package main

import (
	"context"
	"os"
	"time"

	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
	"go.opentelemetry.io/otel/propagation"
	"go.opentelemetry.io/otel/sdk/resource"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	semconv "go.opentelemetry.io/otel/semconv/v1.41.0"
)

func setupTracing(ctx context.Context) (func(context.Context) error, error) {
	endpoint := os.Getenv("OTEL_EXPORTER_OTLP_ENDPOINT")
	if endpoint == "" {
		endpoint = "localhost:4317"
	}

	exporter, err := otlptracegrpc.New(ctx,
		otlptracegrpc.WithEndpoint(endpoint),
		otlptracegrpc.WithInsecure(),
	)
	if err != nil {
		return nil, err
	}

	res, err := resource.Merge(
		resource.Default(),
		resource.NewWithAttributes(
			semconv.SchemaURL,
			semconv.ServiceName("checkout-api"),
			semconv.ServiceVersion("1.0.0"),
		),
	)
	if err != nil {
		return nil, err
	}

	provider := sdktrace.NewTracerProvider(
		sdktrace.WithBatcher(exporter, sdktrace.WithBatchTimeout(time.Second)),
		sdktrace.WithResource(res),
	)

	otel.SetTracerProvider(provider)
	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(
		propagation.TraceContext{},
		propagation.Baggage{},
	))

	return provider.Shutdown, nil
}