From 26254f7022557168d9ffa7a3df37f43913035790 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fe=CC=81lix=20Saparelli?= <felix@passcod.name>
Date: Fri, 24 Dec 2021 02:20:45 +1300
Subject: [PATCH] Add support for "tagged filter files"

---
 cli/src/main.rs                |  2 +
 lib/src/filter/tagged.rs       |  1 +
 lib/src/filter/tagged/files.rs | 90 ++++++++++++++++++++++++++++++++++
 lib/src/ignore_files.rs        |  2 +-
 4 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 lib/src/filter/tagged/files.rs

diff --git a/cli/src/main.rs b/cli/src/main.rs
index a871b68..2e26ab1 100644
--- a/cli/src/main.rs
+++ b/cli/src/main.rs
@@ -130,6 +130,7 @@ async fn main() -> Result<()> {
 		.and_then(|wd| wd.canonicalize())
 		.into_diagnostic()?;
 	for filter in args.values_of("filter").unwrap_or_default() {
+		// TODO: use globset
 		let mut filter: Filter = filter.parse()?;
 		filter.in_path = Some(workdir.clone());
 		filters.push(filter);
@@ -141,6 +142,7 @@ async fn main() -> Result<()> {
 		.map(|s| s.split(',').map(|s| s.trim()))
 		.flatten()
 	{
+		// TODO: use globset
 		filters.push(Filter {
 			in_path: None,
 			on: Matcher::Path,
diff --git a/lib/src/filter/tagged.rs b/lib/src/filter/tagged.rs
index 27ae730..e5e9a54 100644
--- a/lib/src/filter/tagged.rs
+++ b/lib/src/filter/tagged.rs
@@ -24,6 +24,7 @@ use crate::signal::source::MainSignal;
 pub use regex::Regex;
 
 pub mod error;
+pub mod files;
 mod parse;
 pub mod swaplock;
 
diff --git a/lib/src/filter/tagged/files.rs b/lib/src/filter/tagged/files.rs
new file mode 100644
index 0000000..d990599
--- /dev/null
+++ b/lib/src/filter/tagged/files.rs
@@ -0,0 +1,90 @@
+//! Load "tagged filter files".
+
+use std::{
+	env,
+	io::Error,
+	path::{Path, PathBuf},
+	str::FromStr,
+};
+
+use tokio::fs::read_to_string;
+
+use crate::ignore_files::{discover_file, IgnoreFile};
+
+use super::{error::TaggedFiltererError, Filter};
+
+/// A filter file.
+///
+/// This is merely a type wrapper around an [`IgnoreFile`], as the only difference is how the file
+/// is parsed.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct FilterFile(pub IgnoreFile);
+
+/// Finds all filter files that apply to the current runtime.
+///
+/// This considers:
+/// - `$XDG_CONFIG_HOME/watchexec/filter`, as well as other locations (APPDATA on Windows…)
+/// - Files from the `WATCHEXEC_FILTER_FILES` environment variable (comma-separated)
+///
+/// All errors (permissions, etc) are collected and returned alongside the ignore files: you may
+/// want to show them to the user while still using whatever ignores were successfully found. Errors
+/// from files not being found are silently ignored (the files are just not returned).
+pub async fn from_environment() -> (Vec<FilterFile>, Vec<Error>) {
+	let mut files = Vec::new();
+	let mut errors = Vec::new();
+
+	for path in env::var("WATCHEXEC_FILTER_FILES")
+		.unwrap_or_default()
+		.split(',')
+	{
+		discover_file(&mut files, &mut errors, None, None, PathBuf::from(path)).await;
+	}
+
+	let mut wgis = Vec::with_capacity(5);
+	if let Ok(home) = env::var("XDG_CONFIG_HOME") {
+		wgis.push(Path::new(&home).join("watchexec/filter"));
+	}
+	if let Ok(home) = env::var("APPDATA") {
+		wgis.push(Path::new(&home).join("watchexec/filter"));
+	}
+	if let Ok(home) = env::var("USERPROFILE") {
+		wgis.push(Path::new(&home).join(".watchexec/filter"));
+	}
+	if let Ok(home) = env::var("HOME") {
+		wgis.push(Path::new(&home).join(".watchexec/filter"));
+	}
+
+	for path in wgis {
+		if discover_file(&mut files, &mut errors, None, None, path).await {
+			break;
+		}
+	}
+
+	(files.into_iter().map(FilterFile).collect(), errors)
+}
+
+impl FilterFile {
+	/// Read and parse into [`Filter`]s.
+	///
+	/// Empty lines and lines starting with `#` are ignored. The `applies_in` field of the
+	/// [`IgnoreFile`] is used for the `in_path` field of each [`Filter`].
+	///
+	/// This method reads the entire file into memory.
+	pub async fn load(&self) -> Result<Vec<Filter>, TaggedFiltererError> {
+		let content = read_to_string(&self.0.path).await?;
+		let lines = content.lines();
+		let mut filters = Vec::with_capacity(lines.size_hint().0);
+
+		for line in lines {
+			if line.is_empty() || line.starts_with('#') {
+				continue;
+			}
+
+			let mut f = Filter::from_str(line)?;
+			f.in_path = self.0.applies_in.clone();
+			filters.push(f);
+		}
+
+		Ok(filters)
+	}
+}
diff --git a/lib/src/ignore_files.rs b/lib/src/ignore_files.rs
index ecb51a8..824e26b 100644
--- a/lib/src/ignore_files.rs
+++ b/lib/src/ignore_files.rs
@@ -264,7 +264,7 @@ pub async fn from_environment() -> (Vec<IgnoreFile>, Vec<Error>) {
 }
 
 #[inline]
-async fn discover_file(
+pub(crate) async fn discover_file(
 	files: &mut Vec<IgnoreFile>,
 	errors: &mut Vec<Error>,
 	applies_in: Option<PathBuf>,