package client

import (
	"bytes"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"strconv"
	"sync"
	"time"

	"github.com/hashicorp/consul/api"
)

var (
	balancer *ServiceBalancer
	once     sync.Once
)

type ServiceBalancer struct {
	mu         sync.RWMutex
	services   map[string][]string
	indexes    map[string]int
	consulAddr string
}

// Init 初始化客户端，传入Consul地址
func Init(consulAddr string) {
	once.Do(func() {
		balancer = &ServiceBalancer{
			services:   make(map[string][]string),
			indexes:    make(map[string]int),
			consulAddr: consulAddr,
		}
		go balancer.watchConsul()
	})
}

func (s *ServiceBalancer) watchConsul() {
	config := api.DefaultConfig()
	config.Address = s.consulAddr
	client, _ := api.NewClient(config)

	for {
		s.mu.Lock()
		services, _, _ := client.Health().Service("", "", true, nil)

		// 清空旧数据
		s.services = make(map[string][]string)

		for _, entry := range services {
			service := entry.Service.Service
			addr := entry.Service.Address + ":" + strconv.Itoa(entry.Service.Port)

			// 使用map去重
			if s.services[service] == nil {
				s.services[service] = []string{}
			}

			// 检查是否已存在
			exists := false
			for _, existingAddr := range s.services[service] {
				if existingAddr == addr {
					exists = true
					break
				}
			}
			if !exists {
				s.services[service] = append(s.services[service], addr)
			}
		}
		s.mu.Unlock()

		time.Sleep(10 * time.Second)
	}
}

func (s *ServiceBalancer) GetServiceAddr(service string) string {
	s.mu.RLock()
	defer s.mu.RUnlock()

	addrs := s.services[service]
	if len(addrs) == 0 {
		return ""
	}

	idx := s.indexes[service]
	addr := addrs[idx]
	s.indexes[service] = (idx + 1) % len(addrs)

	return addr
}

func Get(service, path string, result interface{}) error {
	if balancer == nil {
		return errors.New("client not initialized, call client.Init() first")
	}

	baseURL := balancer.GetServiceAddr(service)
	if baseURL == "" {
		return errors.New("service unavailable")
	}

	resp, err := http.Get("http://" + baseURL + path)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return errors.New("HTTP error: " + resp.Status)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	return json.Unmarshal(body, result)
}

func Post(service, path string, body, result interface{}) error {
	if balancer == nil {
		return errors.New("client not initialized, call client.Init() first")
	}

	baseURL := balancer.GetServiceAddr(service)
	if baseURL == "" {
		return errors.New("service unavailable")
	}

	jsonBytes, err := json.Marshal(body)
	if err != nil {
		return err
	}

	resp, err := http.Post(
		"http://"+baseURL+path,
		"application/json",
		bytes.NewBuffer(jsonBytes),
	)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return errors.New("HTTP error: " + resp.Status)
	}

	respBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	if result != nil {
		return json.Unmarshal(respBody, result)
	}
	return nil
}