feat(ux): reload config at runtime (#3558)

* feat(ux): reload config at runtime

* style(fmt): rustfmt

3 files changed, 107 insertions, 34 deletions

diff --git a/zellij-client/src/lib.rs b/zellij-client/src/lib.rs
index 9146e755..660fbf0c 100644
--- a/zellij-client/src/lib.rs
+++ b/zellij-client/src/lib.rs
@@ -12,12 +12,14 @@ use log::info;
 use std::env::current_exe;
 use std::io::{self, Write};
 use std::path::Path;
-use std::path::PathBuf;
 use std::process::Command;
 use std::sync::{Arc, Mutex};
 use std::thread;
 use zellij_utils::errors::FatalError;
 
+use zellij_utils::notify_debouncer_full::notify::{self, Event, RecursiveMode, Watcher};
+use zellij_utils::setup::Setup;
+
 use crate::stdin_ansi_parser::{AnsiStdinInstruction, StdinAnsiParser, SyncOutput};
 use crate::{
     command_is_executing::CommandIsExecuting, input_handler::input_loop,
@@ -357,7 +359,13 @@ pub fn start_client(
         .name("signal_listener".to_string())
         .spawn({
             let os_input = os_input.clone();
+            let opts = opts.clone();
             move || {
+                // we keep the config_file_watcher here so that it is only dropped when this thread
+                // exits (which is when the client disconnects/detaches), once it's dropped it
+                // stops watching and we want it to keep watching the config file path for changes
+                // as long as the client is alive
+                let _config_file_watcher = report_changes_in_config_file(&opts, &os_input);
                 os_input.handle_signals(
                     Box::new({
                         let os_api = os_input.clone();
@@ -660,3 +668,57 @@ pub fn start_server_detached(
     os_input.connect_to_server(&*ipc_pipe);
     os_input.send_to_server(first_msg);
 }
+
+fn report_changes_in_config_file(
+    opts: &CliArgs,
+    os_input: &Box<dyn ClientOsApi>,
+) -> Option<Box<dyn Watcher>> {
+    match Config::config_file_path(&opts) {
+        Some(config_file_path) => {
+            let mut watcher = notify::recommended_watcher({
+                let os_input = os_input.clone();
+                let opts = opts.clone();
+                let config_file_path = config_file_path.clone();
+                move |res: Result<Event, _>| match res {
+                    Ok(event)
+                        if (event.kind.is_create() || event.kind.is_modify())
+                            && event.paths.contains(&config_file_path) =>
+                    {
+                        match Setup::from_cli_args(&opts) {
+                            Ok((
+                                new_config,
+                                _layout,
+                                _config_options,
+                                _config_without_layout,
+                                _config_options_without_layout,
+                            )) => {
+                                os_input.send_to_server(ClientToServerMsg::ConfigWrittenToDisk(
+                                    new_config,
+                                ));
+                            },
+                            Err(e) => {
+                                log::error!("Failed to reload config: {}", e);
+                            },
+                        }
+                    },
+                    Err(e) => log::error!("watch error: {:?}", e),
+                    _ => {},
+                }
+            })
+            .unwrap();
+            if let Some(config_file_parent_folder) = config_file_path.parent() {
+                watcher
+                    .watch(&config_file_parent_folder, RecursiveMode::Recursive)
+                    .unwrap();
+                Some(Box::new(watcher))
+            } else {
+                log::error!("Could not find config parent folder");
+                None
+            }
+        },
+        None => {
+            log::error!("Failed to find config path");
+            None
+        },
+    }
+}
diff --git a/zellij-server/src/lib.rs b/zellij-server/src/lib.rs
index b9b23f6c..fe1b3ada 100644
--- a/zellij-server/src/lib.rs
+++ b/zellij-server/src/lib.rs
@@ -157,24 +157,29 @@ impl ErrorInstruction for ServerInstruction {
 #[derive(Debug, Clone, Default)]
 pub(crate) struct SessionConfiguration {
     runtime_config: HashMap<ClientId, Config>, // if present, overrides the saved_config
-    saved_config: HashMap<ClientId, Config>,   // config guaranteed to have been saved to disk
+    saved_config: HashMap<ClientId, Config>,   // the config as it is on disk (not guaranteed),
+                                               // when changed, this resets the runtime config to
+                                               // be identical to it and override any previous
+                                               // changes
 }
 
