Replace common functionality with rust implementation

mgr/src/dmenu.rs

@@ -0,0 +1,66 @@
+use std::{fmt::Write as _, num};
+
+use thiserror::Error;
+use tracing::{Level, event};
+
+use super::cmd;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("rofi did not return an integer: {error}")]
+    RofiNonIntOutput { error: num::ParseIntError },
+    #[error("rofi returned an invalid indexx: {index}")]
+    RofiInvalidIndex { index: usize },
+    #[error(transparent)]
+    Cmd(#[from] cmd::Error),
+}
+
+pub(crate) fn get_choice(actions: &[&'static str]) -> Result<Option<&'static str>, Error> {
+    const ROFI: &str = "rofi";
+
+    event!(Level::DEBUG, "starting rofi");
+
+    let process = cmd::command_output_with_stdin_write(
+        ROFI,
+        &[
+            "-dmenu",
+            "-p",
+            "action",
+            "-l",
+            &actions.len().to_string(),
+            "-no-custom",
+            "-sync",
+            "-format",
+            "i",
+        ],
+        actions
+            .iter()
+            .enumerate()
+            .fold(String::new(), |mut output, (i, action)| {
+                writeln!(
+                    output,
+                    "({i}) {action}",
+                    i = i.checked_add(1).expect("too many action")
+                )
+                .expect("writing to string cannot fail");
+                output
+            })
+            .as_bytes(),
+    )?;
+
+    if process.exit_code == 1 {
+        Ok(None)
+    } else {
+        let choice = process
+            .stdout
+            .trim()
+            .parse::<usize>()
+            .map_err(|error| Error::RofiNonIntOutput { error })?;
+
+        Ok(Some(
+            actions
+                .get(choice)
+                .ok_or(Error::RofiInvalidIndex { index: choice })?,
+        ))
+    }
+}