using System;

using Xamarin.Forms.CustomAttributes;
using System.Threading.Tasks;
using Xamarin.Forms.Internals;

#if UITEST
using Xamarin.UITest;
using NUnit.Framework;
#endif

namespace Xamarin.Forms.Controls.Issues
{
	[Preserve (AllMembers = true)]
	[Issue (IssueTracker.Bugzilla, 31255, "Master's page Icon cause memory leak after MasterDetailPage is popped out by holding on page")]
	public class Bugzilla31255 : TestContentPage // or TestMasterDetailPage, etc ...
	{
		protected override void Init ()
		{
			var stack = new StackLayout () { VerticalOptions = LayoutOptions.Center };

			stack.Children.Add (new Label () { VerticalOptions =
#pragma warning disable 618
				LayoutOptions.Center, XAlign = TextAlignment.Center, Text = "Page 1"
#pragma warning restore 618
			});

			Content = stack;

		}

		WeakReference _page2Tracker;

		protected override async void OnAppearing ()
		{
			base.OnAppearing ();

			if (_page2Tracker == null) {
				var page2 = new Page2 ();

				_page2Tracker = new WeakReference (page2, false);

				await Task.Delay (1000);
				await Navigation.PushModalAsync (page2);

				StartTrackPage2 ();
			}
		}

		async void StartTrackPage2 ()
		{
			while (true) {
				((Label)((StackLayout)Content).Children [0]).Text =
						string.Format ("Page1. But Page2 IsAlive = {0}", _page2Tracker.IsAlive);
				await Task.Delay (1000);
				GC.Collect ();
			}
		}

		[Preserve (AllMembers = true)]
		public class Page2 : MasterDetailPage
		{
			public Page2 ()
			{
				Master = new Page () { Title = "Master", 
					Icon = "Icon.png" 
				};
				Detail = new Page () { Title = "Detail" };
			}

			protected override async void OnAppearing ()
			{
				base.OnAppearing ();

				await Task.Delay (1000);
				await Navigation.PopModalAsync ();
			}
		}

		#if UITEST
		[Test]
		[Ignore("Fails intermittently on TestCloud")]
		public async void Bugzilla31255Test ()
		{
			RunningApp.Screenshot ("I am at Bugzilla 31255");
			await Task.Delay (5000);
			RunningApp.WaitForElement (q => q.Marked ("Page1. But Page2 IsAlive = False"));
		}
		#endif
	}
}