package main

import (
	"context"
	"log"

	apitrace "go.opentelemetry.io/api/trace"
	"go.opentelemetry.io/exporter/trace/stdout"
	sdktrace "go.opentelemetry.io/sdk/trace"
)

func initTracer() {
	sdktrace.Register()

	exporter, err := stdout.NewExporter(stdout.Options{PrettyPrint: true})
	if err != nil {
		log.Fatal(err)
	}

	ssp := sdktrace.NewSimpleSpanProcessor(exporter)
	sdktrace.RegisterSpanProcessor(ssp)

	// For the demonstration, use sdktrace.AlwaysSample sampler to sample all traces.
	// In a production application, use sdktrace.ProbabilitySampler with a desired probability.
	sdktrace.ApplyConfig(sdktrace.Config{DefaultSampler: sdktrace.AlwaysSample()})
}

func main() {
	initTracer()

	apitrace.GlobalTracer().WithSpan(context.Background(), "foo",
		func(ctx context.Context) error {
			apitrace.GlobalTracer().WithSpan(ctx, "bar",
				func(ctx context.Context) error {
					apitrace.GlobalTracer().WithSpan(ctx, "baz",
						func(ctx context.Context) error {
							return nil
						},
					)
					return nil
				},
			)
			return nil
		},
	)
}