package service

import (
	"sync"
)

// listener 监听
type listener struct {
	handler ListenerHandle
}

// listeners 监听器
type listeners struct {
	listener map[interface{}]*listener
	mutex    *sync.RWMutex
}

// ListenerHandle 监听事件
type ListenerHandle interface {
	Handle(args ...interface{})
}

// listenerObject 监听器
var listenerObject = &listeners{
	listener: make(map[interface{}]*listener, 0),
	mutex:    new(sync.RWMutex),
}

// Subscribe 注册事件
func Subscribe(prefix interface{}, handler ListenerHandle) {
	listenerObject.mutex.Lock()
	defer listenerObject.mutex.Unlock()
	listenerObject.listener[prefix] = &listener{handler: handler}
}

// Publish 推送事件
func Publish(prefix interface{}, args ...interface{}) {
	listenerObject.mutex.RLock()
	defer listenerObject.mutex.RUnlock()
	listener, has := listenerObject.listener[prefix]
	if !has {
		return
	}
	listener.handler.Handle(args...)
}

// Unsubscribe 取消监听
func Unsubscribe(prefix interface{}) {
	listenerObject.mutex.Lock()
	defer listenerObject.mutex.Unlock()
	_, has := listenerObject.listener[prefix]
	if !has {
		return
	}
	delete(listenerObject.listener, prefix)
}