using Godot;
using System.Collections.Generic;

namespace Rokojori;

public abstract class LineVFXData
{    
  public abstract int GetUpdateID();
  public abstract IEnumerable<LinePointData> GetPointData();
  public abstract int GetNumSegments();
  public abstract void SetSegmentData( MeshInstance3D mi, int segmentIndex );
  public virtual int GetNumPoints()
  {
    return GetNumSegments() + 1;
  }

  public abstract Vector3 GetPositionAt( int index );
  public Vector3 LerpPositionAt( float normalizedIndex )
  {
    if ( GetNumPoints() == 0 )
    {
      return Vector3.Zero;
    }

    if ( GetNumPoints() == 1 )
    {
      return GetPositionAt( 0 );
    }

    var pointIndex = normalizedIndex * GetNumPoints();

     if ( pointIndex <= 0 )
    {
      return GetPositionAt( 0 );
    }

    if ( pointIndex >= GetNumPoints() - 1 )
    {
      return GetPositionAt( GetNumPoints() - 1 );
    }

    var lowerIndex  = Mathf.FloorToInt( pointIndex );   
    var higherIndex = Mathf.CeilToInt( pointIndex );

    var p0 = GetPositionAt( lowerIndex );
    var p1 = GetPositionAt( higherIndex );

    return p0.Lerp( p1, pointIndex - lowerIndex ); 
  }
}