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use anyhow::Result;
use notify::{Event, RecursiveMode, Watcher};
use std::path::{Path, PathBuf};
use std::sync::mpsc;
use std::time::{Duration, Instant};
use crate::builder::Builder;
use crate::cli::BuildOptions;
use crate::color;
/// Check if a path should be ignored (editor temp files, build artifacts).
/// `output_dir` is the configured global output directory.
fn should_ignore(path: &Path, output_dir: &str) -> bool {
// Ignore .rsconstruct cache directory (match as a path component, not substring)
if path.components().any(|c| c.as_os_str() == ".rsconstruct") {
return true;
}
// Ignore the configured output directory (match as a path component, not substring)
if path.components().any(|c| c.as_os_str() == output_dir) {
return true;
}
// Case-sensitive comparisons are correct here: vim swap files and the
// `.tmp` convention are lowercase by definition, and matching `.SWP`
// would start ignoring real source files on case-insensitive filesystems.
#[allow(clippy::case_sensitive_file_extension_comparisons)]
if let Some(name) = path.file_name().and_then(|n| n.to_str()) {
// Editor temp/swap files
if name.starts_with('.') && name.ends_with(".swp") {
return true;
}
if name.ends_with('~') {
return true;
}
if name.starts_with('#') && name.ends_with('#') {
return true;
}
// Common editor temp patterns
if name.ends_with(".tmp") {
return true;
}
}
false
}
/// Register watch paths with the watcher, returning the list of paths being watched.
fn register_watches(watcher: &mut impl Watcher, paths: &[PathBuf]) {
for path in paths {
let mode = if path.is_dir() {
RecursiveMode::Recursive
} else {
RecursiveMode::NonRecursive
};
// Always warn: an unwatched path silently produces no rebuilds, which
// is much harder to diagnose than this message.
if let Err(e) = watcher.watch(path, mode) {
eprintln!("Warning: could not watch {}: {}", path.display(), e);
}
}
}
pub fn watch(ctx: &crate::build_context::BuildContext, opts: &BuildOptions) -> Result<()> {
let mut builder = Builder::new_with_overrides(ctx, &opts.iset, &opts.pset)?;
let mut watch_paths = builder.watch_paths();
let mut output_dir = builder.output_dir().to_string();
// Register watches BEFORE the initial build: edits made while the (possibly
// long) initial build runs must queue up as events, not vanish.
let (tx, rx) = mpsc::channel::<notify::Result<Event>>();
let mut watcher = notify::recommended_watcher(tx)?;
register_watches(&mut watcher, &watch_paths);
// Initial build
println!("{}", color::bold("Running initial build..."));
if let Err(e) = builder.build(ctx, opts, Vec::new()) {
println!("{}", color::red(&format!("Initial build error: {e}")));
}
drop(builder);
println!(
"{}",
color::green("Watching for changes... (Ctrl+C to stop)")
);
let debounce_duration = Duration::from_millis(200);
let poll_interval = Duration::from_millis(500);
loop {
// Wait for a relevant file-change event, periodically checking the interrupted flag.
// Breaks with `true` on a real event, `false` if the watcher channel disconnects.
let got_event = loop {
if ctx.is_interrupted() {
return Ok(());
}
match rx.recv_timeout(poll_interval) {
Ok(Ok(event)) => {
let all_ignored = event.paths.iter().all(|p| should_ignore(p, &output_dir));
if all_ignored {
continue;
}
break true;
}
Ok(Err(e)) => {
println!("{}", color::red(&format!("Watch error: {e}")));
}
// Nothing arrived within the poll interval: loop round and
// re-check the interrupt flag.
Err(mpsc::RecvTimeoutError::Timeout) => {}
Err(mpsc::RecvTimeoutError::Disconnected) => break false,
}
};
if !got_event {
break;
}
// Debounce: drain further events within the debounce window
let deadline = Instant::now() + debounce_duration;
loop {
let remaining = deadline.saturating_duration_since(Instant::now());
if remaining.is_zero() {
break;
}
match rx.recv_timeout(remaining) {
Ok(_) => {}
Err(mpsc::RecvTimeoutError::Timeout) => break,
Err(mpsc::RecvTimeoutError::Disconnected) => break,
}
}
// Rebuild. A failed builder construction (e.g. rsconstruct.toml saved
// in a momentarily-invalid state) must not kill watch mode: report it
// and keep watching — the next save triggers another attempt.
println!();
println!("{}", color::bold("Change detected, rebuilding..."));
match Builder::new_with_overrides(ctx, &opts.iset, &opts.pset) {
Err(e) => {
println!("{}", color::red(&format!("Config error: {e}")));
}
Ok(mut builder) => {
let new_paths = builder.watch_paths();
output_dir = builder.output_dir().to_string();
if let Err(e) = builder.build(ctx, opts, Vec::new()) {
println!("{}", color::red(&format!("Build error: {e}")));
}
// Update watches if paths changed (e.g., new scan dirs in config)
for path in &new_paths {
if !watch_paths.contains(path) {
register_watches(&mut watcher, std::slice::from_ref(path));
}
}
// Unwatch paths that are no longer relevant
for path in &watch_paths {
if !new_paths.contains(path) {
let _ = watcher.unwatch(path);
}
}
watch_paths = new_paths;
}
}
println!(
"{}",
color::green("Watching for changes... (Ctrl+C to stop)")
);
}
Ok(())
}