feat: interactive CLI with REPL, markdown rendering, and project init

rust/crates/claw-cli/src/input.rs

@@ -0,0 +1,269 @@
+use std::borrow::Cow;
+use std::cell::RefCell;
+use std::io::{self, IsTerminal, Write};
+
+use rustyline::completion::{Completer, Pair};
+use rustyline::error::ReadlineError;
+use rustyline::highlight::{CmdKind, Highlighter};
+use rustyline::hint::Hinter;
+use rustyline::history::DefaultHistory;
+use rustyline::validate::Validator;
+use rustyline::{
+    Cmd, CompletionType, Config, Context, EditMode, Editor, Helper, KeyCode, KeyEvent, Modifiers,
+};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ReadOutcome {
+    Submit(String),
+    Cancel,
+    Exit,
+}
+
+struct SlashCommandHelper {
+    completions: Vec<String>,
+    current_line: RefCell<String>,
+}
+
+impl SlashCommandHelper {
+    fn new(completions: Vec<String>) -> Self {
+        Self {
+            completions,
+            current_line: RefCell::new(String::new()),
+        }
+    }
+
+    fn reset_current_line(&self) {
+        self.current_line.borrow_mut().clear();
+    }
+
+    fn current_line(&self) -> String {
+        self.current_line.borrow().clone()
+    }
+
+    fn set_current_line(&self, line: &str) {
+        let mut current = self.current_line.borrow_mut();
+        current.clear();
+        current.push_str(line);
+    }
+}
+
+impl Completer for SlashCommandHelper {
+    type Candidate = Pair;
+
+    fn complete(
+        &self,
+        line: &str,
+        pos: usize,
+        _ctx: &Context<'_>,
+    ) -> rustyline::Result<(usize, Vec<Self::Candidate>)> {
+        let Some(prefix) = slash_command_prefix(line, pos) else {
+            return Ok((0, Vec::new()));
+        };
+
+        let matches = self
+            .completions
+            .iter()
+            .filter(|candidate| candidate.starts_with(prefix))
+            .map(|candidate| Pair {
+                display: candidate.clone(),
+                replacement: candidate.clone(),
+            })
+            .collect();
+
+        Ok((0, matches))
+    }
+}
+
+impl Hinter for SlashCommandHelper {
+    type Hint = String;
+}
+
+impl Highlighter for SlashCommandHelper {
+    fn highlight<'l>(&self, line: &'l str, _pos: usize) -> Cow<'l, str> {
+        self.set_current_line(line);
+        Cow::Borrowed(line)
+    }
+
+    fn highlight_char(&self, line: &str, _pos: usize, _kind: CmdKind) -> bool {
+        self.set_current_line(line);
+        false
+    }
+}
+
+impl Validator for SlashCommandHelper {}
+impl Helper for SlashCommandHelper {}
+
+pub struct LineEditor {
+    prompt: String,
+    editor: Editor<SlashCommandHelper, DefaultHistory>,
+}
+
+impl LineEditor {
+    #[must_use]
+    pub fn new(prompt: impl Into<String>, completions: Vec<String>) -> Self {
+        let config = Config::builder()
+            .completion_type(CompletionType::List)
+            .edit_mode(EditMode::Emacs)
+            .build();
+        let mut editor = Editor::<SlashCommandHelper, DefaultHistory>::with_config(config)
+            .expect("rustyline editor should initialize");
+        editor.set_helper(Some(SlashCommandHelper::new(completions)));
+        editor.bind_sequence(KeyEvent(KeyCode::Char('J'), Modifiers::CTRL), Cmd::Newline);
+        editor.bind_sequence(KeyEvent(KeyCode::Enter, Modifiers::SHIFT), Cmd::Newline);
+
+        Self {
+            prompt: prompt.into(),
+            editor,
+        }
+    }
+
+    pub fn push_history(&mut self, entry: impl Into<String>) {
+        let entry = entry.into();
+        if entry.trim().is_empty() {
+            return;
+        }
+
+        let _ = self.editor.add_history_entry(entry);
+    }
+
+    pub fn read_line(&mut self) -> io::Result<ReadOutcome> {
+        if !io::stdin().is_terminal() || !io::stdout().is_terminal() {
+            return self.read_line_fallback();
+        }
+
+        if let Some(helper) = self.editor.helper_mut() {
+            helper.reset_current_line();
+        }
+
+        match self.editor.readline(&self.prompt) {
+            Ok(line) => Ok(ReadOutcome::Submit(line)),
