feat(panes): allow defining an expanded stacked pane (#2343)

* feat(panes): allow defining an expanded stacked pane

* style(fmt): rustfmt

47 files changed, 507 insertions, 41 deletions

diff --git a/zellij-utils/src/input/layout.rs b/zellij-utils/src/input/layout.rs
index 78db7ce51..a07e1d313 100644
--- a/zellij-utils/src/input/layout.rs
+++ b/zellij-utils/src/input/layout.rs
@@ -394,6 +394,7 @@ pub struct TiledPaneLayout {
     pub focus: Option<bool>,
     pub external_children_index: Option<usize>,
     pub children_are_stacked: bool,
+    pub is_expanded_in_stack: bool,
 }
 
 impl TiledPaneLayout {
@@ -865,12 +866,15 @@ fn split_space(
 ) -> Result<Vec<(TiledPaneLayout, PaneGeom)>, &'static str> {
     let mut pane_positions = Vec::new();
     let sizes: Vec<Option<SplitSize>> = if layout.children_are_stacked {
+        let index_of_expanded_pane = layout.children.iter().position(|p| p.is_expanded_in_stack);
         let mut sizes: Vec<Option<SplitSize>> = layout
             .children
             .iter()
             .map(|_part| Some(SplitSize::Fixed(1)))
             .collect();
-        if let Some(last_size) = sizes.last_mut() {
+        if let Some(index_of_expanded_pane) = index_of_expanded_pane {
+            *sizes.get_mut(index_of_expanded_pane).unwrap() = None;
+        } else if let Some(last_size) = sizes.last_mut() {
             *last_size = None;
         }
         sizes
diff --git a/zellij-utils/src/input/unit/layout_test.rs b/zellij-utils/src/input/unit/layout_test.rs
index 237cf978c..7ff2567a9 100644
--- a/zellij-utils/src/input/unit/layout_test.rs
+++ b/zellij-utils/src/input/unit/layout_test.rs
@@ -1882,6 +1882,21 @@ fn can_define_stacked_children_for_pane_template() {
 }
 
 #[test]
+fn can_define_a_stack_with_an_expanded_pane() {
+    let kdl_layout = r#"
+        layout {
+           pane stacked=true {
+               pane
+               pane expanded=true
+               pane
+           }
+        }
+    "#;
+    let layout = Layout::from_kdl(kdl_layout, "layout_file_name".into(), None, None).unwrap();
+    assert_snapshot!(format!("{:#?}", layout));
+}
+
+#[test]
 fn cannot_define_stacked_panes_for_bare_node() {
     let kdl_layout = r#"
         layout {
@@ -1893,6 +1908,20 @@ fn cannot_define_stacked_panes_for_bare_node() {
 }
 
