NarKampenTake2/Assets/Scripts/MainScene/TabsController.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UIElements;

public class TabsController : MonoBehaviour
{
    VisualElement root;

    private void OnEnable()
    {
        UIDocument menu = GetComponent<UIDocument>();
        root = menu.rootVisualElement;

        GetAllTabButtons().ForEach(RegisterButtonCallbacks);
    }

    private void RegisterButtonCallbacks(Button b)
    {
        b.RegisterCallback<ClickEvent>(SetTabVisibleViaButton);
    }

    private void SetTabVisibleViaButton(ClickEvent evt)
    {
        Button b = evt.currentTarget as Button;
        VisualElement tabContent = GetAllTabContents().Where((VisualElement tabContent) => tabContent.name.Contains(b.name[..^3])).First();

        SetTabVisible(tabContent);
    }

    private void SetTabVisible(VisualElement tabToActivate)
    {
        UQueryBuilder<VisualElement> tabs = GetAllTabContents();
        tabs.Where((tab) => tab != tabToActivate).ForEach(t => t.style.display = DisplayStyle.None);

        tabToActivate.style.display = DisplayStyle.Flex;
    }

    private UQueryBuilder<VisualElement> GetAllTabContents()
    {
        return root.Query<VisualElement>(className: "tabContent");
    }

    private UQueryBuilder<Button> GetAllTabButtons()
    {
        return root.Query<Button>(className: "tabButton");
    }
}