+            Err(ReadlineError::Interrupted) => {
+                let has_input = !self.current_line().is_empty();
+                self.finish_interrupted_read()?;
+                if has_input {
+                    Ok(ReadOutcome::Cancel)
+                } else {
+                    Ok(ReadOutcome::Exit)
+                }
+            }
+            Err(ReadlineError::Eof) => {
+                self.finish_interrupted_read()?;
+                Ok(ReadOutcome::Exit)
+            }
+            Err(error) => Err(io::Error::other(error)),
+        }
+    }
+
+    fn current_line(&self) -> String {
+        self.editor
+            .helper()
+            .map_or_else(String::new, SlashCommandHelper::current_line)
+    }
+
+    fn finish_interrupted_read(&mut self) -> io::Result<()> {
+        if let Some(helper) = self.editor.helper_mut() {
+            helper.reset_current_line();
+        }
+        let mut stdout = io::stdout();
+        writeln!(stdout)
+    }
+
+    fn read_line_fallback(&self) -> io::Result<ReadOutcome> {
+        let mut stdout = io::stdout();
+        write!(stdout, "{}", self.prompt)?;
+        stdout.flush()?;
+
+        let mut buffer = String::new();
+        let bytes_read = io::stdin().read_line(&mut buffer)?;
+        if bytes_read == 0 {
+            return Ok(ReadOutcome::Exit);
+        }
+
+        while matches!(buffer.chars().last(), Some('\n' | '\r')) {
+            buffer.pop();
+        }
+        Ok(ReadOutcome::Submit(buffer))
+    }
+}
+
+fn slash_command_prefix(line: &str, pos: usize) -> Option<&str> {
+    if pos != line.len() {
+        return None;
+    }
+
+    let prefix = &line[..pos];
+    if prefix.contains(char::is_whitespace) || !prefix.starts_with('/') {
+        return None;
+    }
+
+    Some(prefix)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{slash_command_prefix, LineEditor, SlashCommandHelper};
+    use rustyline::completion::Completer;
+    use rustyline::highlight::Highlighter;
+    use rustyline::history::{DefaultHistory, History};
+    use rustyline::Context;
+
+    #[test]
+    fn extracts_only_terminal_slash_command_prefixes() {
+        assert_eq!(slash_command_prefix("/he", 3), Some("/he"));
+        assert_eq!(slash_command_prefix("/help me", 5), None);
+        assert_eq!(slash_command_prefix("hello", 5), None);
+        assert_eq!(slash_command_prefix("/help", 2), None);
+    }
+
+    #[test]
+    fn completes_matching_slash_commands() {
+        let helper = SlashCommandHelper::new(vec![
+            "/help".to_string(),
+            "/hello".to_string(),
+            "/status".to_string(),
+        ]);
+        let history = DefaultHistory::new();
+        let ctx = Context::new(&history);
+        let (start, matches) = helper
+            .complete("/he", 3, &ctx)
+            .expect("completion should work");
+
+        assert_eq!(start, 0);
+        assert_eq!(
+            matches
+                .into_iter()
+                .map(|candidate| candidate.replacement)
+                .collect::<Vec<_>>(),
+            vec!["/help".to_string(), "/hello".to_string()]
+        );
+    }
+
+    #[test]
+    fn ignores_non_slash_command_completion_requests() {
+        let helper = SlashCommandHelper::new(vec!["/help".to_string()]);
+        let history = DefaultHistory::new();
+        let ctx = Context::new(&history);
+        let (_, matches) = helper
+            .complete("hello", 5, &ctx)
+            .expect("completion should work");
+
+        assert!(matches.is_empty());
+    }
+
+    #[test]
+    fn tracks_current_buffer_through_highlighter() {
+        let helper = SlashCommandHelper::new(Vec::new());
+        let _ = helper.highlight("draft", 5);
+
+        assert_eq!(helper.current_line(), "draft");
+    }
+
+    #[test]
+    fn push_history_ignores_blank_entries() {
+        let mut editor = LineEditor::new("> ", vec!["/help".to_string()]);
+        editor.push_history("   ");
+        editor.push_history("/help");
+
+        assert_eq!(editor.editor.history().len(), 1);
+    }
+}