"""SQLAlchemy-backed per-user preferences repository."""

from __future__ import annotations

from datetime import UTC, datetime
from typing import Any

from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker

from deerflow.persistence.user_preferences.model import UserPreferencesRow


class UserPreferencesRepository:
    def __init__(self, session_factory: async_sessionmaker[AsyncSession]) -> None:
        self._sf = session_factory

    async def get_for_user(self, user_id: str) -> dict[str, Any]:
        """Return the user's stored preferences (empty dict when none)."""
        async with self._sf() as session:
            row = await session.get(UserPreferencesRow, user_id)
            if row is None or not isinstance(row.preferences, dict):
                return {}
            return dict(row.preferences)

    async def merge_for_user(self, user_id: str, patch: dict[str, Any]) -> dict[str, Any]:
        """Shallow-merge ``patch`` into the user's preferences and return the result."""
        now = datetime.now(UTC)
        async with self._sf() as session:
            row = await session.get(UserPreferencesRow, user_id)
            if row is None:
                merged = dict(patch)
                row = UserPreferencesRow(user_id=user_id, preferences=merged, created_at=now, updated_at=now)
                session.add(row)
            else:
                merged = dict(row.preferences or {})
                merged.update(patch)
                # Reassign so SQLAlchemy detects the change on the JSON column.
                row.preferences = merged
                row.updated_at = now
            await session.commit()
            return dict(merged)