#!/usr/bin/python
# -*- coding: utf-8 -*-
"""Wang tile paint program.

This fills the screen with a random array of Wang tiles and invites
you to paint on them.

"""
from random import randrange as rand

import pygame
from pygame import display, image, mixer, event, draw


tile_size = 64


def decompose(pos):
    x, y = pos
    return x // tile_size, y // tile_size, x % tile_size, y % tile_size


def draw_line(s, start, end, color, tiles):
    ww, hh = s.get_size()
    stx, sty, sx, sy = decompose(start)
    etx, ety, ex, ey = decompose(end)

    # XXX this needs to be revamped to break the line into a part for
    # each tile that it crosses
    ex += tile_size * (etx - stx)
    ey += tile_size * (ety - sty)

    d = 8
    surface = pygame.Surface((8, 8), pygame.SRCALPHA)
    draw.ellipse(surface, color, surface.get_rect())

    for yo, tile_row in zip(range(0, hh, tile_size), tiles):
        for xo, tile in zip(range(0, ww, tile_size), tile_row):
            if tile == tiles[sty][stx]:
                s.blit(surface, (xo+ex-d/2, yo+ey-d/2))
                #draw.ellipse(s, color, (xo+ex-4, yo+ey-4, 8, 8))
                #draw.line(s, color, (xo+sx, yo+sy), (xo+ex, yo+ey), 2)


def main():
    s = display.set_mode((0, 0))
    ww, hh = s.get_size()
    # Wang tiles have a “color” on each of their four sides, and the
    # color must be the same for adjacent sides.  So here we choose
    # the colors for the sides at random and use that to determine
    # each tile.
    ncolors = 2
    # Colors of vertical edges.
    vcolors = [[rand(ncolors) for x in range(0, ww+tile_size, tile_size)]
               for y in range(0, hh+tile_size, tile_size)]
    # Colors of horizontal edges.
    hcolors = [[rand(ncolors) for x in range(0, ww+tile_size, tile_size)]
               for y in range(0, hh+tile_size, tile_size)]
    tiles = [[(vcolors[i][j], vcolors[i+1][j],
              hcolors[i][j], hcolors[i][j+1])
              for j in range(len(vcolors[0])-1)]
             for i in range(len(vcolors)-1)]
    #print tiles

    draw_pos = None
    alpha = 32
    color = pygame.Color(64, 64, 192, alpha)
    while True:
        ev = event.poll()

        if ev.type == pygame.QUIT:
            break

        elif ev.type == pygame.MOUSEBUTTONDOWN:
            draw_pos = ev.pos

        elif ev.type == pygame.MOUSEMOTION:
            if draw_pos:
                draw_line(s, draw_pos, ev.pos, color, tiles)
                draw_pos = ev.pos

        elif ev.type == pygame.MOUSEBUTTONUP:
            draw_pos = None

        elif ev.type == pygame.KEYDOWN:
            if ev.unicode in 'cC':
                color = pygame.Color(rand(256), rand(256), rand(256), alpha)
            elif ev.unicode in 'dD':
                s.fill(0)
            elif ev.unicode in '\033':
                break

        display.flip()


if __name__ == '__main__':
    main()