From 9711de94638139b54bc31588e5fbb60a25e1cac6 Mon Sep 17 00:00:00 2001
From: Niklas Gollenstede <n.gollenstede@web.de>
Date: Sun, 26 May 2019 14:29:57 +0200
Subject: [PATCH] handle toolkit.legacyUserProfileCustomizations.stylesheets
 (close #22)

---
 background/chrome/index.js  |  2 +-
 background/chrome/native.js | 63 ++++++++++++++++++++++++++++++-------
 2 files changed, 52 insertions(+), 13 deletions(-)

diff --git a/background/chrome/index.js b/background/chrome/index.js
index 64a7d77..ca2e345 100644
--- a/background/chrome/index.js
+++ b/background/chrome/index.js
@@ -135,7 +135,7 @@ async function writeStyles(process, clear, replace) {
 			loaded[key] = extract(loaded[key].replace(/\r\n?/g, '\n'));
 		});
 	} }
-	(await native.write(files, replace));
+	(await native.write(files, replace, true));
 
 	changed = Object.entries((await loaded)).some(([ key, loaded, ]) => written[key] !== loaded);
 	fireWritten([ changed, ]);
diff --git a/background/chrome/native.js b/background/chrome/native.js
index 5721055..917c0e7 100644
--- a/background/chrome/native.js
+++ b/background/chrome/native.js
@@ -20,31 +20,70 @@ module.exports = {
 
 //// start implementation
 
-const FS = require('fs'), { promisify, } = require('util'), { EOL, } = require('os');
+const FS = require('fs'), { promisify, } = require('util'), { EOL, } = require('os'), VM = require('vm');
 const access = promisify(FS.access), mkdir = promisify(FS.mkdir), readFile = promisify(FS.readFile), writeFile = promisify(FS.writeFile);
 const { profileDir, } = require('browser');
 
-async function write(files, exp = '.*') {
-	try { (await access(profileDir)); } catch (_) { throw new Error(`Cant access profile directory in "${ profileDir }"`); }
+async function write(files, exp = '.*', enable = false) {
+	try { (await access(profileDir)); } catch (_) { throw new Error(`Cant access profile directory in "${profileDir}"`); }
 	try { (await mkdir(profileDir +'/chrome')); } catch (_) { }
 
-	(await Promise.all([ 'chrome', 'content', ].map(async type => {
-		const old = (await readSafe(type));
-		const css = old.replace(new RegExp(exp +'|$'), () => files[type].replace(/\n/g, EOL));
-
-		(await writeFile(profileDir +`/chrome/userC${type.slice(1)}.css`, css, 'utf-8'));
-	})));
+	(await Promise.all([
+		replaceInFile(cssFilePath('chrome'), exp, files.chrome),
+		replaceInFile(cssFilePath('content'), exp, files.content),
+		enable && setUserConfig([
+			{ name: 'toolkit.legacyUserProfileCustomizations.stylesheets', value: true, comment: 'enforced by reStyle, required to apply browser styles', },
+		]).catch(console.error),
+	]));
 }
 
 async function read() {
 	const files = { chrome: '', content: '', };
 	(await Promise.all(Object.keys(files).map(async type => {
-		files[type] = (await readSafe(type));
+		files[type] = (await readIfExists(cssFilePath(type)));
 	})));
 	return files;
 }
 
-async function readSafe(type) {
-	try { return (await readFile(profileDir +`/chrome/userC${type.slice(1)}.css`, 'utf-8')); }
+function cssFilePath(type) { return profileDir +`/chrome/userC${ type.slice(1) }.css`; }
+
+async function readIfExists(path) {
+	try { return (await readFile(path, 'utf-8')); }
 	catch (error) { error && error.code !== 'ENOENT' && console.error(error); return ''; }
 }
+
+async function replaceInFile(path, exp, content) {
+	content = (await readIfExists(path))
+	.replace(new RegExp(exp +'|$'), () => content.replace(/\n/g, EOL));
+	(await writeFile(path, content, 'utf-8'));
+}
+
+/**
+ * Writes `about:config` values to the current profiles `user.js` file.
+ * If one or more entry with the same name exists, the first one will be replaced
+ * and the remaining ones removed. If none existed, the new entry will be appended.
+ * This function currently doesn't handle multi-line entries or comments properly.
+ * @param {[object]}  prefs  Array of objects representing the entries to write:
+ * @property      {string}                 name     Name of the config value.
+ * @property      {string|number|boolean}  value    New value to write.
+ * @property      {string}                 comment  Single-line comment to append to the new line.
+ * @throws {TypeError}  If the `user.js` file is not valid JavaScript before or after replacing the values.
+ */
+async function setUserConfig(prefs) {
+	const path = profileDir +'/user.js';
+	let script = tryCompile((await readIfExists(path)));
+
+	for (const { name, value, comment, } of prefs) {
+		let replaced = false;
+		script = tryCompile(script.replace(new RegExp(
+			`\\n\\s*?user_pref\\((["'])${ name.replace(/([.])/g, '[$1]') }\\1.*|$`, 'g'
+		), match => {
+			if (replaced) { return match ? '\n' : ''; } replaced = true;
+			return `\nuser_pref(${ JSON.stringify(name) }, ${ JSON.stringify(value) });`+ (comment ? ' // '+ comment : '');
+		}));
+	}
+
+	function tryCompile(script) { new VM.Script(script, { filename: 'user.js', }); return script; }
+
+	(await writeFile(path, script, 'utf-8'));
+}