package consul

import (
	"context"
	"errors"
	"fmt"
	"net"
	"net/http"
	"sync"
	"time"

	"github.com/gogf/gf/contrib/registry/consul/v2"
	"github.com/gogf/gf/v2/frame/g"
	"github.com/gogf/gf/v2/net/gsel"
	"github.com/gogf/gf/v2/net/gsvc"
	"github.com/gogf/gf/v2/os/gcfg"
	"github.com/gogf/gf/v2/os/genv"
	"github.com/gogf/gf/v2/util/grand"
	"github.com/hashicorp/consul/api"
	"github.com/r3labs/diff/v2"
)

var (
	registry       gsvc.Registry
	consulAddr     string
	reconnectMutex sync.RWMutex
	reconnectDone  chan struct{}
	connected      bool
	httpClient     *http.Client
)

// connectConsul 连接 Consul
func connectConsul(ctx context.Context) error {
	reconnectMutex.Lock()
	defer reconnectMutex.Unlock()

	// 如果已经连接，不再重复连接
	if connected && registry != nil {
		return nil
	}

	var err error
	registry, err = consul.New(consul.WithAddress(consulAddr))
	if err != nil {
		g.Log().Errorf(ctx, "❌ Consul 连接失败: %v", err)
		return err
	}

	gsvc.SetRegistry(registry)
	gsel.SetBuilder(gsel.NewBuilderRoundRobin())
	connected = true
	g.Log().Infof(ctx, "✅ Consul 初始化成功: %s", consulAddr)

	return nil
}

// startHealthCheckAndReconnect 启动健康检查和自动重连
func startHealthCheckAndReconnect() {
	if reconnectDone != nil {
		close(reconnectDone)
	}

	reconnectDone = make(chan struct{})
	ticker := time.NewTicker(30 * time.Second)
	defer ticker.Stop()

	ctx := context.Background()

	// 初始化HTTP客户端用于健康检查
	httpClient = &http.Client{
		Timeout: 5 * time.Second,
	}

	for {
		select {
		case <-ticker.C:
			// 检查服务发现是否正常工作
			if checkConsulHealth(ctx) {
				continue
			}

			g.Log().Warning(ctx, "⚠️  Consul 连接异常,尝试重新连接...")

			// 重置连接状态并重连
			reconnectMutex.Lock()
			connected = false
			registry = nil
			reconnectMutex.Unlock()

			if err := connectConsul(ctx); err != nil {
				g.Log().Errorf(ctx, "❌ Consul 重连失败: %v,30秒后重试...", err)
			}

		case <-reconnectDone:
			g.Log().Info(ctx, "🛑 Consul 健康检查已停止")
			return
		}
	}
}

// checkConsulHealth 检查 Consul 健康状态
func checkConsulHealth(ctx context.Context) bool {
	reconnectMutex.RLock()
	defer reconnectMutex.RUnlock()

	if registry == nil || !connected {
		return false
	}

	// 使用consul原生API进行健康检查
	// 调用 /v1/agent/self 接口检测连接状态
	url := fmt.Sprintf("http://%s/v1/agent/self", consulAddr)
	resp, err := httpClient.Get(url)
	if err != nil {
		g.Log().Debugf(ctx, "Consul 健康检查失败: %v", err)
		return false
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		g.Log().Debugf(ctx, "Consul 健康检查失败,状态码: %d", resp.StatusCode)
		return false
	}

	//g.Log().Debugf(ctx, "✅ Consul 健康检查通过")
	return true
}

func init() {
	consulAddr = g.Cfg().MustGet(context.Background(), "consul.address").String()
	if consulAddr == "" {
		g.Log().Warning(context.Background(), "⚠️  Consul 配置未找到,跳过初始化")
		return
	}

	if err := connectConsul(context.Background()); err != nil {
		g.Log().Errorf(context.Background(), "❌ Consul 初始化失败: %v", err)
	} else {
		// 连接成功后启动健康检查和自动重连
		go startHealthCheckAndReconnect()
	}

	loadConfigFromConsul()
}

func loadConfigFromConsul() {
	ctx := context.Background()

	serviceName := g.Cfg().MustGet(ctx, "server.name", "admin-go").String()
	env := genv.Get("APP_ENV", "").String()
	fmt.Printf("服务名称: %s, 环境变量 APP_ENV: %s\n", serviceName, env)

	if env == "" {
		panic("未设置 APP_ENV 环境变量，无法从 Consul 加载配置")
	}

	consulData, lastIndex, err := loadEnvFromConsul(env, serviceName)
	if err == nil && len(consulData) > 0 {
		adapter, err := gcfg.NewAdapterContent()
		if err != nil {
			fmt.Printf("创建配置适配器失败: %v\n", err)
			return
		}
		adapter.SetContent(string(consulData))
		g.Cfg().SetAdapter(adapter)

		fmt.Printf("已从 Consul 成功加载初始配置\n")

		go watchConsulConfig(env, serviceName, lastIndex)
	} else {
		fmt.Printf("从 Consul 获取配置失败，使用本地配置文件\n")
	}
}

func loadEnvFromConsul(env string, serviceName string) ([]byte, uint64, error) {
	ctx := context.Background()

	consulAddress := g.Cfg().MustGet(ctx, "consul.address", "127.0.0.1:8500").String()
	fmt.Printf("Consul 地址: %s\n", consulAddress)

