"""
Prometheus metrics definitions for the Trainingssoftware API.

Collectors are registered once at app startup (see apps.py ready()).
The middleware records observations; the /metrics endpoint exposes them.
"""
from prometheus_client import Counter, Histogram, Gauge

# Request latency histogram — buckets tuned for web API (50ms … 10s)
HTTP_REQUEST_DURATION_SECONDS = Histogram(
    "http_request_duration_seconds",
    "HTTP request latency",
    ["method", "path_template", "status_code"],
    buckets=(0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10.0),
)

# Total requests counter (separate from histogram for cheap rate queries)
HTTP_REQUESTS_TOTAL = Counter(
    "http_requests_total",
    "Total HTTP requests",
    ["method", "path_template", "status_code"],
)

# Error rate counter — 5xx responses only
HTTP_SERVER_ERRORS_TOTAL = Counter(
    "http_server_errors_total",
    "Total HTTP 5xx responses",
    ["method", "path_template", "status_code"],
)

# In-flight requests gauge
HTTP_REQUESTS_IN_FLIGHT = Gauge(
    "http_requests_in_flight",
    "Current number of in-flight HTTP requests",
)