"""
Milvus向量数据库连接管理
"""
import os
import logging
from typing import Optional

# 导入配置
from app.core.config import config_handler
from .embedding_connection import get_embedding_model

from langchain_milvus import Milvus, BM25BuiltInFunction

logger = logging.getLogger(__name__)

_milvus_manager = None


def get_milvus_vectorstore(collection_name: str, consistency_level: str = "Strong"):
    """
    获取 Milvus Vectorstore 实例（用于混合搜索）
    
    Args:
        collection_name: 集合名称
        consistency_level: 一致性级别，默认为 "Strong"
    
    Returns:
        Milvus: LangChain 的 Milvus Vectorstore 实例
    """
    try:
        # 直接调用embedding_connection的embedding
        embedding_function = get_embedding_model()
        
        manager = get_milvus_manager()
        connection_args = {
            "uri": f"http://{manager.host}:{manager.port}",
            "user": manager.user,
            "db_name": manager.db_name
        }
        
        if manager.password:
            connection_args["password"] = manager.password

        # 动态检测向量字段名称，兼容旧集合(vector)和新集合(dense)
        vector_field_name = "dense"
        try:
            desc = manager.client.describe_collection(collection_name)
            fields = desc.get("fields", []) if isinstance(desc, dict) else []
            float_vector_fields = []
            for f in fields:
                f_name = f.get("name")
                f_type = f.get("type")
                if not f_name:
                    continue
                # DataType.FLOAT_VECTOR 在 pymilvus 中通常是 101，字符串形式可能为 "FloatVector"
                if f_type == 101 or str(f_type).upper() in ("FLOAT_VECTOR", "FLOATVECTOR"):
                    float_vector_fields.append(f_name)
            # 优先 dense，其次 vector，再次第一个向量字段
            if "dense" in float_vector_fields:
                vector_field_name = "dense"
            elif "vector" in float_vector_fields:
                vector_field_name = "vector"
            elif float_vector_fields:
                vector_field_name = float_vector_fields[0]
        except Exception as e:
            logger.warning(f"自动检测向量字段失败，使用默认 'dense': {e}")
        
        vectorstore = Milvus(
            embedding_function=embedding_function,
            collection_name=collection_name,
            connection_args=connection_args,
            consistency_level=consistency_level,
            builtin_function=BM25BuiltInFunction(),
            vector_field=vector_field_name
        )
        return vectorstore
    except Exception as e:
        logger.error(f"获取 Milvus Vectorstore 失败: {e}")
        raise


class MilvusManager:
    """Milvus管理器"""
    
    def __init__(self):
        self.host: str = config_handler.get("admin_app", "MILVUS_HOST", "localhost")
        self.port: int = config_handler.get_int("admin_app", "MILVUS_PORT", 19530)
        self.db_name: str = config_handler.get("admin_app", "MILVUS_DB", "default")
        self.user: Optional[str] = config_handler.get("admin_app", "MILVUS_USER", "")
        self.password: Optional[str] = config_handler.get("admin_app", "MILVUS_PASSWORD", "")
        
        self.uri = f"http://{self.host}:{self.port}"
        logger.info(f"初始化 MilvusClient: uri={self.uri}, db={self.db_name}")
        
        # 延迟初始化 client
        self._client = None
    
    @property
    def client(self):
        """获取 Milvus 客户端（延迟初始化）"""
        if self._client is None:
            try:
                from pymilvus import MilvusClient
                self._client = MilvusClient(
                    uri=self.uri,
                    user=self.user or "",
                    password=self.password or "",
                    db_name=self.db_name,
                )
                logger.info("Milvus客户端初始化成功")
            except Exception as e:
                logger.error(f"Milvus客户端初始化失败: {e}")
                raise
        return self._client
    
    def close(self) -> None:
        """关闭 Milvus 连接"""
        if self._client:
            try:
                self._client.close()
                logger.info("Milvus连接已关闭")
            except Exception as e:
                logger.error(f"关闭Milvus连接失败: {e}")
            finally:
                self._client = None


def get_milvus_manager() -> MilvusManager:
    """获取 Milvus 管理器单例"""
    global _milvus_manager
    if _milvus_manager is None:
        _milvus_manager = MilvusManager()
    return _milvus_manager


def get_milvus_connection():
    """获取Milvus连接（兼容旧接口）"""
    try:
        return get_milvus_manager().client
    except Exception as e:
        logger.warning(f"Milvus连接失败: {e}")
        return None


async def init_milvus():
    """初始化Milvus连接"""
    try:
        get_milvus_connection()
        logger.info("Milvus初始化成功")
    except Exception as e:
        logger.warning(f"Milvus初始化失败: {e}")


async def close_milvus():
    """关闭Milvus连接"""
    global _milvus_manager
    if _milvus_manager:
        try:
            _milvus_manager.close()
            logger.info("Milvus连接已关闭")
        except Exception as e:
            logger.error(f"关闭Milvus连接失败: {e}")
        finally:
            _milvus_manager = None