// Prometheus metrics. Reusable counters/histograms for the API + cache.

import { Counter, collectDefaultMetrics, Gauge, Histogram, Registry } from 'prom-client';

export const registry = new Registry();
collectDefaultMetrics({ register: registry });

export const httpRequests = new Counter({
  name: 'http_requests_total',
  help: 'Total HTTP requests',
  labelNames: ['method', 'route', 'status'],
  registers: [registry],
});

export const httpDuration = new Histogram({
  name: 'http_request_duration_seconds',
  help: 'HTTP request duration in seconds',
  labelNames: ['method', 'route', 'status'],
  buckets: [0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 5],
  registers: [registry],
});

export const searchCacheHits = new Counter({
  name: 'search_cache_hits_total',
  help: 'Number of search results served from the LRU cache',
  registers: [registry],
});

export const searchCacheMisses = new Counter({
  name: 'search_cache_misses_total',
  help: 'Number of search requests that bypassed the cache',
  registers: [registry],
});

export const imdbRatingsCount = new Gauge({
  name: 'imdb_ratings_total',
  help: 'Number of IMDb ratings currently loaded in memory',
  registers: [registry],
});

export const searchWorkers = new Gauge({
  name: 'search_workers',
  help: 'Number of active search workers per type',
  labelNames: ['type'],
  registers: [registry],
});