Confirm overwriting uncommitted changes on branch change

po/POTFILES

@@ -5,6 +5,7 @@ src/Dialogs/GlobalSearchDialog.vala
 src/Dialogs/NewBranchDialog.vala
 src/Dialogs/PreferencesDialog.vala
 src/Dialogs/RestoreConfirmationDialog.vala
+src/Dialogs/OverwriteUncommittedConfirmationDialog.vala
 src/FolderManager/File.vala
 src/FolderManager/FileItem.vala
 src/FolderManager/FileView.vala

src/Dialogs/OverwriteUncommittedConfirmationDialog.vala

@@ -0,0 +1,49 @@
+/*
+* Copyright 2025 elementary, Inc. (https://elementary.io)
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public
+* License version 3 as published by the Free Software Foundation.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+* General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General Public
+* License along with this program; if not, write to the
+* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+* Boston, MA 02110-1301 USA
+*/
+
+public class Scratch.Dialogs.OverwriteUncommittedConfirmationDialog : Granite.MessageDialog {
+
+    public string branch_name { get; construct; }
+    public OverwriteUncommittedConfirmationDialog (
+        Gtk.Window parent,
+        string new_branch_name,
+        string details
+    ) {
+        Object (
+            buttons: Gtk.ButtonsType.NONE,
+            transient_for: parent,
+            branch_name: new_branch_name
+        );
+
+        show_error_details (details);
+    }
+
+    construct {
+        modal = true;
+        image_icon = new ThemedIcon ("dialog-stop");
+
+        primary_text = _("There are uncommitted changes in the current branch");
+        ///TRANSLATORS '%s' is a placeholder for the name of the branch to be checked out
+        secondary_text = _("Uncommitted changes will be permanently lost if <b>'%s'</b> is checked out now.\n\n<i>It is recommended that uncommitted changes are stashed, committed, or reverted before proceeding </i>").printf (branch_name);
+
+        var proceed_button = (Gtk.Button) add_button (_("Checkout and Overwrite"), Gtk.ResponseType.ACCEPT);
+        proceed_button.get_style_context ().add_class (Gtk.STYLE_CLASS_DESTRUCTIVE_ACTION);
+        var cancel_button = add_button (_("Do not Checkout"), Gtk.ResponseType.REJECT);
+        cancel_button.get_style_context ().add_class (Gtk.STYLE_CLASS_SUGGESTED_ACTION);
+    }
+}

src/FolderManager/ProjectFolderItem.vala

@@ -349,7 +349,7 @@ namespace Scratch.FolderManager {
         private void handle_change_branch_action (GLib.Variant? parameter) {
             var branch_name = parameter.get_string ();
             try {
-                monitored_repo.change_branch (branch_name);
+                monitored_repo.change_local_branch (branch_name);
             } catch (GLib.Error e) {
                 warning ("Failed to change branch to %s. %s", branch_name, e.message);
             }

src/Services/MonitoredRepository.vala

@@ -186,17 +186,43 @@ namespace Scratch.Services {
             return true;
         }
 
-        public void change_branch (string new_branch_name) throws Error {
+        public void change_local_branch (string new_branch_name) throws Error {
             var branch = git_repo.lookup_branch (new_branch_name, Ggit.BranchType.LOCAL);
-            git_repo.set_head (((Ggit.Ref)branch).get_name ());
+            checkout_branch (branch);
+        }
+
+        private void checkout_branch (Ggit.Branch new_head_branch, bool confirm = true) throws Error {
+            if (confirm && has_uncommitted) {
+                confirm_checkout_branch (new_head_branch);
+                return;
+            }
+
+            git_repo.set_head (((Ggit.Ref) new_head_branch).get_name ());
             var options = new Ggit.CheckoutOptions () {
                 //Ensure documents match checked out branch (deal with potential conflicts/losses beforehand)
                 strategy = Ggit.CheckoutStrategy.FORCE
             };
 
             git_repo.checkout_head (options);
 
-            branch_name = new_branch_name;
+            branch_name = new_head_branch.get_name ();
+        }
+
+        private void confirm_checkout_branch (Ggit.Branch new_head_branch) {
+            var parent = ((Gtk.Application)(GLib.Application.get_default ())).get_active_window ();
+            var dialog = new Scratch.Dialogs.OverwriteUncommittedConfirmationDialog (
+                parent,
+                new_head_branch.get_name (),
+                get_project_diff ()
+            );
+            dialog.response.connect ((res) => {
+                dialog.destroy ();
+                if (res == Gtk.ResponseType.ACCEPT) {
+                    checkout_branch (new_head_branch, false);
+                }
+            });
+
+            dialog.present ();
         }
 
         public void create_new_branch (string name) throws Error {
@@ -264,6 +290,41 @@ namespace Scratch.Services {
             return git_repo.path_is_ignored (path);
         }
 
+        public string get_project_diff () throws GLib.Error {
+            var sb = new StringBuilder ("");
+            var repo_diff_list = new Ggit.Diff.index_to_workdir (git_repo, null, null);
+            repo_diff_list.print (Ggit.DiffFormatType.PATCH, (delta, hunk, line) => {
+                unowned var file_diff = delta.get_old_file ();
+                if (file_diff == null) {
+                    return 0;
+                }
+
+                if (line != null) {
+                    var delta_type = line.get_origin ();
+                    string prefix = "?";
+                    switch (delta_type) {
+                        case Ggit.DiffLineType.ADDITION:
+                            prefix = "+";
+                            break;
+                        case Ggit.DiffLineType.DELETION:
+                            prefix = "-";
+                            break;
+                        case Ggit.DiffLineType.CONTEXT:
+                            prefix = " ";
+                            break;
+                        default:
+                            break;
+                    }
+                    //TODO Add color according to linetype
+                    sb.append (prefix + line.get_text ());
+                }
+                return 0;
+            });
+
+            return sb.str;
+        }
+
+
         private bool refreshing = false;
         public void refresh_diff (string file_path, ref Gee.HashMap<int, VCStatus> line_status_map) {
             if (refreshing) {

src/meson.build

@@ -20,6 +20,7 @@ code_files = files(
     'Utils.vala',
     'Dialogs/PreferencesDialog.vala',
     'Dialogs/RestoreConfirmationDialog.vala',
+    'Dialogs/OverwriteUncommittedConfirmationDialog.vala',
     'Dialogs/GlobalSearchDialog.vala',
     'Dialogs/NewBranchDialog.vala',
     'FolderManager/File.vala',