using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;

namespace VRTitle.Input
{
    /// <summary>
    /// VRコントローラーからのポインター入力とUI操作を仲介するコンポーネント
    /// </summary>
    [RequireComponent(typeof(LineRenderer))]
    public class VRLaserPointer : MonoBehaviour
    {
        [Header("Ray Settings")]
        [SerializeField] private float maxDistance = 10f;
        [SerializeField] private LayerMask uiLayerMask = ~0;

        [Header("Visual")]
        [SerializeField] private LineRenderer lineRenderer;

        private GameObject currentHoveredObject;

        private void Reset()
        {
            lineRenderer = GetComponent<LineRenderer>();
            lineRenderer.positionCount = 2;
            lineRenderer.startWidth = 0.005f;
            lineRenderer.endWidth = 0.001f;
        }

        private void Update()
        {
            ProcessPointer();
        }

        private void ProcessPointer()
        {
            Ray ray = new Ray(transform.position, transform.forward);
            PointerEventData pointerData = new PointerEventData(EventSystem.current)
            {
                position = new Vector2(Screen.width / 2f, Screen.height / 2f)
            };

            List<RaycastResult> results = new List<RaycastResult>();
            EventSystem.current?.RaycastAll(pointerData, results);

            Vector3 targetPosition = transform.position + transform.forward * maxDistance;

            if (results.Count > 0)
            {
                RaycastResult hit = results[0];
                targetPosition = hit.worldPosition;
                UpdateHoverState(hit.gameObject, pointerData);
            }
            else
            {
                UpdateHoverState(null, pointerData);
            }

            // ポインター描画の更新
            lineRenderer.SetPosition(0, transform.position);
            lineRenderer.SetPosition(1, targetPosition);
        }

        private void UpdateHoverState(GameObject newHover, PointerEventData pointerData)
        {
            if (currentHoveredObject == newHover) return;

            if (currentHoveredObject != null)
            {
                ExecuteEvents.Execute(currentHoveredObject, pointerData, ExecuteEvents.pointerExitHandler);
            }

            currentHoveredObject = newHover;

            if (currentHoveredObject != null)
            {
                ExecuteEvents.Execute(currentHoveredObject, pointerData, ExecuteEvents.pointerEnterHandler);
            }
        }

        /// <summary>
        /// トリガーボタンが押された時に呼び出す（Input System側から呼び出し可能）
        /// </summary>
        public void OnPrimaryTriggerDown()
        {
            if (currentHoveredObject == null) return;

            PointerEventData pointerData = new PointerEventData(EventSystem.current);
            ExecuteEvents.Execute(currentHoveredObject, pointerData, ExecuteEvents.pointerClickHandler);
        }
    }
}