from datetime import datetime, timedelta
from typing import List, Optional

from sqlalchemy.orm import Session

from app.core.config import settings
from app.models.role import Role
from app.models.user import User
from app.models.user_role import UserRole
from app.schemas.user import UserCreate, UserUpdate
from app.utils.security import get_password_hash, verify_password


def get_user_by_id(db: Session, user_id: int) -> Optional[User]:
    """Get a user by ID."""
    return db.query(User).filter(User.id == user_id).first()


def get_user_by_email(db: Session, email: str) -> Optional[User]:
    """Get a user by email."""
    return db.query(User).filter(User.email == email).first()


def get_users(db: Session, skip: int = 0, limit: int = 100) -> List[User]:
    """Get all users."""
    return db.query(User).offset(skip).limit(limit).all()


def create_user(db: Session, user_in: UserCreate) -> User:
    """Create a new user."""
    # Check if user already exists
    user = get_user_by_email(db, email=user_in.email)
    if user:
        return None

    # Create user object
    db_user = User(
        email=user_in.email,
        hashed_password=get_password_hash(user_in.password),
        first_name=user_in.first_name,
        last_name=user_in.last_name,
        is_active=True,
        is_verified=False,  # Default to not verified
    )
    db.add(db_user)
    db.commit()
    db.refresh(db_user)
    
    # Add default user role
    default_role = db.query(Role).filter(Role.name == "user").first()
    if default_role:
        db_user_role = UserRole(user_id=db_user.id, role_id=default_role.id)
        db.add(db_user_role)
        db.commit()
    else:
        # Create default role if it doesn't exist
        default_role = Role(name="user", description="Regular user with limited access")
        db.add(default_role)
        db.commit()
        db.refresh(default_role)

        # Now assign it
        db_user_role = UserRole(user_id=db_user.id, role_id=default_role.id)
        db.add(db_user_role)
        db.commit()
    
    return db_user


def update_user(db: Session, user_id: int, user_in: UserUpdate) -> Optional[User]:
    """Update a user."""
    user = get_user_by_id(db, user_id=user_id)
    if not user:
        return None
    
    # Update user fields
    update_data = user_in.dict(exclude_unset=True)
    
    # Handle password update separately
    if "password" in update_data:
        password = update_data.pop("password")
        user.hashed_password = get_password_hash(password)
    
    # Update other fields
    for field, value in update_data.items():
        setattr(user, field, value)
    
    user.updated_at = datetime.utcnow()
    db.add(user)
    db.commit()
    db.refresh(user)
    return user


def delete_user(db: Session, user_id: int) -> bool:
    """Delete a user."""
    user = get_user_by_id(db, user_id=user_id)
    if not user:
        return False
    
    db.delete(user)
    db.commit()
    return True


def verify_user(db: Session, user_id: int) -> Optional[User]:
    """Mark a user as verified."""
    user = get_user_by_id(db, user_id=user_id)
    if not user:
        return None
    
    user.is_verified = True
    user.updated_at = datetime.utcnow()
    db.add(user)
    db.commit()
    db.refresh(user)
    return user


def authenticate_user(db: Session, email: str, password: str) -> Optional[User]:
    """Authenticate a user."""
    user = get_user_by_email(db, email=email)
    if not user:
        return None
    
    if not user.is_active:
        return None
    
    if not verify_password(password, user.hashed_password):
        return None
    
    return user