from langchain_core.documents import Document
from langchain_qdrant import QdrantVectorStore
from qdrant_client import QdrantClient
from qdrant_client.models import Filter, FieldCondition, MatchValue, FilterSelector


class RetrieverService:
    """Qdrant 벡터 검색 서비스. LangGraph Tool 및 직접 검색 모두 지원."""

    def __init__(
        self,
        embeddings,
        qdrant_url: str,
        collection_name: str,
        top_k: int,
        reranker=None,
        rerank_fetch_k: int = 10,
    ):
        self._client = QdrantClient(url=qdrant_url)
        self._collection_name = collection_name
        self._store = QdrantVectorStore(
            client=self._client,
            collection_name=collection_name,
            embedding=embeddings,
        )
        self._top_k = top_k
        self._reranker = reranker
        self._rerank_fetch_k = rerank_fetch_k

    def as_retriever(self):
        return self._store.as_retriever(search_kwargs={"k": self._top_k})

    def search(self, query: str) -> list[Document]:
        fetch_k = self._rerank_fetch_k if self._reranker else self._top_k
        docs = self._store.similarity_search(query, k=fetch_k)
        if self._reranker:
            docs = self._reranker.rerank(query, docs, top_k=self._top_k)
        return docs

    def list_documents(self) -> list[str]:
        """Qdrant에 저장된 고유 파일 경로 목록을 반환한다."""
        sources: set[str] = set()
        offset = None
        while True:
            results, next_offset = self._client.scroll(
                collection_name=self._collection_name,
                with_payload=True,
                limit=200,
                offset=offset,
            )
            for point in results:
                src = (point.payload or {}).get("metadata", {}).get("source", "")
                if src:
                    sources.add(src)
            if next_offset is None:
                break
            offset = next_offset
        return sorted(sources)

    def delete_document(self, source: str) -> None:
        """파일 경로로 저장된 모든 청크를 Qdrant에서 삭제한다."""
        try:
            self._client.delete(
                collection_name=self._collection_name,
                points_selector=FilterSelector(
                    filter=Filter(
                        must=[FieldCondition(
                            key="metadata.source",
                            match=MatchValue(value=source),
                        )]
                    )
                ),
            )
        except Exception:
            pass