using System;
using Godot;


namespace Rokojori
{  
  [Tool][GlobalClass ]
  public partial class CompositorVFXFader: Node
  {
    [Export]
    public CompositorVFX[] effects;

    float _value = 0;
    [Export( PropertyHint.Range, "0,1")]
    public float value 
    {
      get { return _value; }
      set 
      {
        _value = value;
        try
        {
          UpdateValue();
        }
        catch( Exception e )
        {
          this.LogError( e );
        }
        
      }
    }

    void UpdateValue()
    {
      if ( effects == null )
      {
        return;
      }

      var position = _value * effects.Length - 1f; // 0 1 2 3

      var lower = Mathf.Floor( position );
      var higher = lower + 1;
      var highAmount = position - lower; 
      var lowAmount = 1f - highAmount;
      
      if ( lower >= effects.Length - 1)
      {
        for ( int i = 0; i < effects.Length; i++ )
        {
          effects[ i ].driverValue = i == effects.Length - 1  ? 1f : 0f;
        }
      }

      for ( int i = 0; i < effects.Length; i++ )
      {
        if ( i != lower && i != higher )
        {
          effects[ i ].driverValue = 0;
          continue;
        }

        if ( i == lower )
        {
          effects[ i ].driverValue = lowAmount;
        }
        else
        {
          effects[ i ].driverValue = highAmount;
        }
      } 
    }

  }
}