"""User service for permanent user information storage

This service handles upsert operations for the users table,
which stores display names and metadata for report generation.
"""
from datetime import datetime
from typing import Optional
from sqlalchemy.orm import Session
from app.modules.auth.models import User


def upsert_user(
    db: Session,
    user_id: str,
    display_name: str,
    office_location: Optional[str] = None,
    job_title: Optional[str] = None,
) -> User:
    """Create or update user record with AD information

    This function is called on every successful login to keep
    user information up to date. Uses SQLAlchemy merge for
    atomic upsert operation.

    Args:
        db: Database session
        user_id: User email address (primary key)
        display_name: Display name from AD API
        office_location: Office location from AD API (optional)
        job_title: Job title from AD API (optional)

    Returns:
        User: The created or updated user record
    """
    # Check if user exists
    existing_user = db.query(User).filter(User.user_id == user_id).first()

    if existing_user:
        # Update existing user
        existing_user.display_name = display_name
        existing_user.office_location = office_location
        existing_user.job_title = job_title
        existing_user.last_login_at = datetime.utcnow()
        db.commit()
        db.refresh(existing_user)
        return existing_user
    else:
        # Create new user
        new_user = User(
            user_id=user_id,
            display_name=display_name,
            office_location=office_location,
            job_title=job_title,
            last_login_at=datetime.utcnow(),
            created_at=datetime.utcnow(),
        )
        db.add(new_user)
        db.commit()
        db.refresh(new_user)
        return new_user


def get_user_by_id(db: Session, user_id: str) -> Optional[User]:
    """Get user by user_id (email)

    Args:
        db: Database session
        user_id: User email address

    Returns:
        User or None if not found
    """
    return db.query(User).filter(User.user_id == user_id).first()


def get_display_name(db: Session, user_id: str) -> str:
    """Get display name for a user, falling back to email if not found

    Args:
        db: Database session
        user_id: User email address

    Returns:
        Display name or email address as fallback
    """
    user = get_user_by_id(db, user_id)
    if user:
        return user.display_name
    return user_id  # Fallback to email if user not in database