feat(layouts): exact panes constraint (#2206)

* style(fmt): remove warnings

* fix(swap-layouts): introduce exact panes constraint

* fix(swap-layouts): improve floating pane swap layout ux

* style(fmt): rustfmt

3 files changed, 168 insertions, 24 deletions

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..ee6c00399 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 +1827,41 @@ 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",