From 7f0d366d0169521beb33335dadfbd306375096d7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bart=C5=82omiej=20Dach?= <dach.bartlomiej@gmail.com>
Date: Sat, 3 Dec 2022 16:59:43 +0100
Subject: [PATCH] Extract common part of regex to separate method

---
 osu.Game/Utils/NamingUtils.cs | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/osu.Game/Utils/NamingUtils.cs b/osu.Game/Utils/NamingUtils.cs
index fa102ff56f..97220f4201 100644
--- a/osu.Game/Utils/NamingUtils.cs
+++ b/osu.Game/Utils/NamingUtils.cs
@@ -29,7 +29,7 @@ namespace osu.Game.Utils
         /// </remarks>
         public static string GetNextBestName(IEnumerable<string> existingNames, string desiredName)
         {
-            string pattern = $@"^(?i){Regex.Escape(desiredName)}(?-i)( \((?<copyNumber>[1-9][0-9]*)\))?$";
+            string pattern = $@"^{getBaselineNameDetectingPattern(desiredName)}$";
             var regex = new Regex(pattern, RegexOptions.Compiled);
 
             int bestNumber = findBestNumber(existingNames, regex);
@@ -48,7 +48,7 @@ namespace osu.Game.Utils
             string name = Path.GetFileNameWithoutExtension(desiredFilename);
             string extension = Path.GetExtension(desiredFilename);
 
-            string pattern = $@"^(?i){Regex.Escape(name)}(?-i)( \((?<copyNumber>[1-9][0-9]*)\))?(?i){Regex.Escape(extension)}(?-i)$";
+            string pattern = $@"^{getBaselineNameDetectingPattern(name)}(?i){Regex.Escape(extension)}(?-i)$";
             var regex = new Regex(pattern, RegexOptions.Compiled);
 
             int bestNumber = findBestNumber(existingFilenames, regex);
@@ -58,6 +58,22 @@ namespace osu.Game.Utils
                 : $"{name} ({bestNumber.ToString()}){extension}";
         }
 
+        /// <summary>
+        /// Generates a basic regex pattern that will match all possible conflicting filenames when picking the best available name, given the <paramref name="desiredName"/>.
+        /// The generated pattern can be composed into more complicated regexes for particular uses, such as picking filenames, which need additional file extension handling.
+        /// </summary>
+        /// <remarks>
+        /// The regex shall detect:
+        /// <list type="bullet">
+        /// <item>all strings that are equal to <paramref name="desiredName"/>,</item>
+        /// <item>all strings of the format <c>desiredName (number)</c>, where <c>number</c> is a number written using Arabic numerals.</item>
+        /// </list>
+        /// All comparisons are made in a case-insensitive manner.
+        /// If a number is detected in the matches, it will be output to the <c>copyNumber</c> named group.
+        /// </remarks>
+        private static string getBaselineNameDetectingPattern(string desiredName)
+            => $@"(?i){Regex.Escape(desiredName)}(?-i)( \((?<copyNumber>[1-9][0-9]*)\))?";
+
         private static int findBestNumber(IEnumerable<string> existingNames, Regex regex)
         {
             var takenNumbers = new HashSet<int>();