import os
import time
import uuid
from typing import AsyncIterator

from langchain_core.messages import AIMessage, AIMessageChunk, HumanMessage, SystemMessage
from langchain_core.runnables import RunnableConfig
from langgraph.checkpoint.memory import MemorySaver
from langgraph.config import get_stream_writer
from langgraph.graph import END, START, MessagesState, StateGraph
from langgraph.prebuilt import ToolNode

from services.agent.tools import get_current_date, make_memory_tools, make_retriever_tool, make_search_tool, web_search


class AgentService:
    """LangGraph ReAct 에이전트 서비스.

    Tool Calling 루프, 대화 히스토리, 조건부 라우팅을 LangGraph가 담당한다.
    """

    def __init__(
        self,
        chat_model,
        retriever_service,
        system_prompt: str,
        rag_verbose: bool = False,
        rag_show_sources: bool = False,
        langgraph_verbose: bool = False,
        think_verbose: bool = False,
        query_rewrite_enabled: bool = False,
        user_profile_repository=None,
        conversation_repository=None,
        user_id: str = "default",
    ):
        self._system_prompt = system_prompt
        self._rag_verbose = rag_verbose
        self._rag_show_sources = rag_show_sources
        self._langgraph_verbose = langgraph_verbose
        self._think_verbose = think_verbose
        self._query_rewrite_enabled = query_rewrite_enabled
        self._source_buffer: list[dict] = []
        self._thread_id = "default"
        self._profile_repo = user_profile_repository
        self._conv_repo = conversation_repository
        self._conv_id: int | None = None
        self._pending_history: list = []
        self._user_id = user_id
        self._last_run_id: str | None = None

        if conversation_repository:
            try:
                self._conv_id = conversation_repository.get_latest_conversation_id(user_id)
                if self._conv_id is None:
                    self._conv_id = conversation_repository.create_conversation(user_id)
                else:
                    turns = conversation_repository.load_turns_after(self._conv_id, None, limit=10)
                    for turn in turns:
                        if turn["role"] == "user":
                            self._pending_history.append(HumanMessage(content=turn["content"]))
                        elif turn["role"] == "assistant":
                            self._pending_history.append(AIMessage(content=turn["content"]))
                    if self._pending_history:
                        print(f"[Agent] 이전 대화 {len(self._pending_history) // 2}턴 복원")
            except Exception as e:
                print(f"[Agent] 이력 복원 실패: {e}")
                self._conv_id = None
                self._pending_history = []

        if rag_show_sources:
            search_tool = make_search_tool(retriever_service, self._source_buffer)
        else:
            search_tool = make_retriever_tool(retriever_service)
        tools = [search_tool, web_search, get_current_date]
        if user_profile_repository is not None:
            remember_tool, recall_tool = make_memory_tools(user_profile_repository, user_id)
            tools += [remember_tool, recall_tool]
        llm_with_tools = chat_model.bind_tools(tools)

