import os, random, sys
# if you're using Pillow use this
from PIL import Image
# if you're using PIL you can just import Image
from collections import defaultdict


# Build a table keyed by rgb tuples and returning a list of tuples consisting of the
# color of each neighboring pixel and its relative position. For example ((39, 20, 13), (-1, -1))
def buildTable( imageFilename ):

    im = Image.open(imageFilename)
    table = defaultdict(list)
    w, h = im.size
    print w*h

    for x in xrange(w):
        for y in xrange(h):
            p = im.getpixel((x, y))
            # for each of the pixel's neighbors
            for x2 in xrange(-1, 2):
                for y2 in xrange(-1, 2):
                    if x2 == 0 and y2 == 0:
                        continue
                    pn = im.getpixel( ((x+x2)%w, (y+y2)%h) )
                    table[p].append((pn, (x2, y2)))

    print len(table)
    #im.close()
    return table

# Draw in the pixel and all of its neighbors, choose a random neighbor, repeat
def markovImage4( imageFilename, width=512, height=512, table=None ):

    if not table:
        table = buildTable(imageFilename)

    x = width/2
    y = height/2
    color = random.choice(table.keys())
    im = Image.new("RGB", (width, height), color)
    # This is a random walk so you're not guaranteed to hit every pixel
    # but doing w*h iterations is enough to get most of them
    for i in xrange( width*height ):

        im.putpixel((x, y), color)
        neighbors = table[color]
        n_neighbors = len(neighbors)
        # Just grab a random point in the list of neighbors and take it
        # and the next 7. They probably won't all be original neighbors.
        start = random.randint(0, n_neighbors-1)
        for j in xrange(start, start+8):
            n = neighbors[j%n_neighbors]
            color = n[0]
            offset = n[1]
            xo = (x+offset[0])%width
            yo = (y+offset[1])%height
            im.putpixel((xo, yo), color)
        # Since we picked a random neighbor to start with we can just use
        # j to pick the next point
        n = neighbors[j%n_neighbors]
        color = n[0]
        # using a multiplier of 4 creates a grid
        x = (x+3*n[1][0]) % width
        y = (y+3*n[1][1]) % height

    outFilename = "markovImage4 - %s.png" % (imageFilename.split(".")[0])
    out = open(outFilename, 'wb')
    im.save(out, "PNG")
    out.close()