package otel

import (
	"context"
	"errors"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/exporters/jaeger"
	"go.opentelemetry.io/otel/propagation"
	"go.opentelemetry.io/otel/sdk/resource"
	"go.opentelemetry.io/otel/sdk/trace"
	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
)

// SetupOTelSDK 初始化 OpenTelemetry SDK，配置 Jaeger 作为追踪数据的后端
func SetupOTelSDK(ctx context.Context, serviceName string, jaegerEndpoint string) (shutdown func(context.Context) error, err error) {
	var shutdownFuncs []func(context.Context) error

	// 定义关闭函数，用于在程序退出时关闭 OpenTelemetry SDK
	shutdown = func(ctx context.Context) error {
		var err error
		for _, fn := range shutdownFuncs {
			err = errors.Join(err, fn(ctx))
		}
		shutdownFuncs = nil
		return err
	}

	// 处理错误，如果发生错误，调用关闭函数并返回错误
	handleErr := func(inErr error) {
		err = errors.Join(inErr, shutdown(ctx))
	}

	// 创建 Jaeger Exporter，用于将追踪数据发送到 Jaeger 后端
	exporter, err := jaeger.New(
		jaeger.WithCollectorEndpoint(jaeger.WithEndpoint(jaegerEndpoint)), // 指定 Jaeger 的 Collector Endpoint
	)
	if err != nil {
		handleErr(err)
		return
	}
	shutdownFuncs = append(shutdownFuncs, exporter.Shutdown)

	// 创建 TracerProvider，配置 Jaeger Exporter 和服务资源信息
	tp := trace.NewTracerProvider(
		trace.WithBatcher(exporter), // 使用 Jaeger Exporter
		trace.WithResource(resource.NewSchemaless(
			semconv.ServiceNameKey.String(serviceName), // 设置服务名称
		)),
	)
	shutdownFuncs = append(shutdownFuncs, tp.Shutdown)
	otel.SetTracerProvider(tp) // 设置全局 TracerProvider

	// 设置全局 TextMapPropagator
	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))

	return
}