        async def call_model(state: MessagesState, config: RunnableConfig) -> dict:
            from datetime import date
            system_content = (
                "【언어 규칙】모든 사고 과정(thinking)과 답변을 반드시 한국어로 작성하세요. "
                "영어 사용 금지. Think in Korean only.\n\n"
                f"오늘 날짜: {date.today().isoformat()}\n\n"
                + self._system_prompt
            )
            if self._profile_repo:
                profile = self._profile_repo.get_all(self._user_id)
                if profile:
                    import re
                    from datetime import date
                    today = date.today()
                    current_year = today.year
                    _DATE_KEYS = ("생년월일", "생년", "생일")
                    lines = []
                    for k, v in profile.items():
                        if any(term in k for term in _DATE_KEYS):
                            full_date = re.search(r'(\d{4})[년\-/.]\s*(\d{1,2})[월\-/.]\s*(\d{1,2})', v)
                            year_only = re.search(r'\b(19|20)\d{2}\b', v)
                            age_key = re.sub(r'생년월일|생년|생일', '나이', k)
                            if full_date:
                                by, bm, bd = int(full_date.group(1)), int(full_date.group(2)), int(full_date.group(3))
                                korean_age = current_year - by + 1
                                intl_age = current_year - by - (1 if today < date(current_year, bm, bd) else 0)
                                lines.append(f"- {age_key}: 한국 나이 {korean_age}세, 만 {intl_age}세")
                            elif year_only:
                                by = int(year_only.group())
                                korean_age = current_year - by + 1
                                intl_age = current_year - by
                                lines.append(f"- {age_key}: 한국 나이 {korean_age}세, 만 {intl_age}~{intl_age - 1}세 (생일에 따라 다름)")
                            else:
                                lines.append(f"- {k}: {v}")
                        else:
                            lines.append(f"- {k}: {v}")
                    system_content += f"\n\n## 사용자 정보 (이전 대화에서 기억된 내용)\n" + "\n".join(lines)
            msgs = [SystemMessage(content=system_content)] + state["messages"]
            thinking_acc, content_acc, tool_calls_acc = "", "", []
            try:
                writer = get_stream_writer()
            except Exception:
                writer = None
            # LLM 추론 시작 직전에 즉시 신호 emit — UI에 "분석 중" 표시
            if writer:
                writer({"__start": True})
            # 체크박스 값을 모델의 enable_thinking으로 전달 (런타임 오버라이드)
            show_thinking = config.get("configurable", {}).get("show_thinking", False)
            _llm = llm_with_tools.bind(enable_thinking=show_thinking) if show_thinking != chat_model.enable_thinking else llm_with_tools
            async for chunk in _llm.astream(msgs, config):
                t = chunk.additional_kwargs.get("thinking", "")
                if t:
                    thinking_acc += t
                    if writer:
                        writer({"__thinking": t})
                if chunk.content and isinstance(chunk.content, str):
                    content_acc += chunk.content
                if chunk.tool_calls:
                    tool_calls_acc.extend(chunk.tool_calls)
            extra = {"thinking": thinking_acc} if thinking_acc else {}
            return {"messages": [AIMessage(
                content=content_acc,
                tool_calls=tool_calls_acc,
                additional_kwargs=extra,
            )]}

        async def query_rewrite_node(state: MessagesState, config: RunnableConfig) -> dict:
            last_msg = state["messages"][-1]
            if not (hasattr(last_msg, "tool_calls") and last_msg.tool_calls):
                return {}

            # 최근 사용자 메시지 2개를 컨텍스트로 활용 (대명사·지시어 해소)
            recent_human = [m.content for m in state["messages"][:-1]
                            if isinstance(m, HumanMessage)][-2:]
            ctx = ("\n\n이전 대화 컨텍스트:\n" + "\n".join(f"- {m}" for m in recent_human)
                   if recent_human else "")

            try:
                writer = get_stream_writer()
            except Exception:
                writer = None

            _rewrite_llm = chat_model.bind(enable_thinking=False)
            new_tool_calls = []
            for tc in last_msg.tool_calls:
                if tc["name"] == "search_documents":
                    original = tc["args"].get("query", "")
                    prompt = (
                        f"다음 구어체 질문을 문서 검색에 최적화된 키워드 중심 문장으로 변환하세요.{ctx}\n\n"
                        f"규칙:\n"
                        f"- 핵심 개념과 전문용어를 포함하세요\n"
                        f"- 대명사(이것, 그것, 그 논문 등)는 구체적인 명칭으로 교체하세요\n"
                        f"- 변환된 질문만 한 문장으로 출력하세요. 부가 설명 없이 질문만 출력하세요\n\n"
                        f"원본 질문: {original}\n최적화된 질문:"
                    )
                    try:
                        result = await _rewrite_llm.ainvoke([HumanMessage(content=prompt)])
                        rewritten = result.content.strip()
                    except Exception as e:
                        print(f"[QueryRewrite] 실패: {e}")
                        rewritten = original
                    if rewritten and rewritten != original:
                        new_tool_calls.append({**tc, "args": {**tc["args"], "query": rewritten}})
                        if writer:
                            writer({"__query_rewrite": {"original": original, "rewritten": rewritten}})
                    else:
                        new_tool_calls.append(tc)
                else:
                    new_tool_calls.append(tc)

            if not last_msg.id:
                return {}
            new_msg = AIMessage(
                id=last_msg.id,
                content=last_msg.content,
                tool_calls=new_tool_calls,
                additional_kwargs=last_msg.additional_kwargs,
            )
            return {"messages": [new_msg]}

        def route_after_agent(state: MessagesState) -> str:
            last_msg = state["messages"][-1]
            if not (hasattr(last_msg, "tool_calls") and last_msg.tool_calls):
                return END
            if self._query_rewrite_enabled:
                if any(tc["name"] == "search_documents" for tc in last_msg.tool_calls):
                    return "query_rewrite"
            return "tools"

        builder = StateGraph(MessagesState)
        builder.add_node("agent", call_model)
        builder.add_node("query_rewrite", query_rewrite_node)
        builder.add_node("tools", ToolNode(tools))
        builder.add_edge(START, "agent")
        builder.add_conditional_edges("agent", route_after_agent)
        builder.add_edge("query_rewrite", "tools")
        builder.add_edge("tools", "agent")

        self._agent = builder.compile(checkpointer=MemorySaver())