 #[test]
+fn cannot_define_an_expanded_pane_outside_of_a_stack() {
+    let kdl_layout = r#"
+        layout {
+            pane {
+                pane
+                pane expanded=true
+            }
+        }
+    "#;
+    let layout = Layout::from_kdl(kdl_layout, "layout_file_name".into(), None, None);
+    assert!(layout.is_err(), "error provided for tab name with space");
+}
+
+#[test]
 fn cannot_define_stacked_panes_with_vertical_split_direction() {
     let kdl_layout = r#"
         layout {
diff --git a/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__args_added_to_args_in_template.snap b/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__args_added_to_args_in_template.snap
index 799908327..65450c122 100644
--- a/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__args_added_to_args_in_template.snap
+++ b/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__args_added_to_args_in_template.snap
@@ -1,6 +1,6 @@
 ---
 source: zellij-utils/src/input/./unit/layout_test.rs
-assertion_line: 1266
+assertion_line: 1322
 expression: "format!(\"{:#?}\", layout)"
 ---
 Layout {
@@ -32,6 +32,7 @@ Layout {
                         focus: None,
                         external_children_index: None,
                         children_are_stacked: false,
+                        is_expanded_in_stack: false,
                     },
                     TiledPaneLayout {
                         children_split_direction: Horizontal,
@@ -56,6 +57,7 @@ Layout {
                         focus: None,
                         external_children_index: None,
                         children_are_stacked: false,
+                        is_expanded_in_stack: false,
                     },
                 ],
                 split_size: None,
@@ -64,6 +66,7 @@ Layout {
                 focus: None,
                 external_children_index: None,
                 children_are_stacked: false,
+                is_expanded_in_stack: false,
             },
             [],
         ),
diff --git a/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__args_override_args_in_template.snap b/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__args_override_args_in_template.snap
index bb691fe76..5db6198b3 100644
--- a/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__args_override_args_in_template.snap
+++ b/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__args_override_args_in_template.snap
@@ -1,6 +1,6 @@
 ---
 source: zellij-utils/src/input/./unit/layout_test.rs
-assertion_line: 1231
+assertion_line: 1287
 expression: "format!(\"{:#?}\", layout)"
 ---
 Layout {
@@ -35,6 +35,7 @@ Layout {
                         focus: None,
                         external_children_index: None,
                         children_are_stacked: false,
+                        is_expanded_in_stack: false,
                     },
                     TiledPaneLayout {
                         children_split_direction: Horizontal,
@@ -59,6 +60,7 @@ Layout {
                         focus: None,
                         external_children_index: None,
                         children_are_stacked: false,
+                        is_expanded_in_stack: false,
                     },
                 ],
                 split_size: None,
@@ -67,6 +69,7 @@ Layout {
                 focus: None,
                 external_children_index: None,
                 children_are_stacked: false,
+                is_expanded_in_stack: false,
             },
             [],
         ),
diff --git a/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__can_define_a_stack_with_an_expanded_pane.snap b/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__can_define_a_stack_with_an_expanded_pane.snap
new file mode 100644
index 000000000..92e0e4365
--- /dev/null
+++ b/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__can_define_a_stack_with_an_expanded_pane.snap
@@ -0,0 +1,79 @@
+---
+source: zellij-utils/src/input/./unit/layout_test.rs
+assertion_line: 1896
+expression: "format!(\"{:#?}\", layout)"
+---
+Layout {
+    tabs: [],
+    focused_tab_index: None,
+    template: Some(
+        (
+            TiledPaneLayout {
+                children_split_direction: Horizontal,
+                name: None,
+                children: [
+                    TiledPaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [
+                            TiledPaneLayout {
+                                children_split_direction: Horizontal,
+                                name: None,
+                                children: [],
+                                split_size: None,
+                                run: None,
+                                borderless: false,
+                                focus: None,
+                                external_children_index: None,
+                                children_are_stacked: false,
+                                is_expanded_in_stack: false,
+                            },
+                            TiledPaneLayout {
+                                children_split_direction: Horizontal,
+                                name: None,
+                                children: [],
+                                split_size: None,
+                                run: None,
+                                borderless: false,
+                                focus: None,
+                                external_children_index: None,
+                                children_are_stacked: false,
+                                is_expanded_in_stack: true,
+                            },
+                            TiledPaneLayout {
+                                children_split_direction: Horizontal,
+                                name: None,
+                                children: [],
+                                split_size: None,
+                                run: None,
+                                borderless: false,
+                                focus: None,
+                                external_children_index: None,
+                                children_are_stacked: false,
+                                is_expanded_in_stack: false,
+                            },
+                        ],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                        children_are_stacked: true,
+                        is_expanded_in_stack: false,
+                    },
+                ],
+                split_size: None,
+                run: None,
+                borderless: false,
+                focus: None,
+                external_children_index: None,
+                children_are_stacked: false,
+                is_expanded_in_stack: false,
+            },
+            [],
+        ),
+    ),
+    swap_layouts: [],
+    swap_tiled_layouts: [],
+    swap_floating_layouts: [],
+}
diff --git a/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__can_define_stacked_children_for_pane_node.snap b/zellij-utils/src/input/unit/snapshots/zellij_utils__input__layout__layout_test__can_define_stacked_children_for_pane_node.snap
index 74a872bcf..c9aa7f872 100644
--- a/