using NUnit.Framework;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
using XGame;

public sealed class UIManagerAttachTests
{
    [TearDown]
    public void TearDown()
    {
        DestroyIfExists("ZeroSizedCanvas");
        DestroyIfExists("UIRoot");
        EventSystem eventSystem = Object.FindObjectOfType<EventSystem>();
        if (eventSystem != null)
        {
            Object.DestroyImmediate(eventSystem.gameObject);
        }
    }

    [Test]
    public void AttachTo_StretchesZeroSizedCanvasRootAndAppliesUiLayer()
    {
        GameObject ui = new GameObject("ZeroSizedCanvas", typeof(RectTransform), typeof(Canvas));
        GameObject child = new GameObject("Child", typeof(RectTransform), typeof(Image));
        child.transform.SetParent(ui.transform, false);

        RectTransform rt = ui.GetComponent<RectTransform>();
        rt.anchorMin = Vector2.zero;
        rt.anchorMax = Vector2.zero;
        rt.sizeDelta = Vector2.zero;

        UIManager.AttachTo(UILayer.Normal, ui);

        int uiLayer = LayerMask.NameToLayer("UI");
        Assert.That(rt.anchorMin, Is.EqualTo(Vector2.zero));
        Assert.That(rt.anchorMax, Is.EqualTo(Vector2.one));
        Assert.That(rt.offsetMin, Is.EqualTo(Vector2.zero));
        Assert.That(rt.offsetMax, Is.EqualTo(Vector2.zero));
        Assert.That(ui.layer, Is.EqualTo(uiLayer));
        Assert.That(child.layer, Is.EqualTo(uiLayer));
    }

    private static void DestroyIfExists(string name)
    {
        GameObject go = GameObject.Find(name);
        if (go != null)
        {
            Object.DestroyImmediate(go);
        }
    }
}