fix(compatibility): handle cursor movements outside scroll region (#746)

* fix(compatibility): handle cursor movements outside scroll region

* style(fmt): make clippy happy

4 files changed, 110 insertions, 9 deletions

diff --git a/src/tests/fixtures/move_cursor_below_scroll_region b/src/tests/fixtures/move_cursor_below_scroll_region
new file mode 100755
index 000000000..fddccf650
--- /dev/null
+++ b/src/tests/fixtures/move_cursor_below_scroll_region
@@ -0,0 +1,42 @@
+
+
1foo
+
2foo
+
3foo
+
4foo
+
5foo
+
6foo
+
7foo
+
8foo
+
9foo
+
10foo
+
11foo
+
12foo
+
13foo
+
14foo
+
15foo
+
16foo
+
17foo
+
18foo
+
19foo
+
20foo
+
21foo
+
22foo
+
23foo
+
24foo
+
25foo
+
26foo
+
27foo
+
28foo
+
29foo
+
30foo
+
31foo
+
32foo
+
33foo
+
34foo
+
35foo
+
+
1bar
+
2bar
+
3bar
+
4bar
+
5zz
\ No newline at end of file
diff --git a/zellij-server/src/panes/grid.rs b/zellij-server/src/panes/grid.rs
index 2d2354c67..f157b3274 100644
--- a/zellij-server/src/panes/grid.rs
+++ b/zellij-server/src/panes/grid.rs
@@ -883,14 +883,16 @@ impl Grid {
             self.viewport.push(new_row);
         }
         if self.cursor.y == self.height - 1 {
-            let row_count_to_transfer = 1;
-            transfer_rows_from_viewport_to_lines_above(
-                &mut self.viewport,
-                &mut self.lines_above,
-                row_count_to_transfer,
-                self.width,
-            );
-            self.selection.move_up(1);
+            if self.scroll_region.is_none() {
+                let row_count_to_transfer = 1;
+                transfer_rows_from_viewport_to_lines_above(
+                    &mut self.viewport,
+                    &mut self.lines_above,
+                    row_count_to_transfer,
+                    self.width,
+                );
+                self.selection.move_up(1);
+            }
             self.output_buffer.update_all_lines();
         } else {
             self.cursor.y += 1;
@@ -1051,7 +1053,11 @@ impl Grid {
                 } else {
                     0
                 };
-                self.cursor.y = std::cmp::min(scroll_region_bottom, y + y_offset);
+                if y >= scroll_region_top && y <= scroll_region_bottom {
+                    self.cursor.y = std::cmp::min(scroll_region_bottom, y + y_offset);
+                } else {
+                    self.cursor.y = std::cmp::min(self.height - 1, y + y_offset);
+                }
                 self.pad_lines_until(self.cursor.y, pad_character);
                 self.pad_current_line_until(self.cursor.x);
             }
diff --git a/zellij-server/src/panes/unit/grid_tests.rs b/zellij-server/src/panes/unit/grid_tests.rs
index 34236f7e8..1ecc10a90 100644
--- a/zellij-server/src/panes/unit/grid_tests.rs
+++ b/zellij-server/src/panes/unit/grid_tests.rs
@@ -998,3 +998,15 @@ pub fn scroll_up_increase_width_and_scroll_down() {
     }
     assert_snapshot!(format!("{:?}", grid));
 }
+
+#[test]
+pub fn move_cursor_below_scroll_region() {
+    let mut vte_parser = vte::Parser::new();
+    let mut grid = Grid::new(34, 114, Palette::default());
+    let fixture_name = "move_cursor_below_scroll_region";
+    let content = read_fixture(fixture_name);
+    for byte in content {
+        vte_parser.advance(&mut grid, byte);
+    }
+    assert_snapshot!(format!("{:?}", grid));
+}
diff --git a/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__move_cursor_below_scroll_region.snap b/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__move_cursor_below_scroll_region.snap
new file mode 100644
index 000000000..ae731f374
--- /dev/null
+++ b/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__move_cursor_below_scroll_region.snap
@@ -0,0 +1,41 @@
+---
+source: zellij-server/src/panes/./unit/grid_tests.rs
+expression: "format!(\"{:?}\", grid)"
+
+---
+00 (C): 7foo
+01 (C): 8foo
+02 (C): 9foo
+03 (C): 10foo
+04 (C): 11foo
+05 (C): 12foo
+06 (C): 13foo
+07 (C): 14foo
+08 (C): 15foo
+09 (C): 16foo
+10 (C): 17foo
+11 (C): 18foo
+12 (C): 19foo
+13 (C): 20foo
+14 (C): 21foo
+15 (C): 22foo
+16 (C): 23foo
+17 (C): 24foo
+18 (C): 25foo
+19 (C): 26foo
+20 (C): 27foo
+21 (C): 28foo
+22 (C): 29foo
+23 (C): 30foo                                                                                                             
+24 (C): 31foo                                                                                                             
+25 (C): 32foo                                                                                                             
+26 (C): 33foo                                                                                                             
+27 (C): 34foo                                                                                                             
+28 (C): 35foo                                                                                                             
+29 (C):                                                                                                                   
+30 (C):                                                                                                                   
+31 (C):                                                                                                                   
+32 (C):                                                                                                                   
+33 (C): 5zzr                                                                                                              
+34 (C): 
+