fix(compatibility): adjust saved cursor position on resize (#1362)

* fix(compatibility): adjust saved cursor position on resize

* style(fmt): rustfmt

3 files changed, 54 insertions, 0 deletions

diff --git a/zellij-server/src/panes/grid.rs b/zellij-server/src/panes/grid.rs
index f34ad143..ec2d7e9b 100644
--- a/zellij-server/src/panes/grid.rs
+++ b/zellij-server/src/panes/grid.rs
@@ -699,6 +699,12 @@ impl Grid {
             }
             self.cursor.y = new_cursor_y;
             self.cursor.x = new_cursor_x;
+            self.saved_cursor_position
+                .as_mut()
+                .map(|saved_cursor_position| {
+                    saved_cursor_position.y = new_cursor_y;
+                    saved_cursor_position.x = new_cursor_x;
+                });
         } else if new_columns != self.width
             && self.alternate_lines_above_viewport_and_cursor.is_some()
         {
@@ -723,13 +729,24 @@ impl Grid {
                     );
                     let rows_pulled = self.viewport.len() - current_viewport_row_count;
                     self.cursor.y += rows_pulled;
+                    self.saved_cursor_position
+                        .as_mut()
+                        .map(|saved_cursor_position| saved_cursor_position.y += rows_pulled);
                 }
                 Ordering::Greater => {
                     let row_count_to_transfer = current_viewport_row_count - new_rows;
                     if row_count_to_transfer > self.cursor.y {
                         self.cursor.y = 0;
+                        self.saved_cursor_position
+                            .as_mut()
+                            .map(|saved_cursor_position| saved_cursor_position.y = 0);
                     } else {
                         self.cursor.y -= row_count_to_transfer;
+                        self.saved_cursor_position
+                            .as_mut()
+                            .map(|saved_cursor_position| {
+                                saved_cursor_position.y -= row_count_to_transfer
+                            });
                     }
                     if self.alternate_lines_above_viewport_and_cursor.is_none() {
                         transfer_rows_from_viewport_to_lines_above(
diff --git a/zellij-server/src/tab/unit/snapshots/zellij_server__tab__tab_integration_tests__save_cursor_position_across_resizes.snap b/zellij-server/src/tab/unit/snapshots/zellij_server__tab__tab_integration_tests__save_cursor_position_across_resizes.snap
new file mode 100644
index 00000000..278b856a
--- /dev/null
+++ b/zellij-server/src/tab/unit/snapshots/zellij_server__tab__tab_integration_tests__save_cursor_position_across_resizes.snap
@@ -0,0 +1,11 @@
+---
+source: zellij-server/src/tab/./unit/tab_integration_tests.rs
+assertion_line: 1153
+expression: snapshot
+---
+00 (C): ┌ Pane #1 ─────────────────────────────────────────────────────────────────────────── SCROLL:  0/4 ┐
+01 (C): │                                       Let's save the cursor position here this overwrote me!tten │
+02 (C): └──────────────────────────────────────────────────────────────────────────────────────────────────┘
+03 (C):                                                                                                     
+04 (C):                                                                                                     
+
diff --git a/zellij-server/src/tab/unit/tab_integration_tests.rs b/zellij-server/src/tab/unit/tab_integration_tests.rs
index 636d9ba6..352efadc 100644
--- a/zellij-server/src/tab/unit/tab_integration_tests.rs
+++ b/zellij-server/src/tab/unit/tab_integration_tests.rs
@@ -1117,3 +1117,29 @@ fn wide_characters_in_left_title_side() {
     );
     assert_snapshot!(snapshot);
 }
+
+#[test]
+fn save_cursor_position_across_resizes() {
+    // the save cursor position ANSI instruction (CSI s) needs to point to the same character after we
+    // resize the pane
+    let size = Size { cols: 100, rows: 5 };
+    let client_id = 1;
+    let mut tab = create_new_tab(size);
+    let mut output = Output::default();
+
+    tab.handle_pty_bytes(
+        1,
+        Vec::from("\n\nI am some text\nI am another line of text\nLet's save the cursor position here \u{1b}[sI should be ovewritten".as_bytes()),
+    );
+    tab.resize_whole_tab(Size { cols: 100, rows: 3 });
+    tab.handle_pty_bytes(1, Vec::from("\u{1b}[uthis overwrote me!".as_bytes()));
+
+    tab.render(&mut output, None);
+    let snapshot = take_snapshot(
+        output.serialize().get(&client_id).unwrap(),
+        size.rows,
+        size.cols,
+        Palette::default(),
+    );
+    assert_snapshot!(snapshot);
+}