// Copyright (c) 2023 Proton AG
//
// This file is part of Proton Mail Bridge.
//
// Proton Mail Bridge is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Proton Mail Bridge is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.

package events

import (
	"context"
	"fmt"

	"github.com/ProtonMail/gluon/async"
	"github.com/ProtonMail/gluon/watcher"
)

type Event interface {
	fmt.Stringer

	_isEvent()
}

type eventBase struct{}

func (eventBase) _isEvent() {}

type EventPublisher interface {
	PublishEvent(ctx context.Context, event Event)
}

type NullEventPublisher struct{}

func (NullEventPublisher) PublishEvent(_ context.Context, _ Event) {}

type Subscription interface {
	Add(ofType ...Event) *watcher.Watcher[Event]
	Remove(watcher *watcher.Watcher[Event])
}

type NullSubscription struct{}

func (n NullSubscription) Add(ofType ...Event) *watcher.Watcher[Event] {
	return watcher.New[Event](&async.NoopPanicHandler{}, ofType...)
}

func (n NullSubscription) Remove(watcher *watcher.Watcher[Event]) {
	watcher.Close()
}

func NewNullSubscription() *NullSubscription {
	return &NullSubscription{}
}
