package ecs

import (
	"fmt"
	"reflect"
	"sync"

	"github.com/yohamta/donburi"
	"github.com/yohamta/donburi/features/events"
)

// 事件订阅发布功能,底层使用donburi事件订阅发布
// 注意:事件订阅处理中应避免再次发布事件

// 事件相关定义
type (
	// 事件类型定义
	EventType[T any] struct {
		et     *events.EventType[T]
		mu     sync.Mutex // 锁
		subMap map[string]events.Subscriber[T]
	}
	// 事件订阅者定义
	Subscriber[T any] func(w World, event T)
)

// 开启底层事件处理调试
func EventsDebugEnable() {
	events.Debug = true
}

// 创建事件类型的实例
func NewEventType[T any]() *EventType[T] {
	return &EventType[T]{
		et:     events.NewEventType[T](),
		mu:     sync.Mutex{},
		subMap: make(map[string]events.Subscriber[T], 0),
	}
}

// 迭代处理所有事件
func processAllEvents(w World) {
	events.ProcessAllEvents(w)
}

// 执行事件
func (me *EventType[T]) ProcessEvents(wd World) {
	me.mu.Lock()
	defer me.mu.Unlock()
	me.et.ProcessEvents(wd)
}

// 发布该类型的事件
func (me *EventType[T]) Publish(wd World, event *T) {
	me.mu.Lock()
	defer me.mu.Unlock()
	me.et.Publish(wd, *event)
}

// 订阅该类型的事件
func (me *EventType[T]) Subscribe(wd World, subscriber Subscriber[T]) {
	me.mu.Lock()
	defer me.mu.Unlock()
	sp := buildKey(wd, subscriber)
	if _, ok := me.subMap[sp]; ok { // 已经订阅过
		return
	}
	sub := func(w donburi.World, event T) {
		subscriber(wd, event)
	}
	me.subMap[sp] = sub
	me.et.Subscribe(wd, sub)
}

// 取消订阅该类型的事件
func (me *EventType[T]) Unsubscribe(wd World, subscriber Subscriber[T]) {
	me.mu.Lock()
	defer me.mu.Unlock()
	sp := buildKey(wd, subscriber)
	if sub, ok := me.subMap[sp]; ok { // 存在, 取消订阅
		me.et.Unsubscribe(wd, sub)
	}
}

// 生成订阅键
func buildKey[T any](wd World, subscriber Subscriber[T]) string {
	sp := fmt.Sprintf("%v_%v", wd.Id(), reflect.ValueOf(subscriber).Pointer())
	return sp
}