// Package balance ...
//
// Description : 轮询机制的负载均衡
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2021-10-19 12:35 下午
package balance

import (
	"net/http"
	"sync"

	"git.zhangdeman.cn/zhangdeman/gopkg/balance/define"
	"github.com/pkg/errors"
)

// NewPoll 获取轮询实例
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 12:40 下午 2021/10/19
func NewPoll(serverList []*define.ServerNode) (IBalance, error) {
	if nil == serverList || len(serverList) == 0 {
		return nil, errors.New("server list is empty")
	}
	return &Poll{
		base: base{
			lock:      &sync.RWMutex{},
			severList: serverList,
		},
		currentServerIndex: 0,
	}, nil
}

// Poll ...
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 12:41 下午 2021/10/19
type Poll struct {
	base
	currentServerIndex int
}

// GetServerNode 获取服务节点
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 12:43 下午 2021/10/19
func (p *Poll) GetServerNode(req *http.Request) (*define.ServerNode, error) {
	p.RLock()
	defer p.RUnlock()
	var (
		serverNode *define.ServerNode
	)
	// 循环次数
	loopTimes := 0
	for loopTimes < len(p.severList) {
		loopTimes++
		p.currentServerIndex = (p.currentServerIndex + 1) % len(p.severList)
		if serverNode = p.severList[p.currentServerIndex]; serverNode.Status != define.ServerNodeStatusNormal {
			continue
		}
		break
	}

	if nil == serverNode || serverNode.Status != define.ServerNodeStatusNormal {
		return nil, errors.New("has no server node be used")
	}

	return serverNode, nil
}