import time

from fastapi import FastAPI, HTTPException, Request, Response
from prometheus_client import CONTENT_TYPE_LATEST, Counter, Histogram, generate_latest

app = FastAPI(title="DevOps Test Service")

REQUESTS = Counter(
    "http_requests_total", "Total HTTP requests", ["method", "path", "status"]
)
LATENCY = Histogram(
    "http_request_duration_seconds", "Request latency in seconds", ["path"]
)


@app.middleware("http")
async def track_metrics(request: Request, call_next):
    start = time.perf_counter()
    response = await call_next(request)
    path = request.url.path
    REQUESTS.labels(request.method, path, response.status_code).inc()
    LATENCY.labels(path).observe(time.perf_counter() - start)
    return response


@app.get("/")
def index():
    return {"message": "Hello from the DevOps test service"}


@app.get("/health")
def health():
    return {"status": "ok"}


@app.get("/error")
def error():
    # Used to generate 5xx responses and trigger the high-error-rate alert
    raise HTTPException(status_code=500, detail="simulated failure")


@app.get("/metrics")
def metrics():
    return Response(generate_latest(), media_type=CONTENT_TYPE_LATEST)