
                    return true;
                }
            }

        }
        return false;
    }

    //check that its allowed to put the number but make no changes
    @Override
    public boolean isLegal(int row, int col, int val) {
        return row>=0 && row<9 && col>=0 && col<9
                && val>0 && val<=9 && board[row][col]==0;
    }

    // solve the sudoku puzzle
    // iteratively search for a solution for a given puzzle
    // if solution found, return true
    // if solution not found, return false and continue loop until solution found
    @Override
    public boolean solve() {
//      System.out.println("inside solve");
        for (int row = 0; row < 9; row++) {
            for (int col = 0; col < 9; col++) {
             // we search an empty cell
             if (board[row][col] == 0) {
               // we try possible numbers
               for (int number = 1; number <= 9; number++) {
                 if (isLegal(row, col, number)) {
                   // number ok. it respects sudoku constraints
                   board[row][col] = number;

                   if (solve()) { // we start backtracking recursively
                     return true;
                   } else { // if not a solution, we empty the cell and we continue
                     board[row][col] = 0;
                   }
                }
               }

               return false; // we return false
              }
             }
            }

            return true; // sudoku solved

    }

    //copy the model
    @Override
    public SudokuModel copy() {
//      System.out.println("inside copy");
        // TODO Auto-generated method stub
        return null;
    }


}