package main

import (
	"log"
	"net/http"

	"github.com/darkit/goproxy"
	"github.com/darkit/goproxy/pkg/loadbalance"
)

// LoadBalanceDelegate 负载均衡委托
type LoadBalanceDelegate struct {
	goproxy.DefaultDelegate
	lb loadbalance.LoadBalancer
}

// ResolveBackend 解析后端服务器
func (d *LoadBalanceDelegate) ResolveBackend(req *http.Request) (string, error) {
	backend, err := d.lb.Next(req.URL.Host)
	if err != nil {
		return "", err
	}
	if backend == nil {
		return "", nil
	}
	return backend.String(), nil
}

// 运行负载均衡代理服务器
func main() {
	// 创建后端服务器列表
	backends := []string{
		"http://backend1:8081",
		"http://backend2:8082",
		"http://backend3:8083",
	}

	// 创建负载均衡器
	lb := loadbalance.NewRoundRobinBalancer()

	// 添加后端服务器
	for _, backend := range backends {
		if err := lb.Add(backend, 1); err != nil {
			log.Fatalf("Error: %v", err)
			return
		}
	}

	// 创建负载均衡委托
	delegate := &LoadBalanceDelegate{
		lb: lb,
	}

	// 创建代理实例
	proxy := goproxy.NewProxy(
		goproxy.WithDelegate(delegate),
		goproxy.WithLoadBalancer(lb),
	)

	// 启动代理服务器
	log.Println("负载均衡代理服务器启动在 :8080")
	log.Println("后端服务器列表:")
	for _, backend := range backends {
		log.Printf("- %s\n", backend)
	}
	http.ListenAndServe(":8080", proxy)
}