package main

import (
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/aliyun/alibaba-cloud-sdk-go/services/alidns"
)

// getPublicIP 通过外部 API 获取公网 IPv4 地址
func getPublicIP() (string, error) {
	// 使用多个 IP 查询服务作为备选
	apis := []string{
		"https://api.ipify.org",
		"https://ifconfig.me/ip",
		"https://ipecho.net/plain",
	}

	for _, api := range apis {
		resp, err := http.Get(api)
		if err != nil {
			log.Printf("Error fetching IP from %s: %v", api, err)
			continue
		}

		body, err := io.ReadAll(resp.Body)
		resp.Body.Close()
		if err != nil {
			log.Printf("Error reading response from %s: %v", api, err)
			continue
		}

		ip := strings.TrimSpace(string(body))
		if net.ParseIP(ip) != nil {
			return ip, nil
		}
	}

	return "", fmt.Errorf("failed to get public IP from all APIs")
}

func main() {
	domain := os.Getenv("DOMAIN")
	rr := os.Getenv("RR")
	regionID := os.Getenv("REGIONID")
	if regionID == "" {
		regionID = "cn-hangzhou"
	}
	accessKeyID := os.Getenv("ACCESSKEYID")
	accessSecret := os.Getenv("ACCESSSECRET")

	ip4 := ""
	for {
		time.Sleep(10 * time.Second)

		currentIPV4, err := getPublicIP()
		if err != nil {
			log.Println("Error getting public IP:", err)
			continue
		}

		if currentIPV4 == "" || currentIPV4 == ip4 {
			continue
		}

		client, err := alidns.NewClientWithAccessKey(regionID, accessKeyID, accessSecret)
		if err != nil {
			log.Println(err.Error())
			continue
		}

		drRequest := alidns.CreateDescribeDomainRecordsRequest()
		drRequest.KeyWord = rr
		drRequest.DomainName = domain
		drRequest.TypeKeyWord = "A"

		drResponse, err := client.DescribeDomainRecords(drRequest)
		if err != nil {
			log.Println(err)
			continue
		}
		if !drResponse.IsSuccess() {
			continue
		}

		rid := ""
		for _, r := range drResponse.DomainRecords.Record {
			rid = r.RecordId
			if r.Value == currentIPV4 {
				ip4 = currentIPV4
				rid = ""
			}
			break
		}

		if rid == "" {
			continue
		}

		//修改域名对应的IP，修改成功后continue
		req := alidns.CreateUpdateDomainRecordRequest()
		req.Scheme = "https"
		req.RR = rr
		req.RecordId = rid
		req.Value = currentIPV4
		req.Type = "A"

		resp, err := client.UpdateDomainRecord(req)
		if err != nil {
			log.Println(err.Error())
			if !strings.Contains(err.Error(), fmt.Sprintf("not %s", domain)) {
				continue
			}
		}

		if resp.IsSuccess() {
			ip4 = currentIPV4
			log.Println("update success: ", ip4)
			continue
		}

		//当域名修改失败时判断是否是没有对应的记录，不存在时创建新的域名记录
		request := alidns.CreateAddDomainRecordRequest()
		request.Scheme = "https"
		request.Value = currentIPV4
		request.Type = "A"
		request.RR = rr
		request.DomainName = domain
		response, err := client.AddDomainRecord(request)
		if err != nil {
			fmt.Print(err.Error())
			continue
		}
		if !response.IsSuccess() {
			fmt.Print(response.GetHttpContentString())
			ip4 = currentIPV4
		}
	}
}