#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
Usage: python3 dupeframes.py image.png...

Check for duplicate frames in Pokemon sprites (vertical strips of square frames).

Copyright (c) 2024, Rangi42
SPDX-License-Identifier: MIT
"""

import sys

import png

def duplicate_frames(filename):
	with open(filename, 'rb') as file:
		width, height, rows = png.Reader(file).asRGBA8()[:3]
		rows = list(rows)
	if height % width:
		print(f'{filename} is not a vertical strip of square frames!', file=sys.stderr)
		return
	num_frames = height // width
	frames = [rows[i*width:(i+1)*width] for i in range(num_frames)]
	yield from ((i, j) for i in range(num_frames) for j in range(i+1, num_frames) if frames[i] == frames[j])

def main():
	if len(sys.argv) < 2:
		print(f'Usage: {sys.argv[0]} image.png...', file=sys.stderr)
		sys.exit(1)
	for filename in sys.argv[1:]:
		if not filename.lower().endswith('.png'):
			print(f'{filename} is not a .png file!', file=sys.stderr)
		else:
			for (i, j) in duplicate_frames(filename):
				print(f'{filename}: frame {j} is a duplicate of frame {i}')

if __name__ == '__main__':
	main()