"""Product knowledge base module (obsidian-wiki compatible).

Self-contained: knowledge ingestion, storage (DB mirror + Markdown vault),
search and graph export all live here. The Gateway only depends on
:class:`KnowledgeService` via :func:`make_knowledge_service`.
"""

from __future__ import annotations

from typing import TYPE_CHECKING

from deerflow.knowledge.obsidian_adapter import ObsidianWikiAdapter
from deerflow.knowledge.repository import KnowledgeRepository
from deerflow.knowledge.service import EmptyThreadError, KnowledgeService

if TYPE_CHECKING:
    from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker

    from deerflow.config.knowledge_config import KnowledgeConfig

__all__ = [
    "EmptyThreadError",
    "KnowledgeRepository",
    "KnowledgeService",
    "ObsidianWikiAdapter",
    "make_knowledge_service",
]


def make_knowledge_service(
    session_factory: async_sessionmaker[AsyncSession] | None,
    config: KnowledgeConfig,
) -> KnowledgeService | None:
    """Build the knowledge service.

    Returns ``None`` when persistence is memory-only (no session factory) or
    the feature is disabled — the router then responds 503.
    """
    if session_factory is None or not config.enabled:
        return None
    return KnowledgeService(KnowledgeRepository(session_factory), config)