package main

import "sync"

type SyncFilter[MsgType any] interface {
	Then(what SyncFilter[MsgType]) SyncFilter[MsgType]
	Call(msg MsgType)
}

type SyncFilterImpl[MsgType any] struct {
	next SyncFilter[MsgType]
}

func (impl *SyncFilterImpl[MsgType]) Then(what SyncFilter[MsgType]) SyncFilter[MsgType] {
	impl.next = what
	return what
}

func (impl *SyncFilterImpl[MsgType]) CallNext(msg MsgType) {
	if impl.next != nil {
		impl.next.Call(msg)
	}
}

type CollectFromChannel struct{ SyncFilterImpl[GenericMessage] }

func (collect *CollectFromChannel) Call(msg GenericMessage) {
	collect.CallNext(msg)
}

func (collect CollectFromChannel) Collect(events <-chan GenericMessage, wg *sync.WaitGroup) {
	wg.Add(1)
	go func() {
		defer wg.Done()

		for e := range events {
			collect.Call(e)
		}
	}()
}