	config := api.DefaultConfig()
	config.Address = consulAddress

	client, err := api.NewClient(config)
	if err != nil {
		fmt.Printf("创建 Consul 客户端失败: %v\n", err)
		return nil, 0, err
	}
	consulKey := fmt.Sprintf("config/%s/%s-%s", serviceName, serviceName, env)
	fmt.Printf("从 Consul 读取配置键: %s\n", consulKey)

	kv := client.KV()

	opts := &api.QueryOptions{
		WaitIndex: 0,
		WaitTime:  60 * time.Second,
	}

	pair, meta, err := kv.Get(consulKey, opts)
	if err != nil {
		fmt.Printf("从 Consul 读取配置失败: %v\n", err)
		return nil, 0, err
	}

	if pair == nil {
		fmt.Printf("Consul 中未找到配置键: %s\n", consulKey)
		return nil, 0, nil
	}

	fmt.Printf("已从 Consul 加载配置, Index: %d\n", meta.LastIndex)
	return pair.Value, meta.LastIndex, nil
}

func watchConsulConfig(env string, serviceName string, lastIndex uint64) {
	ctx := context.Background()

	consulAddress := g.Cfg().MustGet(ctx, "consul.address", "127.0.0.1:8500").String()
	config := api.DefaultConfig()
	config.Address = consulAddress

	client, err := api.NewClient(config)
	if err != nil {
		fmt.Printf("创建 Consul 监听客户端失败: %v\n", err)
		return
	}

	consulKey := fmt.Sprintf("config/%s/%s-%s", serviceName, serviceName, env)

	for {
		opts := &api.QueryOptions{
			WaitIndex: lastIndex,
			WaitTime:  60 * time.Second,
		}

		pair, meta, err := client.KV().Get(consulKey, opts)
		if err != nil {
			fmt.Printf("Consul 监听出错: %v, 5秒后重试...\n", err)
			time.Sleep(5 * time.Second)
			continue
		}

		if meta.LastIndex == lastIndex {
			continue
		}

		if pair == nil {
			fmt.Printf("Consul 配置被删除: %s\n", consulKey)
			lastIndex = meta.LastIndex
			continue
		}

		fmt.Printf("检测到 Consul 配置变更: %s, New Index: %d\n", consulKey, meta.LastIndex)

		updateLocalConfig(pair.Value)

		lastIndex = meta.LastIndex
	}
}

func updateLocalConfig(content []byte) {
	ctx := context.Background()

	oldConfig, _ := g.Cfg().Data(ctx)

	adapter, err := gcfg.NewAdapterContent()
	if err != nil {
		fmt.Printf("创建新配置适配器失败: %v\n", err)
		return
	}
	adapter.SetContent(string(content))
	g.Cfg().SetAdapter(adapter)

	newConfig, _ := g.Cfg().Data(ctx)

	changelog, err := diff.Diff(oldConfig, newConfig)
	if err != nil {
		fmt.Printf("配置对比失败: %v\n", err)
		return
	}

	if len(changelog) == 0 {
		fmt.Printf("配置已热更新成功（内容无实质变化）\n")
		return
	}

	fmt.Printf("=== 检测到配置变更 (%d 项) ===\n", len(changelog))
	for _, change := range changelog {
		switch change.Type {
		case "create":
			fmt.Printf("[+] 新增: %s = %v\n", change.Path, change.To)
		case "update":
			fmt.Printf("[~] 修改: %s: %v -> %v\n", change.Path, change.From, change.To)
		case "delete":
			fmt.Printf("[-] 删除: %s (原值: %v)\n", change.Path, change.From)
		}
	}
	fmt.Printf("=================================\n")
}

func getLocalIP() (string, error) {
	// 获取本机所有网络接口
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return "", err
	}

	for _, addr := range addrs {
		// 检查是否是IP地址
		if ipNet, ok := addr.(*net.IPNet); ok && !ipNet.IP.IsLoopback() {
			if ipNet.IP.To4() != nil {
				// 返回第一个非回环的IPv4地址
				return ipNet.IP.String(), nil
			}
		}
	}

	return "", fmt.Errorf("无法找到本地IP地址")
}
func getInstanceAddrByIp(ctx context.Context, ip string, services []gsvc.Service) (addr string) {
	for _, s := range services {
		if s.GetEndpoints()[0].Host() == ip {
			addr = s.GetEndpoints()[0].String()
			return
		}
	}
	return
}
func GetInstanceAddr(ctx context.Context, name string) (addr string, err error) {
	watch, err := gsvc.GetRegistry().Watch(ctx, name)
	if err != nil {
		err = errors.New("获取服务监听器失败")
		return
	}

	service, err := watch.Proceed()
	if err != nil || service == nil {
		err = errors.New("获取服务实例失败")
		return
	}
	//优先使用客户端IP获取实例(前后端在同一台机器调试)
	addr = getInstanceAddrByIp(ctx, g.RequestFromCtx(ctx).GetClientIp(), service)
	if !g.IsEmpty(addr) {
		return
	}
	//优先使用gateway同IP的服务实例(前后端不同机器调试)
	addr, err = getLocalIP()
	if err != nil {
		return
	}
	addr = getInstanceAddrByIp(ctx, addr, service)
	if !g.IsEmpty(addr) {
		return
	}
	//随机获取一个服务实例
	maxService := grand.N(0, len(service)-1)
	addr = service[maxService].GetEndpoints()[0].String()
	return
}