package obsx

import (
	"context"
	"testing"

	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/sdk/resource"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	"go.opentelemetry.io/otel/sdk/trace/tracetest"
	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
)

func setupTestTracer(t *testing.T) *tracetest.InMemoryExporter {
	t.Helper()
	exp := tracetest.NewInMemoryExporter()
	tp := sdktrace.NewTracerProvider(sdktrace.WithSyncer(exp))
	otel.SetTracerProvider(tp)
	t.Cleanup(func() { _ = tp.Shutdown(context.Background()) })
	return exp
}

func TestSetupTracer_SetsGlobalProvider(t *testing.T) {
	prev := otel.GetTracerProvider()
	t.Cleanup(func() { otel.SetTracerProvider(prev) })

	cfg := TracerConfig{
		ServiceName: "test-service",
		Endpoint:    "localhost:4317",
	}

	shutdown, err := SetupTracer(context.Background(), cfg)
	if err != nil {
		t.Fatalf("SetupTracer returned error: %v", err)
	}
	t.Cleanup(func() { _ = shutdown(context.Background()) })

	tp := otel.GetTracerProvider()
	if _, ok := tp.(*sdktrace.TracerProvider); !ok {
		t.Errorf("expected *sdktrace.TracerProvider, got %T", tp)
	}
}

func TestSetupTracer_DefaultSampler(t *testing.T) {
	cfg := TracerConfig{Sampler: 0}
	cfg.defaults()

	if cfg.Sampler != 1.0 {
		t.Errorf("expected default sampler=1.0, got %f", cfg.Sampler)
	}
}

func TestSetupTracer_NegativeSampler(t *testing.T) {
	cfg := TracerConfig{Sampler: -0.5}
	cfg.defaults()

	if cfg.Sampler != 1.0 {
		t.Errorf("expected default sampler=1.0 for negative value, got %f", cfg.Sampler)
	}
}

func TestSetupTracer_ServiceVersion(t *testing.T) {
	prev := otel.GetTracerProvider()
	t.Cleanup(func() { otel.SetTracerProvider(prev) })

	exp := tracetest.NewInMemoryExporter()

	res, err := resource.New(context.Background(),
		resource.WithAttributes(
			semconv.ServiceName("version-test"),
			semconv.ServiceVersion("1.2.3"),
		),
	)
	if err != nil {
		t.Fatalf("resource.New returned error: %v", err)
	}

	tp := sdktrace.NewTracerProvider(
		sdktrace.WithSyncer(exp),
		sdktrace.WithResource(res),
	)
	otel.SetTracerProvider(tp)
	t.Cleanup(func() { _ = tp.Shutdown(context.Background()) })

	_, span := StartSpan(context.Background(), "test-span")
	span.End()

	spans := exp.GetSpans()
	if len(spans) == 0 {
		t.Fatal("expected at least one span")
	}

	found := false
	for _, attr := range spans[0].Resource.Attributes() {
		if string(attr.Key) == "service.version" && attr.Value.AsString() == "1.2.3" {
			found = true
			break
		}
	}
	if !found {
		t.Errorf("service.version=1.2.3 not found in resource attributes: %v", spans[0].Resource.Attributes())
	}
}

func TestStartSpan_CreatesSpan(t *testing.T) {
	prev := otel.GetTracerProvider()
	t.Cleanup(func() { otel.SetTracerProvider(prev) })

	exp := setupTestTracer(t)

	ctx, span := StartSpan(context.Background(), "my-operation")
	if ctx == nil {
		t.Fatal("StartSpan returned nil context")
	}
	span.End()

	spans := exp.GetSpans()
	if len(spans) == 0 {
		t.Fatal("expected at least one span")
	}
	if spans[0].Name != "my-operation" {
		t.Errorf("expected span name 'my-operation', got %q", spans[0].Name)
	}
}