from sqlalchemy.orm import Session
from typing import Optional
import httpx

from app.database.models import User
from app.utils.password import hash_password, verify_password
from app.utils.jwt import create_access_token, create_refresh_token
from app.utils.helpers import generate_id

try:
    from google.oauth2 import id_token
    from google.auth.transport import requests as google_requests
    GOOGLE_AUTH_AVAILABLE = True
except ImportError:
    GOOGLE_AUTH_AVAILABLE = False
    print("⚠️ WARNING: google-auth libraries not found. Google Login will fail.")


class AuthService:
    """Service for authentication operations."""
    
    @staticmethod
    def create_user(db: Session, email: str, password: str, name: Optional[str] = None) -> User:
        """
        Create a new user with email and password.
        
        Args:
            db: Database session
            email: User email
            password: Plain text password
            name: Optional user name
            
        Returns:
            Created User object
            
        Raises:
            ValueError: If email already exists
        """
        # Check if user exists
        existing_user = db.query(User).filter(User.email == email).first()
        if existing_user:
            raise ValueError("Email already registered")
        
        # Hash password
        password_hash = hash_password(password)
        
        # Create user
        import os
        admin_email = os.environ.get('ADMIN_EMAIL')
        is_admin_user = 1 if admin_email and email == admin_email else 0
        
        user = User(
            id=generate_id(),
            email=email,
            password_hash=password_hash,
            name=name,
            is_admin=is_admin_user
        )
        
        db.add(user)
        db.commit()
        db.refresh(user)
        
        if is_admin_user:
            print(f"✅ User {email} registered and granted ADMIN privileges!")
        
        return user
    
    @staticmethod
    def authenticate_user(db: Session, email: str, password: str) -> Optional[User]:
        """
        Authenticate a user with email and password.
        
        Args:
            db: Database session
            email: User email
            password: Plain text password
            
        Returns:
            User object if authentication successful, None otherwise
        """
        user = db.query(User).filter(User.email == email).first()
        
        if not user or not user.password_hash:
            return None
        
        if not verify_password(password, user.password_hash):
            return None
        
        return user
    
    @staticmethod
    async def verify_google_token(credential: str, client_id: str) -> dict:
        """
        Verify Google OAuth token and extract user info.
        
        Args:
            credential: Google JWT token from frontend
            client_id: Google OAuth client ID from settings
            
        Returns:
            Dictionary with user info (email, name, google_id, picture)
            
        Raises:
            ValueError: If token is invalid or verification fails
        """
        if not GOOGLE_AUTH_AVAILABLE:
            raise ValueError("Google Auth libraries are not installed on this server.")
        
        try:
            # Verify the token with Google
            idinfo = id_token.verify_oauth2_token(
                credential, 
                google_requests.Request(), 
                client_id
            )
            
            # Extract user information from the token
            return {
                "email": idinfo.get("email"),
                "name": idinfo.get("name"),
                "google_id": idinfo.get("sub"),  # 'sub' is the Google user ID
                "picture": idinfo.get("picture")
            }
            
        except Exception as e:
            print(f"❌ Error verifying Google token: {e}")
            raise ValueError(f"Invalid Google token: {str(e)}")
    
    @staticmethod
    def create_user_from_google(
        db: Session, 
        google_id: str, 
        email: str, 
        name: Optional[str] = None
    ) -> User:
        """
        Create or get user from Google OAuth.
        
        Args:
            db: Database session
            google_id: Google user ID
            email: User email
            name: Optional user name
            
        Returns:
            User object
        """
        # Check if user exists with this Google ID
        user = db.query(User).filter(User.google_id == google_id).first()
        
        if user:
            return user
        
        # Check if user exists with this email
        user = db.query(User).filter(User.email == email).first()
        
        if user:
            # Link Google account
            user.google_id = google_id
            if name and not user.name:
                user.name = name
            db.commit()
            db.refresh(user)
            return user
        
        # Create new user
        import os
        admin_email = os.environ.get('ADMIN_EMAIL')
        is_admin_user = 1 if admin_email and email == admin_email else 0
        
        user = User(
            id=generate_id(),
            email=email,
            google_id=google_id,
            name=name,
            is_admin=is_admin_user
        )
        
        db.add(user)
        db.commit()
        db.refresh(user)
        
        if is_admin_user:
            print(f"✅ User {email} registered via Google and granted ADMIN privileges!")
        
        return user
    
    @staticmethod
    def get_user_by_id(db: Session, user_id: str) -> Optional[User]:
        """
        Get user by ID.
        
        Args:
            db: Database session
            user_id: User ID
            
        Returns:
            User object if found, None otherwise
        """
        return db.query(User).filter(User.id == user_id).first()
    
    @staticmethod
    def generate_tokens(user: User) -> dict:
        """
        Generate access and refresh tokens for a user.
        
        Args:
            user: User object
            
        Returns:
            Dictionary with access_token and refresh_token
        """
        access_token = create_access_token(user.id)
        refresh_token = create_refresh_token(user.id)
        
        return {
            "access_token": access_token,
            "refresh_token": refresh_token
        }