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

namespace AsbCloudInfrastructure.Background
{
    /// <summary>
    /// Класс разовой работы.
    /// Разовая работа приоритетнее периодической.
    /// </summary>
    public class WorkBase : BackgroudWorkDto
    {
        internal Func<string, IServiceProvider, Action<string, double?>, CancellationToken, Task> ActionAsync { get; }

        /// <summary>
        /// Делегат обработки ошибки.
        /// Не должен выполняться долго.
        /// </summary>
        public Func<string, Exception, CancellationToken, Task>? OnErrorAsync { get; set; }

        public TimeSpan OnErrorHandlerTimeout { get; set; } = TimeSpan.FromSeconds(5);

        /// <summary>
        /// Базовая работа
        /// </summary>
        /// <param name="id"></param>
        /// <param name="actionAsync">
        /// Делегат работы.
        /// <para>
        /// Параметры:
        ///   <list type="number">
        ///     <item>
        ///         <term>string</term>
        ///         <description>Id Идентификатор работы</description>
        ///     </item>
        ///     <item>
        ///         <term>IServiceProvider</term>
        ///         <description>Поставщик сервисов</description>
        ///     </item>
        ///     <item>
        ///         <term>Action&lt;string, double?&gt;</term>
        ///         <description>on progress callback. String - new state text. double? - optional progress 0-100%.</description>
        ///     </item>
        ///     <item>
        ///         <term>CancellationToken</term>
        ///         <description>Токен отмены задачи</description>
        ///     </item>
        ///   </list>
        /// </para>
        /// </param>
        public WorkBase(string id, Func<string, IServiceProvider, Action<string, double?>, CancellationToken, Task> actionAsync)
        {
            Id = id;
            ActionAsync = actionAsync;
        }
        
        /// <summary>
        /// Запустить работу
        /// </summary>
        /// <param name="services"></param>
        /// <param name="token"></param>
        /// <returns>True - susess, False = Fail</returns>
        public async Task<bool> Start(IServiceProvider services, CancellationToken token)
        {
            SetStatusStart();
            try
            {
                var task = ActionAsync(Id, services, UpdateStatus, token);
                await task.WaitAsync(Timeout, token);
                SetStatusComplete(task.Status);
                return true;
            }
            catch (Exception exception)
            {
                SetLastError(exception.Message);
                if (OnErrorAsync is not null)
                {
                    var task = Task.Run(
                        async () => await OnErrorAsync(Id, exception, token),
                        token);
                    await task.WaitAsync(OnErrorHandlerTimeout, token);
                }
            }
            return false;
        }
    }
}