From 12abbb79b18f2bae4e6e73b725bcd2909e9ee652 Mon Sep 17 00:00:00 2001
From: Robert McRackan <rmcrackan@metabolon.com>
Date: Fri, 6 May 2022 16:00:37 -0400
Subject: [PATCH] Don't allow multiple simultaneous imports

---
 AppScaffolding/AppScaffolding.csproj   |  2 +-
 ApplicationServices/LibraryCommands.cs | 23 +++++++++++++++++++----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/AppScaffolding/AppScaffolding.csproj b/AppScaffolding/AppScaffolding.csproj
index 9df8e828..04cc9388 100644
--- a/AppScaffolding/AppScaffolding.csproj
+++ b/AppScaffolding/AppScaffolding.csproj
@@ -3,7 +3,7 @@
 
   <PropertyGroup>
     <TargetFramework>net6.0-windows</TargetFramework>
-    <Version>7.1.0.1</Version>
+    <Version>7.1.1.1</Version>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/ApplicationServices/LibraryCommands.cs b/ApplicationServices/LibraryCommands.cs
index d966d8d9..3bbf93c5 100644
--- a/ApplicationServices/LibraryCommands.cs
+++ b/ApplicationServices/LibraryCommands.cs
@@ -15,7 +15,19 @@ namespace ApplicationServices
 {
 	public static class LibraryCommands
 	{
-		public static async Task<List<LibraryBook>> FindInactiveBooks(Func<Account, Task<ApiExtended>> apiExtendedfunc, List<LibraryBook> existingLibrary, params Account[] accounts)
+		public static event EventHandler<int> ScanBegin;
+		public static event EventHandler ScanEnd;
+
+		public static bool Scanning { get; private set; }
+		private static object _lock { get; } = new();
+
+		static LibraryCommands()
+		{
+			ScanBegin += (_, __) => Scanning = true;
+			ScanEnd += (_, __) => Scanning = false;
+		}
+
+        public static async Task<List<LibraryBook>> FindInactiveBooks(Func<Account, Task<ApiExtended>> apiExtendedfunc, List<LibraryBook> existingLibrary, params Account[] accounts)
 		{
 			logRestart();
 
@@ -72,8 +84,6 @@ namespace ApplicationServices
 			}
 		}
 
-		public static event EventHandler<int> ScanBegin;
-		public static event EventHandler ScanEnd;
 		#region FULL LIBRARY scan and import
 		public static async Task<(int totalCount, int newCount)> ImportAccountAsync(Func<Account, Task<ApiExtended>> apiExtendedfunc, params Account[] accounts)
 		{
@@ -84,7 +94,12 @@ namespace ApplicationServices
 
 			try
 			{
-				ScanBegin?.Invoke(null, accounts.Length);
+				lock (_lock)
+                {
+					if (Scanning)
+						return (0, 0);
+					ScanBegin?.Invoke(null, accounts.Length);
+				}
 
 				logTime($"pre {nameof(scanAccountsAsync)} all");
 				var importItems = await scanAccountsAsync(apiExtendedfunc, accounts, LibraryOptions.ResponseGroupOptions.ALL_OPTIONS);