 impl SessionConfiguration {
-    pub fn new_saved_config(&mut self, client_id: ClientId, mut new_saved_config: Config) {
+    pub fn new_saved_config(
+        &mut self,
+        client_id: ClientId,
+        new_saved_config: Config,
+    ) -> Vec<(ClientId, Config)> {
         self.saved_config
             .insert(client_id, new_saved_config.clone());
-        if let Some(runtime_config) = self.runtime_config.get_mut(&client_id) {
-            match new_saved_config.merge(runtime_config.clone()) {
-                Ok(_) => {
-                    *runtime_config = new_saved_config;
-                },
-                Err(e) => {
-                    log::error!("Failed to update runtime config: {}", e);
-                },
+
+        let mut config_changes = vec![];
+        for (client_id, current_runtime_config) in self.runtime_config.iter_mut() {
+            if *current_runtime_config != new_saved_config {
+                *current_runtime_config = new_saved_config.clone();
+                config_changes.push((*client_id, new_saved_config.clone()))
             }
         }
-        // TODO: handle change by propagating to all the relevant places
+        config_changes
     }
     pub fn set_client_saved_configuration(&mut self, client_id: ClientId, client_config: Config) {
         self.saved_config.insert(client_id, client_config);
@@ -255,6 +260,24 @@ impl SessionMetaData {
             self.current_input_modes.insert(client_id, input_mode);
         }
     }
+    pub fn propagate_configuration_changes(&mut self, config_changes: Vec<(ClientId, Config)>) {
+        for (client_id, new_config) in config_changes {
+            self.senders
+                .send_to_screen(ScreenInstruction::Reconfigure {
+                    client_id,
+                    keybinds: Some(new_config.keybinds.clone()),
+                    default_mode: new_config.options.default_mode,
+                })
+                .unwrap();
+            self.senders
+                .send_to_plugin(PluginInstruction::Reconfigure {
+                    client_id,
+                    keybinds: Some(new_config.keybinds),
+                    default_mode: new_config.options.default_mode,
+                })
+                .unwrap();
+        }
+    }
 }
 
 impl Drop for SessionMetaData {
@@ -1032,38 +1055,26 @@ pub fn start_server(mut os_input: Box<dyn ServerOsApi>, socket_path: PathBuf) {
                         session_data
                             .write()
                             .unwrap()
-                            .as_ref()
+                            .as_mut()
                             .unwrap()
-                            .senders
-                            .send_to_screen(ScreenInstruction::Reconfigure {
-                                client_id,
-                                keybinds: Some(new_config.keybinds.clone()),
-                                default_mode: new_config.options.default_mode,
-                            })
-                            .unwrap();
-                        session_data
-                            .write()
-                            .unwrap()
-                            .as_ref()
-                            .unwrap()
-                            .senders
-                            .send_to_plugin(PluginInstruction::Reconfigure {
-                                client_id,
-                                keybinds: Some(new_config.keybinds),
-                                default_mode: new_config.options.default_mode,
-                            })
-                            .unwrap();
+                            .propagate_configuration_changes(vec![(client_id, new_config)]);
                     }
                 }
             },
             ServerInstruction::ConfigWrittenToDisk(client_id, new_config) => {
-                session_data
+                let changes = session_data
                     .write()
                     .unwrap()
                     .as_mut()
                     .unwrap()
                     .session_configuration
                     .new_saved_config(client_id, new_config);
+                session_data
+                    .write()
+                    .unwrap()
+                    .as_mut()
+                    .unwrap()
+                    .propagate_configuration_changes(changes);
             },
             ServerInstruction::FailedToWriteConfigToDisk(client_id, file_path) => {
                 session_data
diff --git a/zellij-utils/src/input/config.rs b/zellij-utils/src/input/config.rs
index 92174eb2..cf3ba2cc 100644
--- a/zellij-utils/src/input/config.rs
+++ b/zellij-utils/src/input/config.rs
@@ -234,7 +234,7 @@ impl Config {
         self.env = self.env.merge(other.env);
         Ok(())
     }
-    fn config_file_path(opts: &CliArgs) -> Option<PathBuf> {
+    pub fn config_file_path(opts: &CliArgs) -> Option<PathBuf> {
         opts.config_dir
             .clone()
             .or_else(home::find_default_config_dir)