// Package balance...
//
// Description : balance...
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2021-11-22 6:58 下午
package balance

import (
	"net/http"
	"sync"

	"github.com/pkg/errors"

	"git.zhangdeman.cn/zhangdeman/gopkg/balance/define"
)

// NewWeightServerRoundRobin ...
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 6:58 下午 2021/11/22
func NewWeightServerRoundRobin(severList []*define.ServerNode) (IBalance, error) {
	if nil == severList || len(severList) == 0 {
		return nil, errors.New("sever list is empty")
	}
	return &WeightServerRoundRobin{
		base: base{
			lock:      &sync.RWMutex{},
			severList: severList,
		},
		effectiveWeight: 0,
	}, nil
}

// WeightServerRoundRobin 加权轮询
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 6:58 下午 2021/11/22
type WeightServerRoundRobin struct {
	base
	effectiveWeight float64
}

// GetServerNode ...
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 7:00 下午 2021/11/22
func (w *WeightServerRoundRobin) GetServerNode(req *http.Request) (*define.ServerNode, error) {
	w.RLock()
	defer w.RUnlock()
	if len(w.severList) == 0 {
		return nil, errors.New("sever list is empty")
	}
	var expectBackendServer *define.ServerNode
	for _, backendServer := range w.severList {
		// 给每个后端服务增加自身权重
		backendServer.CurrentWeight += backendServer.Weight
		if expectBackendServer == nil {
			expectBackendServer = backendServer
		}
		if backendServer.CurrentWeight > expectBackendServer.CurrentWeight {
			expectBackendServer = backendServer
		}
	}
	// 把选择的后端服务权重减掉总权重
	expectBackendServer.CurrentWeight -= w.effectiveWeight
	return expectBackendServer, nil
}

// AddServerNode 新添加一个服务器节点
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 10:07 下午 2021/10/20
func (w *WeightServerRoundRobin) AddServerNode(node *define.ServerNode) error {
	if len(node.HostIP) == 0 || node.Port <= 0 {
		return errors.New("host ip or port is invalid")
	}
	w.Lock()
	defer w.Unlock()
	for _, item := range w.severList {
		if item.HostIP == node.HostIP && item.Port == node.Port {
			return errors.New("host config is already exist")
		}
	}
	w.effectiveWeight += node.Weight
	w.severList = append(w.severList, node)
	return nil
}

// Remove 移除一个节点, force = true , 强制删除, force = false 逻辑删除, 设置状态
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 10:19 下午 2021/10/20
func (w *WeightServerRoundRobin) Remove(hostIP string, port int, force bool) {
	w.Lock()
	defer w.Unlock()
	tmpServerNode := make([]*define.ServerNode, 0)
	for _, item := range w.severList {
		if item.HostIP == hostIP && item.Port == port {
			if force {
				continue
			}
			item.Status = define.ServerNodeStatusRemove
		}
		tmpServerNode = append(tmpServerNode, item)
	}
	w.severList = tmpServerNode
}