using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace Blog3000.Server
{
      

    internal class BlogPostRepoUpdater : IHostedService, IDisposable
    {

        private readonly ILogger logger;
        private readonly BlogPostRepo repo;

        private Timer timer;

        public BlogPostRepoUpdater(ILogger<BlogPostRepoUpdater> logger, BlogPostRepo repo)
        {
            this.logger = logger;
            this.repo = repo;

        }

        public void Dispose()
        {
            timer?.Dispose();
        }


        public Task StartAsync(CancellationToken cancellationToken)
        {
            logger.LogInformation("BlogPostRepoUpdater Service starting...");

            // Time so cache should never be expired, when a request comes in
            timer = new Timer(DoWork, null, TimeSpan.Zero, TimeSpan.FromSeconds(5*60-30));

            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            logger.LogInformation("BlogPostRepoUpdater Service stopping."); 

            timer?.Dispose();
            timer = null;

            return Task.CompletedTask;
        }

        private void DoWork(object state)
        {
            logger.LogInformation("BlogPostRepoUpdater updating BlogPostRepo");

            repo.UpdateCache();
        }
    }
}