package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"net/http/httputil"
	"net/url"
	"os"
)

type Config struct {
	Server   string   `json:"server"`
	Upstream []string `json:"upstream"`
}

var loadBalancer = NewWeightedRR(RR_NGINX)

type handle struct {
	addrs []string
}

func (this *handle) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	addr := loadBalancer.Next().(string)
	remote, err := url.Parse("http://" + addr)
	if err != nil {
		panic(err)
	}
	proxy := httputil.NewSingleHostReverseProxy(remote)
	proxy.ServeHTTP(w, r)
}

func startServer(server string, upstream []string) {
	//被代理的服务器host和port
	h := &handle{}
	h.addrs = upstream

	w := 1
	for _, e := range h.addrs {
		loadBalancer.Add(e, w)
		w++
	}
	err := http.ListenAndServe(server, h)
	if err != nil {
		log.Fatalln("ListenAndServe: ", err)
	}
}

func readConfig() Config {
	file, err := ioutil.ReadFile("./config.json")
	if err != nil {
		fmt.Printf("File error: %v\n", err)
		os.Exit(1)
	}

	var config Config
	json.Unmarshal(file, &config)
	fmt.Printf("%v", config.Upstream)
	fmt.Printf("%v", config.Server)
	return config
}

func main() {
	config := readConfig()
	startServer(config.Server, config.Upstream)
}