package main

import "fmt"

// Memento 定义备忘录接口，仅暴露必要的方法
type Memento interface {
    getState() string
}

// originatorState 是发起人内部状态（包内私有）
type originatorState struct {
    state string
}

// Originator 发起人结构体
type Originator struct {
    state string
}

func (o *Originator) SetState(state string) {
    o.state = state
    fmt.Printf("状态设置为: %s\n", state)
}

func (o *Originator) S*eToMemento() Memento {
    return &originatorState{state: o.state}
}

func (o *Originator) RestoreFromMemento(m Memento) {
    if m != nil {
        o.state = m.getState()
        fmt.Printf("状态恢复为: %s\n", o.state)
    }
}

// 实现 Memento 接口
func (s *originatorState) getState() string {
    return s.state
}

// Caretaker 管理者，持有备忘录列表
type Caretaker struct {
    mementos []Memento
}

func (c *Caretaker) Add(m Memento) {
    c.mementos = append(c.mementos, m)
}

func (c *Caretaker) Get(index int) Memento {
    if index >= 0 && index < len(c.mementos) {
        return c.mementos[index]
    }
    return nil
}

func main() {
    originator := &Originator{}
    caretaker := &Caretaker{}

    originator.SetState("状态1")
    caretaker.Add(originator.S*eToMemento())

    originator.SetState("状态2")
    caretaker.Add(originator.S*eToMemento())

    originator.SetState("状态3")
    originator.RestoreFromMemento(caretaker.Get(1)) // 恢复到状态2
}

func NewOriginator() (*OriginatorClosure, func() map[string]interface{}, func(map[string]interface{})) {
    state := make(map[string]interface{})
    
    s*e := func() map[string]interface{} {
        snapshot := make(map[string]interface{})
        for k, v := range state {
            snapshot[k] = v
        }
        return snapshot
    }

    restore := func(memento map[string]interface{}) {
        state = make(map[string]interface{})
        for k, v := range memento {
            state[k] = v
        }
        fmt.Println("状态已恢复")
    }

    return &OriginatorClosure{setState: func(k string, v interface{}) {
        state[k] = v
        fmt.Printf("设置 %s = %v\n", k, v)
    }}, s*e, restore
}

type OriginatorClosure struct {
    setState func(string, interface{})
}