main.py

import time

from kivy.app               import App
from kivy.uix.label         import Label
from kivy.uix.textinput     import TextInput
from kivy.uix.floatlayout   import FloatLayout
from kivy.clock             import Clock

from sudoku import Sudoku

class SudokuGame(FloatLayout):
    # Initialize the grid of text inputs
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.text_inputs    = []
        self.error_messages = []

        grid = self.ids["grid"]
        for i in range(81):
            text_input = SudokuCell()
            grid.add_widget(text_input)
            self.text_inputs.append(text_input)

        # Test grid: supposedly the most complicated Sudoku in the world
        # self.text_inputs[ 0].text = "8";
        # self.text_inputs[11].text = "3";
        # self.text_inputs[12].text = "6";
        # self.text_inputs[19].text = "7";
        # self.text_inputs[22].text = "9";
        # self.text_inputs[24].text = "2";
        # self.text_inputs[28].text = "5";
        # self.text_inputs[32].text = "7";
        # self.text_inputs[40].text = "4";
        # self.text_inputs[41].text = "5";
        # self.text_inputs[42].text = "7";
        # self.text_inputs[48].text = "1";
        # self.text_inputs[52].text = "3";
        # self.text_inputs[56].text = "1";
        # self.text_inputs[61].text = "6";
        # self.text_inputs[62].text = "8";
        # self.text_inputs[65].text = "8";
        # self.text_inputs[66].text = "5";
        # self.text_inputs[70].text = "1";
        # self.text_inputs[73].text = "9";
        # self.text_inputs[78].text = "4";

    # Get the value in a given cell
    # Return 0 if no value is specified
    def get_value(self, row, col):
        text  = self.text_inputs[9 * row + col].text
        return int(text) if len(text) > 0 else 0

    # Solve the current board
    def solve(self):
        # Read values from the grid
        values = [[self.get_value(row, col) for col in range(9)] for row in range(9)]
        # Try to solve the Sudoku
        solver = Sudoku(values)
        if solver.solve():
            for row in range(9):
                for col in range(9):
                    self.text_inputs[9 * row + col].text = str(solver.get_value(row, col))
        else:
            error_message = ErrorMessage()
            self.error_messages.append(error_message)
            self.add_widget(error_message)
            Clock.schedule_once(self.remove_error_message, 2)

    # Remove the last error message on screen
    def remove_error_message(self, dt):
        error_message = self.error_messages.pop()
        self.remove_widget(error_message)

    # Remove all values on the board
    def clear(self):
        for text_input in self.ids["grid"].children:
            text_input.text = ""


class SudokuCell(TextInput):
    pass


class ErrorMessage(Label):
    pass


class SudokuApp(App):
    def build(self):
        return SudokuGame()


if __name__ == '__main__':
    SudokuApp().run()