Validate Special Folder Format doesn't match excluded folder

Closes #8339

src/NzbDrone.Core/MediaFiles/DiskScanService.cs

@@ -245,6 +245,28 @@ namespace NzbDrone.Core.MediaFiles
             return filteredPaths;
         }
 
+        public static List<string> FilteredSubFolderMatches(string subfolder)
+        {
+            var matches = new List<string>();
+
+            foreach (var match in ExcludedSubFoldersRegex.Matches(subfolder))
+            {
+                matches.Add(match.ToString());
+            }
+
+            foreach (var match in ExcludedExtrasSubFolderRegex.Matches(subfolder))
+            {
+                matches.Add(match.ToString());
+            }
+
+            foreach (var match in ExcludedExtraFilesRegex.Matches(subfolder))
+            {
+                matches.Add(match.ToString());
+            }
+
+            return matches;
+        }
+
         private void SetPermissions(string path)
         {
             if (!_configService.SetPermissionsLinux)

src/NzbDrone.Core/Organizer/FileNameValidation.cs

@@ -5,6 +5,7 @@ using System.Text.RegularExpressions;
 using FluentValidation;
 using FluentValidation.Validators;
 using NzbDrone.Common.Extensions;
+using NzbDrone.Core.MediaFiles;
 
 namespace NzbDrone.Core.Organizer
 {
@@ -59,8 +60,9 @@ namespace NzbDrone.Core.Organizer
         public static IRuleBuilderOptions<T, string> ValidSpecialsFolderFormat<T>(this IRuleBuilder<T, string> ruleBuilder)
         {
             ruleBuilder.SetValidator(new NotEmptyValidator(null));
+            ruleBuilder.SetValidator(new IllegalCharactersValidator());
 
-            return ruleBuilder.SetValidator(new IllegalCharactersValidator());
+            return ruleBuilder.SetValidator(new FilteredSubfolderValidator());
         }
 
         public static IRuleBuilderOptions<T, string> ValidCustomColonReplacement<T>(this IRuleBuilder<T, string> ruleBuilder)
@@ -177,4 +179,32 @@ namespace NzbDrone.Core.Organizer
             return true;
         }
     }
+
+    public class FilteredSubfolderValidator : PropertyValidator
+    {
+        private static readonly char[] InvalidPathChars = Path.GetInvalidPathChars();
+
+        protected override string GetDefaultMessageTemplate() => "Matches excluded subfolder pattern: {FilteredSubfolders}";
+
+        protected override bool IsValid(PropertyValidatorContext context)
+        {
+            var value = context.PropertyValue as string;
+
+            if (value.IsNullOrWhiteSpace())
+            {
+                return true;
+            }
+
+            var subfolder = value + Path.DirectorySeparatorChar;
+            var matches = DiskScanService.FilteredSubFolderMatches(subfolder);
+
+            if (matches.Any())
+            {
+                context.MessageFormatter.AppendArgument("FilteredSubfolders", string.Join("", matches.Select(m => m.TrimEnd(Path.DirectorySeparatorChar))));
+                return false;
+            }
+
+            return true;
+        }
+    }
 }