Add Zellij support

src/app_state.rs

@@ -1,5 +1,6 @@
 use anyhow::{Context, Error, Result, bail};
 use crossterm::{QueueableCommand, cursor, terminal};
+use serde::Deserialize;
 use std::{
     collections::HashSet,
     env,
@@ -11,7 +12,7 @@ use std::{
         atomic::{AtomicUsize, Ordering::Relaxed},
         mpsc,
     },
-    thread,
+    thread::{self, JoinHandle},
 };
 
 use crate::{
@@ -49,6 +50,44 @@ pub enum CheckProgress {
     Pending,
 }
 
+#[derive(Deserialize)]
+struct Pane {
+    id: u32,
+}
+
+#[must_use]
+pub struct EditCmdJoinHandle(Option<JoinHandle<Result<(String, u32)>>>);
+
+fn parse_pane_id(b: &[u8]) -> Option<(String, u32)> {
+    // Remove newline
+    let b = b.get("terminal_".len()..b.len().saturating_sub(1))?;
+    let id_str = str::from_utf8(b).ok()?;
+
+    let (first, rest) = b.split_first()?;
+    let mut id = u32::from(first - b'0');
+
+    for c in rest {
+        id = 10 * id + u32::from(c - b'0');
+    }
+
+    Some((id_str.to_owned(), id))
+}
+
+fn close_pane(pane_id: &str) -> Result<()> {
+    Command::new("zellij")
+        .arg("action")
+        .arg("close-pane")
+        .arg("-p")
+        .arg(pane_id)
+        .stdin(Stdio::null())
+        .stdout(Stdio::null())
+        .stderr(Stdio::null())
+        .status()
+        .context("Failed to run `zellij action close-pane -p ID`")?;
+
+    Ok(())
+}
+
 pub struct AppState {
     current_exercise_ind: usize,
     exercises: Vec<Exercise>,
@@ -61,12 +100,15 @@ pub struct AppState {
     official_exercises: bool,
     cmd_runner: CmdRunner,
     emit_file_links: bool,
+    zellij: bool,
+    open_pane: Option<(String, u32, usize)>,
 }
 
 impl AppState {
     pub fn new(
         exercise_infos: Vec<ExerciseInfo>,
         final_message: &'static str,
+        zellij: bool,
     ) -> Result<(Self, StateFileStatus)> {
         let cmd_runner = CmdRunner::build()?;
         let mut state_file = OpenOptions::new()
@@ -175,6 +217,8 @@ impl AppState {
             cmd_runner,
             // VS Code has its own file link handling
             emit_file_links: env::var_os("TERM_PROGRAM").is_none_or(|v| v != "vscode"),
+            zellij,
+            open_pane: None,
         };
 
         Ok((slf, state_file_status))
@@ -553,6 +597,86 @@ impl AppState {
 
         Ok(())
     }
+
+    pub fn close_pane(&mut self) -> Result<()> {
+        if let Some((pane_id_str, _, _)) = self.open_pane.take() {
+            close_pane(&pane_id_str)?;
+        }
+
+        Ok(())
+    }
+
+    pub fn edit_cmd(&mut self) -> Result<EditCmdJoinHandle> {
+        if !self.zellij {
+            return Ok(EditCmdJoinHandle(None));
+        }
+
+        let open_pane = self.open_pane.take();
+        let current_exercise_ind = self.current_exercise_ind;
+        let mut edit_cmd = Command::new("zellij");
+        edit_cmd
+            .arg("action")
+            .arg("edit")
+            .arg(&self.current_exercise().path)
+            .stdin(Stdio::null())
+            .stderr(Stdio::null());
+
+        let handle = thread::Builder::new()
+            .spawn(move || {
+                if let Some((pane_id_str, pane_id, exercise_ind)) = open_pane {
+                    if exercise_ind == current_exercise_ind {
+                        // Check if the pane is still open
+                        let mut output = Command::new("zellij")
+                            .arg("action")
+                            .arg("list-panes")
+                            .arg("-j")
+                            .stdin(Stdio::null())
+                            .stderr(Stdio::null())
+                            .output()
+                            .context("Failed to run `zellij action list-panes -j`")?;
+
+                        if !output.status.success() {
+                            bail!("`zellij action list-panes -j` didn't exit successfully");
+                        }
+
+                        // Remove newline
+                        output.stdout.pop();
+
+                        let panes = serde_json::de::from_slice::<Vec<Pane>>(&output.stdout)
+                            .context(
+                                "Failed to parse the output of `zellij action list-panes -j`",
+                            )?;
+
+                        if panes.iter().any(|pane| pane.id == pane_id) {
+                            return Ok((pane_id_str, pane_id));
+                        }
+                    } else {
+                        close_pane(&pane_id_str)?;
+                    }
+                }
+
+                let output = edit_cmd.output()?;
+
+                if !output.status.success() {
+                    bail!("Failed to open a new Zellij editor pane");
+                }
+
+                parse_pane_id(&output.stdout)
+                    .context("Failed to parse the ID of the new Zellij pane")
+            })
+            .context("Failed to spawn a thread to open and close Zellij panes")?;
+
+        Ok(EditCmdJoinHandle(Some(handle)))
+    }
+
+    pub fn join_edit_cmd(&mut self, handle: EditCmdJoinHandle) -> Result<()> {
+        if let Some(handle) = handle.0 {
+            let (pane_id_str, pane_id) = handle.join().unwrap()?;
+            self.open_pane = Some((pane_id_str, pane_id, self.current_exercise_ind));
+        }
+
+        Ok(())
+    }
 }
 
