// 摘自 MediatR 14.2.0，许可声明与修改记录见 LICENSE.md 和 UPSTREAM.md。
namespace MAX.Notification.Wrappers;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;


public abstract class NotificationHandlerWrapper
{
    public abstract Task Handle(INotification notification, IServiceProvider serviceFactory,
        Func<IEnumerable<NotificationHandlerExecutor>, INotification, CancellationToken, Task> publish,
        CancellationToken cancellationToken);
}

public class NotificationHandlerWrapperImpl<TNotification> : NotificationHandlerWrapper
    where TNotification : INotification
{
    public override Task Handle(INotification notification, IServiceProvider serviceFactory,
        Func<IEnumerable<NotificationHandlerExecutor>, INotification, CancellationToken, Task> publish,
        CancellationToken cancellationToken)
    {
        var handlers = ((IEnumerable<INotificationHandler<TNotification>>?)serviceFactory.GetService(typeof(IEnumerable<INotificationHandler<TNotification>>)) ?? Array.Empty<INotificationHandler<TNotification>>())
            .GroupBy(static x => x.GetType())
            .Select(static g => g.First())
            .Select(static x => new NotificationHandlerExecutor(x, (theNotification, theToken) => x.Handle((TNotification)theNotification, theToken)));

        return publish(handlers, notification, cancellationToken);
    }
}