"""Small-thumbnail quality heuristics. Never delete or modify source photos."""

import hashlib
from io import BytesIO

from PIL import Image, ImageFilter, ImageOps, ImageStat


def photo_quality(data):
    with Image.open(BytesIO(data)) as source:
        image = ImageOps.exif_transpose(source).convert("L")
        image.thumbnail((256, 256))
        brightness = ImageStat.Stat(image).mean[0]
        edges = image.filter(ImageFilter.FIND_EDGES)
        sharpness = ImageStat.Stat(
            edges.crop((2, 2, max(3, image.width - 2), max(3, image.height - 2)))
        ).var[0]
        small = image.resize((9, 8))
        pixels = list(small.tobytes())
        bits = "".join(
            "1" if pixels[y * 9 + x] > pixels[y * 9 + x + 1] else "0"
            for y in range(8)
            for x in range(8)
        )
        return {
            "brightness": round(brightness, 2),
            "sharpness": round(sharpness, 2),
            "fingerprint": f"{int(bits, 2):016x}",
            "sha256": hashlib.sha256(data).hexdigest(),
        }


def passes(result, source):
    return (
        result["sharpness"] >= source.minimum_sharpness
        and source.minimum_brightness
        <= result["brightness"]
        <= source.maximum_brightness
    )