"""HEIC/HEIF thumbnailer for the freedesktop (GNOME/GTK) thumbnail system.

Decodes a HEIC/HEIF file's SDR base image with pillow-heif (which bundles a
modern libheif) and writes a PNG thumbnail.  Used on Linux systems whose
*system* libheif is too old to thumbnail iPhone HDR HEICs; installed under
/usr/local by scripts/install_heic_thumbnailer.sh so it is reachable inside
GNOME's bwrap thumbnailer sandbox (which binds /usr but not $HOME).

Invoked by the thumbnail system as:  ... -s SIZE INPUT OUTPUT
"""
import sys


def main(argv):
    args = argv[1:]
    size, rest = 256, []
    i = 0
    while i < len(args):
        if args[i] == "-s":
            size = int(args[i + 1]); i += 2
        else:
            rest.append(args[i]); i += 1
    if len(rest) < 2:
        sys.stderr.write("usage: heic_thumbnailer.py -s SIZE INPUT OUTPUT\n")
        return 2
    inp, outp = rest[0], rest[1]

    import pillow_heif
    pillow_heif.register_heif_opener()
    from PIL import Image

    im = Image.open(inp)
    im.load()
    im = im.convert("RGB")
    im.thumbnail((size, size), Image.LANCZOS)
    im.save(outp, "PNG")
    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv))