fix(swap-layouts): introduce exact panes constraint

6 files changed, 201 insertions, 51 deletions

diff --git a/zellij-server/src/tab/swap_layouts.rs b/zellij-server/src/tab/swap_layouts.rs
index 57085779f..942a65408 100644
--- a/zellij-server/src/tab/swap_layouts.rs
+++ b/zellij-server/src/tab/swap_layouts.rs
@@ -40,12 +40,14 @@ impl SwapLayouts {
         let mut base_swap_floating_layout = BTreeMap::new();
         let tiled_panes_count = layout.0.pane_count();
         let floating_panes_count = layout.1.len();
-        // we set MaxPanes to the current panes in the layout, because the base layout is not
+        // we set ExactPanes to the current panes in the layout, because the base layout is not
         // intended to be progressive - i.e. to have additional panes added to it
+        // we also don't want it to be applied for less than the expected amount of panes, because
+        // then unintended things can happen
         // we still want to keep it around in case we'd like to swap layouts without adding panes
-        base_swap_tiled_layout.insert(LayoutConstraint::MaxPanes(tiled_panes_count), layout.0);
+        base_swap_tiled_layout.insert(LayoutConstraint::ExactPanes(tiled_panes_count), layout.0);
         base_swap_floating_layout
-            .insert(LayoutConstraint::MaxPanes(floating_panes_count), layout.1);
+            .insert(LayoutConstraint::ExactPanes(floating_panes_count), layout.1);
         self.swap_tiled_layouts
             .insert(0, (base_swap_tiled_layout, Some("BASE".into())));
         self.swap_floating_layouts
@@ -174,6 +176,9 @@ impl SwapLayouts {
             LayoutConstraint::MinPanes(min_panes) => {
                 tiled_panes.visible_panes_count() >= *min_panes
             },
+            LayoutConstraint::ExactPanes(pane_count) => {
+                tiled_panes.visible_panes_count() == *pane_count
+            },
             LayoutConstraint::NoConstraint => true,
         }
     }
@@ -189,6 +194,9 @@ impl SwapLayouts {
             LayoutConstraint::MinPanes(min_panes) => {
                 floating_panes.visible_panes_count() >= *min_panes
             },
+            LayoutConstraint::ExactPanes(pane_count) => {
+                floating_panes.visible_panes_count() == *pane_count
+            },
             LayoutConstraint::NoConstraint => true,
         }
     }
diff --git a/zellij-server/src/tab/unit/snapshots/zellij_server__tab__tab_integration_tests__when_closing_a_pane_in_auto_layout_the_focus_goes_to_last_focused_pane.snap b/zellij-server/src/tab/unit/snapshots/zellij_server__tab__tab_integration_tests__when_closing_a_pane_in_auto_layout_the_focus_goes_to_last_focused_pane.snap
index 8f548b1dc..48fb7d0cd 100644
--- a/zellij-server/src/tab/unit/snapshots/zellij_server__tab__tab_integration_tests__when_closing_a_pane_in_auto_layout_the_focus_goes_to_last_focused_pane.snap
+++ b/zellij-server/src/tab/unit/snapshots/zellij_server__tab__tab_integration_tests__when_closing_a_pane_in_auto_layout_the_focus_goes_to_last_focused_pane.snap
@@ -1,26 +1,26 @@
 ---
 source: zellij-server/src/tab/./unit/tab_integration_tests.rs
-assertion_line: 5333
+assertion_line: 5700
 expression: snapshot
 ---
-00 (C): ┌ Pane #1 ──────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
-01 (C): │                                                                                                                       │
-02 (C): │                                                                                                                       │
-03 (C): │                                                                                                                       │
-04 (C): │                                                                                                                       │
-05 (C): │                                                                                                                       │
-06 (C): │                                                                                                                       │
-07 (C): │                                                                                                                       │
-08 (C): │                                                                                                                       │
-09 (C): └───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
-10 (C): ┌ Pane #2 ──────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
-11 (C): │                                                                                                                       │
-12 (C): │                                                                                                                       │
-13 (C): │                                                                                                                       │
-14 (C): │                                                                                                                       │
-15 (C): │                                                                                                                       │
-16 (C): │                                                                                                                       │
-17 (C): │                                                                                                                       │
-18 (C): │                                                                                                                       │
-19 (C): └───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
+00 (C): ┌ Pane #1 ──────────────────────────────────────────────────┐┌ Pane #2 ─────────────────────────────────────────────────┐
+01 (C): │                                                           ││                                                          │
+02 (C): │                                                           ││                                                          │
+03 (C): │                                                           ││                                                          │
+04 (C): │                                                           ││                                                          │
+05 (C): │                                                           ││                                                          │
+06 (C): │                                                           ││                                                          │
+07 (C): │                                                           ││                                                          │
+08 (C): │                                                           ││                                                          │
+09 (C): │                                                           ││                                                          │
+10 (C): │                                                           ││                                                          │
+11 (C): │                                                           ││                                                          │
+12 (C): │                                                           ││                                                          │
+13 (C): │                                                           ││                                                          │
+14 (C): │                                                           ││                                                          │
+15 (C): │                                                           ││                                                          │
+16 (C): │                                                           ││                                                          │
+17 (C): │                                                           ││                                                          │
+18 (C): │                                                           ││                                                          │
+19 (C): └───────────────────────────────────────────────────────────┘└──────────────────────────────────────────────────────────┘
 
diff --git a/zellij-server/src/tab/unit/tab_integration_tests.rs b/zellij-server/src/tab/unit/tab_integration_tests.rs
index 45b3defdf..11de1c298 100644
--- a/zellij-server/src/tab/unit/tab_integration_tests.rs
+++ b/zellij-server/src/tab/unit/tab_integration_tests.rs
@@ -5681,8 +5681,8 @@ fn when_closing_a_pane_in_auto_layout_the_focus_goes_to_last_focused_pane() {
         )),
         true,
     );
-    tab.move_focus_down(client_id);
-    tab.move_focus_down(client_id);
+    let _ = tab.move_focus_down(client_id);
+    let _ = tab.move_focus_down(client_id);
     tab.close_pane(PaneId::Terminal(3), false, Some(client_id));
     tab.render(&mut output, None).unwrap();
 
@@ -5694,7 +5694,7 @@ fn when_closing_a_pane_in_auto_layout_the_focus_goes_to_last_focused_pane() {
     );
     assert_eq!(
         cursor_coordinates,
-        Some((1, 11)),
+        Some((62, 1)),
         "cursor coordinates moved to the new pane",
     );
     assert_snapshot!(snapshot);
diff --git a/zellij-utils/src/input/layout.rs b/zellij-utils/src/input/layout.rs
index d6f5a2f7d..915c348a8 100644
--- a/zellij-utils/src/input/layout.rs
+++ b/zellij-utils/src/input/layout.rs
@@ -252,6 +252,7 @@ impl fmt::Display for RunPluginLocation {
 pub enum LayoutConstraint {
     MaxPanes(usize),
     MinPanes(usize),
+    ExactPanes(usize),
     NoConstraint,
 }
 
