package telemetry

import (
	"context"
	"errors"

	"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, serviceName string, version string) (func(context.Context) error, error) {
	var shutdownFns []func(context.Context) error

	shutdown := func(ctx context.Context) error {
		var err error
		for _, fn := range shutdownFns {
			err = errors.Join(err, fn(ctx))
		}
		shutdownFns = nil
		return err
	}

	res, err := resource.New(ctx,
		resource.WithAttributes(
			semconv.ServiceName(serviceName),
			semconv.ServiceVersion(version),
		),
	)
	if err != nil {
		return shutdown, err
	}

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

	traceExporter, err := otlptracegrpc.New(ctx)
	if err != nil {
		return shutdown, err
	}

	tracerProvider := sdktrace.NewTracerProvider(
		sdktrace.WithBatcher(traceExporter),
		sdktrace.WithResource(res),
	)
	otel.SetTracerProvider(tracerProvider)
	shutdownFns = append(shutdownFns, tracerProvider.Shutdown)

	return shutdown, nil
}