fix(config): add support for Ctrl and Alt modifiers on function keys in keybindings (#3179)

Previously, it was not possible to define keybindings with a modifier
and a function key. The `Key` enum only supported combinging the Ctrl
and Alt modifiers with letters. This is somewhat limiting: I would like
to make the Zellij keybindings more "distant" than those used in the
programs I use from within Zelilj, so that Zellij does not intefere with
those programs. Thus I would like to move some of the keybindings from
Ctrl+<character> to Ctrl+<function key>.

This change adds:

  * support for function keys with the Ctrl and Alt modifiers in the
    `Key` enum,
  * support for parsing such keybindings from the configuration file,
  * support for such keybindings in the protobuf which communicates the
    keybindings to plugins, and
  * support for these keybindings in the plugin API.

This is tested by modifying one of the e2e tests to include an example
of such keybindings. This verifies that the configuration is correctly
parsed, communicated with the plugin, and rendered.

1 files changed, 61 insertions, 25 deletions

diff --git a/zellij-utils/src/plugin_api/key.rs b/zellij-utils/src/plugin_api/key.rs
index 7cef4ba76..c5ce10870 100644
--- a/zellij-utils/src/plugin_api/key.rs
+++ b/zellij-utils/src/plugin_api/key.rs
@@ -12,12 +12,21 @@ impl TryFrom<ProtobufKey> for Key {
         let key_modifier = parse_optional_modifier(&protobuf_key);
         match key_modifier {
             Some(KeyModifier::Ctrl) => {
-                let character = char_from_main_key(protobuf_key.main_key)?;
-                Ok(Key::Ctrl(character))
+                if let Ok(character) = char_from_main_key(protobuf_key.main_key.clone()) {
+                    Ok(Key::Ctrl(character))
+                } else {
+                    let index = fn_index_from_main_key(protobuf_key.main_key)?;
+                    Ok(Key::CtrlF(index))
+                }
             },
             Some(KeyModifier::Alt) => {
-                let char_or_arrow = CharOrArrow::from_main_key(protobuf_key.main_key)?;
-                Ok(Key::Alt(char_or_arrow))
+                if let Ok(char_or_arrow) = CharOrArrow::from_main_key(protobuf_key.main_key.clone())
+                {
+                    Ok(Key::Alt(char_or_arrow))
+                } else {
+                    let index = fn_index_from_main_key(protobuf_key.main_key)?;
+                    Ok(Key::AltF(index))
+                }
             },
             None => match protobuf_key.main_key.as_ref().ok_or("invalid key")? {
                 MainKey::Char(_key_index) => {
@@ -81,27 +90,18 @@ impl TryFrom<Key> for ProtobufKey {
                 modifier: None,
                 main_key: Some(MainKey::Key(NamedKey::Insert as i32)),
             }),
-            Key::F(index) => {
-                let main_key = match index {
-                    1 => Some(MainKey::Key(NamedKey::F1 as i32)),
-                    2 => Some(MainKey::Key(NamedKey::F2 as i32)),
-                    3 => Some(MainKey::Key(NamedKey::F3 as i32)),
-                    4 => Some(MainKey::Key(NamedKey::F4 as i32)),
-                    5 => Some(MainKey::Key(NamedKey::F5 as i32)),
-                    6 => Some(MainKey::Key(NamedKey::F6 as i32)),
-                    7 => Some(MainKey::Key(NamedKey::F7 as i32)),
-                    8 => Some(MainKey::Key(NamedKey::F8 as i32)),
-                    9 => Some(MainKey::Key(NamedKey::F9 as i32)),
-                    10 => Some(MainKey::Key(NamedKey::F10 as i32)),
-                    11 => Some(MainKey::Key(NamedKey::F11 as i32)),
-                    12 => Some(MainKey::Key(NamedKey::F12 as i32)),
-                    _ => return Err("Invalid key"),
-                };
-                Ok(ProtobufKey {
-                    modifier: None,
-                    main_key,
-                })
-            },
+            Key::F(index) => Ok(ProtobufKey {
+                modifier: None,
+                main_key: Some(fn_index_to_main_key(index)?),
+            }),
+            Key::CtrlF(index) => Ok(ProtobufKey {
+                modifier: Some(KeyModifier::Ctrl as i32),
+                main_key: Some(fn_index_to_main_key(index)?),
+            }),
+            Key::AltF(index) => Ok(ProtobufKey {
+                modifier: Some(KeyModifier::Alt as i32),
+                main_key: Some(fn_index_to_main_key(index)?),
+            }),
             Key::Char(character) => Ok(ProtobufKey {
                 modifier: None,
                 main_key: Some(MainKey::Char((character as u8) as i32)),
@@ -147,6 +147,24 @@ impl TryFrom<Key> for ProtobufKey {
     }
 }
 
+fn fn_index_to_main_key(index: u8) -> Result<MainKey, &'static str> {
+    match index {
+        1 => Ok(MainKey::Key(NamedKey::F1 as i32)),
+        2 => Ok(MainKey::Key(NamedKey::F2 as i32)),
+        3 => Ok(MainKey::Key(NamedKey::F3 as i32)),
+        4 => Ok(MainKey::Key(NamedKey::F4 as i32)),
+        5 => Ok(MainKey::Key(NamedKey::F5 as i32)),
+        6 => Ok(MainKey::Key(NamedKey::F6 as i32)),
+        7 => Ok(MainKey::Key(NamedKey::F7 as i32)),
+        8 => Ok(MainKey::Key(NamedKey::F8 as i32)),
+        9 => Ok(MainKey::Key(NamedKey::F9 as i32)),
+        10 => Ok(MainKey::Key(NamedKey::F10 as i32)),
+        11 => Ok(MainKey::Key(NamedKey::F11 as i32)),
+        12 => Ok(MainKey::Key(NamedKey::F12 as i32)),
+        _ => Err("Invalid key"),
+    }
+}
+
 impl CharOrArrow {
     pub fn from_main_key(
         main_key: std::option::Option<MainKey>,
@@ -191,6 +209,24 @@ fn char_from_main_key(main_key: Option<MainKey>) -> Result<char, &'static str> {
     }
 }
 
+fn fn_index_from_main_key(main_key: Option<MainKey>) -> Result<u8, &'static str> {
+    match main_key {
+        Some(MainKey::Key(n)) if n == NamedKey::F1 as i32 => Ok(1),
+        Some(MainKey::Key(n)) if n == NamedKey::F2 as i32 => Ok(2),
+        Some(MainKey::Key(n)) if n == NamedKey::F3 as i32 => Ok(3),
+        Some(MainKey::Key(n)) if n == NamedKey::F4 as i32 => Ok(4),
+        Some(MainKey::Key(n)) if n == NamedKey::F5 as i32 => Ok(5),
+        Some(MainKey::Key(n)) if n == NamedKey::F6 as i32 => Ok(6),
+        Some(MainKey::Key(n)) if n == NamedKey::F7 as i32 => Ok(7),
+        Some(MainKey::Key(n)) if n == NamedKey::F8 as i32 => Ok(8),
+        Some(MainKey::Key(n)) if n == NamedKey::F9 as i32 => Ok(9),
+        Some(MainKey::Key(n)) if n == NamedKey::F10 as i32 => Ok(10),
+        Some(MainKey::Key(n)) if n == NamedKey::F11 as i32 => Ok(11),
+        Some(MainKey::Key(n)) if n == NamedKey::F12 as i32 => Ok(12),
+        _ => Err("Unsupported key"),
+    }
+}
+
 fn named_key_to_key(named_key: NamedKey) -> Key {
     match named_key {
         NamedKey::PageDown => Key::PageDown,