"""Session management service

處理 user_sessions 資料庫操作：
- 建立/查詢/刪除 session
- 更新活動時間戳
- 管理 refresh 重試計數器
"""
import uuid
from datetime import datetime
from sqlalchemy.orm import Session
from app.modules.auth.models import UserSession


class SessionService:
    """Session management service"""

    def create_session(
        self,
        db: Session,
        username: str,
        display_name: str,
        ad_token: str,
        encrypted_password: str,
        ad_token_expires_at: datetime,
    ) -> UserSession:
        """Create new user session

        Args:
            db: Database session
            username: User email from AD
            display_name: Display name from AD
            ad_token: AD API token
            encrypted_password: Encrypted password for auto-refresh
            ad_token_expires_at: AD token expiry datetime

        Returns:
            Created UserSession object
        """
        # Generate unique internal token
        internal_token = str(uuid.uuid4())

        session = UserSession(
            username=username,
            display_name=display_name,
            internal_token=internal_token,
            ad_token=ad_token,
            encrypted_password=encrypted_password,
            ad_token_expires_at=ad_token_expires_at,
            refresh_attempt_count=0,
            last_activity=datetime.utcnow(),
        )

        db.add(session)
        db.commit()
        db.refresh(session)

        return session

    def get_session_by_token(self, db: Session, internal_token: str) -> UserSession | None:
        """Get session by internal token

        Args:
            db: Database session
            internal_token: Internal session token (UUID)

        Returns:
            UserSession if found, None otherwise
        """
        return db.query(UserSession).filter(UserSession.internal_token == internal_token).first()

    def update_activity(self, db: Session, session_id: int) -> None:
        """Update last_activity timestamp

        Args:
            db: Database session
            session_id: Session ID
        """
        db.query(UserSession).filter(UserSession.id == session_id).update(
            {"last_activity": datetime.utcnow()}
        )
        db.commit()

    def update_ad_token(
        self, db: Session, session_id: int, new_ad_token: str, new_expires_at: datetime
    ) -> None:
        """Update AD token after successful refresh

        Args:
            db: Database session
            session_id: Session ID
            new_ad_token: New AD token
            new_expires_at: New expiry datetime
        """
        db.query(UserSession).filter(UserSession.id == session_id).update(
            {
                "ad_token": new_ad_token,
                "ad_token_expires_at": new_expires_at,
                "refresh_attempt_count": 0,  # Reset counter on success
            }
        )
        db.commit()

    def increment_refresh_attempts(self, db: Session, session_id: int) -> int:
        """Increment refresh attempt counter

        Args:
            db: Database session
            session_id: Session ID

        Returns:
            New refresh_attempt_count value
        """
        session = db.query(UserSession).filter(UserSession.id == session_id).first()
        if session:
            session.refresh_attempt_count += 1
            db.commit()
            return session.refresh_attempt_count
        return 0

    def reset_refresh_attempts(self, db: Session, session_id: int) -> None:
        """Reset refresh attempt counter

        Args:
            db: Database session
            session_id: Session ID
        """
        db.query(UserSession).filter(UserSession.id == session_id).update(
            {"refresh_attempt_count": 0}
        )
        db.commit()

    def delete_session(self, db: Session, session_id: int) -> None:
        """Delete session

        Args:
            db: Database session
            session_id: Session ID
        """
        db.query(UserSession).filter(UserSession.id == session_id).delete()
        db.commit()


# Singleton instance
session_service = SessionService()