feat(script): new watch mode

Resolves #30

Cargo.lock

@@ -1948,6 +1948,15 @@ dependencies = [
  "lazy_static",
 ]
 
+[[package]]
+name = "signal-hook-registry"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e51e73328dc4ac0c7ccbda3a494dfa03df1de2f46018127f60c693f2648455b0"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "slab"
 version = "0.4.7"
@@ -2209,6 +2218,7 @@ dependencies = [
  "mio",
  "num_cpus",
  "pin-project-lite",
+ "signal-hook-registry",
  "socket2",
  "tokio-macros",
  "winapi",

Cargo.toml

@@ -10,7 +10,7 @@ derive_builder = "0.11.2"
 gtk = "0.16.0"
 gtk-layer-shell = "0.5.0"
 glib = "0.16.2"
-tokio = { version = "1.21.2", features = ["macros", "rt-multi-thread", "time"] }
+tokio = { version = "1.21.2", features = ["macros", "rt-multi-thread", "time", "process"] }
 tracing = "0.1.37"
 tracing-subscriber = { version = "0.3.16", features = ["env-filter"] }
 tracing-error = "0.2.0"

src/modules/script.rs

@@ -1,23 +1,41 @@
 use crate::modules::{Module, ModuleInfo, ModuleUpdateEvent, ModuleWidget, WidgetContext};
 use crate::script::exec_command;
-use color_eyre::Result;
+use color_eyre::{Help, Report, Result};
 use gtk::prelude::*;
 use gtk::Label;
 use serde::Deserialize;
-use tokio::spawn;
+use std::process::Stdio;
+use tokio::io::{AsyncBufReadExt, BufReader};
+use tokio::process::Command;
 use tokio::sync::mpsc::{Receiver, Sender};
 use tokio::time::sleep;
+use tokio::{select, spawn};
 use tracing::error;
 
+#[derive(Debug, Deserialize, Clone, Copy)]
+#[serde(rename_all = "kebab-case")]
+enum Mode {
+    Poll,
+    Watch,
+}
+
 #[derive(Debug, Deserialize, Clone)]
 pub struct ScriptModule {
     /// Path to script to execute.
     path: String,
+    /// Script execution mode
+    #[serde(default = "default_mode")]
+    mode: Mode,
     /// Time in milliseconds between executions.
     #[serde(default = "default_interval")]
     interval: u64,
 }
 
+/// `Mode::Poll`
+const fn default_mode() -> Mode {
+    Mode::Poll
+}
+
 /// 5000ms
 const fn default_interval() -> u64 {
     5000
@@ -35,7 +53,9 @@ impl Module<Label> for ScriptModule {
     ) -> Result<()> {
         let interval = self.interval;
         let path = self.path.clone();
-        spawn(async move {
+
+        match self.mode {
+            Mode::Poll => spawn(async move {
                 loop {
                     match exec_command(&path) {
                         Ok(stdout) => tx
@@ -47,7 +67,62 @@ impl Module<Label> for ScriptModule {
 
                     sleep(tokio::time::Duration::from_millis(interval)).await;
                 }
-        });
+            }),
+            Mode::Watch => spawn(async move {
+                loop {
+                    let mut handle = Command::new("sh")
+                        .args(["-c", &path])
+                        .stdout(Stdio::piped())
+                        .stderr(Stdio::piped())
+                        .stdin(Stdio::null())
+                        .spawn()
+                        .expect("Failed to spawn process");
+
+                    let mut stdout_lines = BufReader::new(
+                        handle
+                            .stdout
+                            .take()
+                            .expect("Failed to take script handle stdout"),
+                    )
+                    .lines();
+
+                    let mut stderr_lines = BufReader::new(
+                        handle
+                            .stderr
+                            .take()
+                            .expect("Failed to take script handle stderr"),
+                    )
+                    .lines();
+
+                    loop {
+                        select! {
+                            _ = handle.wait() => break,
+                            Ok(Some(line)) = stdout_lines.next_line() => {
+                                tx.send(ModuleUpdateEvent::Update(line.to_string()))
+                            .await
+                            .expect("Failed to send stdout");
+                            }
+                            Ok(Some(line)) = stderr_lines.next_line() => {
+                                error!("{:?}", Report::msg(line)
+                                    .wrap_err("Watched script error:")
+                                    .suggestion("Check the path to your script")
+                                    .suggestion("Check the script for errors")
+                                    .suggestion("If you expect the script to write to stderr, consider redirecting its output to /dev/null to suppress these messages")
+                                )
+                            }
+                        }
+                    }
+
+                    while let Ok(Some(line)) = stdout_lines.next_line().await {
+                        tx.send(ModuleUpdateEvent::Update(line.to_string()))
+                            .await
+                            .expect("Failed to send stdout");
+                    }
+
+                    sleep(tokio::time::Duration::from_millis(interval)).await;
+                }
+            }),
+        };
 
         Ok(())
     }