from typing import Literal, List, Generator, Optional
import json
import threading

from fastapi import APIRouter, HTTPException, Request
from fastapi.responses import StreamingResponse
from pydantic import BaseModel, Field

from backend.services.chat import ChatService  # Import the service class
from backend.services.event_logger import log_error
from backend.services.llm_override import ProviderOverride
from postgres_client import pg

router = APIRouter(prefix="/api", tags=["chat"])

# Pydantic models for request/response validation
class ChatMessage(BaseModel):
    role: Literal["system", "user", "assistant"]
    content: str = Field(..., min_length=1)

class ChatRequest(BaseModel):
    messages: List[ChatMessage]
    top_k: int = Field(default=5, ge=1, le=10)
    focus_ids: List[str] | None = Field(default=None, description="Optional ids from previously shared results.")
    provider_override: ProviderOverride | None = Field(default=None, description="Optional user-supplied provider.")
    use_editor: bool = Field(default=False, description="Run the editor pass (fact-check + language polish) before returning.")
    quick: bool = Field(default=False, description="Skip the planner/Researcher pre-pass and let the orchestrator answer directly. Faster, less thorough.")
    session_id: str | None = Field(default=None, description="Browser session id; used to group opt-in TEST eval logs.")

class ChatSource(BaseModel):
    _id: str
    chunk_index: int
    heading: str | None
    debateurl: str | None
    snippet: str
    speaker: str | None = None
    party: str | None = None
    intressent_id: str | None = None
    date: str | None = None

class PersonRef(BaseModel):
    intressent_id: str
    name: str
    party: str


class AttributionWarning(BaseModel):
    paragraph_idx: int
    name: str
    party: str
    cited_ns: List[int] = Field(default_factory=list)
    reason: str


class ChatResponse(BaseModel):
    answer: str
    sources: List[ChatSource]
    persons: List[PersonRef] = Field(default_factory=list)
    tables: List[dict] = Field(default_factory=list)
    focus_ids: List[str] = Field(default_factory=list)
    attribution_warnings: List[AttributionWarning] = Field(default_factory=list)

# Instantiate the chat service once (can be reused for all requests)
chat_service = ChatService()

@router.post("/chat", response_model=ChatResponse)
def chat_endpoint(payload: ChatRequest, request: Request) -> ChatResponse:
    """
    Handles chat requests from the frontend. Uses ChatService to generate a response.

    Args:
        payload (ChatRequest): The chat history and parameters from the frontend.

    Returns:
        ChatResponse: The assistant's answer and a list of sources.
    """
    # Convert Pydantic models to dicts for the service
    messages = [msg.model_dump() for msg in payload.messages]
    try:
        result = chat_service.get_chat_response(
            messages=messages,
            top_k=payload.top_k,
            focus_ids=payload.focus_ids or [],
            provider_override=payload.provider_override,
            use_editor=payload.use_editor,
            quick=payload.quick,
            session_id=payload.session_id or request.headers.get("X-Session-Id"),
        )
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))
    except Exception as e:
        import traceback
        print("UNHANDLED ERROR in chat_endpoint:", e)
        traceback.print_exc()
        log_error("http_500", e, route="/api/chat")
        raise HTTPException(status_code=500, detail=f"Internal server error: {e}")
    raw_answer = result.get("answer", "")
    if not isinstance(raw_answer, str):
        raw_answer = str(raw_answer)

    raw_sources = result.get("sources", [])
    if not isinstance(raw_sources, list):
        raw_sources = []

    sources = [
        ChatSource(
            _id=src.get("_id", ""),
            chunk_index=src.get("chunk_index", 0),
            heading=src.get("heading"),
            debateurl=src.get("debateurl"),
            snippet=src.get("snippet", ""),
            speaker=src.get("speaker"),
            party=src.get("party"),
            intressent_id=src.get("intressent_id"),
            date=src.get("date"),
        )
        for src in raw_sources
    ]
    persons = [
        PersonRef(**p) for p in result.get("persons", [])
        if isinstance(p, dict) and "intressent_id" in p and "name" in p
    ]
    warnings = [
        AttributionWarning(**w) for w in result.get("attribution_warnings", [])
        if isinstance(w, dict) and "paragraph_idx" in w and "name" in w
    ]
    return ChatResponse(
        answer=raw_answer,
        sources=sources,
        persons=persons,
        tables=result.get("tables", []),
        focus_ids=result.get("focus_ids", []),
        attribution_warnings=warnings,
    )