 const BAD_INDEX_ERR: &str = "The current exercise index is higher than the number of exercises";
@@ -608,6 +732,8 @@ mod tests {
             official_exercises: true,
             cmd_runner: CmdRunner::build().unwrap(),
             emit_file_links: true,
+            zellij: false,
+            open_pane: None,
         };
 
         let mut assert = |done: [bool; 3], expected: [Option<usize>; 3]| {

src/cli.rs

@@ -9,28 +9,33 @@ pub struct Args {
     #[command(subcommand)]
     pub command: Option<Command>,
     /// Manually run the current exercise using `r` in the watch mode.
-    /// Only use this if Rustlings fails to detect exercise file changes.
+    /// Only use this if Rustlings fails to detect exercise file changes
     #[arg(long)]
     pub manual_run: bool,
+    /// Open the current exercise in a new Zellij pane and close the last one if exists
+    #[arg(long)]
+    pub zellij: bool,
 }
 
 #[derive(Subcommand)]
 pub enum Command {
     /// Initialize the official Rustlings exercises
     Init,
-    /// Run a single exercise. Runs the next pending exercise if the exercise name is not specified
+    /// Run a single exercise.
+    /// Runs the next pending exercise if the exercise name is not specified
     Run {
         /// The name of the exercise
         name: Option<String>,
     },
-    /// Check all the exercises, marking them as done or pending accordingly.
+    /// Check all the exercises, marking them as done or pending accordingly
     CheckAll,
     /// Reset a single exercise
     Reset {
         /// The name of the exercise
         name: String,
     },
-    /// Show a hint. Shows the hint of the next pending exercise if the exercise name is not specified
+    /// Show a hint.
+    /// Shows the hint of the next pending exercise if the exercise name is not specified
     Hint {
         /// The name of the exercise
         name: Option<String>,

src/main.rs

@@ -61,6 +61,7 @@ fn main() -> Result<ExitCode> {
     let (mut app_state, state_file_status) = AppState::new(
         info_file.exercises,
         info_file.final_message.unwrap_or_default(),
+        args.zellij,
     )?;
 
     // Show the welcome message if the state file doesn't exist yet.

src/watch/state.rs

@@ -78,14 +78,16 @@ impl<'a> WatchState<'a> {
         // Ignore any input until running the exercise is done.
         let _input_pause_guard = InputPauseGuard::scoped_pause();
 
-        self.show_hint = false;
-
         writeln!(
             stdout,
             "\nChecking the exercise `{}`. Please wait…",
             self.app_state.current_exercise().name,
         )?;
 
+        let edit_cmd_handle = self.app_state.edit_cmd()?;
+
+        self.show_hint = false;
+
         let success = self
             .app_state
             .current_exercise()
@@ -105,7 +107,9 @@ impl<'a> WatchState<'a> {
             self.done_status = DoneStatus::Pending;
         }
 
+        self.app_state.join_edit_cmd(edit_cmd_handle)?;
         self.render(stdout)?;
+
         Ok(())
     }
 
@@ -127,9 +131,10 @@ impl<'a> WatchState<'a> {
 
                 match answer[0] {
                     b'y' | b'Y' => {
+                        self.app_state.close_pane()?;
                         self.app_state.reset_current_exercise()?;
 
-                        // The file watcher reruns the exercise otherwise.
+                        // The file watcher reruns the exercise otherwise
                         if self.manual_run {
                             self.run_current_exercise(stdout)?;
                         }

tmp.txt

@@ -0,0 +1 @@
+226.867688ms