package load_balance

import (
 "errors"
 "strconv"

)

type WeightRoundRobinBalance struct {
 curIndex int
 rss      []*WeightNode
 rsw      []int

 //觀察主體
 conf LoadBalanceConf
}

// 配置主題
type LoadBalanceConf interface {
 GetConf() []string
 WatchConf()
 UpdateConf(conf []string)
}

type WeightNode struct {
 addr            string // 服務器地址
 weight          int //權重值
 currentWeight   int //節點當前權重
 effectiveWeight int //有效權重
}

func (r *WeightRoundRobinBalance) Add(params ...string) error {
 if len(params) != 2 {
  return errors.New("param len need 2")
 }
 parInt, err := strconv.ParseInt(params[1], 10, 64)
 if err != nil {
  return err
 }
 node := WeightNode{addr: params[0], weight: int(parInt)}
 node.effectiveWeight = node.weight
 r.rss = append(r.rss, node)
 return nil
}

func (r *WeightRoundRobinBalance) Next() string {
 total := 0
 var best *WeightNode
 for i := 0; i  len(r.rss); i++ {
  w := r.rss[i]
  //step 1 統計所有有效權重之和
  total += w.effectiveWeight

  //step 2 變更節點臨時權重為的節點臨時權重+節點有效權重
  w.currentWeight += w.effectiveWeight

  //step 3 有效權重默認與權重相同，通訊異常時-1, 通訊成功+1，直到恢復到weight大小
  if w.effectiveWeight  w.weight {
   w.effectiveWeight++
  }
  //step 4 選擇最大臨時權重點節點
  if best == nil || w.currentWeight > best.currentWeight {
   best = w
  }
 }
 if best == nil {
  return ""
 }
 //step 5 變更臨時權重為 臨時權重-有效權重之和
 best.currentWeight -= total
 return best.addr
}

func (r *WeightRoundRobinBalance) Get(key string) (string, error) {
 return r.Next(), nil
}

func (r *WeightRoundRobinBalance) SetConf(conf LoadBalanceConf) {
 r.conf = conf
}

package load_balance

import (
 "fmt"
 "testing"
)

func TestLB(t *testing.T) {
 rb := WeightRoundRobinBalance{}
 rb.Add("127.0.0.1:2003", "4") //0
 // rb.Add("127.0.0.1:2004", "3") //1
 rb.Add("127.0.0.1:2005", "2") //2

 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
}