feature: supports parameters in commit template (#487)

- ${files_num} will be replaced with staged changes count
- ${files} will be replaced with changed file paths
- ${files:N} will be replaced with top N changes file paths and with `and {TOTAL - N} other files` at end of replaced string.

src/Models/CommitTemplate.cs

@@ -1,9 +1,17 @@
-using CommunityToolkit.Mvvm.ComponentModel;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Text.RegularExpressions;
+
+using CommunityToolkit.Mvvm.ComponentModel;
 
 namespace SourceGit.Models
 {
-    public class CommitTemplate : ObservableObject
+    public partial class CommitTemplate : ObservableObject
     {
+        [GeneratedRegex(@"\$\{files(\:\d+)?\}")]
+        private static partial Regex REG_COMMIT_TEMPLATE_FILES();
+
         public string Name
         {
             get => _name;
@@ -16,6 +24,56 @@ namespace SourceGit.Models
             set => SetProperty(ref _content, value);
         }
 
+        public string Apply(List<Change> changes)
+        {
+            var content = _content.Replace("${files_num}", $"{changes.Count}");
+            var matches = REG_COMMIT_TEMPLATE_FILES().Matches(content);
+            if (matches.Count == 0)
+                return content;
+
+            var builder = new StringBuilder();
+            var last = 0;
+            for (int i = 0; i < matches.Count; i++)
+            {
+                var match = matches[i];
+                if (!match.Success)
+                    continue;
+
+                var start = match.Index;
+                if (start != last)
+                    builder.Append(content.Substring(last, start - last));
+
+                var countStr = match.Groups[1].Value;
+                var paths = new List<string>();
+                var more = string.Empty;
+                if (countStr is { Length: <= 1 })
+                {
+                    foreach (var c in changes)
+                        paths.Add(c.Path);
+                }
+                else
+                {
+                    var count = Math.Min(int.Parse(countStr.Substring(1)), changes.Count);
+                    for (int j = 0; j < count; j++)
+                        paths.Add(changes[i].Path);
+
+                    if (count < changes.Count)
+                        more = $" and {changes.Count - count} other files";
+                }
+
+                builder.Append(string.Join(", ", paths));
+                if (!string.IsNullOrEmpty(more))
+                    builder.Append(more);
+
+                last = start + match.Length;
+            }
+
+            if (last != content.Length - 1)
+                builder.Append(content.Substring(last));
+
+            return builder.ToString();
+        }
+
         private string _name = string.Empty;
         private string _content = string.Empty;
     }

src/ViewModels/WorkingCopy.cs

@@ -780,13 +780,9 @@ namespace SourceGit.ViewModels
                 foreach (var change in _selectedUnstaged)
                 {
                     if (change.IsConflit)
-                    {
                         hasConflicts = true;
-                    }
                     else
-                    {
                         hasNoneConflicts = true;
-                    }
                 }
 
                 if (hasConflicts)
@@ -1160,7 +1156,7 @@ namespace SourceGit.ViewModels
                     item.Icon = App.CreateMenuIcon("Icons.Code");
                     item.Click += (_, e) =>
                     {
-                        CommitMessage = template.Content;
+                        CommitMessage = template.Apply(_staged);
                         e.Handled = true;
                     };
                     menu.Items.Add(item);