"""Authentication service."""
from datetime import datetime, timedelta
from typing import Optional
from uuid import UUID

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.security import (
    create_access_token,
    create_refresh_token,
    get_password_hash,
    verify_password,
)
from app.models.user import User


class AuthService:
    """Service for authentication operations."""

    def __init__(self, db: AsyncSession):
        self.db = db

    async def register(
        self,
        email: str,
        username: str,
        password: str,
        display_name: Optional[str] = None,
    ) -> User:
        """
        Register a new user.

        Args:
            email: User email
            username: Username
            password: Plain text password
            display_name: Optional display name

        Returns:
            Created user

        Raises:
            ValueError: If email or username already exists
        """
        # Check if email exists
        result = await self.db.execute(
            select(User).where(User.email == email)
        )
        if result.scalar_one_or_none():
            raise ValueError("Email already registered")

        # Check if username exists
        result = await self.db.execute(
            select(User).where(User.username == username)
        )
        if result.scalar_one_or_none():
            raise ValueError("Username already taken")

        # Create user
        user = User(
            email=email,
            username=username,
            password_hash=get_password_hash(password),
            display_name=display_name or username,
        )

        self.db.add(user)
        await self.db.commit()
        await self.db.refresh(user)

        return user

    async def login(self, email: str, password: str) -> User:
        """
        Authenticate user with email and password.

        Args:
            email: User email
            password: Plain text password

        Returns:
            Authenticated user

        Raises:
            ValueError: If credentials are invalid
        """
        # Find user by email
        result = await self.db.execute(
            select(User).where(User.email == email)
        )
        user = result.scalar_one_or_none()

        if not user:
            raise ValueError("Invalid email or password")

        # Verify password
        if not verify_password(password, user.password_hash):
            raise ValueError("Invalid email or password")

        # Update last login
        user.last_login = datetime.utcnow()
        await self.db.commit()

        return user

    async def get_user_by_id(self, user_id: UUID) -> Optional[User]:
        """
        Get user by ID.

        Args:
            user_id: User UUID

        Returns:
            User or None
        """
        result = await self.db.execute(
            select(User).where(User.id == user_id)
        )
        return result.scalar_one_or_none()

    async def update_user(
        self,
        user_id: UUID,
        display_name: Optional[str] = None,
        avatar_url: Optional[str] = None,
        date_of_birth: Optional[datetime] = None,
        country: Optional[str] = None,
    ) -> User:
        """
        Update user profile.

        Args:
            user_id: User UUID
            display_name: Optional display name
            avatar_url: Optional avatar URL
            date_of_birth: Optional date of birth
            country: Optional country code

        Returns:
            Updated user

        Raises:
            ValueError: If user not found
        """
        result = await self.db.execute(
            select(User).where(User.id == user_id)
        )
        user = result.scalar_one_or_none()

        if not user:
            raise ValueError("User not found")

        # Update fields
        if display_name is not None:
            user.display_name = display_name
        if avatar_url is not None:
            user.avatar_url = avatar_url
        if date_of_birth is not None:
            user.date_of_birth = date_of_birth
        if country is not None:
            user.country = country

        user.updated_at = datetime.utcnow()
        await self.db.commit()
        await self.db.refresh(user)

        return user

    def create_tokens(self, user_id: UUID) -> tuple[str, str]:
        """
        Create access and refresh tokens for user.

        Args:
            user_id: User UUID

        Returns:
            Tuple of (access_token, refresh_token)
        """
        access_token = create_access_token(subject=str(user_id))
        refresh_token = create_refresh_token(subject=str(user_id))
        return access_token, refresh_token