library-desk/src/clients/settings_client.py

"""
Client for central Tatlock settings database.

Reads settings from the shared system_settings PostgreSQL database.
Writes are done via psql CLI or future CRUD manager.
"""

import asyncpg
import logging
from typing import Optional, Any

logger = logging.getLogger(__name__)


class SettingsClient:
    """Client for system_settings database."""

    def __init__(self, dsn: str):
        """
        Initialize settings client.

        Args:
            dsn: PostgreSQL connection string
                 e.g., "postgresql://settings:password@postgres-shared:5432/system_settings"
        """
        self.dsn = dsn
        self._pool: Optional[asyncpg.Pool] = None

    async def connect(self):
        """Initialize connection pool."""
        if not self._pool:
            try:
                self._pool = await asyncpg.create_pool(
                    self.dsn,
                    min_size=1,
                    max_size=5,
                    command_timeout=10,
                )
                logger.info("Connected to system_settings database")
            except Exception as e:
                logger.error(f"Failed to connect to system_settings: {e}")
                raise

    async def close(self):
        """Close connection pool."""
        if self._pool:
            await self._pool.close()
            self._pool = None
            logger.info("Disconnected from system_settings database")

    async def health_check(self) -> bool:
        """Check database connectivity."""
        try:
            await self.connect()
            async with self._pool.acquire() as conn:
                await conn.fetchval("SELECT 1")
            return True
        except Exception as e:
            logger.error(f"Settings database health check failed: {e}")
            return False

    async def get(self, key: str, user_scope: str = "global") -> Optional[Any]:
        """
        Get a setting by key with user fallback to global.

        Args:
            key: Setting key (e.g., "api.openmeteo", "weather.units")
            user_scope: User identifier or "global"

        Returns:
            Setting value (parsed from JSONB) or None if not found.
            User-specific value takes precedence over global.
        """
        await self.connect()
        async with self._pool.acquire() as conn:
            row = await conn.fetchrow(
                """
                SELECT value FROM settings
                WHERE key = $1 AND user_scope IN ($2, 'global')
                ORDER BY CASE WHEN user_scope = $2 THEN 0 ELSE 1 END
                LIMIT 1
                """,
                key, user_scope
            )
            if row:
                return row["value"]
            return None

    async def get_with_schema(self, key: str, user_scope: str = "global") -> Optional[dict]:
        """
        Get a setting with its JSON Schema.

        Returns:
            Dict with "value" and "schema" keys, or None if not found.
        """
        await self.connect()
        async with self._pool.acquire() as conn:
            row = await conn.fetchrow(
                """
                SELECT value, schema FROM settings
                WHERE key = $1 AND user_scope IN ($2, 'global')
                ORDER BY CASE WHEN user_scope = $2 THEN 0 ELSE 1 END
                LIMIT 1
                """,
                key, user_scope
            )
            if row:
                return {"value": row["value"], "schema": row["schema"]}
            return None

    async def get_by_prefix(self, prefix: str, user_scope: str = "global") -> dict[str, Any]:
        """
        Get all settings matching a key prefix.

        Args:
            prefix: Key prefix (e.g., "api." for all API configs)
            user_scope: User identifier or "global"

        Returns:
            Dict mapping keys to values. User-specific values override global.
        """
        await self.connect()
        async with self._pool.acquire() as conn:
            rows = await conn.fetch(
                """
                SELECT DISTINCT ON (key) key, value FROM settings
                WHERE key LIKE $1 AND user_scope IN ($2, 'global')
                ORDER BY key, CASE WHEN user_scope = $2 THEN 0 ELSE 1 END
                """,
                f"{prefix}%", user_scope
            )
            return {row["key"]: row["value"] for row in rows}

    async def get_api_config(self, service: str) -> Optional[dict]:
        """
        Get API configuration for a service.

        Args:
            service: Service name (e.g., "openmeteo", "nos", "alphavantage")

        Returns:
            API config dict or None if not found.
        """
        value = await self.get(f"api.{service}")
        if isinstance(value, dict):
            return value
        return None

    async def get_api_key(self, service: str) -> Optional[str]:
        """
        Get API key for a service if enabled.

        Args:
            service: Service name (e.g., "alphavantage")

        Returns:
            API key string or None if not found or disabled.
        """
        config = await self.get_api_config(service)
        if config:
            # Check if explicitly disabled
            if config.get("enabled") is False:
                return None
            return config.get("api_key")
        return None

    async def is_api_enabled(self, service: str) -> bool:
        """
        Check if an API service is enabled.

        Args:
            service: Service name (e.g., "alphavantage", "openmeteo")

        Returns:
            True if enabled (or no explicit setting), False if disabled.
        """
        config = await self.get_api_config(service)
        if config:
            # Default to enabled if not specified
            return config.get("enabled", True)
        return False  # No config means not available

    async def get_user_preference(self, key: str, user: str) -> Optional[Any]:
        """
        Get a user-specific preference.

        Args:
            key: Preference key (e.g., "weather.units", "news.sources")
            user: User identifier

        Returns:
            Preference value or None if not set.
        """
        return await self.get(key, user_scope=user)

    async def list_keys(self, user_scope: Optional[str] = None) -> list[str]:
        """
        List all setting keys, optionally filtered by user_scope.

        Args:
            user_scope: Filter by scope (None for all)

        Returns:
            List of setting keys.
        """
        await self.connect()
        async with self._pool.acquire() as conn:
            if user_scope:
                rows = await conn.fetch(
                    "SELECT key FROM settings WHERE user_scope = $1 ORDER BY key",
                    user_scope
                )
            else:
                rows = await conn.fetch(
                    "SELECT DISTINCT key FROM settings ORDER BY key"
                )
            return [row["key"] for row in rows]