from pathlib import Path
from fastapi import UploadFile, HTTPException
from PIL import Image, UnidentifiedImageError
from io import BytesIO

from app.config import ALLOWED_IMAGE_EXTENSIONS, SUPPORTED_CROPS


def validate_crop(crop: str) -> str:
    crop = crop.lower().strip()

    if crop not in SUPPORTED_CROPS:
        raise HTTPException(
            status_code=400,
            detail=f"Unsupported crop '{crop}'. Supported crops: {SUPPORTED_CROPS}",
        )

    return crop


async def read_image_file(file: UploadFile) -> Image.Image:
    filename = file.filename or ""
    extension = Path(filename).suffix.lower()

    if extension not in ALLOWED_IMAGE_EXTENSIONS:
        raise HTTPException(
            status_code=400,
            detail=f"Unsupported image type '{extension}'. Allowed: {sorted(ALLOWED_IMAGE_EXTENSIONS)}",
        )

    content = await file.read()

    if not content:
        raise HTTPException(status_code=400, detail="Uploaded image is empty.")

    try:
        image = Image.open(BytesIO(content)).convert("RGB")
        return image
    except UnidentifiedImageError:
        raise HTTPException(status_code=400, detail="Uploaded file is not a valid image.")