Support persisting unminified external stylesheets (#33919)

* Support local tweaking of external stylesheets

Signed-off-by: Taym <haddadi.taym@gmail.com>

* Remove duplicated code between unminify_css and unminify_js

Signed-off-by: Taym <haddadi.taym@gmail.com>

* Add License

Signed-off-by: Taym <haddadi.taym@gmail.com>

* Use js-beautify instead of npx

Signed-off-by: Taym <haddadi.taym@gmail.com>

* Fix clippy warning

Signed-off-by: Taym <haddadi.taym@gmail.com>

---------

Signed-off-by: Taym <haddadi.taym@gmail.com>

components/script/unminify.rs

@@ -0,0 +1,100 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::fs::{create_dir_all, File};
+use std::io::{Error, ErrorKind};
+use std::path::{Path, PathBuf};
+use std::process::Command;
+
+use servo_url::ServoUrl;
+use tempfile::NamedTempFile;
+use uuid::Uuid;
+
+pub fn create_temp_files() -> Option<(NamedTempFile, File)> {
+    // Write the minified code to a temporary file and pass its path as an argument
+    // to js-beautify to read from. Meanwhile, redirect the process' stdout into
+    // another temporary file and read that into a string. This avoids some hangs
+    // observed on macOS when using direct input/output pipes with very large
+    // unminified content.
+    let (input, output) = (NamedTempFile::new(), tempfile::tempfile());
+    if let (Ok(input), Ok(output)) = (input, output) {
+        Some((input, output))
+    } else {
+        log::warn!("Error creating input and output temp files");
+        None
+    }
+}
+
+#[derive(Debug)]
+pub enum BeautifyFileType {
+    Css,
+    Js,
+}
+
+pub fn execute_js_beautify(input: &Path, output: File, file_type: BeautifyFileType) -> bool {
+    let mut cmd = Command::new("js-beautify");
+    match file_type {
+        BeautifyFileType::Js => (),
+        BeautifyFileType::Css => {
+            cmd.arg("--type").arg("css");
+        },
+    }
+    match cmd.arg(input).stdout(output).status() {
+        Ok(status) => status.success(),
+        _ => {
+            log::warn!(
+                "Failed to execute js-beautify --type {:?}, Will store unmodified script",
+                file_type
+            );
+            false
+        },
+    }
+}
+
+pub fn create_output_file(
+    unminified_dir: Option<String>,
+    url: &ServoUrl,
+    external: Option<bool>,
+) -> Result<File, Error> {
+    let path = match unminified_dir {
+        Some(unminified_dir) => PathBuf::from(unminified_dir),
+        None => {
+            warn!("Unminified file directory not found");
+            return Err(Error::new(
+                ErrorKind::NotFound,
+                "Unminified file directory not found",
+            ));
+        },
+    };
+
+    let (base, has_name) = match url.as_str().ends_with('/') {
+        true => (
+            path.join(&url[url::Position::BeforeHost..])
+                .as_path()
+                .to_owned(),
+            false,
+        ),
+        false => (
+            path.join(&url[url::Position::BeforeHost..])
+                .parent()
+                .unwrap()
+                .to_owned(),
+            true,
+        ),
+    };
+
+    create_dir_all(&base)?;
+
+    let path = if external.unwrap_or(true) && has_name {
+        // External.
+        path.join(&url[url::Position::BeforeHost..])
+    } else {
+        // Inline file or url ends with '/'
+        base.join(Uuid::new_v4().to_string())
+    };
+
+    debug!("Unminified files will be stored in {:?}", path);
+
+    File::create(path)
+}