package load_balancer

import (
	"errors"
	"fmt"
	"gitee.com/os-lee/easy-paas/common"
	"gitee.com/os-lee/easy-paas/common/discovery"
	"gitee.com/os-lee/easy-paas/gateway/internal/dao"
	"net/http"
	"net/url"
	"sync"
)

type Server struct {
	URL    *url.URL
	Weight int // 权重，用于权重负载均衡
}

// Balancer 接口定义了所有负载均衡策略都应实现的公共方法
type Balancer interface {
	Pick(*http.Request) *Server
}

type BaseBalancer struct {
	servers []Server
	mu      sync.RWMutex
}

// Handler 各个业务的负载均衡器
var Handler *LoadBalancer

func init() {
	Handler = newLoadBalancer()
}

type LoadBalancer struct {
	// key:ServiceName val:load_balancer.Balancer
	LoadBalancerMap sync.Map
}

func newLoadBalancer() *LoadBalancer {
	return &LoadBalancer{
		LoadBalancerMap: sync.Map{},
	}
}

func (l *LoadBalancer) Get(service *dao.ServiceDetail) (Balancer, error) {
	key := service.Info.ServiceName
	if value, ok := l.LoadBalancerMap.Load(key); ok {
		return value.(Balancer), nil
	}
	// 服务发现
	rMsgs, err := discovery.EtcdCli.DiscoverServices(service.LoadBalance.ProxyName)
	if err != nil || len(rMsgs) == 0 {
		msg := fmt.Sprintf("没有可用的地址，服务名: %s, 被代理名: %s, err:%v",
			service.Info.ServiceName, service.LoadBalance.ProxyName, err)
		return nil, errors.New(msg)
	}
	var servers []Server
	for _, msg := range rMsgs {
		server := Server{
			URL:    common.MustParseURL(common.ProtocolConverter(msg.ServiceProtocolCode) + msg.ServiceAddr),
			Weight: 1,
		}
		servers = append(servers, server)
	}
	// 获取负载均衡器
	lb := new(Factory).Produce(service.LoadBalance.RoundType, servers)
	l.LoadBalancerMap.Store(key, lb)

	return lb, err
}

func (l *LoadBalancer) Update(serviceName string) {
	// 直接删除即可，获取时会重新创建
	l.LoadBalancerMap.Delete(serviceName)
}