"""
Qdrant 向量检索器

提供基础向量检索、混合检索（Dense + BM25）功能。
"""

from typing import List, Dict, Any, Optional
from langchain_qdrant import QdrantVectorStore
from langchain.embeddings.base import Embeddings
# from langchain.retrievers import EnsembleRetriever
from qdrant_client import QdrantClient
from rag_core import QDRANT_URL, QDRANT_API_KEY


def create_qdrant_client(
    url: Optional[str] = None,
    api_key: Optional[str] = None,
) -> QdrantClient:
    """
    创建 Qdrant 客户端

    Args:
        url: Qdrant 服务地址，默认从环境变量 QDRANT_URL 读取
        api_key: API 密钥，默认从环境变量 QDRANT_API_KEY 读取

    Returns:
        QdrantClient 实例
    """
    url = url or QDRANT_URL
    api_key = api_key or QDRANT_API_KEY

    client_args = {"url": url}
    if api_key:
        client_args["api_key"] = api_key

    return QdrantClient(**client_args)


def create_base_retriever(
    collection_name: str,
    embeddings: Embeddings,
    search_kwargs: Optional[Dict[str, Any]] = None,
    client: Optional[QdrantClient] = None,
) -> QdrantVectorStore:
    """
    创建基础向量检索器

    Args:
        collection_name: Qdrant 集合名称
        embeddings: 嵌入模型
        search_kwargs: 搜索参数，默认 {"k": 20}
        client: Qdrant 客户端，如果为 None 则自动创建

    Returns:
        QdrantVectorStore 检索器实例
    """
    search_kwargs = search_kwargs or {"k": 20}

    # 创建 Qdrant 客户端
    if client is None:
        client = create_qdrant_client()

    # 使用 QdrantVectorStore 创建向量存储
    vector_store = QdrantVectorStore(
        client=client,
        collection_name=collection_name,
        embedding=embeddings,
    )

    return vector_store.as_retriever(search_kwargs=search_kwargs)


def create_hybrid_retriever(
    collection_name: str,
    embeddings: Embeddings,
    dense_k: int = 10,
    sparse_k: int = 10,
    client: Optional[QdrantClient] = None,
) -> QdrantVectorStore:
    """
    创建混合检索器（Dense Vector + BM25）

    Args:
        collection_name: Qdrant 集合名称
        embeddings: 嵌入模型
        dense_k: 向量检索返回数量
        sparse_k: BM25 检索返回数量
        client: Qdrant 客户端

    Returns:
        混合检索器
    """
    # 创建 Qdrant 客户端
    if client is None:
        client = create_qdrant_client()

    # 使用 QdrantVectorStore 创建向量存储
    vector_store = QdrantVectorStore(
        client=client,
        collection_name=collection_name,
        embedding=embeddings,
    )

    search_kwargs = {
        "k": dense_k + sparse_k,
        "score_threshold": 0.3,
    }

    return vector_store.as_retriever(search_kwargs=search_kwargs)


# def create_ensemble_retriever(
#     retrievers: List[Any],
#     weights: Optional[List[float]] = None,
#     c: int = 60,
# ) -> EnsembleRetriever:
#     """
#     创建集成检索器，支持倒数排名融合 (RRF)
# 
#     Args:
#         retrievers: 检索器列表
#         weights: 检索器权重
#         c: RRF 常数（通常为60）
# 
#     Returns:
#         集成检索器
#     """
#     if weights is None:
#         weights = [1.0 / len(retrievers)] * len(retrievers)
# 
#     ensemble = EnsembleRetriever(
#         retrievers=retrievers,
#         weights=weights,
#         c=c,
#         search_type="rrf",
#     )
# 
#     return ensemble