feat: read checklist from file

src/main.rs

@@ -1,10 +1,10 @@
-/// A simple terminal checklist application.
+//! A simple terminal checklist application.
 mod event_source;
 mod terminal_guard;
-/// UI components (todo list)
 mod todo_list;
 
 use anyhow::{Context as _, Result, anyhow, bail};
+use argh::FromArgs;
 use core::time::Duration;
 use crossterm::event::{self, EnableMouseCapture, Event, KeyCode};
 use crossterm::execute;
@@ -16,11 +16,14 @@ use ratatui::backend::CrosstermBackend;
 use std::io::{self, Read as _};
 use terminal_guard::TerminalModeGuard;
 use todo_list::TodoList;
-use argh::FromArgs;
 
 #[derive(FromArgs)]
 /// chkr - terminal checklist
 struct Args {
+    /// load checklist from file instead of stdin
+    #[argh(option, short = 'f', long = "file")]
+    file: Option<String>,
+
     /// print version and exit
     #[argh(switch, short = 'V', long = "version")]
     version: bool,
@@ -34,13 +37,20 @@ fn main() -> Result<()> {
         return Ok(());
     }
 
+    let input: String = if let Some(path) = args.file {
+        std::fs::read_to_string(&path).with_context(|| format!("reading file {path}"))?
+    } else {
         let mut input = String::new();
         io::stdin()
             .read_to_string(&mut input)
             .context("reading stdin")?;
+        input
+    };
 
     if input.trim().is_empty() {
-        eprintln!("Provide text via stdin (pipe or heredoc). Example: \n  cat file.txt | chkr");
+        eprintln!(
+            "Provide text via stdin (pipe or heredoc), or use --file. Example: \n  cat file.txt | chkr"
+        );
         return Ok(());
     }