const opentelemetry = require('@opentelemetry/api');
const { registerInstrumentations } = require('@opentelemetry/instrumentation');
const { NodeTracerProvider } = require('@opentelemetry/sdk-trace-node');
const { Resource } = require('@opentelemetry/resources');
const { SemanticResourceAttributes } = require('@opentelemetry/semantic-conventions');
const { BatchSpanProcessor } = require('@opentelemetry/sdk-trace-base');
const { JaegerExporter } = require('@opentelemetry/exporter-jaeger');
const { ZipkinExporter } = require('@opentelemetry/exporter-zipkin');
const { CollectorTraceExporter } =  require('@opentelemetry/exporter-collector');
//const { HttpInstrumentation } = require('@opentelemetry/instrumentation-http');
//const { ExpressInstrumentation } = require('@opentelemetry/instrumentation-express');
//const { PinoInstrumentation } = require('@opentelemetry/instrumentation-pino');

module.exports = (serviceName) => {
  if (process.env.JAMBONES_OTEL_ENABLED) {
    const {version} = require('./package.json');
    const provider = new NodeTracerProvider({
      resource: new Resource({
        [SemanticResourceAttributes.SERVICE_NAME]: serviceName,
        [SemanticResourceAttributes.SERVICE_VERSION]: version,
      }),
    });

    let exporter;
    if (process.env.OTEL_EXPORTER_JAEGER_AGENT_HOST) {
      exporter = new JaegerExporter();
    }
    else if (process.env.OTEL_EXPORTER_ZIPKIN_URL) {
      exporter = new ZipkinExporter({url:process.env.OTEL_EXPORTER_ZIPKIN_URL});
    }
    else {
      exporter = new CollectorTraceExporter({
        url: process.OTEL_EXPORTER_COLLECTOR_URL
      });
    }

    provider.addSpanProcessor(new BatchSpanProcessor(exporter, {
      // The maximum queue size. After the size is reached spans are dropped.
      maxQueueSize: 100,
      // The maximum batch size of every export. It must be smaller or equal to maxQueueSize.
      maxExportBatchSize: 10,
      // The interval between two consecutive exports
      scheduledDelayMillis: 500,
      // How long the export can run before it is cancelled
      exportTimeoutMillis: 30000,
    }));

    // Initialize the OpenTelemetry APIs to use the NodeTracerProvider bindings
    provider.register();
    registerInstrumentations({
      instrumentations: [
        //new HttpInstrumentation(),
        //new ExpressInstrumentation(),
        //new PinoInstrumentation()
      ],
    });
  }

  return opentelemetry.trace.getTracer(serviceName);
};