package tracer

import (
	"context"
	"log/slog"
	"time"

	"github.com/spf13/viper"
	"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/v1.24.0"
)

func Init(ctx context.Context) func(context.Context) error {
	endpoint := viper.GetString("tracer.otel_controller_endpoint")
	if endpoint == "" {
		endpoint = "localhost:4317"
	}

	clientCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
	defer cancel()

	exporter, err := otlptracegrpc.New(clientCtx,
		otlptracegrpc.WithEndpoint(endpoint),
		otlptracegrpc.WithInsecure(),
	)
	if err != nil {
		slog.Error("[Tracer] Failed to create trace exporter", "err", err)
		return func(context.Context) error { return nil }
	}

	res, err := resource.New(ctx,
		resource.WithAttributes(
			semconv.ServiceNameKey.String("nixcn-cms-backend"),
		),
	)
	if err != nil {
		slog.Error("[Tracer] Failed to create resource", "err", err)
	}

	tp := sdktrace.NewTracerProvider(
		sdktrace.WithBatcher(exporter),
		sdktrace.WithResource(res),
		sdktrace.WithSampler(sdktrace.AlwaysSample()),
	)

	otel.SetTracerProvider(tp)

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

	return tp.Shutdown
}