@router.post("/chat/stream")
def chat_stream_endpoint(payload: ChatRequest, request: Request) -> StreamingResponse:
    """
    SSE endpoint: streams tool-call progress events followed by the final answer.
    Each event is a line of the form:  data: <json>\\n\\n
    Event types: "tool_call", "status", "answer", "error".
    Using streaming avoids Cloudflare's 100-second proxy timeout for long-running queries.
    """
    messages = [msg.model_dump() for msg in payload.messages]
    session_id = payload.session_id or request.headers.get("X-Session-Id")

    def generate() -> Generator[str, None, None]:
        # SSE comment keepalive: nginx and Cloudflare buffer connections until
        # data arrives. By sending a ": keepalive\n\n" comment every 5 seconds
        # we force buffer flushes so progress hints reach the browser in real-time.
        import queue as _queue
        import time as _time

        done_event = threading.Event()
        pipe: _queue.Queue[str] = _queue.Queue()

        def produce() -> None:
            try:
                for event in chat_service.stream_chat_response(
                    messages=messages,
                    top_k=payload.top_k,
                    focus_ids=payload.focus_ids or [],
                    provider_override=payload.provider_override,
                    use_editor=payload.use_editor,
                    quick=payload.quick,
                    session_id=session_id,
                ):
                    pipe.put(f"data: {json.dumps(event, ensure_ascii=False)}\n\n")
                    if event.get("type") in ("answer", "error"):
                        break
            except Exception as exc:
                import traceback
                traceback.print_exc()
                log_error("sse_stream_exception", exc, route="/api/chat/stream")
                pipe.put(f"data: {json.dumps({'type': 'error', 'message': str(exc)})}\n\n")
            finally:
                done_event.set()

        threading.Thread(target=produce, daemon=True).start()

        while not done_event.is_set() or not pipe.empty():
            try:
                chunk = pipe.get(timeout=5)
                yield chunk
            except _queue.Empty:
                # No data for 5 s — send an SSE comment to keep the connection alive
                # and force proxies/CDNs to flush their buffers.
                if not done_event.is_set():
                    yield ": keepalive\n\n"

    return StreamingResponse(
        generate(),
        media_type="text/event-stream",
        headers={
            "Cache-Control": "no-cache",
            "X-Accel-Buffering": "no",  # Disable nginx buffering for SSE
        },
    )


# ── Provider list + model list proxy ─────────────────────────────────────────

@router.get("/providers")
def list_providers() -> dict:
    """Return all configured providers from providers.yaml (no secrets included)."""
    from backend.services.provider_registry import list_providers as _list
    return {
        "providers": [
            {"id": p.id, "name": p.name, "user_api_key": p.user_api_key}
            for p in _list()
        ]
    }

@router.get("/providers/{provider_id}/models")
def list_provider_models(provider_id: str, request: Request) -> dict:
    """
    Proxy GET {provider_base_url}/models with the user-supplied API key.
    The key must be passed in the X-Provider-Key header — it is never logged or stored.
    """
    import requests as _requests
    from backend.services.provider_registry import get_provider

    provider = get_provider(provider_id)
    if provider is None:
        raise HTTPException(status_code=404, detail=f"Unknown provider: {provider_id!r}")

    api_key = request.headers.get("X-Provider-Key", "").strip()
    if not api_key:
        raise HTTPException(status_code=400, detail="X-Provider-Key header is required")

    base = provider.base_url.rstrip("/")

    # OpenRouter supports a query param to filter by tool-capable models directly.
    params = {}
    if "openrouter.ai" in base:
        params["supported_parameters"] = "tools"

    try:
        resp = _requests.get(
            f"{base}/models",
            headers={"Authorization": f"Bearer {api_key}"},
            params=params,
            timeout=10,
        )
    except Exception as exc:
        raise HTTPException(status_code=502, detail=f"Could not reach provider: {exc}")

    if not resp.ok:
        raise HTTPException(status_code=resp.status_code, detail=f"Provider error: {resp.text[:200]}")

    data = resp.json()
    raw_models = [m for m in data.get("data", []) if isinstance(m, dict) and "id" in m]

