refactor<*>: rewrite all with AvaloniaUI

src/Commands/SaveChangesAsPatch.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+
+namespace SourceGit.Commands {
+    public static class SaveChangesAsPatch {
+        public static bool Exec(string repo, List<Models.Change> changes, bool isUnstaged, string saveTo) {
+            using (var sw = File.Create(saveTo)) {
+                foreach (var change in changes) {
+                    if (!ProcessSingleChange(repo, new Models.DiffOption(change, isUnstaged), sw)) return false;
+                }
+            }
+
+            return true;
+        }
+
+        private static bool ProcessSingleChange(string repo, Models.DiffOption opt, FileStream writer) {
+            var starter = new ProcessStartInfo();
+            starter.WorkingDirectory = repo;
+            starter.FileName = Native.OS.GitExecutableFile;
+            starter.Arguments = $"diff --ignore-cr-at-eol --unified=4 {opt}";
+            starter.UseShellExecute = false;
+            starter.CreateNoWindow = true;
+            starter.WindowStyle = ProcessWindowStyle.Hidden;
+            starter.RedirectStandardOutput = true;
+
+            try {
+                var proc = new Process() { StartInfo = starter };
+                proc.Start();
+                proc.StandardOutput.BaseStream.CopyTo(writer);
+                proc.WaitForExit();
+                var rs = proc.ExitCode == 0;
+                proc.Close();
+
+                return rs;
+            } catch (Exception e) {
+                App.RaiseException(repo, "Save change to patch failed: " + e.Message);
+                return false;
+            }
+        }
+    }
+}