    @property
    def last_run_id(self) -> str | None:
        return self._last_run_id

    def _make_config(self, show_thinking: bool = False) -> dict:
        return {"configurable": {"thread_id": self._thread_id, "show_thinking": show_thinking}}

    async def stream_response(self, user_input: str, show_thinking: bool | None = None) -> AsyncIterator[str | dict]:
        """사용자 입력을 받아 응답 토큰을 순서대로 yield한다.

        실제 답변: plain str
        진행/thinking/출처 메타데이터: {"__meta": str}  ← 소비자가 TTS 등에서 필터링 가능
        """
        _think_verbose = show_thinking if show_thinking is not None else self._think_verbose
        self._source_buffer.clear()
        run_id = uuid.uuid4()
        run_config = {**self._make_config(_think_verbose), "run_id": str(run_id)}

        # 재시작 후 첫 호출 시 MySQL 이력을 초기 상태에 주입
        if self._pending_history:
            all_messages = self._pending_history + [HumanMessage(content=user_input)]
            self._pending_history = []
        else:
            all_messages = [HumanMessage(content=user_input)]
        messages = {"messages": all_messages}
        response_content = ""  # 실제 답변 내용만 누적 (MySQL 저장용)
        pending_tool_calls: dict = {}  # tool_call_id → {name, args}
        prev_node: str = ""
        lg = self._langgraph_verbose
        thinking_open = False   # [사고 과정] 헤더 출력 여부
        content_started = False # 노드 당 레이블 1회 출력 제어
        start_time = time.perf_counter()

        async for stream_event in self._agent.astream(
            messages, run_config, stream_mode=["messages", "custom"]
        ):
            mode, data = stream_event

            # ── custom 이벤트 ────────────────────────────────────────────
            if mode == "custom":
                if isinstance(data, dict) and "__start" in data:
                    # call_model 시작 즉시 emit — LLM 추론 전에 상태 표시
                    label = "검색 결과를 분석하고 있습니다..." if prev_node == "tools" else "질문을 분석하고 있습니다..."
                    yield {"__status": label}
                    continue
                if isinstance(data, dict) and "__query_rewrite" in data:
                    info = data["__query_rewrite"]
                    if lg or self._rag_verbose:
                        yield {"__meta": f'\n쿼리 최적화: "{info["original"]}" → "{info["rewritten"]}"\n'}
                    continue
                if isinstance(data, dict) and "__thinking" in data:
                    # thinking 첫 토큰 도착 시 agent 레이블 + prev_node 갱신
                    if "agent" != prev_node:
                        thinking_open = False
                        content_started = False
                        if lg:
                            elapsed = time.perf_counter() - start_time
                            label = "agent: 검색 결과 반영 중" if prev_node == "tools" else "agent: 질문 분석 중"
                            yield {"__meta": f"\n[LangGraph → {label}] ({elapsed:.2f}s)\n"}
                        prev_node = "agent"
                    if _think_verbose:
                        thinking_open = True
                        yield {"__thinking": data["__thinking"]}
                continue

            # ── messages 이벤트 ──────────────────────────────────────
            chunk, metadata = data
            node = metadata.get("langgraph_node", "")

            # ── 노드 전환 시 플래그 리셋 + 레이블 출력 ──────────────
            # (agent 레이블은 custom 이벤트 핸들러에서 이미 처리될 수 있으므로 중복 방지)
            if node != prev_node:
                thinking_open = False
                content_started = False
                if lg:
                    elapsed = time.perf_counter() - start_time
                    if node == "agent":
                        label = "agent: 검색 결과 반영 중" if prev_node == "tools" else "agent: 질문 분석 중"
                        yield {"__meta": f"\n[LangGraph → {label}] ({elapsed:.2f}s)\n"}
                    elif node == "query_rewrite":
                        yield {"__meta": f"\n[LangGraph → query_rewrite: 쿼리 최적화 중] ({elapsed:.2f}s)\n"}
                    elif node == "tools":
                        yield {"__meta": f"\n[LangGraph → tools: 도구 실행 중] ({elapsed:.2f}s)\n"}
                prev_node = node

