File name substitution WIP

NAPS2.Core/ImportExport/FileNameSubstitution.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text.RegularExpressions;
+
+namespace NAPS2.ImportExport
+{
+    public class FileNameSubstitution
+    {
+        private static readonly Dictionary<string, Func<string>> Subs = new Dictionary<string, Func<string>>
+        {
+            { "$(YYYY)", () => DateTime.Now.ToString("yyyy") }
+        };
+
+        private static readonly Regex NumberSubPattern = new Regex(@"\$\{n+\}");
+
+        public string SubstituteFileName(string fileNameWithPath, int numberSkip = 0, int autoNumberDigits = 0)
+        {
+            // Most subs don't need a special case
+            string result = Subs.Aggregate(fileNameWithPath, (current, sub) => current.Replace(sub.Key, sub.Value()));
+            // One does, however
+            var match = NumberSubPattern.Match(result);
+            if (match.Success)
+            {
+                result = NumberSubPattern.Replace(result, "");
+                result = SubNumber(result, match.Index, match.Length - 3, numberSkip);
+            }
+            else if (autoNumberDigits > 0)
+            {
+                result = SubNumber(result, result.Length - Path.GetExtension(result).Length, autoNumberDigits, numberSkip);
+            }
+            return result;
+        }
+
+        private string SubNumber(string path, int insertionIndex, int minDigits, int skip)
+        {
+            string result;
+            int i = skip;
+            do
+            {
+                ++i;
+                result = path.Insert(insertionIndex, i.ToString("D" + minDigits));
+            } while (File.Exists(result));
+            return result;
+        }
+    }
+}

NAPS2.Core/NAPS2.Core.csproj

@@ -88,6 +88,7 @@
     <Compile Include="Config\ProfileManager.cs" />
     <Compile Include="Config\UserConfig.cs" />
     <Compile Include="Config\UserConfigManager.cs" />
+    <Compile Include="ImportExport\FileNameSubstitution.cs" />
     <Compile Include="ImportExport\Email\EmailSettings.cs" />
     <Compile Include="ImportExport\Email\EmailSettingsContainer.cs" />
     <Compile Include="ImportExport\Pdf\IPdfPasswordProvider.cs" />