from __future__ import annotations

import imghdr
from io import BytesIO
from pathlib import Path
from tempfile import NamedTemporaryFile
from time import time

from fastapi import UploadFile
from PIL import Image, ImageFilter
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.user import User


ALLOWED_IMAGE_TYPES = {"jpeg", "png"}
UPLOAD_ROOT = Path(__file__).resolve().parent.parent / "static" / "uploads"


def _validate_image(content: bytes) -> str:
    image_type = imghdr.what(None, h=content)
    if image_type not in ALLOWED_IMAGE_TYPES:
        raise ValueError("仅支持 jpg/png 图片")
    return image_type


def _save_optimized_variants(content: bytes) -> tuple[str, str, str]:
    _validate_image(content)

    with Image.open(BytesIO(content)) as image:
        image = image.convert("RGB")
        image.thumbnail((800, 800))

        with NamedTemporaryFile(delete=False, suffix=".jpg") as main_file:
            image.save(main_file.name, format="JPEG", quality=85)
            main_path = main_file.name

        blur_image = image.filter(ImageFilter.GaussianBlur(radius=15))
        with NamedTemporaryFile(delete=False, suffix="_blur.jpg") as blur_file:
            blur_image.save(blur_file.name, format="JPEG", quality=80)
            blur_path = blur_file.name

    timestamp = str(int(time()))
    return main_path, blur_path, timestamp


def _persist_avatar_files(user_id: int, timestamp: str, main_path: str, blur_path: str) -> tuple[str, str]:
    user_dir = UPLOAD_ROOT / "avatars" / str(user_id)
    user_dir.mkdir(parents=True, exist_ok=True)

    avatar_name = f"{timestamp}.jpg"
    blur_name = f"{timestamp}_blur.jpg"
    avatar_path = user_dir / avatar_name
    blur_target_path = user_dir / blur_name

    avatar_path.write_bytes(Path(main_path).read_bytes())
    blur_target_path.write_bytes(Path(blur_path).read_bytes())

    return avatar_name, blur_name


async def upload_user_avatar(session: AsyncSession, user: User, file: UploadFile) -> dict:
    content = await file.read()
    if not content:
        raise ValueError("上传文件不能为空")
    if len(content) > 5 * 1024 * 1024:
        raise ValueError("图片大小不能超过 5MB")

    main_path, blur_path, timestamp = _save_optimized_variants(content)

    try:
        avatar_name, blur_name = _persist_avatar_files(user.id, timestamp, main_path, blur_path)
        avatar_url = f"/static/uploads/avatars/{user.id}/{avatar_name}"
        blur_url = f"/static/uploads/avatars/{user.id}/{blur_name}"

        user.avatar_url = avatar_url
        user.avatar_blur_url = blur_url

        session.add(user)
        await session.commit()
        await session.refresh(user)

        return {
            "avatar_url": user.avatar_url,
            "avatar_blur_url": user.avatar_blur_url,
            "local_files": {
                "avatar": avatar_name,
                "blur": blur_name,
            },
        }
    finally:
        Path(main_path).unlink(missing_ok=True)
        Path(blur_path).unlink(missing_ok=True)