"""Case-specific deterministic QA routes.

These endpoints expose validated reproduction-case packages before they are
merged into the general RAG chat route. They do not call an LLM.
"""

from functools import lru_cache
from pathlib import Path
from typing import Any

from fastapi import APIRouter, HTTPException
from pydantic import BaseModel, Field

from src.rag.unified.case_qa import CasePackageQAEngine


PROJECT_ROOT = Path(__file__).resolve().parents[1]
FT_SPL_CASE_PACKAGE = PROJECT_ROOT / "data" / "ft_spl_reproduction_case_package.json"

router = APIRouter()


class CaseQARequest(BaseModel):
    query: str = Field(..., min_length=1)


class CaseQAResponse(BaseModel):
    query: str
    intent: str
    answer: str
    citations: list[str]
    facts: dict[str, Any]


class CaseStatusResponse(BaseModel):
    case_id: str
    package_path: str
    package_exists: bool
    supported: bool


@lru_cache(maxsize=1)
def get_ft_spl_engine() -> CasePackageQAEngine:
    if not FT_SPL_CASE_PACKAGE.exists():
        raise FileNotFoundError(str(FT_SPL_CASE_PACKAGE))
    return CasePackageQAEngine(FT_SPL_CASE_PACKAGE)


@router.get("/ft-spl/status", response_model=CaseStatusResponse)
async def ft_spl_case_status():
    return CaseStatusResponse(
        case_id="ft_spl_reproduction_job_1777615271527",
        package_path=str(FT_SPL_CASE_PACKAGE),
        package_exists=FT_SPL_CASE_PACKAGE.exists(),
        supported=FT_SPL_CASE_PACKAGE.exists(),
    )


@router.post("/ft-spl/qa", response_model=CaseQAResponse)
async def ft_spl_case_qa(request: CaseQARequest):
    try:
        response = get_ft_spl_engine().answer(request.query)
    except FileNotFoundError as exc:
        raise HTTPException(status_code=503, detail=f"Case package missing: {exc}") from exc
    return CaseQAResponse(
        query=response.query,
        intent=response.intent,
        answer=response.answer,
        citations=response.citations,
        facts=response.facts,
    )