#!/usr/bin/env python3
# The Picture row's check (FORGE.md 14.18):  the screenshots an original and its port took at the
# same moments (compare.sh with PORT_SHOTS=N and SINGE_SHOTS=<dir>), paired by number, and how much
# of each picture differs.  A pixel differs when any channel is more than TOLERANCE apart, since
# the two runs decode the same video but may round a scaled frame differently.
#
#     testScripts/ports/shotDiff.py <shots dir> [<out dir>]
#
# prints one line a pair and a summary;  with <out dir>, writes each pair side by side with the
# differing pixels marked in the third panel, for a person to look at.
import os
import re
import sys

import numpy
from PIL import Image

TOLERANCE = 24          # Per channel, out of 255:  video rounding, not a missing prompt
MARK      = (255, 0, 255)
PAIR      = re.compile(r"^(original|port)-shot-((?:run\d+-)?\d+)-(\w+)\.png$")


def main():
    shots = sys.argv[1] if len(sys.argv) > 1 else sys.exit("usage:  shotDiff.py <shots dir> [<out dir>]")
    out   = sys.argv[2] if len(sys.argv) > 2 else None
    found = {}

    for name in os.listdir(shots):
        match = PAIR.match(name)
        if match:
            found.setdefault((match.group(2), match.group(3)), {})[match.group(1)] = os.path.join(shots, name)
    if out:
        os.makedirs(out, exist_ok=True)
    worst = 0.0
    for (number, why), pair in sorted(found.items()):
        if "original" not in pair or "port" not in pair:
            print("%s %-6s  only the %s took it" % (number, why, "original" if "original" in pair else "port"))
            continue
        a = numpy.asarray(Image.open(pair["original"]).convert("RGB"), dtype=numpy.int16)
        b = numpy.asarray(Image.open(pair["port"]).convert("RGB"), dtype=numpy.int16)
        if a.shape != b.shape:
            print("%s %-6s  sizes differ:  %s and %s" % (number, why, a.shape, b.shape))
            continue
        differs = (numpy.abs(a - b) > TOLERANCE).any(axis=2)
        percent = 100.0 * differs.mean()
        worst   = max(worst, percent)
        print("%s %-6s  %6.2f%% of the picture differs" % (number, why, percent))
        if out:
            marked          = a.copy()
            marked[differs] = MARK
            side            = numpy.concatenate([a, b, marked], axis=1).astype(numpy.uint8)
            Image.fromarray(side).save(os.path.join(out, "%s-%s.png" % (number, why)))
    print("%d pairs;  the worst differs in %.2f%% of its picture" % (len(found), worst))


if __name__ == "__main__":
    main()