From 37589f0f41fa67c03340f0e2e5ec439e43d9ba2d Mon Sep 17 00:00:00 2001
From: Shane Neuville <shneuvil@microsoft.com>
Date: Fri, 14 Jan 2022 02:15:48 -0600
Subject: [PATCH] Route Shell Modal Navigation through ShellSection (#15053)

---
 .../ShellModalTests.cs                        | 28 +++++++++++++++++++
 Xamarin.Forms.Core/Shell/Shell.cs             | 15 ++++++++++
 2 files changed, 43 insertions(+)

diff --git a/Xamarin.Forms.Core.UnitTests/ShellModalTests.cs b/Xamarin.Forms.Core.UnitTests/ShellModalTests.cs
index 415fff80ea7..85af9de08e6 100644
--- a/Xamarin.Forms.Core.UnitTests/ShellModalTests.cs
+++ b/Xamarin.Forms.Core.UnitTests/ShellModalTests.cs
@@ -431,6 +431,34 @@ public async Task CanCancelPushModalAsync()
 			Assert.AreEqual(0, shell.Navigation.ModalStack.Count);
 		}
 
+		[Test]
+		public async Task PopModalFromShellNavigationProxy()
+		{
+			Routing.RegisterRoute("ModalTestPage", typeof(ModalTestPage));
+			Shell shell = new Shell();
+			shell.Items.Add(CreateShellItem(shellItemRoute: "NewRoute"));
+
+			await shell.GoToAsync("ModalTestPage");
+			await shell.Navigation.PopModalAsync();
+
+			Assert.AreEqual("//NewRoute", shell.CurrentState.Location.ToString());
+		}
+
+		[Test]
+		public async Task PushModalFromShellNavigationProxy()
+		{
+			ModalTestPage modalTestPage = new ModalTestPage();
+			Routing.SetRoute(modalTestPage, "ModalTestPage");
+
+			Routing.RegisterRoute("ModalTestPage", typeof(ModalTestPage));
+			Shell shell = new Shell();
+			shell.Items.Add(CreateShellItem(shellItemRoute: "NewRoute"));
+			await shell.Navigation.PushModalAsync(modalTestPage);
+
+			Assert.AreEqual("//NewRoute/ModalTestPage", shell.CurrentState.Location.ToString());
+		}
+
+
 		[QueryProperty("SomeQueryParameter", "SomeQueryParameter")]
 		public class ModalTestPageBase : ShellLifeCycleTests.LifeCyclePage
 		{
diff --git a/Xamarin.Forms.Core/Shell/Shell.cs b/Xamarin.Forms.Core/Shell/Shell.cs
index 2e8671db5e8..909cada11a3 100644
--- a/Xamarin.Forms.Core/Shell/Shell.cs
+++ b/Xamarin.Forms.Core/Shell/Shell.cs
@@ -1308,6 +1308,13 @@ class NavigationImpl : NavigationProxy
 
 			protected override async Task<Page> OnPopModal(bool animated)
 			{
+				if (!_shell.NavigationManager.AccumulateNavigatedEvents)
+				{
+					var page = _shell.CurrentPage;
+					await _shell.GoToAsync("..", animated);
+					return page;
+				}
+
 				if (ModalStack.Count > 0)
 					ModalStack[ModalStack.Count - 1].SendDisappearing();
 
@@ -1327,6 +1334,14 @@ protected override async Task<Page> OnPopModal(bool animated)
 
 			protected override async Task OnPushModal(Page modal, bool animated)
 			{
+				if (!_shell.NavigationManager.AccumulateNavigatedEvents)
+				{
+					// This will route the modal push through the shell section which is setup
+					// to update the shell state after a modal push
+					await _shell.CurrentItem.CurrentItem.Navigation.PushModalAsync(modal, animated);
+					return;
+				}
+
 				if (ModalStack.Count == 0)
 					_shell.CurrentItem.SendDisappearing();