using System.Collections;
using System.Collections.Generic;
using System.Text;
using System;
using System.Linq;


namespace Rokojori
{   
  public class EventSlot<T>
  {
    protected List<Action<T>> _actions = new List<Action<T>>();
    List<Action<T>> _once = new List<Action<T>>();

    protected bool _canModify = true;
    List<Action<T>> _additions = new List<Action<T>>();
    List<Action<T>> _onceAdditions = new List<Action<T>>();
    List<Action<T>> _removals = new List<Action<T>>();


    public bool hasListeners => _once.Count > 0 || _actions.Count > 0;

    public void ResetAndClearAll()
    {
      _actions.Clear();
      _once.Clear();

      _additions.Clear();
      _onceAdditions.Clear();

      _removals.Clear();
      _canModify = true;
    }

    public void AddAction( Action<T> action )
    {
      if ( HasAction( action ) )
      {
        RJLog.Error( this, "This action already exists", action );
        return;
      }

      if ( _canModify )
      {
        _actions.Add( action );
      }
      else
      {
       
        _additions.Add( action );
      }      
    }

    public void RemoveAction( Action<T> action )
    {
      if ( _canModify )
      {
        var removed = _actions.Remove( action );

        // RJLog.Log( "Removed:", action, removed );
      }
      else
      {
        _removals.Add( action );
      }        
    }

    public bool HasAction( Action<T> action )
    {
      return _actions.Has( action ) || _additions.Has( action ) || _onceAdditions.Has( action );
    }

    public void Once( Action<T> action )
    {
      if ( HasAction( action ) )
      {
        RJLog.Error( this, "This action already exists", action );
        return;
      }

      if ( _canModify )
      {
        _actions.Add( action );
        _once.Add( action );
      }
      else
      {
        _onceAdditions.Add( action );
      }        
    }

    protected void _UpdateLists()
    {
      _once.ForEach( a => { _actions.Remove( a ); } );
      _once.Clear();

      if ( _removals.Count > 0 )
      {
        Lists.RemoveRange( _actions, _removals );

        // _removals.ForEach( 
        //   r => 
        //   {
        //     var removed = _actions.Remove( r );
        //     RJLog.Log( "Removed:", r, removed );
        //   } 
        // );

        _removals.Clear();
      }         
      
      if ( _additions.Count > 0 )
      {
        _actions.AddRange( _additions ); 
        _additions.Clear();
      }

      if ( _onceAdditions.Count > 0 )
      {
        _once.AddRange( _onceAdditions );
        _actions.AddRange( _onceAdditions );
      }      
      

    } 

    public void DispatchEvent( T t )
    {
      _canModify = false;

      _actions.ForEach( a => { if ( a != null ){ a( t ); } } );

      _UpdateLists();
      
      _canModify = true;

    }
  }
  
}