'use strict';

const opentelemetry = require('@opentelemetry/api');
const { NodeTracerProvider } = require('@opentelemetry/node');
const { SimpleSpanProcessor } = require('@opentelemetry/tracing');
const { JaegerExporter } = require('@opentelemetry/exporter-jaeger');
const { ZipkinExporter } = require('@opentelemetry/exporter-zipkin');

const EXPORTER = process.env.EXPORTER || '';


module.exports = (serviceName) => {
  const provider = new NodeTracerProvider({
    plugins: {
      express: {
        enabled: true,
        path: '@opentelemetry/plugin-express',
      },
      http: {
        enabled: true,
        path: '@opentelemetry/plugin-http',
      },
    },
  });

  let exporter;
  if (EXPORTER.toLowerCase().startsWith('z')) {
    exporter = new ZipkinExporter({
      serviceName,
    });
  } else {
    exporter = new JaegerExporter({
      serviceName,
    });
  }

  provider.addSpanProcessor(new SimpleSpanProcessor(exporter));

  // Initialize the OpenTelemetry APIs to use the NodeTracerProvider bindings
  opentelemetry.trace.initGlobalTracerProvider(provider);

  return opentelemetry.trace.getTracer('express-example');
};