import pygame

def create_grid(rows, cols):
    """
    This function creates and returns a list of lists, intended to
    represent a grid. All of the grid cells are filled with 0.
    """
    grid = []
    for r in range(0,rows):
        row = []
        for c in range(0, cols):
            row = row + [0]
        grid = grid + [row]
    return grid


def draw_grid(win, grid, x_offset, y_offset, size, margin):
    """
    This function takes a grid representation and draws it. 0 is
    represented as magenta, 1 as orange.
    """
    
    for row_index in range(0,len(grid)):
        for col_index in range(0, len(grid[row_index])):
            if grid[row_index][col_index] == 0:
                color = pygame.color.Color("darkmagenta")
            else:
                color = pygame.color.Color("orange")
            x = col_index*(size+margin) + x_offset
            y = row_index*(size+margin) + y_offset
            pygame.draw.rect(win,color,(x, y, size, size))


def run_game():
    
    ## Initialize the pygame submodules and set up the display window.

    pygame.init()

    width = 650
    height = 620
    my_win = pygame.display.set_mode((width,height))


    ## Initialize game objects.
    rows = 50
    cols = 50
    x_offset = 0
    y_offset = 0
    margin = 2
    size = 10
    grid = create_grid(50, 50)
    
    ## The game loop starts here.
    
    keepGoing = True    
    while (keepGoing):

        ## Handle events.

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                keepGoing = False
            elif event.type == pygame.MOUSEBUTTONDOWN:

                (mouse_x, mouse_y) = event.pos

                # mouse click on the grid
                if (mouse_x >= x_offset and mouse_x <= x_offset + (margin + size) * rows
                    and mouse_y >= y_offset and mouse_x <= y_offset + (margin + size) * cols):

                    col = (mouse_x - x_offset) / (size + margin)
                    row = (mouse_y - y_offset) / (size + margin)
                    if grid[row][col] == 0:
                        grid[row][col] = 1
                    else:
                        grid[row][col] = 0


        ## Update game objects.

        ## Draw picture and update display.

        my_win.fill(pygame.color.Color("lightblue"))

        draw_grid(my_win, grid, x_offset, y_offset, size, margin)

        pygame.display.update()

    ## The game loop ends here.

    pygame.quit()


## Call the function run_game.

run_game()