AppExperiments

using Leap.Unity.Attributes;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace Leap.Unity.UI {

public class PagedContentController : MonoBehaviour {

    public GameObject[] pages;

    [SerializeField, OnEditorChange("pageIdx")]
    private int _pageIdx = 0;
    public int pageIdx {
      get {
        return _pageIdx;
      }
      set {
        _pageIdx = Mathf.Max(0, Mathf.Min(pages.Length - 1, value));

        disableOtherPages(_pageIdx);
        enablePage(_pageIdx);
      }
    }

    [Header("Page Index Controller")]
    public RadioToggleGroup pageIndexController;

    void OnValidate() {
      _pageIdx = Mathf.Max(0, Mathf.Min(pages.Length, pageIdx));
    }

    void Awake() {
      pageIndexController.OnIndexToggled += (i) => {
        pageIdx = i;
      };
    }

    #region Hacky Page Initialization

    // Sucks that this is necessary but, there's lots of important initialization logic
    // in UI MonoBehaviours that really _needs_ to run so that sliders and buttons are in
    // a valid state and value change events are hooked up. So we activate all pages at 
    // once to make sure they are initialized properly and THEN on the NEXT FRAME we hide
    // all but the active page.
    private bool _firstFrame = true;
    private bool _secondFrame = false;
    void Update() {
      if (_secondFrame && !_firstFrame) {
        pageIdx = pageIdx;
        _secondFrame = false;
      }

      if (_firstFrame) {
        for (int i = 0; i < pages.Length; i++) {
          if (i == pageIdx) continue;
          pages[i].SetActive(true);
        }
        _firstFrame = false;
        _secondFrame = true;
      }
    }

    #endregion

    private void disableOtherPages(int pageIdx) {
      for (int i = 0; i < pages.Length; i++) {
        if (i == pageIdx) continue;
        pages[i].SetActive(false);
      }
    }

    private void enablePage(int pageIdx) {
      pages[pageIdx].SetActive(true);
    }

  }

}