1 files changed, 100 insertions, 0 deletions

diff --git a/zellij-server/src/screen.rs b/zellij-server/src/screen.rs
index 2e351cff4..4594fe3cb 100644
--- a/zellij-server/src/screen.rs
+++ b/zellij-server/src/screen.rs
@@ -7,6 +7,7 @@ use std::rc::Rc;
 use std::str;
 use std::time::Duration;
 
+use log::{debug, warn};
 use zellij_utils::data::{
     Direction, PaneManifest, PluginPermission, Resize, ResizeStrategy, SessionInfo,
 };
@@ -238,6 +239,8 @@ pub enum ScreenInstruction {
     ToggleTab(ClientId),
     UpdateTabName(Vec<u8>, ClientId),
     UndoRenameTab(ClientId),
+    MoveTabLeft(ClientId),
+    MoveTabRight(ClientId),
     TerminalResize(Size),
     TerminalPixelDimensions(PixelDimensions),
     TerminalBackgroundColor(String),
@@ -447,6 +450,8 @@ impl From<&ScreenInstruction> for ScreenContext {
             ScreenInstruction::GoToTabName(..) => ScreenContext::GoToTabName,
             ScreenInstruction::UpdateTabName(..) => ScreenContext::UpdateTabName,
             ScreenInstruction::UndoRenameTab(..) => ScreenContext::UndoRenameTab,
+            ScreenInstruction::MoveTabLeft(..) => ScreenContext::MoveTabLeft,
+            ScreenInstruction::MoveTabRight(..) => ScreenContext::MoveTabRight,
             ScreenInstruction::TerminalResize(..) => ScreenContext::TerminalResize,
             ScreenInstruction::TerminalPixelDimensions(..) => {
                 ScreenContext::TerminalPixelDimensions
@@ -1585,6 +1590,91 @@ impl Screen {
         }
     }
 
+    pub fn move_active_tab_to_left(&mut self, client_id: ClientId) -> Result<()> {
+        if self.tabs.len() < 2 {
+            debug!("cannot move tab to left: only one tab exists");
+            return Ok(());
+        }
+        let Some(client_id) = self.client_id(client_id) else {
+            return Ok(());
+        };
+        let Some(&active_tab_idx) = self.active_tab_indices.get(&client_id) else {
+            return Ok(());
+        };
+
+        // wraps around: [tab1, tab2, tab3] => [tab1, tab2, tab3]
+        //                 ^                                 ^
+        //          active_tab_idx                     left_tab_idx
+        let left_tab_idx = (active_tab_idx + self.tabs.len() - 1) % self.tabs.len();
+
+        self.switch_tabs(active_tab_idx, left_tab_idx, client_id);
+        self.log_and_report_session_state()
+            .context("failed to move tab to left")?;
+        Ok(())
+    }
+
+    fn client_id(&mut self, client_id: ClientId) -> Option<u16> {
+        if self.get_active_tab(client_id).is_ok() {
+            Some(client_id)
+        } else {
+            self.get_first_client_id()
+        }
+    }
+
+    fn switch_tabs(&mut self, active_tab_idx: usize, other_tab_idx: usize, client_id: u16) {
+        if !self.tabs.contains_key(&active_tab_idx) || !self.tabs.contains_key(&other_tab_idx) {
+            warn!(
+                "failed to switch tabs: index {} or {} not found in {:?}",
+                active_tab_idx,
+                other_tab_idx,
+                self.tabs.keys()
+            );
+            return;
+        }
+
+        // NOTE: Can `expect` here, because we checked that the keys exist above
+        let mut active_tab = self
+            .tabs
+            .remove(&active_tab_idx)
+            .expect("active tab not found");
+        let mut other_tab = self
+            .tabs
+            .remove(&other_tab_idx)
+            .expect("other tab not found");
+
+        std::mem::swap(&mut active_tab.index, &mut other_tab.index);
+        std::mem::swap(&mut active_tab.position, &mut other_tab.position);
+
+        // now, `active_tab.index` is changed, so we need to update it
+        self.active_tab_indices.insert(client_id, active_tab.index);
+
+        self.tabs.insert(active_tab.index, active_tab);
+        self.tabs.insert(other_tab.index, other_tab);
+    }
+
+    pub fn move_active_tab_to_right(&mut self, client_id: ClientId) -> Result<()> {
+        if self.tabs.len() < 2 {
+            debug!("cannot move tab to right: only one tab exists");
+            return Ok(());
+        }
+        let Some(client_id) = self.client_id(client_id) else {
+            return Ok(());
+        };
+        let Some(&active_tab_idx) = self.active_tab_indices.get(&client_id) else {
+            return Ok(());
+        };
+
+        // wraps around: [tab1, tab2, tab3] => [tab1, tab2, tab3]
+        //                             ^          ^
+        //                     active_tab_idx   right_tab_idx
+        let right_tab_idx = (active_tab_idx + 1) % self.tabs.len();
+
+        self.switch_tabs(active_tab_idx, right_tab_idx, client_id);
+        self.log_and_report_session_state()
+            .context("failed to move active tab to right")?;
+        Ok(())
+    }
+
     pub fn change_mode(&mut self, mut mode_info: ModeInfo, client_id: ClientId) -> Result<()> {
         if mode_info.session_name.as_ref() != Some(&self.session_name) {
             mode_info.session_name = Some(self.session_name.clone());
@@ -2989,6 +3079,16 @@ pub(crate) fn screen_thread_main(
                 screen.unblock_input()?;
                 screen.render(None)?;
             },
+            ScreenInstruction::MoveTabLeft(client_id) => {
+                screen.move_active_tab_to_left(client_id)?;
+                screen.unblock_input()?;
+                screen.render(None)?;
+            },
+            ScreenInstruction::MoveTabRight(client_id) => {
+                screen.move_active_tab_to_right(client_id)?;
+                screen.unblock_input()?;
+                screen.render(None)?;
+            },
             ScreenInstruction::TerminalResize(new_size) => {
                 screen.resize_to_screen(new_size)?;
                 screen.log_and_report_session_state()?; // update tabs so that the ui indication will be send to the plugins