// OpenTelemetry tracing and logging initialization for gibbz backend
'use strict';

const process = require('process');
const { NodeSDK } = require('@opentelemetry/sdk-node');
const { getNodeAutoInstrumentations } = require('@opentelemetry/auto-instrumentations-node');
const { OTLPTraceExporter } = require('@opentelemetry/exporter-trace-otlp-http');
const { OTLPLogExporter } = require('@opentelemetry/exporter-logs-otlp-http');
const { BatchLogRecordProcessor } = require('@opentelemetry/sdk-logs');
const { resourceFromAttributes } = require('@opentelemetry/resources');
const { ATTR_SERVICE_NAME, ATTR_SERVICE_VERSION } = require('@opentelemetry/semantic-conventions');

const serviceName = process.env.OTEL_SERVICE_NAME || 'gibbz';
const serviceRelease = process.env.SERVICE_RELEASE || process.env.OTEL_SERVICE_RELEASE || process.env.APP_RELEASE || 'dev';
const environment = process.env.ENVIRONMENT || process.env.NODE_ENV || 'production';
const otelUrl = (process.env.OTEL_EXPORTER_OTLP_ENDPOINT || process.env.OTEL_URL || 'https://otel.k6n.net').replace(/\/+$/, '');
const ingestKey = process.env.OTEL_INGEST_KEY || '';

const headers = {};
if (ingestKey) {
  headers['X-Otel-Ingest-Key'] = ingestKey;
}

const resource = resourceFromAttributes({
  [ATTR_SERVICE_NAME]: serviceName,
  [ATTR_SERVICE_VERSION]: serviceRelease,
  'service.name': serviceName,
  'service.release': serviceRelease,
  'service.environment': environment,
});

// Configure trace exporter
const traceExporter = new OTLPTraceExporter({
  url: `${otelUrl}/v1/traces`,
  headers,
});

// Configure logs exporter
const logExporter = new OTLPLogExporter({
  url: `${otelUrl}/v1/logs`,
  headers,
});

const logRecordProcessor = new BatchLogRecordProcessor(logExporter);

const sdk = new NodeSDK({
  resource,
  traceExporter,
  logRecordProcessor,
  instrumentations: [
    getNodeAutoInstrumentations({
      '@opentelemetry/instrumentation-fs': { enabled: false },
    }),
  ],
});

try {
  sdk.start();
  console.log(`[otel] Initialized OpenTelemetry for ${serviceName} (release: ${serviceRelease}, env: ${environment}) -> ${otelUrl}`);
} catch (err) {
  console.error('[otel] Failed to start OpenTelemetry SDK:', err);
}

process.on('SIGTERM', () => {
  sdk.shutdown()
    .then(() => console.log('[otel] SDK shut down successfully'))
    .catch((err) => console.error('[otel] Error shutting down SDK', err))
    .finally(() => process.exit(0));
});

module.exports = { sdk };