from __future__ import annotations

from app.config import Settings
from app.decision_engine import create_decision_engine
from app.embeddings import create_embedding_provider
from app.graph import GraphBuilder, build_graph
from app.milvus_store import MilvusVectorStore
from app.schemas import QueryRequest, QueryResponse, RouteDecision
from app.sql_store import IncidentRepository
from app.tools import (
    SQLQueryTool,
    TavilyWebSearchProvider,
    VectorSearchTool,
    WebSearchTool,
)


class AgenticRAGService:
    """组装 VPN 故障诊断 Agent，并提供单次查询入口。"""

    def __init__(self, settings: Settings) -> None:
        self.settings = settings

        embeddings = create_embedding_provider(settings)
        vector_store = MilvusVectorStore(
            uri=settings.milvus_uri,
            token=settings.milvus_token.get_secret_value(),
            collection_name=settings.milvus_collection,
            embeddings=embeddings,
        )
        vector_tool = VectorSearchTool(vector_store)

        incident_repository = IncidentRepository(settings.sqlite_path)
        sql_tool = SQLQueryTool(incident_repository)

        web_provider = TavilyWebSearchProvider(
            settings.tavily_api_key.get_secret_value()
        )
        web_tool = WebSearchTool(web_provider)

        graph_builder = GraphBuilder(
            settings=settings,
            engine=create_decision_engine(settings),
            vector_tool=vector_tool,
            sql_tool=sql_tool,
            web_tool=web_tool,
        )
        self.graph = build_graph(graph_builder)

    def invoke(self, request: QueryRequest) -> QueryResponse:
        """为每次请求创建独立 State 并运行 LangGraph。"""
        state = self.graph.invoke(
            {
                "original_query": request.query,
                "current_query": request.query,
                "session_id": request.session_id,
                "debug": request.debug,
                "evidence": [],
                "tool_results": [],
                "executed_queries": [],
                "retrieval_round": 0,
                "errors": [],
                "trace": [],
            },
            config={"recursion_limit": 20},
        )

        route = state.get("route_decision")
        if route is None:
            route = RouteDecision(
                needs_retrieval=False,
                intent="internal_error",
                reason_code="MISSING_ROUTE_DECISION",
            )

        return QueryResponse(
            answer=state.get("final_answer", "系统未生成诊断结论。"),
            citations=state.get("evidence", []),
            route=route,
            executed_queries=(
                state.get("executed_queries", []) if request.debug else []
            ),
            trace=state.get("trace", []) if request.debug else [],
            termination_reason=state.get("termination_reason", "unknown"),
        )