"""services/copilot/api.py — FastAPI router for the RAG copilot.

Mounted at /api/v1/copilot in app/main.py. Follows the same auth pattern as
the rest of this backend (require_api_key — see app/security.py) since
there's no per-user auth yet.
"""
from __future__ import annotations

import logging

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import Settings, get_settings
from app.database import get_db
from app.security import rate_limit, require_api_key
from app.services.copilot import db as copilot_db
from app.services.copilot.engine import answer_chat
from app.services.copilot.models import ChatRequest, ChatResponse

logger = logging.getLogger(__name__)
router = APIRouter(prefix="/copilot", tags=["Copilot"])


@router.post(
    "/chat",
    response_model=ChatResponse,
    dependencies=[Depends(require_api_key), Depends(rate_limit(limit=20, window_seconds=60))],
    summary="Ask Shield Copilot a question, grounded in the app's knowledge base",
)
async def chat(
    request: ChatRequest,
    session: AsyncSession = Depends(get_db),
    settings: Settings = Depends(get_settings),
) -> ChatResponse:
    try:
        return await answer_chat(session, request, settings)
    except Exception as exc:
        # copilot_chunks / pgvector may be entirely unavailable in this
        # deployment (see database.py::_create_copilot_table_if_possible) —
        # surface a clear 503 rather than a generic 500.
        logger.exception("Copilot chat failed: %s", exc)
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail="Copilot is temporarily unavailable. Please try again shortly.",
        ) from exc


@router.get("/health", summary="Copilot subsystem status (chunk count)")
async def copilot_health(session: AsyncSession = Depends(get_db)) -> dict:
    try:
        count = await copilot_db.chunk_count(session)
        return {"status": "ready" if count > 0 else "empty", "indexed_chunks": count}
    except Exception as exc:
        return {"status": "unavailable", "detail": str(exc)}