using System;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.EventSystems;
using UnityEngine.UI;

namespace NightclubArcadia.UI.Menu
{
    /// <summary>
    /// Selects among menu tabs. Panels are toggled via CanvasGroup (never
    /// SetActive) so TMP's cached Canvas stays valid. Each tab can fire an
    /// Inspector-wired UnityEvent on show — used by SkillsPanelView.Refresh
    /// without a cross-assembly interface.
    /// </summary>
    public sealed class MenuTabBar : MonoBehaviour
    {
        [Serializable]
        public struct TabEntry
        {
            public Button button;
            public CanvasGroup panel;
            public UnityEvent onShown;
        }

        [SerializeField] TabEntry[] tabs = Array.Empty<TabEntry>();

        int currentIndex = -1;
        bool bound;

        void OnEnable()
        {
            BindButtons();
        }

        void BindButtons()
        {
            if (bound || tabs == null)
            {
                return;
            }

            for (var i = 0; i < tabs.Length; i++)
            {
                var index = i;
                if (tabs[i].button != null)
                {
                    tabs[i].button.onClick.RemoveAllListeners();
                    tabs[i].button.onClick.AddListener(() => SelectTab(index));
                }
            }

            bound = tabs.Length > 0;
        }

        /// <summary>Runtime / bootstrap entry point for assigning tabs after AddComponent.</summary>
        public void SetTabs(TabEntry[] entries)
        {
            tabs = entries ?? System.Array.Empty<TabEntry>();
            bound = false;
            BindButtons();
        }

        public void SelectTab(int index)
        {
            if (tabs == null || tabs.Length == 0)
            {
                return;
            }

            index = Mathf.Clamp(index, 0, tabs.Length - 1);
            currentIndex = index;

            for (var i = 0; i < tabs.Length; i++)
            {
                var active = i == index;
                var panel = tabs[i].panel;
                if (panel != null)
                {
                    panel.alpha = active ? 1f : 0f;
                    panel.interactable = active;
                    panel.blocksRaycasts = active;
                }
            }

            tabs[index].onShown?.Invoke();

            if (tabs[index].button != null && EventSystem.current != null)
            {
                EventSystem.current.SetSelectedGameObject(tabs[index].button.gameObject);
            }
        }
    }
}