"""Base search provider with visibility filter — all search providers should inherit from this.

This ensures that search results respect row-level security automatically.
Plugins that provide search functionality should use this base class.
"""

from __future__ import annotations

import logging
import uuid
from typing import Any

from sqlalchemy import text
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import settings

logger = logging.getLogger(__name__)


class BaseSearchProvider:
    """Base class for search providers with built-in visibility filtering.

    Subclasses must implement _search_fts_filtered() and _search_vector_filtered().
    The base class handles loading visible IDs and passing them to the subclass.
    """

    # Capability flags — override in subclass
    supports_fts: bool = True
    supports_vector: bool = True
    supports_rag: bool = False
    supports_graph: bool = False

    entity_type: str = ""  # Override in subclass

    async def search_fts(
        self,
        db: AsyncSession,
        tsquery: str,
        tenant_id: uuid.UUID,
        limit: int,
        user_id: uuid.UUID | None = None,
        is_system_admin: bool = False,
    ) -> list[dict[str, Any]]:
        """Full-text search with visibility filter."""
        if is_system_admin or not user_id:
            return await self._search_fts_filtered(db, tsquery, tenant_id, limit, None)

        visible_ids = await self._get_visible_ids(db, tenant_id, user_id)
        if not visible_ids:
            return []
        return await self._search_fts_filtered(db, tsquery, tenant_id, limit, visible_ids)

    async def search_vector(
        self,
        db: AsyncSession,
        embedding: list[float],
        tenant_id: uuid.UUID,
        limit: int,
        user_id: uuid.UUID | None = None,
        is_system_admin: bool = False,
    ) -> list[dict[str, Any]]:
        """Semantic vector search with visibility filter.

        Uses over-fetch strategy: fetch limit*3 from HNSW without permission
        filter, then post-filter in Python. This avoids the 15x performance
        hit of `id = ANY($uuid[])` on HNSW results found in SPIKE-E.
        """
        # Set HNSW ef_search parameter for this transaction
        await db.execute(text(f"SET LOCAL hnsw.ef_search = {settings.hnsw_ef_search}"))
        if is_system_admin or not user_id:
            return await self._search_vector_filtered(db, embedding, tenant_id, limit, None)

        visible_ids = await self._get_visible_ids(db, tenant_id, user_id)
        if not visible_ids:
            return []

        # Over-fetch 3x the limit, then post-filter in Python
        over_fetch_limit = limit * 3
        results = await self._search_vector_filtered(db, embedding, tenant_id, over_fetch_limit, None)
        filtered = [r for r in results if r.get("id") in visible_ids]
        return filtered[:limit]

    async def _get_visible_ids(
        self, db: AsyncSession, tenant_id: uuid.UUID, user_id: uuid.UUID
    ) -> set[uuid.UUID] | None:
        """Get visible entity IDs for the user."""
        from app.services.entity_permission_service import get_visible_ids
        visible, _ = await get_visible_ids(db, tenant_id, user_id, self.entity_type)
        return visible if visible else None

    async def _search_fts_filtered(
        self,
        db: AsyncSession,
        tsquery: str,
        tenant_id: uuid.UUID,
        limit: int,
        visible_ids: set[uuid.UUID] | None,
    ) -> list[dict[str, Any]]:
        """Override: FTS search filtered by visible_ids. If visible_ids is None, no filter."""
        raise NotImplementedError

    async def _search_vector_filtered(
        self,
        db: AsyncSession,
        embedding: list[float],
        tenant_id: uuid.UUID,
        limit: int,
        visible_ids: set[uuid.UUID] | None,
    ) -> list[dict[str, Any]]:
        """Override: Vector search filtered by visible_ids. If visible_ids is None, no filter."""
        raise NotImplementedError

    async def get_embedding_text(
        self, db: AsyncSession, entity_id: uuid.UUID, tenant_id: uuid.UUID
    ) -> str:
        """Override: Get text for embedding generation."""
        raise NotImplementedError