            # ── agent 노드 — AIMessageChunk만 처리 (중복 방지) ──────
            if node == "agent" and isinstance(chunk, AIMessageChunk):
                if chunk.tool_calls:
                    thinking_open = False
                    for tc in chunk.tool_calls:
                        pending_tool_calls[tc["id"]] = tc
                        if tc.get("name") == "search_documents":
                            query = tc.get("args", {}).get("query", "")
                            yield {"__meta": f'\n문서 검색 중... ("{query}")\n'} if query else {"__meta": "\n문서 검색 중...\n"}
                        elif tc.get("name") == "web_search":
                            query = tc.get("args", {}).get("query", "")
                            yield {"__meta": f'\n웹 검색 중... ("{query}")\n'} if query else {"__meta": "\n웹 검색 중...\n"}
                        elif lg:
                            args_str = ", ".join(f'{k}="{v}"' for k, v in tc["args"].items())
                            yield {"__meta": f"  [tool_call: {tc['name']}({args_str})]\n"}

                elif chunk.content:
                    thinking_open = False
                    if lg and not content_started:
                        yield {"__meta": "\n[LangGraph → agent: 최종 답변 생성]\n\n"}
                        content_started = True
                    response_content += chunk.content
                    yield chunk.content

            # ── agent 노드 — AIMessage(최종 state) ──────────────────
            # 청크 스트리밍이 없었던 경우(edge case)에만 처리
            elif node == "agent" and isinstance(chunk, AIMessage):
                if not content_started and not thinking_open:
                    thinking = chunk.additional_kwargs.get("thinking", "")
                    if thinking and _think_verbose:
                        yield {"__thinking": thinking}
                    if chunk.content:
                        if lg:
                            yield {"__meta": "\n[LangGraph → agent: 최종 답변 생성]\n\n"}
                        response_content += chunk.content
                        yield chunk.content

            # ── tools 노드 ───────────────────────────────────────────
            elif node == "tools" and hasattr(chunk, "name") and chunk.name == "search_documents":
                if lg:
                    result_lines = [b for b in chunk.content.split("\n\n") if b.strip()]
                    yield {"__meta": f"  [결과: {len(result_lines)}개 문서 반환 → agent 복귀]\n"}

                if self._rag_verbose:
                    tc = pending_tool_calls.get(chunk.tool_call_id, {})
                    query = tc.get("args", {}).get("query", "")
                    yield {"__meta": f'\n[문서 검색: "{query}"]\n'}
                    for block in chunk.content.split("\n\n"):
                        if block.strip():
                            preview = block.strip().replace("\n", " ")[:80]
                            yield {"__meta": f"  → {preview}\n"}
                    yield {"__meta": "\n"}

            elif node == "tools" and hasattr(chunk, "name") and chunk.name == "web_search":
                if lg:
                    result_lines = [b for b in chunk.content.split("\n\n") if b.strip()]
                    yield {"__meta": f"  [웹 검색 결과: {len(result_lines)}건 → agent 복귀]\n"}

        thinking_open = False
        self._last_run_id = str(run_id)

        # 대화 내용을 MySQL에 저장
        if self._conv_repo and self._conv_id and response_content:
            try:
                self._conv_repo.save_message(self._conv_id, "user", user_input)
                self._conv_repo.save_message(self._conv_id, "assistant", response_content)
            except Exception as e:
                print(f"[Agent] 대화 저장 실패: {e}")

        if self._rag_show_sources and self._source_buffer:
            sources = []
            for src in self._source_buffer:
                entry = {"filename": os.path.basename(src["source"])}
                if "page" in src:
                    entry["page"] = src["page"]
                sources.append(entry)
            yield {"__sources": sources}

    def reset(self) -> None:
        """새 thread_id로 대화 히스토리를 초기화한다."""
        self._thread_id = str(uuid.uuid4())
        self._pending_history = []
        if self._conv_repo:
            try:
                self._conv_id = self._conv_repo.create_conversation(self._user_id)
            except Exception:
                self._conv_id = None