using Sandbox;
using System.Collections.Generic;

/// <summary>
/// Locks this GameObject to wherever it started - position and rotation
/// snap back every frame, and any velocity a Rigidbody/PlayerController
/// picked up gets zeroed out immediately. Use this for a seated/stationary
/// player that should never be pushed, shoved, or drift away from a fixed
/// spot, regardless of what physics forces act on it.
///
/// Also separately locks any bones you drag into "Locked Bones" (e.g.
/// the pelvis) to THEIR starting LOCAL position/rotation each frame -
/// this handles bone-level jitter from the animation rig's own partial
/// ragdoll/IK physics blending, which is a different problem than the
/// whole-body physics push the main lock above handles, and needs
/// resetting separately since it happens in local (bone-relative) space
/// rather than world space.
///
/// SETUP: Attach directly to the same GameObject as your PlayerController
/// (or Body, whichever one is actually moving/drifting). Drag "pelvis"
/// (and any other bones you see drifting) into the "Locked Bones" list.
/// </summary>
public sealed class LockToSeat : Component
{
	[Property] public List<GameObject> LockedBones { get; set; } = new();

	private Vector3 _anchorPosition;
	private Rotation _anchorRotation;

	private Rigidbody _rigidbody;
	private PlayerController _playerController;

	private readonly List<Vector3> _bonePositions = new();
	private readonly List<Rotation> _boneRotations = new();

	protected override void OnStart()
	{
		_anchorPosition = Transform.Position;
		_anchorRotation = Transform.Rotation;

		_rigidbody = Components.Get<Rigidbody>();
		_playerController = Components.Get<PlayerController>();

		_bonePositions.Clear();
		_boneRotations.Clear();

		foreach ( var bone in LockedBones )
		{
			if ( bone is null )
				continue;

			_bonePositions.Add( bone.Transform.LocalPosition );
			_boneRotations.Add( bone.Transform.LocalRotation );
		}
	}

	protected override void OnFixedUpdate()
	{
		Transform.Position = _anchorPosition;
		Transform.Rotation = _anchorRotation;

		if ( _rigidbody is not null )
		{
			_rigidbody.Velocity = Vector3.Zero;
			_rigidbody.AngularVelocity = Vector3.Zero;
		}

		for ( int i = 0; i < LockedBones.Count; i++ )
		{
			var bone = LockedBones[i];

			if ( bone is null )
				continue;

			bone.Transform.LocalPosition = _bonePositions[i];
			bone.Transform.LocalRotation = _boneRotations[i];
		}
	}
}