import base64
import json
import os
from pathlib import Path

import firebase_admin
from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from firebase_admin import auth, credentials
from logger import logger

_BASE_DIR = Path(__file__).parent.parent.parent


def _get_sa_key() -> str | None:
    sa_key = os.getenv("FIREBASE_SA_KEY")
    if sa_key:
        return sa_key
    env_local = _BASE_DIR / ".env.local"
    if env_local.exists():
        for line in env_local.read_text().splitlines():
            if line.startswith("FIREBASE_SA_KEY="):
                return line.partition("=")[2].strip()
    return None


def initialize_firebase():
    try:
        sa_key = _get_sa_key()
        if sa_key:
            cred = credentials.Certificate(json.loads(base64.b64decode(sa_key)))
            firebase_admin.initialize_app(cred)
        else:
            firebase_admin.initialize_app()
        print("Firebase app initialized successfully.")
    except Exception as e:
        print(f"Failed to initialize Firebase: {e}")


def get_user_token(
    credential: HTTPAuthorizationCredentials = Depends(
        HTTPBearer(auto_error=False)),
):
    if credential is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Authorization credentials not provided",
            headers={"WWW-Authenticate": 'Bearer error="invalid_token"'},
        )

    try:
        decoded_token = auth.verify_id_token(
            credential.credentials, clock_skew_seconds=60)
        logger.info("Token verified successfully.")
        user_id = decoded_token.get("user_id")
        return user_id
    except Exception as err:
        logger.error(f"Token verification failed: {err}")
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail=f"Invalid User. {err}",
            headers={"WWW-Authenticate": 'Bearer error="invalid_token"'},
        )