using System;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using BotFramework;
using Microsoft.Extensions.Logging;
using Telegram.Bot.Exceptions;
using Telegram.Bot.Types;

namespace Kruzya.TelegramBot.Core.Service
{
    public abstract class AbstractTimedHostedService
    {
        private Timer _timer;
        
        protected readonly ILogger _logger;
        protected readonly ITelegramBot _bot;
        
        protected virtual TimeSpan TimerPeriod => TimeSpan.FromSeconds(45);

        protected AbstractTimedHostedService(ILogger logger, ITelegramBot bot)
        {
            _bot = bot;
            _logger = logger;
        }

        #region IHostedService

        public Task StartAsync(CancellationToken cancellationToken)
        {
            _logger.LogInformation("Message sender service is starting.");
            _timer = new Timer(Run, null, TimeSpan.Zero, TimeSpan.FromSeconds(1));

            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            _logger.LogInformation("Message sender service is stopping.");
            _timer?.Change(Timeout.Infinite, 0);

            return Task.CompletedTask;
        }
        
        #endregion
        #region IDisposable
        /// <summary>
        /// Disposes the timer.
        /// </summary>
        public void Dispose()
        {
            _timer?.Dispose();
        }
        #endregion

        private async void Run(object state)
        {
            _timer?.Change(Timeout.Infinite, 0);

            try
            {
                await OnRun();
            }
            finally
            {
                var timerPeriod = this.TimerPeriod;
                _timer?.Change(timerPeriod, timerPeriod);
            }
        }
        
        protected virtual async Task OnRun()
        {
            await Task.Delay(500);
        }
    }
}