#include "Grid.h"
#include "iostream"
#include "vector"
#include <math.h>

bool Grid::checkPossible(unsigned int digit, unsigned int columnNr, unsigned int lineNr) {

    for (int i = 0; i < 9; ++i) {
        if(_grid[lineNr][i] == digit)
            return false;
    }
    for (int i = 0; i < 9; ++i) {
        if(_grid[i][columnNr] == digit)
            return false;
    }
    unsigned int columnNr0 = (std::floor(columnNr/3))*3;
    unsigned int lineNr0 = (std::floor(lineNr/3))*3;
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
            if(_grid[columnNr0+i][lineNr0+j] == digit)
                return false;
        }
    }
    return true;
}

bool Grid::checkFinished() {
    for (unsigned int i = 0; i < 9; i++)
    {
        for (unsigned int j = 0; j < 9; j++)
        {
            if (_grid[j][i] == 10) {
                return false;
            }
        }
    }
    return true;
}

void Grid::print() {
    std::cout << "-------" << std::endl;
    for (unsigned x = 0; x < 9; x++)
    {
        for (unsigned int y = 0; y < 9; y++)
        {
            std::cout << _grid[x][y] << " ";
        }
        std::cout << std::endl;
    }
    std::cout << std::endl << "------" << std::endl;
}

bool Grid::solve() {
    for (unsigned int x = 0; x < 9 ; x++)
    {
        for (unsigned int y = 0; y < 9; y++)
        {
            if (checkFinished())
            {
                Grid::print();
                return true;
            }

            if (_grid[y][x] == 10) {
                for (unsigned int i = 1; i < 10; i++)
                {
                    if (checkPossible(i, x, y)) {
                        _grid[y][x] = i;
                        if (Grid::solve())
                            return true;
                        _grid[y][x] = 10;
                    }
                }
            }
        }
    }
    return false;
}