using System.Collections.Generic;
using Unity.XR.CoreUtils;
using UnityEngine;
using UnityEngine.Animations;
using UnityEngine.XR.Interaction.Toolkit;
using UnityEngine.XR.Interaction.Toolkit.Interactables;

public class RideController : MonoBehaviour
{
    [SerializeField] private Transform _itemRoot;
    [SerializeField, Min(0f)] private float _settleVelocity = 0.1f;
    [SerializeField, Min(0f)] private float _settleDuration = 0.3f;

    private ParentConstraint _parentConstraint;
    private readonly Dictionary<Rigidbody, float> _settleTimer = new();

    private void Awake()
    {
        _parentConstraint = GetComponent<ParentConstraint>();

        if (_parentConstraint.sourceCount == 0 ||
            _parentConstraint.GetSource(0).sourceTransform == null)
        {
            var xrOrigin = FindFirstObjectByType<XROrigin>();
            if (xrOrigin == null)
            {
                Debug.LogWarning("RideController: 씬에서 XROrigin을 찾지 못했습니다.");
                return;
            }

            var source = new ConstraintSource
            {
                sourceTransform = xrOrigin.transform,
                weight = 1f
            };

            if (_parentConstraint.sourceCount == 0)
                _parentConstraint.AddSource(source);
            else
                _parentConstraint.SetSource(0, source);

        }
    }

    public void ActiveRide()
    {
        _parentConstraint.constraintActive = true;
    }

    public void DeactiveRide()
    {
        _parentConstraint.constraintActive = false;
    }

    public void OnDetectionStay(Collider other)
    {
        var rb = other.attachedRigidbody;
        if (rb == null || rb.isKinematic) return;
        if (!rb.TryGetComponent(out XRGrabInteractable grab)) return;

        if (grab.isSelected)
        {
            _settleTimer.Remove(rb);
            return;
        }

        if (rb.linearVelocity.magnitude > _settleVelocity)
        {
            _settleTimer[rb] = 0f;
            return;
        }

        float elapsed = _settleTimer.GetValueOrDefault(rb, 0f) + Time.deltaTime;
        if (elapsed >= _settleDuration)
        {
            AttachToCart(grab, rb);
            _settleTimer.Remove(rb);
        }
        else
        {
            _settleTimer[rb] = elapsed;
        }
    }

    public void OnDetectionExit(Collider other)
    {
        var rb = other.attachedRigidbody;
        if (rb != null) _settleTimer.Remove(rb);
    }

    private void AttachToCart(XRGrabInteractable grab, Rigidbody rb)
    {
        grab.transform.SetParent(_itemRoot);
        rb.linearVelocity = Vector3.zero;
        rb.angularVelocity = Vector3.zero;
        rb.isKinematic = true;

        // 잡았다 놓을 때 XRGrabInteractable이 parent를 ItemRoot로 되돌리는 것 방지
        grab.retainTransformParent = false;

        grab.selectEntered.AddListener(OnPickedUpFromCart);
    }

    private void OnPickedUpFromCart(SelectEnterEventArgs args)
    {
        if (args.interactableObject is not XRGrabInteractable grab) return;

        grab.transform.SetParent(null);

        grab.selectEntered.RemoveListener(OnPickedUpFromCart);
        grab.selectExited.AddListener(OnReleasedAfterPickup);
    }

    private void OnReleasedAfterPickup(SelectExitEventArgs args)
    {
        if (args.interactableObject is not XRGrabInteractable grab) return;

        // XRGrabInteractable이 original(kinematic=true)로 복원한 것을 덮어씀
        if (grab.TryGetComponent(out Rigidbody rb)) rb.isKinematic = false;

        grab.selectExited.RemoveListener(OnReleasedAfterPickup);
    }
}