# app.py
import base64
import os
import uuid
from pathlib import Path
from typing import Dict
from PIL import Image
from io import BytesIO

from fastapi import FastAPI, HTTPException, APIRouter
from fastapi.responses import FileResponse

BASE_DIR = Path(__file__).parent
ASSETS_DIR = BASE_DIR / "cdn-assets"
ASSETS_DIR.mkdir(exist_ok=True)

image_registry: Dict[str, Path] = {}
asset_router = APIRouter(prefix="/asset-cdn", tags=["asset-cdn"])

def save_base64_image(b64_data: str) -> str:
    """
    Decodes a base64 string, converts the image to PNG, stores it in /cdn-assets and returns the
    unique image_id that can be used in the public URL.
    """

    if "," in b64_data:
        _, b64_data = b64_data.split(",", 1)

    try:
        decoded = base64.b64decode(b64_data)
    except (base64.binascii.Error, ValueError) as exc:
        raise ValueError("Invalid base64 data") from exc

    image = Image.open(BytesIO(decoded))

    image_id = uuid.uuid4().hex
    file_path = ASSETS_DIR / f"{image_id}.png"

    image.save(file_path, "PNG")

    image_registry[image_id] = file_path

    return image_id


@asset_router.get("/assets/{image_id}")
def get_image(image_id: str):
    """
    FastAPI route that streams the requested image to the client.
    If the image was cleaned up or never existed, a 404 is returned.
    """
    file_path = image_registry.get(image_id)
    if not file_path or not file_path.exists():
        raise HTTPException(status_code=404, detail="Image not found")

    return FileResponse(path=file_path, media_type="image/png")

def cleanup_image(image_id: str) -> bool:
    """
    Deletes the image file and removes it from the registry.
    Returns True if the image existed and was removed, otherwise False.
    """
    file_path = image_registry.pop(image_id, None)
    if file_path and file_path.exists():
        try:
            file_path.unlink()
        except Exception:
            image_registry[image_id] = file_path
            return False
        return True
    return False

def is_base64_image(value: str) -> bool:
    if not isinstance(value, str):
        return False
    if value.startswith("http://") or value.startswith("https://"):
        return False
    if value.startswith("data:image"):
        return True
    return False