using TMPro;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

namespace RR.Common.UI
{
    /// <summary>
    /// Меняет цвет TMP-текста внутри кнопки при фокусе и наведении.
    /// </summary>
    public class ButtonTextFocusColor : MonoBehaviour, ISelectHandler, IDeselectHandler, IPointerEnterHandler, IPointerExitHandler
    {
        [SerializeField] private TextMeshProUGUI targetText;
        [SerializeField] private Color normalColor = new(0f, 0.29411766f, 0.1882353f, 1f);
        [SerializeField] private Color focusedColor = Color.white;

        private Selectable _selectable;
        private bool _isPointerInside;
        private bool _lastFocusedState;
        private bool _hasAppliedState;

        private void Awake()
        {
            ResolveReferences();
            RefreshVisualState(force: true);
        }

        private void OnEnable()
        {
            ResolveReferences();
            RefreshVisualState(force: true);
        }

        private void OnDisable()
        {
            _isPointerInside = false;
            _lastFocusedState = false;
            _hasAppliedState = false;
            ApplyTextColor(normalColor);
        }

        private void LateUpdate()
        {
            RefreshVisualState();
        }

        public void OnSelect(BaseEventData eventData)
        {
            RefreshVisualState(force: true);
        }

        public void OnDeselect(BaseEventData eventData)
        {
            RefreshVisualState(force: true);
        }

        public void OnPointerEnter(PointerEventData eventData)
        {
            _isPointerInside = true;
            RefreshVisualState(force: true);
        }

        public void OnPointerExit(PointerEventData eventData)
        {
            _isPointerInside = false;
            RefreshVisualState(force: true);
        }

        private void RefreshVisualState(bool force = false)
        {
            ResolveReferences();

            bool isFocused = IsFocusedNow();
            if (!force && _hasAppliedState && _lastFocusedState == isFocused)
            {
                return;
            }

            _lastFocusedState = isFocused;
            _hasAppliedState = true;
            ApplyTextColor(isFocused ? focusedColor : normalColor);
        }

        private bool IsFocusedNow()
        {
            if (!isActiveAndEnabled)
            {
                return false;
            }

            if (_selectable != null && (!_selectable.IsActive() || !_selectable.IsInteractable()))
            {
                return false;
            }

            bool isSelected = EventSystem.current != null
                && EventSystem.current.currentSelectedGameObject == gameObject;

            return isSelected || _isPointerInside;
        }

        private void ApplyTextColor(Color color)
        {
            if (targetText == null)
            {
                return;
            }

            targetText.color = color;
        }

        private void ResolveReferences()
        {
            if (_selectable == null)
            {
                _selectable = GetComponent<Selectable>();
            }

            if (targetText == null)
            {
                targetText = GetComponentInChildren<TextMeshProUGUI>(true);
            }
        }

#if UNITY_EDITOR
        private void Reset()
        {
            ResolveReferences();
        }

        private void OnValidate()
        {
            ResolveReferences();

            if (!Application.isPlaying)
            {
                RefreshVisualState(force: true);
            }
        }
#endif
    }
}