#!/usr/bin/env python3

import argparse
from PIL import Image
from collections import OrderedDict

__doc__ = """Utility for stripping non-unique tiles from a tileset image.
Outputs the uniquified image, and an index map file from original tile indices
to new tile indices."""

parser = argparse.ArgumentParser()
parser.add_argument("input", help="Input file name")
parser.add_argument("output", help="Output file name")
parser.add_argument("--tilesize", "-t", help="Tile size (pixels), default 8",
	default="8", choices=["8", "16"])
parser.epilog = __doc__
args = parser.parse_args()

img = Image.open(args.input)
tilesize = int(args.tilesize)

tile_first_seen = {}
index_mapping = []
output_images = []

src_index = 0
for y in range(0, img.height - (tilesize - 1), tilesize):
	for x in range(0, img.width - (tilesize - 1), tilesize):
		tile = img.crop((x, y, x + tilesize, y + tilesize))
		tiledata = tuple(tile.getdata())
		if tiledata in tile_first_seen:
			index_mapping.append((src_index, tile_first_seen[tiledata]))
		else:
			tile_first_seen[tiledata] = len(output_images)
			index_mapping.append((src_index, len(output_images)))
			output_images.append(tile)
		src_index += 1

print("Found {} unique tile images".format(len(output_images)))

oimg = Image.new("RGBA", (tilesize * len(output_images), tilesize))
for i, tile in enumerate(output_images):
	oimg.paste(tile, (i * tilesize, 0))

with open(args.output, "wb") as ofile:
	oimg.save(ofile)
with open(args.output + ".index_map", "w") as mapfile:
	for old, new in index_mapping:
		mapfile.write("{}, {}\n".format(old, new))