Restructured for new direction.

Assets/Scripts/UI/Menus/Components/UnderlineButton.cs

@@ -0,0 +1,158 @@
+using TMPro;
+using UnityEngine;
+using UnityEngine.EventSystems;
+using UnityEngine.UI;
+using System;
+
+namespace BriarQueen.UI.Menus.Components
+{
+    [RequireComponent(typeof(Button))]
+    public class UnderlineButton : MonoBehaviour,
+        IPointerEnterHandler,
+        IPointerExitHandler,
+        IPointerClickHandler,
+        ISelectHandler,
+        IDeselectHandler
+    {
+        [Header("References")]
+        [SerializeField] private TextMeshProUGUI _label;
+
+        private Button              _button;
+        private UnderlineButtonGroup _group;
+        private bool                _isHovered;
+
+        public event Action<UnderlineButton> SelectionRequested;
+        public event Action<UnderlineButton> HoverEntered;
+        public event Action<UnderlineButton> HoverExited;
+
+        public bool IsSelected { get; private set; }
+
+        // True when this button is registered with a group
+        public bool IsGrouped => _group != null;
+
+        private void Awake()
+        {
+            _button = GetComponent<Button>();
+            SetUnderline(false);
+        }
+
+        private void OnDisable()
+        {
+            _isHovered = false;
+            SetUnderline(false);
+        }
+
+        // ── Group registration ────────────────────────────────────────
+
+        /// <summary>Called by UnderlineButtonGroup when this button is bound.</summary>
+        internal void RegisterGroup(UnderlineButtonGroup group)
+        {
+            _group = group;
+        }
+
+        /// <summary>Called by UnderlineButtonGroup when this button is unbound.</summary>
+        internal void UnregisterGroup()
+        {
+            _group = null;
+        }
+
+        // ── Pointer / Selection events ────────────────────────────────
+
+        public void OnPointerEnter(PointerEventData eventData)
+        {
+            if (_button != null && !_button.interactable) return;
+
+            _isHovered = true;
+
+            if (IsGrouped)
+                HoverEntered?.Invoke(this);
+            else
+                RefreshStandaloneState();
+        }
+
+        public void OnPointerExit(PointerEventData eventData)
+        {
+            _isHovered = false;
+
+            if (IsGrouped)
+                HoverExited?.Invoke(this);
+            else
+                RefreshStandaloneState();
+        }
+
+        public void OnPointerClick(PointerEventData eventData)
+        {
+            if (_button != null && !_button.interactable) return;
+            SelectionRequested?.Invoke(this);
+        }
+
+        public void OnSelect(BaseEventData eventData)
+        {
+            if (_button != null && !_button.interactable) return;
+
+            _isHovered = true;
+
+            if (IsGrouped)
+            {
+                HoverEntered?.Invoke(this);
+                SelectionRequested?.Invoke(this);
+            }
+            else
+            {
+                IsSelected = true;
+                RefreshStandaloneState();
+            }
+        }
+
+        public void OnDeselect(BaseEventData eventData)
+        {
+            _isHovered = false;
+
+            if (IsGrouped)
+                HoverExited?.Invoke(this);
+            else
+            {
+                IsSelected = false;
+                RefreshStandaloneState();
+            }
+        }
+
+        // ── Public API ────────────────────────────────────────────────
+
+        /// <summary>Called by the group to update logical selected state.</summary>
+        public void SetSelectedState(bool selected)
+        {
+            IsSelected = selected;
+        }
+
+        /// <summary>Called by the group to drive the underline visual directly.</summary>
+        public void SetUnderline(bool underlined)
+        {
+            if (_label == null) return;
+
+            if (underlined)
+                _label.fontStyle |= FontStyles.Underline;
+            else
+                _label.fontStyle &= ~FontStyles.Underline;
+        }
+
+        public GameObject GetSelectableGameObject() => gameObject;
+
+        // ── Standalone logic ──────────────────────────────────────────
+
+        /// <summary>
+        /// Used when not in a group — the button manages its own
+        /// underline based on hover and selected state directly.
+        /// </summary>
+        private void RefreshStandaloneState()
+        {
+            if (_button != null && !_button.interactable)
+            {
+                SetUnderline(false);
+                return;
+            }
+
+            SetUnderline(IsSelected || _isHovered);
+        }
+    }
+}