const { trace } = require('@opentelemetry/api');
const { BasicTracerProvider } = require('@opentelemetry/sdk-trace-base');

// To start a trace, you first need to initialize the Tracer provider.
// NOTE: The default OpenTelemetry tracer provider does not record any tracing information.
//       Registering a working tracer provider allows the API methods to record traces.
trace.setGlobalTracerProvider(new BasicTracerProvider());

// Important: requires a context manager and propagator to be registered manually.
// propagation.setGlobalPropagator(propagator);     // replace `propagator` with your `TextMapPropagator`, for example: `W3CTraceContextPropagator` from `@openetelemetry/core`
// context.setGlobalContextManager(contextManager); // replace `contextManager` with your `ContextManager`: `AsyncLocalStorageContextManager` from `@openetelemetry/async-hooks`

// To create a span in a trace, we used the global singleton tracer to start a new span.
const span = trace.getTracer('default').startSpan('foo');

// Set a span attribute
span.setAttribute('key', 'value');

// We must end the spans so they become available for exporting.
span.end();

const {
  AlwaysOnSampler,
  BasicTracerProvider,
} = require("@opentelemetry/sdk-trace-base");

const tracerProvider = new BasicTracerProvider({
  sampler: new AlwaysOnSampler()
});

const {
  AlwaysOffSampler,
  BasicTracerProvider,
} = require("@opentelemetry/sdk-trace-base");

const tracerProvider = new BasicTracerProvider({
  sampler: new AlwaysOffSampler()
});

const {
  BasicTracerProvider,
  TraceIdRatioBasedSampler,
} = require("@opentelemetry/sdk-trace-base");

const tracerProvider = new BasicTracerProvider({
  // See details of ParentBasedSampler below
  sampler: new ParentBasedSampler({
    // Trace ID Ratio Sampler accepts a positional argument
    // which represents the percentage of traces which should
    // be sampled.
    root: new TraceIdRatioBasedSampler(0.5)
  });
});

const {
  AlwaysOffSampler,
  BasicTracerProvider,
  ParentBasedSampler,
  TraceIdRatioBasedSampler,
} = require("@opentelemetry/sdk-trace-base");

const tracerProvider = new BasicTracerProvider({
  sampler: new ParentBasedSampler({
    // By default, the ParentBasedSampler will respect the parent span's sampling
    // decision. This is configurable by providing a different sampler to use
    // based on the situation. See configuration details above.
    //
    // This will delegate the sampling decision of all root traces (no parent)
    // to the TraceIdRatioBasedSampler.
    // See details of TraceIdRatioBasedSampler above.
    root: new TraceIdRatioBasedSampler(0.5)
  })
});