import os
from typing import NamedTuple

from PIL import Image

pillow_extensions = {
    ext for ext, f in Image.registered_extensions().items() if f in Image.OPEN
}


class ThumbnailParameters(NamedTuple):
    bounds: tuple[int, int]
    options: dict


def params_from(config):
    return {
        "full": ThumbnailParameters(
            bounds=(
                config.getint("import.scale.full", "width", fallback=4200),
                config.getint("import.scale.full", "height", fallback=2000),
            ),
            options={"quality": 82, "method": 5},
        ),
        "thumb": ThumbnailParameters(
            bounds=(
                config.getint("import.scale.thumb", "width", fallback=1680),
                config.getint("import.scale.thumb", "height", fallback=800),
            ),
            options={"quality": 75, "method": 5},
        ),
    }


def object_path(directory, hash, suffix):
    return os.path.join(directory, hash[:2], f"{hash[2:]}_{suffix}.webp")


class Thumbnailer:
    def __init__(self, directory, params):
        self.directory = directory
        self.params = params

    @classmethod
    def can_process(cls, extension):
        return extension in pillow_extensions

    def object(self, hash, suffix):
        return object_path(self.directory, hash, suffix)

    def process(self, handle, hash, reprocess=False):
        size = None

        for suffix, parameters in self.params.items():
            source = Image.open(handle, mode="r")

            if not size:
                size = source.size

            output = self.object(hash, suffix)

            if os.path.exists(output) and not reprocess:
                continue
            else:
                os.makedirs(os.path.dirname(output), exist_ok=True)

            if source.mode != "RGB":
                target = source.convert()
            else:
                target = source

            target.thumbnail(parameters.bounds, resample=Image.Resampling.LANCZOS)
            target.save(output, **parameters.options)

        return size