From 69ea52d097e5bcb0413f774813745e4283b06805 Mon Sep 17 00:00:00 2001
From: Wolf Vollprecht <w.vollprecht@gmail.com>
Date: Fri, 6 Sep 2024 21:41:18 +0200
Subject: [PATCH] feat: add completion (#42)

---
 crates/shell/src/completion.rs | 102 +++++++++++++++++++++++++++++++++
 crates/shell/src/main.rs       |  15 ++++-
 2 files changed, 115 insertions(+), 2 deletions(-)
 create mode 100644 crates/shell/src/completion.rs

diff --git a/crates/shell/src/completion.rs b/crates/shell/src/completion.rs
new file mode 100644
index 0000000..7de7937
--- /dev/null
+++ b/crates/shell/src/completion.rs
@@ -0,0 +1,102 @@
+use rustyline::completion::{Completer, Pair};
+use rustyline::error::ReadlineError;
+use rustyline::highlight::Highlighter;
+use rustyline::hint::Hinter;
+use rustyline::validate::Validator;
+use rustyline::{Context, Helper};
+use std::borrow::Cow::{self, Owned};
+use std::env;
+use std::fs;
+
+pub struct ShellCompleter;
+
+impl Completer for ShellCompleter {
+    type Candidate = Pair;
+
+    fn complete(
+        &self,
+        line: &str,
+        pos: usize,
+        _ctx: &Context<'_>,
+    ) -> Result<(usize, Vec<Pair>), ReadlineError> {
+        let mut matches = Vec::new();
+        let (start, word) = extract_word(line, pos);
+
+        // Complete filenames
+        complete_filenames(word, &mut matches);
+
+        // Complete shell commands
+        complete_shell_commands(word, &mut matches);
+
+        // Complete executables in PATH
+        complete_executables_in_path(word, &mut matches);
+
+        Ok((start, matches))
+    }
+}
+
+fn extract_word(line: &str, pos: usize) -> (usize, &str) {
+    let words: Vec<_> = line[..pos].split_whitespace().collect();
+    let word_start = words.last().map_or(0, |w| line.rfind(w).unwrap());
+    (word_start, &line[word_start..pos])
+}
+
+fn complete_filenames(word: &str, matches: &mut Vec<Pair>) {
+    if let Ok(entries) = fs::read_dir(".") {
+        for entry in entries.flatten() {
+            if let Ok(name) = entry.file_name().into_string() {
+                if name.starts_with(word) {
+                    matches.push(Pair {
+                        display: name.clone(),
+                        replacement: name,
+                    });
+                }
+            }
+        }
+    }
+}
+
+fn complete_shell_commands(word: &str, matches: &mut Vec<Pair>) {
+    let shell_commands = ["ls", "cat", "cd", "pwd", "echo", "grep"];
+    for &cmd in &shell_commands {
+        if cmd.starts_with(word) {
+            matches.push(Pair {
+                display: cmd.to_string(),
+                replacement: cmd.to_string(),
+            });
+        }
+    }
+}
+
+fn complete_executables_in_path(word: &str, matches: &mut Vec<Pair>) {
+    if let Ok(paths) = env::var("PATH") {
+        for path in env::split_paths(&paths) {
+            if let Ok(entries) = fs::read_dir(path) {
+                for entry in entries.flatten() {
+                    if let Ok(name) = entry.file_name().into_string() {
+                        if name.starts_with(word) && entry.path().is_file() {
+                            matches.push(Pair {
+                                display: name.clone(),
+                                replacement: name,
+                            });
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+impl Hinter for ShellCompleter {
+    type Hint = String;
+}
+
+impl Highlighter for ShellCompleter {
+    fn highlight_hint<'h>(&self, hint: &'h str) -> Cow<'h, str> {
+        Owned("\x1b[1m".to_owned() + hint + "\x1b[m")
+    }
+}
+
+impl Validator for ShellCompleter {}
+
+impl Helper for ShellCompleter {}
diff --git a/crates/shell/src/main.rs b/crates/shell/src/main.rs
index 0ba916a..a6fff98 100644
--- a/crates/shell/src/main.rs
+++ b/crates/shell/src/main.rs
@@ -4,14 +4,16 @@ use std::rc::Rc;
 
 use anyhow::Context;
 use clap::Parser;
+use completion::ShellCompleter;
 use deno_task_shell::{
     execute_sequential_list, AsyncCommandBehavior, ExecuteResult, ShellCommand, ShellPipeReader,
     ShellPipeWriter, ShellState,
 };
 use rustyline::error::ReadlineError;
-use rustyline::DefaultEditor;
+use rustyline::{CompletionType, Config, Editor};
 
 mod commands;
+mod completion;
 
 fn commands() -> HashMap<String, Rc<dyn ShellCommand>> {
     HashMap::from([(
@@ -67,7 +69,16 @@ fn init_state() -> ShellState {
 }
 
 async fn interactive() -> anyhow::Result<()> {
-    let mut rl = DefaultEditor::new()?;
+    let config = Config::builder()
+        .history_ignore_space(true)
+        .completion_type(CompletionType::List)
+        .build();
+
+    let mut rl = Editor::with_config(config)?;
+
+    let h = ShellCompleter {};
+
+    rl.set_helper(Some(h));
 
     let mut state = init_state();