"""
FastAPI dependencies for authentication and authorization.
"""

from typing import Optional
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlmodel import select

from src.db.firebase import get_firebase_db
from src.db.models import User
from src.auth.security import decode_access_token
from src.utils.logger import setup_logger

logger = setup_logger(__name__)

# OAuth2 scheme for extracting bearer tokens from Authorization header
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/auth/login")

from firebase_admin import auth as firebase_auth
from src.db.firebase import verify_token


import inspect
import time

async def get_current_user(
    token: str = Depends(oauth2_scheme)
) -> User:
    """
    Get the currently authenticated user with support for Firebase and custom JWT.
    """
    db = get_firebase_db()
    firebase_error = None

    # Log token prefix for debugging
    token_prefix = token[:10] if token else "None"
    logger.info(f"Authenticating token starting with: {token_prefix}...")

    # 1. Try Firebase Verification
    try:
        firebase_result = verify_token(token)
        
        # Check if verify_token returned a dict, otherwise it's an internal error
        if not isinstance(firebase_result, dict):
            firebase_error = f"Internal Error [CP0]: verify_token returned {type(firebase_result)} (Expected dict)"
            firebase_payload = None
        else:
            firebase_payload = firebase_result.get("payload")
            firebase_error = firebase_result.get("error")
        
        if firebase_payload is not None:
            uid = firebase_payload.get("uid")
            email = firebase_payload.get("email")
            
            if not uid:
                 logger.error("Firebase payload missing 'uid' [CP1]")
                 raise HTTPException(status_code=401, detail="Invalid Firebase token payload [CP1]")
            
            if db is None:
                 logger.warning(f"Firestore not available, returning transient user for {email} [CP2]")
                 return User(id=uid, email=email or "unknown@example.com", username=firebase_payload.get("name", uid), role="user")

            # Retrieve from Firestore
            user_doc = db.collection("users").document(uid).get()
            if user_doc.exists:
                user_data = user_doc.to_dict()
                user_data["id"] = user_doc.id
                
                # Ensure compatibility fields are set for User model instantiation
                user_data.setdefault("email", email or "unknown@example.com")
                user_data.setdefault("username", firebase_payload.get("name", uid))
                user_data.setdefault("role", user_data.get("role", "user"))
                
                # Pydantic model instantiation (Resilient to missing password_hash due to model defaults)
                return User(**user_data)
            else:
                logger.info(f"New Firebase user detected: {email or uid} [CP3]")
                return User(
                    id=uid,
                    email=email or "unknown@example.com",
                    username=firebase_payload.get("name", uid),
                    # password_hash is optional in User model, or can be set to ""
                    role="user"
                )
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Error in Firebase auth path: {repr(e)} [CP4]")
        firebase_error = str(e) or repr(e)

    # 2. Fallback to Custom JWT Decoding
    try:
        payload = decode_access_token(token)
        if payload:
            username: Optional[str] = payload.get("sub")
            if not username:
                raise HTTPException(status_code=401, detail="Token missing subject claim [CP5]")

            if db is None:
                # For custom JWT, if DB is not available, we can't verify user existence
                # This path should ideally not be hit if Firebase is the primary auth
                logger.warning(f"Firestore not available, returning mock user for {username} [CP5a]")
                return User(id="mock_id", email="mock@example.com", username=username, role="user")

            users_ref = db.collection("users")
            query = users_ref.where("username", "==", username).limit(1).stream()
            user_doc = next(query, None)

            if user_doc:
                user_data = user_doc.to_dict()
                user_data["id"] = user_doc.id
                return User(**user_data)
            else:
                logger.error(f"User {username} not found in database [CP6]")
                raise HTTPException(status_code=401, detail="User account not found [CP6]")
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Error in custom JWT auth path: {repr(e)} [CP7]")

    # If both failed, then it's a 401
    error_detail = f"Authentication failed [CP8]: {firebase_error if firebase_error else 'Invalid credentials'}"
    logger.error(error_detail)
    raise HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail=error_detail,
        headers={"WWW-Authenticate": "Bearer"},
    )


async def get_current_active_user(
    current_user: User = Depends(get_current_user),
) -> User:
    """
    Get the current active user (for future soft-delete support).

    Currently returns the user as-is, but can be extended to check
    for account status, email verification, banned users, etc.

    Args:
        current_user: User from get_current_user dependency

    Returns:
        User object if user is active

    Raises:
        HTTPException: 400 Bad Request if user is inactive

    Usage:
        @app.get("/protected")
        async def protected_route(user: User = Depends(get_current_active_user)):
            return {"message": f"Hello active user {user.username}"}
    """
    # Future: Check if user.is_active, user.is_verified, etc.
    # if not current_user.is_active:
    #     raise HTTPException(status_code=400, detail="Inactive user")

    return current_user