    # Filter to tool-capable models. Each provider exposes this differently.
    if "berget.ai" in base:
        # Berget exposes capabilities.function_calling per model.
        raw_models = [m for m in raw_models if m.get("capabilities", {}).get("function_calling")]
    elif "openai.com" in base:
        # OpenAI /v1/models includes embeddings, TTS, image models — keep only text generation.
        _SKIP = ("whisper", "tts", "dall-e", "embedding", "moderation", "babbage", "davinci", "o1-mini", "realtime")
        raw_models = [m for m in raw_models if not any(s in m["id"] for s in _SKIP)]
    # OpenRouter already filtered by ?supported_parameters=tools above.

    models = [m["id"] for m in raw_models]
    return {"models": sorted(models)}


# ── MP (person) endpoints ──────────────────────────────────────────────────────

class Uppdrag(BaseModel):
    typ: str | None = None
    organ_kod: str | None = None
    roll_kod: str | None = None
    status: str | None = None
    uppgift: str | None = None
    from_: str | None = Field(None, alias="from")
    tom: str | None = None

    model_config = {"populate_by_name": True}


class PersonDetail(BaseModel):
    intressent_id: str
    namn: str
    tilltalsnamn: str | None = None
    efternamn: str | None = None
    parti: str | None = None
    valkrets: str | None = None
    status: str | None = None
    bild_url_192: str | None = None
    fodd_ar: str | None = None
    uppdrag: list[Uppdrag] | None = None


@router.get("/person/{intressent_id}", response_model=PersonDetail)
def get_person(intressent_id: str) -> PersonDetail:
    """Fetch basic person data for a Riksdag member."""
    rows = pg.execute(
        """SELECT intressent_id, namn, tilltalsnamn, efternamn, parti, valkrets,
                  status, bild_url_192, fodd_ar, personuppdrag
           FROM people WHERE intressent_id = %s""",
        (intressent_id,)
    )
    if not rows:
        raise HTTPException(status_code=404, detail="Person not found")
    row = dict(rows[0])
    raw = row.pop("personuppdrag", None) or {}
    uppdrag_list = raw.get("uppdrag", []) if isinstance(raw, dict) else []
    return PersonDetail(**row, uppdrag=[Uppdrag(**u) for u in uppdrag_list])


class MpChatRequest(BaseModel):
    messages: List[ChatMessage]
    intressent_id: str
    initial_talk_id: Optional[str] = None
    provider_override: ProviderOverride | None = Field(default=None, description="Optional user-supplied provider.")


@router.post("/chat/mp/stream")
def mp_chat_stream_endpoint(payload: MpChatRequest) -> StreamingResponse:
    """
    SSE streaming endpoint for chatting with an MP persona.
    The LLM role-plays as the specified person, grounded in their actual speeches.
    """
    from backend.services.mp_chat import MpChatService

    try:
        mp_service = MpChatService(
            intressent_id=payload.intressent_id,
            initial_talk_id=payload.initial_talk_id,
            provider_override=payload.provider_override,
        )
    except ValueError as e:
        # Same exception type covers "no such person" and "no such provider";
        # only the former should read as a missing resource.
        status = 400 if "provider" in str(e).lower() else 404
        raise HTTPException(status_code=status, detail=str(e))

    messages = [msg.model_dump() for msg in payload.messages]

    def generate() -> Generator[str, None, None]:
        import queue as _queue

        done_event = threading.Event()
        pipe: _queue.Queue[str] = _queue.Queue()

        def produce() -> None:
            try:
                for event in mp_service.stream_chat_response(messages=messages):
                    pipe.put(f"data: {json.dumps(event, ensure_ascii=False)}\n\n")
                    if event.get("type") in ("answer", "error"):
                        break
            except Exception as exc:
                import traceback
                traceback.print_exc()
                log_error("sse_stream_exception", exc, route="/api/chat/mp/stream")
                pipe.put(f"data: {json.dumps({'type': 'error', 'message': str(exc)})}\n\n")
            finally:
                done_event.set()

        threading.Thread(target=produce, daemon=True).start()

        while not done_event.is_set() or not pipe.empty():
            try:
                chunk = pipe.get(timeout=5)
                yield chunk
            except _queue.Empty:
                if not done_event.is_set():
                    yield ": keepalive\n\n"

    return StreamingResponse(
        generate(),
        media_type="text/event-stream",
        headers={
            "Cache-Control": "no-cache",
            "X-Accel-Buffering": "no",
        },
    )