using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Mail;
using System.Text;
using System.Threading.Tasks;

namespace Firebird2D.EventPipelines
{
    public class Pipeline <T> : I_Pipeline where T : EventArgs
    {
        public object PipelineMaster { get; }

        private event EventHandler<T>? OnEvent;

        public Pipeline(object pipelineMaster)
        {
            PipelineMaster = pipelineMaster;
        }

        public bool IsEventEmpty { get {  return OnEvent != null; } }

        public void Subscribe(Delegate handler)
        {
            OnEvent += (EventHandler<T>)handler;
        }

        public void Unsubscribe(Delegate handler)
        {
            OnEvent -= (EventHandler<T>)handler;
        }

        public void SendEvent(object sender, T args)
        {
            if (sender == null || args == null) throw new ArgumentNullException(nameof(sender));
            if (args is not T) throw new ArgumentException($"Invalid EventArgs type. Expected {typeof(T)}");
            if (sender.Equals(PipelineMaster)) throw new InvalidDataException("Only the pipeline master is allowed to send events through this pipeline.");

            OnEvent?.Invoke(sender, args);

        }
    }
}