Dist es

Es.cs

namespace EsAr
{
    class Program
    {
        static void Main(string[] args)
        {
            var s0 = new List<object>()
            {
                new UserCreated("1000"), 
                new UserCreated("1001")
            };

            var v0 = new UniqueUsersAuthoritySaga(s0);
            v0.NewUser("1002");

            var s1 = new List<object>(s0);
            s1.AddRange(v0.UncommittedEvents);

        }
    }

    public class Saga
    {
        public readonly List<object> UncommittedEvents = new List<object>();

        protected void Apply(object evt)
        {
            // are you master

            UncommittedEvents.Add(evt);
            ((dynamic)this).When((dynamic)evt);
        }

        public Saga(List<object> evts)
        {
            foreach (var evt in evts)
                ((dynamic) this).When((dynamic) evt);
        }
    }

    public class UniqueUsersAuthoritySaga : Saga
    {
        public readonly List<string> Users = new List<string>();

        public UniqueUsersAuthoritySaga(List<object> evts) : base(evts){}

        public void NewUser(string name)
        {
            if(Users.Contains(name))
                throw new Exception(name + " alreadey exists");

            Apply(new UserCreated(name));
        }

        public void When(UserCreated evt)
        {
            Users.Add(evt.Name);
        }
    }

    public class UserCreated
    {
        public string Name { get; set; }

        public UserCreated(string name)
        {
            Name = name;
        }
    }
}