package problem

import "fmt"

// Subject 主题接口
type Subject interface {
	Register(observer Observer)
	Deregister(observer Observer)
	Notify(data interface{})
}

// Observer 观察者接口
type Observer interface {
	Update(data interface{})
}

// BaseSubject 主题基类实现
type BaseSubject struct {
	observers []Observer
}

func (s *BaseSubject) Register(observer Observer) {
	s.observers = append(s.observers, observer)
}

func (s *BaseSubject) Deregister(observer Observer) {
	for i, obs := range s.observers {
		if obs == observer {
			s.observers = append(s.observers[:i], s.observers[i+1:]...)
			return
		}
	}
}

func (s *BaseSubject) Notify(data interface{}) {
	for _, obs := range s.observers {
		obs.Update(data)
	}
}

//// 主题实现
//type ConcreteSubject struct {
//	BaseSubject
//}
//
//// 观察者实现
//type ConcreteObserver struct {
//	name string
//}
//
//func (o *ConcreteObserver) Update(data interface{}) {
//	fmt.Printf("%s 收到通知：%v\n", o.name, data)
//}
//
//func main() {
//	subject := &ConcreteSubject{}
//
//	observer1 := &ConcreteObserver{name: "观察者1"}
//	observer2 := &ConcreteObserver{name: "观察者2"}
//
//	subject.Register(observer1)
//	subject.Register(observer2)
//
//	subject.Notify("新数据1")
//	subject.Deregister(observer1)
//
//	subject.Notify("新数据2")
//}

// 主题实现
type EventSubject struct {
	BaseSubject
}

// 观察者实现
type EventObserver struct {
	name string
}

func (o *EventObserver) Update(data interface{}) {
	fmt.Printf("%s 收到通知：%v\n", o.name, data)
}