// OpenTween - Client of Twitter
// Copyright (c) 2019 kim_upsilon (@kim_upsilon) <https://upsilo.net/~upsilon/>
// All rights reserved.
//
// This file is part of OpenTween.
//
// This program 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.
//
// 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 General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. If not, see <http://www.gnu.org/licenses/>, or write to
// the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
// Boston, MA 02110-1301, USA.

#nullable enable

using System;
using System.Threading;
using System.Threading.Tasks;

namespace OpenTween
{
    public sealed class AsyncTimer : ITimer
    {
        public TimeSpan DueTime { get; private set; } = Timeout.InfiniteTimeSpan;

        public TimeSpan Period { get; private set; } = Timeout.InfiniteTimeSpan;

        private readonly Func<Task> callback;
        private readonly Timer timer;

        public static event EventHandler<ThreadExceptionEventArgs>? UnhandledException;

        public AsyncTimer(Func<Task> callback)
        {
            this.callback = callback;
            this.timer = new Timer(this.TimerCallback);
        }

        private async void TimerCallback(object state)
        {
            try
            {
                await this.callback().ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                UnhandledException?.Invoke(this, new ThreadExceptionEventArgs(ex));
            }
        }

        public void Change(TimeSpan dueTime, TimeSpan period)
        {
            this.DueTime = dueTime;
            this.Period = period;
            this.timer.Change(dueTime, period);
        }

        public void Dispose()
            => this.timer.Dispose();
    }

    public interface ITimer : IDisposable
    {
        void Change(TimeSpan dueTime, TimeSpan period);
    }
}
