"""Prometheus metrics for gateway tier/lane routing."""

from __future__ import annotations

from prometheus_client import CONTENT_TYPE_LATEST, Counter, Histogram, generate_latest

REQUESTS = Counter(
    "ai_router_requests_total",
    "Total routed requests",
    ["tier", "lane", "model", "status"],
)
ESCALATIONS = Counter(
    "ai_router_escalations_total",
    "Lane escalations",
    ["from_lane", "to_lane", "reason"],
)
CLASSIFY = Counter(
    "ai_router_classify_total",
    "Classification results",
    ["tier"],
)
CLASSIFY_LLM = Counter(
    "ai_router_classify_llm_total",
    "LLM classifier invocations (GigaChat)",
    ["tier", "status"],
)
DURATION = Histogram(
    "ai_router_request_duration_seconds",
    "Request duration",
    ["tier", "model"],
    buckets=(0.1, 0.25, 0.5, 1, 2, 5, 10, 30, 60, 120, 180),
)


def metrics_payload() -> tuple[bytes, str]:
    return generate_latest(), CONTENT_TYPE_LATEST