#!/usr/bin/env python3
"""Prepare a reference for feature matching without changing its artwork."""
import argparse
from pathlib import Path
from PIL import Image

def main():
    p = argparse.ArgumentParser()
    p.add_argument('--input', required=True)
    p.add_argument('--output', required=True)
    p.add_argument('--target', type=int, default=1024)
    a = p.parse_args()
    im = Image.open(a.input).convert('RGBA')
    longest = max(im.width, im.height)
    if longest < a.target:
        scale = a.target / longest
        size = (max(1, round(im.width * scale)), max(1, round(im.height * scale)))
        # Nearest-neighbour preserves pixel-art edges and transparency.
        im = im.resize(size, Image.Resampling.NEAREST)
    im.save(a.output)
    print(f'Reference prepared: {im.width}x{im.height}')

if __name__ == '__main__': main()