from time import sleep
from random import randint
import pygame

def createScreen():
    print 'available resolutions', pygame.display.list_modes(0)
    #@todo make this a command line switch
    #the next two lines set up full screen options, to run in a window see below
    screen_width, screen_height = pygame.display.list_modes(0)[0] 
    # we use the 1st resolution which is the largest, and ought to give us the full multi-monitor
    options = pygame.FULLSCREEN | pygame.HWSURFACE | pygame.DOUBLEBUF        
    
    #the next two lines set up windowed options - swap these with above to run full screen instead
    #screen_width, screen_height = (600,600)
    #options=0
    
    #create the screen with the options
    screen = pygame.display.set_mode(
        (screen_width, screen_height), options)
    print "screen created, size is:", screen.get_size()
    return screen
    
def evolve_cell(alive, neighbours):
    return neighbours == 3 or (alive and neighbours == 2)

def count_neighbours(grid, position):
    x,y = position
    neighbour_cells = [(x - 1, y - 1), (x - 1, y + 0), (x - 1, y + 1),
                       (x + 0, y - 1),                 (x + 0, y + 1),
                       (x + 1, y - 1), (x + 1, y + 0), (x + 1, y + 1)]
    count = 0
    for x,y in neighbour_cells:
        if x >= 0 and y >= 0:
            try:
                count += grid[x][y]
            except:
                pass
    return count

def make_empty_grid(x, y):
    grid = []
    for r in range(x):
        row = []
        for c in range(y):
            row.append(0)
        grid.append(row)
    return grid

def make_random_grid(x, y):
        grid = []
        for r in range(x):
            row = []
            for c in range(y):
                row.append(randint(0,1))
            grid.append(row)
        return grid

def evolve(grid):
    x = len(grid)
    y = len(grid[0])
    new_grid = make_empty_grid(x, y)
    for r in range(x):
        for c in range(y):
            cell = grid[r][c]
            neighbours = count_neighbours(grid, (r, c))
            new_grid[r][c] = 1 if evolve_cell(cell, neighbours) else 0
    return new_grid

BLACK = (0, 0, 0)

def draw_block(x, y, alive_color):
    block_size = 9
    x *= block_size
    y *= block_size
    center_point = ((x + (block_size / 2)), (y + (block_size / 2)))
    pygame.draw.circle(screen, alive_color, center_point, block_size / 2,0)

#this is where we register our event listeners
#yes, we're just calling methods
#@todo create proper event listeners
def handleInputEvents(xlen, ylen):
    for event in pygame.event.get():
        if(event.type == pygame.MOUSEBUTTONDOWN):
            if(event.button==1): #left click
                global world
                world = make_random_grid(xlen, ylen)
        if(event.type == pygame.KEYDOWN):
            sys.exit(0) #quit on any key
        if (event.type == pygame.QUIT):  #pygame issues a quit event, for e.g. by closing the window
            print "quitting"
            sys.exit(0)
            
            
def main():

    pygame.init()
    clock = pygame.time.Clock()
    global screen 
    screen = createScreen()
    (xmax,ymax)= screen.get_size()
    h = 0
    cell_number = 0
    alive_color = pygame.Color(0,0,0)
    alive_color.hsva = [h, 100, 100]
    xlen = xmax / 9
    ylen = ymax / 9
    global world
    world = make_random_grid(xlen, ylen)
    while True:
            handleInputEvents(xlen, ylen)
            clock.tick(40)
            for x in range(xlen):
                for y in range(ylen):
                    alive = world[x][y]
                    cell_number += 1
                    cell_color = alive_color if alive else BLACK
                    draw_block(x, y, cell_color)
            pygame.display.flip()
            h = (h + 2) % 360
            alive_color.hsva = (h, 100, 100)
            world = evolve(world)
            cell_number = 0

if __name__ == '__main__':
    main()