diff --git a/zellij-utils/src/kdl/kdl_layout_parser.rs b/zellij-utils/src/kdl/kdl_layout_parser.rs
index cf6afaf70..7ad0895fd 100644
--- a/zellij-utils/src/kdl/kdl_layout_parser.rs
+++ b/zellij-utils/src/kdl/kdl_layout_parser.rs
@@ -119,6 +119,7 @@ impl<'a> KdlLayoutParser<'a> {
             || property_name == "children"
             || property_name == "max_panes"
             || property_name == "min_panes"
+            || property_name == "exact_panes"
     }
     fn assert_legal_node_name(&self, name: &str, kdl_node: &KdlNode) -> Result<(), ConfigError> {
         if name.contains(char::is_whitespace) {
@@ -1747,6 +1748,12 @@ impl<'a> KdlLayoutParser<'a> {
                                 tab_template_kdl_node,
                             )?;
                             swap_tiled_layout.insert(layout_constraint, layout);
+                        } else {
+                            return Err(ConfigError::new_layout_kdl_error(
+                                format!("Unknown layout node: '{}'", layout_node_name),
+                                layout.span().offset(),
+                                layout.span().len(),
+                            ));
                         }
                     }
                     swap_tiled_layouts.push((swap_tiled_layout, swap_layout_name));
@@ -1787,6 +1794,12 @@ impl<'a> KdlLayoutParser<'a> {
                                 tab_template_kdl_node,
                             )?;
                             swap_floating_layout.insert(layout_constraint, layout);
+                        } else {
+                            return Err(ConfigError::new_layout_kdl_error(
+                                format!("Unknown layout node: '{}'", layout_node_name),
+                                layout.span().offset(),
+                                layout.span().len(),
+                            ));
                         }
                     }
                     swap_floating_layouts.push((swap_floating_layout, swap_layout_name));
@@ -1814,17 +1827,39 @@ impl<'a> KdlLayoutParser<'a> {
                 layout_node
             ));
         };
+        if let Some(exact_panes) = kdl_get_string_property_or_child_value!(layout_node, "exact_panes") {
+            return Err(kdl_parsing_error!(
+                format!(
+                    "exact_panes should be a fixed number (eg. 1) and not a quoted string (\"{}\")",
+                    exact_panes,
+                ),
+                layout_node
+            ));
+        };
         let max_panes = kdl_get_int_property_or_child_value!(layout_node, "max_panes");
         let min_panes = kdl_get_int_property_or_child_value!(layout_node, "min_panes");
-        match (min_panes, max_panes) {
-            (Some(_min_panes), Some(_max_panes)) => Err(kdl_parsing_error!(
+        let exact_panes = kdl_get_int_property_or_child_value!(layout_node, "exact_panes");
+        let mut constraint_count = 0;
+        let mut constraint = None;
+        if let Some(max_panes) = max_panes {
+            constraint_count += 1;
+            constraint = Some(LayoutConstraint::MaxPanes(max_panes as usize));
+        }
+        if let Some(min_panes) = min_panes {
+            constraint_count += 1;
+            constraint = Some(LayoutConstraint::MinPanes(min_panes as usize));
+        }
+        if let Some(exact_panes) = exact_panes {
+            constraint_count += 1;
+            constraint = Some(LayoutConstraint::ExactPanes(exact_panes as usize));
+        }
+        if constraint_count > 1 {
+            return Err(kdl_parsing_error!(
                 format!("cannot have more than one constraint (eg. max_panes + min_panes)'"),
                 layout_node
-            )),
-            (Some(min_panes), None) => Ok(LayoutConstraint::MinPanes(min_panes as usize)),
-            (None, Some(max_panes)) => Ok(LayoutConstraint::MaxPanes(max_panes as usize)),
-            _ => Ok(LayoutConstraint::NoConstraint),
+            ));
         }
+        Ok(constraint.unwrap_or(LayoutConstraint::NoConstraint))
     }
     fn populate_one_swap_tiled_layout(
         &self,
diff --git a/zellij-utils/src/snapshots/zellij_utils__setup__setup_test__default_config_with_no_cli_arguments-2.snap b/zellij-utils/src/snapshots/zellij_utils__setup__setup_test__default_config_with_no_cli_arguments-2.snap
index b87b9344c..f53ecc5ef 100644
--- a/zellij-utils/src/snapshots/zellij_utils__setup__setup_test__default_config_with_no_cli_arguments-2.snap
+++ b/zellij-utils/src/snapshots/zellij_utils__setup__setup_test__default_config_with_no_cli_arguments-2.snap
@@ -1,6 +1,6 @@
 ---
 source: zellij-utils/src/setup.rs
-assertion_line: 601
+assertion_line: 622
 expression: "format!(\"{:#?}\", layout)"
 ---
 Layout {
@@ -1213,8 +1213,8 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
-                                1,
+                            Percent(
+                                5,
                             ),
                         ),
                         y: Some(
@@ -1238,8 +1238,8 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
-                                2,
+                            Percent(
+                                5,
                             ),
                         ),
                         y: Some(
@@ -1263,8 +1263,8 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
-                                3,
+                            Percent(
+                                5,
                             ),
                         ),
                         y: Some(
@@ -1288,8 +1288,8 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
-                                4,
+                            Percent(
+                                5,
                             ),
                         ),
                         y: Some(
@@ -1313,7 +1313,7 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
+                            Percent(
                                 5,
                             ),
                         ),
@@ -1338,8 +1338,8 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
-                                6,
+                            Percent(
+                                5,
                             ),
                         ),
                         y: Some(
@@ -1363,8 +1363,8 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
-                                7,
+                            Percent(
+                                5,
                             ),
                         ),
                         y: Some(
@@ -1388,8 +1388,8 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
-                                8,
+                            Percent(
+                                5,
                             ),
                         ),
                         y: Some(
@@ -1413,8 +1413,8 @@ Layout {
                             ),
                         ),
                         x: Some(
-                            Fixed(
-                                9,
+                            Percent(
+                                5,
                             ),
                         ),
                         y: Some(
@@ -1596,6 +1596,112 @@ Layout {
                         focus: None,
                     },
                 ],
+                MaxPanes(
+                    4,
+                ): [
+                    FloatingPaneLayout {
+                        name: None,
+                        height: Some(
+                            Percent(
+                                45,
+                            ),
+                        ),
+                        width: Some(
+                            Percent(
+                                45,
+                            ),
+                        ),
+                        x: Some(
+                            Percent(
+                                1,
+                            ),
+                        ),
+                        y: Some(
+                            Percent(
+                                55,
+                            ),
+                        ),
+                        run: None,
+                        focus: None,
+                    },
+                    FloatingPaneLayout {
+                        name: None,
+                        height: Some(
+                            Percent(
+                                45,
+                            ),
+                        ),
+                        width: Some(
+                            Percent(
+                                45,
+                            ),
+                        ),
+                        x: Some(
+                            Percent(
+                                50,
+                            ),
+                        ),
+                        y: Some(
+                            Percent(
+                                55,
+                            ),
+                        ),
+                        run: None,
+                        focus: Some(
+                            true,
+                        ),
+                    },
+                    FloatingPaneLayout {
+                        name: None,
+                        height: Some(
+                            Percent(
+                                45,
+                            ),
+                        ),
+                        width: Some(
+                            Percent(
+                                45,
+                            ),
+                        ),
+                        x: Some(
+                            Percent(
+                                1,
+                            ),
+                        ),
+                        y: Some(
+                            Percent(
+                                1,
+                            ),
+                        ),
+                        run: None,
+                        focus: None,
+                    },
+                    FloatingPaneLayout {
+                        name: None,
+                        height: Some(
+                            Percent(
+                                45,
+                            ),
+                        ),
+                        width: Some(
+                            Percent(
+                                45,
+                            ),
+                        ),
+                        x: Some(
+                            Percent(
+                                50,
+                            ),
+                        ),
+                        y: Some(
+                            Percent(
+                                1,
+                            ),
+                        ),
+                        run: None,
+                        focus: None,
+                    },
+                ],
             },
             Some(
                 "spread",