/**
 * Prometheus metrics
 */

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

export const register = new Registry();

// HTTP request metrics
export const httpRequestDuration = new Histogram({
  name: 'http_request_duration_seconds',
  help: 'Duration of HTTP requests in seconds',
  labelNames: ['method', 'route', 'status_code'],
  registers: [register],
});

export const httpRequestTotal = new Counter({
  name: 'http_requests_total',
  help: 'Total number of HTTP requests',
  labelNames: ['method', 'route', 'status_code'],
  registers: [register],
});

// Database metrics
export const dbQueryDuration = new Histogram({
  name: 'db_query_duration_seconds',
  help: 'Duration of database queries in seconds',
  labelNames: ['query', 'status'],
  registers: [register],
});

export const dbConnectionsActive = new Gauge({
  name: 'db_connections_active',
  help: 'Number of active database connections',
  registers: [register],
});

// Verifiable credentials metrics
export const vcIssued = new Counter({
  name: 'verifiable_credentials_issued_total',
  help: 'Total number of verifiable credentials issued',
  registers: [register],
});

/**
 * Get metrics in Prometheus format
 */
export async function getMetrics(): Promise<string> {
  return register.metrics();
}