using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Threading;
using System.Threading.Tasks;

namespace AsbCloudInfrastructure.Background;

/// <summary>
/// Сервис для фонового выполнения работы
/// </summary>
public class BackgroundWorker : BackgroundService
{
    private static readonly TimeSpan executePeriod = TimeSpan.FromSeconds(10);
    private static readonly TimeSpan minDelay = TimeSpan.FromSeconds(2);
    private readonly IServiceProvider serviceProvider;

    public WorkStore WorkStore { get; } = new WorkStore();
    public Work? CurrentWork;

    public BackgroundWorker(IServiceProvider serviceProvider)
    {
        this.serviceProvider = serviceProvider;
    }

    protected override async Task ExecuteAsync(CancellationToken token)
    {
        while (!token.IsCancellationRequested)
        {
            var work = WorkStore.GetNext();
            if (work is null)
            {
                await Task.Delay(executePeriod, token);
                continue;
            }

            CurrentWork = work;
            using var scope = serviceProvider.CreateScope();

            var result = await work.Start(scope.ServiceProvider, token);

            if (!result)
                WorkStore.Felled.Add(work);

            CurrentWork = null;
            await Task.Delay(minDelay, token);
        }
    }
}