using Godot;
using System.Collections.Generic;

namespace Rokojori;

[Tool]
[GlobalClass ]
public partial class LineVFX:Node3D
{
  [ExportToolButton( "Force Update")]
  public Callable forceUpdateButton => Callable.From(
    () =>
    {      
      ClearLine();
    }
  );

  public void ClearLine()
  {
    _lastUpdateID = -1;    
    _data = null;    
    this.DestroyChildren();      
  }

  [Export]
  public LinePreset preset;

  [ExportGroup("References")]
  [Export]
  public Node3D followSource;

  [Export]
  public Node3D childPositionsParent;

  [ExportGroup("Shader Setup")]
  [Export]
  public Vector3PropertyName startPositionName;

  [Export]
  public Vector3PropertyName startForwardName;

  [Export]
  public Vector3PropertyName startUpName;

  [Export]
  public Vector3PropertyName endPositionName;

  [Export]
  public Vector3PropertyName endForwardName;

  [Export]
  public Vector3PropertyName endUpName;



  
  LineVFXData _data;
  int _lastUpdateID = -1;

  public void SetData( LineVFXData data )
  {
    _data = data;
  }

  public LineVFXData GetData()
  {
    return _data;
  }

  public override void _Process( double delta )
  {
    if ( preset == null )
    {
      return;
    }

    preset.Update( this, delta );

    if ( _data == null || _lastUpdateID == _data.GetUpdateID() )
    {
      return;
    }

    _lastUpdateID = _data.GetUpdateID();
    UpdateSegments();

    
  }

  public Vector3 GetLerpedLinePositionAt( float t )
  {
    return _data == null ? Vector3.Zero : _data.LerpPositionAt( t );
  }

  void UpdateSegments()
  {
    var segments = Mathf.Max( 0, _data.GetNumSegments() );


    this.EnsureChildCount<MeshInstance3D>( segments, 
      ( mi )=>
      {
        mi.Mesh = preset.meshGenerator.GetMesh( this, mi );
        preset.materialPreset.CreateMaterial( this, mi );
      }
    );
    

    var points = _data.GetPointData();

    LinePointData start = null;
    var segmentIndex = 0;

    foreach ( var p in points )
    {
      if ( start == null )
      {
        start = p;

        // if ( lineStart != null )
        // {
        //   lineStart.GlobalPosition = start.GetPosition();
        //   lineStart.LookAt( start.GetPosition() + start.GetForward(), start.GetUp() );
        // }

        continue;
      }

      var end = p;
      var mi = GetChild( segmentIndex ) as MeshInstance3D;
      segmentIndex++;

      preset.materialPreset.SetPointData( this, mi, start, true );
      preset.materialPreset.SetPointData( this, mi, end, false );
      // AssignPointData( mi, start, startPositionName, startForwardName, startUpName );
      // AssignPointData( mi, end, endPositionName, endForwardName, endUpName );

      var startPosition = start.GetPosition();
      var endPosition = end.GetPosition();

      var bounds = Box3.Create( startPosition, endPosition );
      bounds.Extend( 1 + ( endPosition - startPosition ).Length() );
      mi.CustomAabb = bounds;

      start = end;
    }

    
    // if ( lineEnd != null )
    // {
    //   lineEnd.GlobalPosition = start.GetPosition();
    //   lineEnd.LookAt( start.GetPosition() + start.GetForward(), start.GetUp() );
    // }

    // for ( int i = 0; i < segments; i++ )
    // {
    //   var mi = GetChild( i ) as MeshInstance3D;
      
    // }
  }

  // void AssignPointData( GeometryInstance3D gi, LinePointData lp, 
  //   Vector3PropertyName p, Vector3PropertyName f, Vector3PropertyName u )
  // {
  //   p.SetInstance( gi, lp.GetPosition() );
  //   f.SetInstance( gi, lp.GetForward() );
  //   u.SetInstance( gi, lp.GetUp() );
  // }
}