package telemetry

import (
	"context"
	"log"
	"net/http"

	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/exporters/jaeger"
	"go.opentelemetry.io/otel/sdk/resource"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
)

// newJaegerExporter creates a new Jaeger exporter.
func newJaegerExporter() (sdktrace.SpanExporter, error) {
	return jaeger.New(jaeger.WithCollectorEndpoint(jaeger.WithEndpoint("http://localhost:14268/api/traces")))
}

// NewTracerProvider creates a new tracer provider.
func NewTracerProvider(exp sdktrace.SpanExporter) *sdktrace.TracerProvider {
	res := resource.NewWithAttributes(
		semconv.SchemaURL,
		semconv.ServiceName("gralias"),
		semconv.ServiceVersion("v0.1.0"),
	)

	tracerProvider := sdktrace.NewTracerProvider(
		sdktrace.WithSampler(sdktrace.AlwaysSample()),
		sdktrace.WithResource(res),
		sdktrace.WithBatcher(exp),
	)
	return tracerProvider
}

// OtelMiddleware wraps the provided http.Handler with OpenTelemetry tracing.
func OtelMiddleware(handler http.Handler) http.Handler {
	return otelhttp.NewHandler(handler, "http.server")
}

func InitTracer() func() {
	exp, err := newJaegerExporter()
	if err != nil {
		log.Fatalf("failed to create exporter: %v", err)
	}

	tp := NewTracerProvider(exp)
	otel.SetTracerProvider(tp)

	return func() {
		if err := tp.Shutdown(context.Background()); err != nil {
			log.Printf("Error shutting down tracer provider: %v", err)
		}
		if err := exp.Shutdown(context.Background()); err != nil {
			log.Printf("Error shutting down exporter: %v", err)
		}
	}
}