/**
 * Standalone signaling server for the Nextcloud Spreed app.
 * Copyright (C) 2022 struktur AG
 *
 * @author Joachim Bauch <bauch@struktur.de>
 *
 * @license GNU AGPL version 3 or any later version
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package async

import (
	"context"
	"sync"
	"testing"
	"testing/synctest"
	"time"

	"github.com/stretchr/testify/assert"
)

func TestSingleNotifierNoWaiter(t *testing.T) {
	t.Parallel()
	var notifier SingleNotifier

	// Notifications can be sent even if no waiter exists.
	notifier.Notify()
}

func TestSingleNotifierSimple(t *testing.T) {
	t.Parallel()

	var notifier SingleNotifier
	waiter := notifier.NewWaiter()
	defer notifier.Release(waiter)

	var wg sync.WaitGroup
	wg.Go(func() {
		ctx, cancel := context.WithTimeout(context.Background(), time.Second)
		defer cancel()
		assert.NoError(t, waiter.Wait(ctx))
	})

	notifier.Notify()
	wg.Wait()
}

func TestSingleNotifierMultiNotify(t *testing.T) {
	t.Parallel()
	var notifier SingleNotifier

	waiter := notifier.NewWaiter()
	defer notifier.Release(waiter)

	notifier.Notify()
	// The second notification will be ignored while the first is still pending.
	notifier.Notify()
}

func TestSingleNotifierWaitClosed(t *testing.T) {
	t.Parallel()
	var notifier SingleNotifier

	waiter := notifier.NewWaiter()
	notifier.Release(waiter)

	assert.NoError(t, waiter.Wait(context.Background()))
}

func TestSingleNotifierWaitClosedMulti(t *testing.T) {
	t.Parallel()
	var notifier SingleNotifier

	waiter1 := notifier.NewWaiter()
	waiter2 := notifier.NewWaiter()
	notifier.Release(waiter1)
	notifier.Release(waiter2)

	assert.NoError(t, waiter1.Wait(context.Background()))
	assert.NoError(t, waiter2.Wait(context.Background()))
}

func TestSingleNotifierResetWillNotify(t *testing.T) {
	t.Parallel()

	var notifier SingleNotifier
	waiter := notifier.NewWaiter()
	defer notifier.Release(waiter)

	var wg sync.WaitGroup
	wg.Go(func() {
		ctx, cancel := context.WithTimeout(context.Background(), time.Second)
		defer cancel()
		assert.NoError(t, waiter.Wait(ctx))
	})

	notifier.Reset()
	wg.Wait()
}

func TestSingleNotifierDuplicate(t *testing.T) {
	t.Parallel()
	synctest.Test(t, func(t *testing.T) {
		var notifier SingleNotifier
		var done sync.WaitGroup

		for range 2 {
			done.Go(func() {
				waiter := notifier.NewWaiter()
				defer notifier.Release(waiter)

				ctx, cancel := context.WithTimeout(context.Background(), time.Second)
				defer cancel()
				assert.NoError(t, waiter.Wait(ctx))
			})
		}

		synctest.Wait()
		notifier.Notify()
		done.Wait()
	})
}