import os
from pathlib import Path
from typing import Union

import cv2
import numpy as np
from basicsr.archs.rrdbnet_arch import RRDBNet
from basicsr.utils.download_util import load_file_from_url
from PIL import Image
from realesrgan import RealESRGANer
from util.commons import read_url


class Upscaler:
    __model_esrgan_url = "https://github.com/xinntao/Real-ESRGAN/releases/download/v0.1.0/RealESRGAN_x4plus.pth"
    __model_esrgan_anime_url = "https://github.com/xinntao/Real-ESRGAN/releases/download/v0.2.2.4/RealESRGAN_x4plus_anime_6B.pth"

    def load(self):
        download_dir = Path(Path.home() / ".cache" / "realesrgan")
        download_dir.mkdir(parents=True, exist_ok=True)

        self.__model_path = self.__preload_model(self.__model_esrgan_url, download_dir)
        self.__model_path_anime = self.__preload_model(
            self.__model_esrgan_anime_url, download_dir
        )

    def upscale(self, image: Union[str, bytes]) -> bytes:
        model = RRDBNet(
            num_in_ch=3,
            num_out_ch=3,
            num_feat=64,
            num_block=23,
            num_grow_ch=32,
            scale=4,
        )
        return self.__internal_upscale(image, self.__model_path, model)

    def upscale_anime(self, image: Union[str, bytes]) -> bytes:
        model = RRDBNet(
            num_in_ch=3,
            num_out_ch=3,
            num_feat=64,
            num_block=23,
            num_grow_ch=32,
            scale=4,
        )
        return self.__internal_upscale(image, self.__model_path_anime, model)

    def __preload_model(self, url: str, download_dir: Path):
        name = url.split("/")[-1]
        if not os.path.exists(str(download_dir / name)):
            return load_file_from_url(
                url=url,
                model_dir=str(download_dir),
                progress=True,
                file_name=None,
            )
        else:
            return str(download_dir / name)

    def __internal_upscale(
        self,
        image: Union[str, bytes],
        model_path: str,
        rrbdnet: RRDBNet,
    ) -> bytes:
        if type(image) is str:
            image = read_url(image)

        upsampler = RealESRGANer(
            scale=4, model_path=model_path, model=rrbdnet, half="fp16", gpu_id="0"
        )
        image_array = np.frombuffer(image, dtype=np.uint8)
        input_image = cv2.imdecode(image_array, cv2.IMREAD_COLOR)
        output, _ = upsampler.enhance(input_image, outscale=4)
        out_bytes = cv2.imencode(".png", output)[1].tobytes()
        return out_bytes