"""Prometheus metrics endpoint."""

from __future__ import annotations

from fastapi import APIRouter, Header, HTTPException, Response, status
from prometheus_client import CONTENT_TYPE_LATEST, generate_latest

from src.contract_check.core.config import get_settings

router = APIRouter(tags=["metrics"])


@router.get("/metrics")
async def metrics(authorization: str | None = Header(default=None)) -> Response:
    token = get_settings().metrics_bearer_token
    if token:
        if not authorization or not authorization.lower().startswith("bearer "):
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED, detail="missing bearer token"
            )
        if authorization[7:].strip() != token:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED, detail="invalid bearer token"
            )
    return Response(generate_latest(), media_type=CONTENT_TYPE_LATEST)