package main

import (
	"errors"
	"fmt"
	"os"
)

type CircleQueue struct {
	maxSize int
	array [5]int
	head int
	tail int
}

func (this *CircleQueue) Push (val int) (err error){
	if this.IsFull() {
		return errors.New("已经满了")
	}
	fmt.Println("加入", val)
	this.array[this.tail % this.maxSize] = val
	this.tail ++
	return
}

func (this *CircleQueue) Pop() (val int, err error) {
	if this.IsEmpty() {
		return 0, errors.New("为空")
	}
	val = this.array[this.head % this.maxSize]
	this.head ++
	return
}

// IsFull 队列shi不是满了
func (this *CircleQueue) IsFull() bool{
	return (this.tail + 1) % this.maxSize == this.head
}

func (this *CircleQueue) IsEmpty() bool {
	return this.tail == this.head
}

func (this *CircleQueue) Size() int {
	return (this.tail + this.maxSize - this.head) % this.maxSize
}
func (this *CircleQueue) ListQueue() {
	size := this.Size()
	if size == 0{
		fmt.Println("为空")
	}
	temHEead := this.head
	for i:=0;i < size; i++ {
		fmt.Printf("arr[%d]=%d\n", temHEead, this.array[temHEead])
		temHEead = (temHEead + 1) % this.maxSize
	}
}

func main() {
	queue := &CircleQueue{
		maxSize: 5,
		head: 0,
		tail: 0,
	}
	var key string
	var val int
	for {
		fmt.Println("add")
		fmt.Println("get")
		fmt.Println("show")
		fmt.Println("exit")
		fmt.Scanln(&key)
		switch key {
			case "add":
				fmt.Println("添加")
				fmt.Scanln(&val)
				err := queue.Push(val)
				if err != nil {
					fmt.Println(err.Error())
				} else {
					fmt.Println("加入成功")
				}
		case "get":
			val, err := queue.Pop()
			if err != nil{
				fmt.Println(err.Error())
			}else {
				fmt.Println("取出一个数", val)
			}
		case "show":
			queue.ListQueue()
		case "exit":
			os.Exit(0)
		}
	}
}