from __future__ import annotations

from fastapi import FastAPI
from prometheus_fastapi_instrumentator import Instrumentator

from app.core.config import settings


def setup_metrics(app: FastAPI) -> None:
    """Configure Prometheus metrics instrumentation."""
    if not settings.prometheus_enabled:
        return

    instrumentator = Instrumentator(
        should_group_status_codes=True,
        should_ignore_untemplated=True,
        should_respect_env_var=False,
        excluded_handlers=["/metrics", "/api/v1/health", "/docs", "/openapi.json"],
        env_var_name="PROMETHEUS_ENABLED",
        inprogress_name="docengine_inprogress_requests",
        inprogress_labels=True,
    )

    instrumentator.instrument(app).expose(
        app,
        endpoint="/metrics",
        include_in_schema=False,
        should_gzip=True,
    )