/**
 * OpenTelemetry instrumentation — auto-instrumentat pe Express, HTTP, pg, redis, ioredis.
 * Trimite trace-uri la OTel Collector → Jaeger.
 *
 * Activează cu env var OTEL_ENABLED=true (off implicit ca să nu impacteze cold start).
 */

import { NodeSDK } from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-http';
import { Resource } from '@opentelemetry/resources';
import { SemanticResourceAttributes } from '@opentelemetry/semantic-conventions';

const SERVICE_NAME = process.env.OTEL_SERVICE_NAME || 'didi-framework';
const ENDPOINT = process.env.OTEL_EXPORTER_OTLP_ENDPOINT || 'http://didi-otel-collector:4318/v1/traces';

let sdk: NodeSDK | null = null;

export function startOtel() {
  if (process.env.OTEL_ENABLED !== 'true') return;
  if (sdk) return;

  sdk = new NodeSDK({
    resource: new Resource({
      [SemanticResourceAttributes.SERVICE_NAME]: SERVICE_NAME,
      [SemanticResourceAttributes.SERVICE_VERSION]: process.env.SERVICE_VERSION || '1.0.0',
    }),
    traceExporter: new OTLPTraceExporter({ url: ENDPOINT }),
    instrumentations: [
      getNodeAutoInstrumentations({
        '@opentelemetry/instrumentation-fs': { enabled: false },
      }),
    ],
  });
  sdk.start();
  // eslint-disable-next-line no-console
  console.log(`[otel] started, exporting to ${ENDPOINT} as ${SERVICE_NAME}`);
}

process.on('SIGTERM', () => {
  if (sdk) {
    sdk.shutdown().finally(() => process.exit(0));
  }
});