Ruby script to toggle night-mode hack on Slack Desktop app - Mac only, maybe linux

README.md

- IMPORTANT

For security, since this script injects CSS via AJAX, first fork the main slack night mode repo. The reason is explained here

UPDATE: The code has been modified to download the remote css to a local file and use ruby sass compiler to verify there is no malicious code in the remote css. This will error if the code has been modified to include anything malicious (i.e. script or img tags etc.) It's also been refactored to use the local file inside the js injection, it makes sure it's safe first in the very unlikely event the local file somehow differs from the remote css. The chances of this happening are remote, but this should suffice for safety.

Installation

• save this script wherever you keep your ruby scripts for example ~/lacostenycoder/scripts/ruby/
• change the URL in the remote_repo variable in ruby script to use YOUR repo. The rawgit.com file is created when you fork the repo.
• For non-MacOS, find where the slack files are and replace line 20 to point to correct path, thanks simbalinux so you would change line 20 for ubuntu like this
  • @file_target = '/usr/lib/slack/resources/app.asar.unpacked/src/static/'
• make script executable sudo chmod +x nightslack
• symlink to a PATH load for example: ln -s /Users/lacostenycoder/dev/ruby/nightslack.rb /usr/local/bin/nightslack
• Or if you prefer just drop the .rb from the filename and move it directly to /usr/local/bin/nightslack

How to use this

From a terminal simply type nightslack to start desktop app in night-mode.

To toggle back to day mode, simpley run nightslack -d to pass the day mode option. This will start or restart a running slack desktop in the desired mode!

Keeping your forked repo up to date

• To update styles, sync your forked repo with upstream but be sure to inspect the css to insure it doesn't contain js code injeciton.

nightslack.rb

#!/usr/bin/env ruby
require 'open-uri'
require 'sass'

JS_ERROR_MSG = "Possible js code injection found in remote css... check your repo!".freeze
remote_repo = 'https://raw.githubusercontent.com/lacostenycoder/slack-night-mode/master/css/raw/black.css'
remote_css = open(remote_repo) { |f| f.read }

# Check for possible js code injection in css
abort(JS_ERROR_MSG + "\n#{remote_repo}") if remote_css.index('<script>')

# double check if ruby sass compiles correctly. Will raise if any html or non css
begin
  compsass = Sass::Engine.new(remote_css, :syntax => :scss, :style => :compressed).render
rescue Sass::SyntaxError => e
  puts e
  abort(JS_ERROR_MSG)
end

static_path = '/Applications/Slack.app/Contents/Resources/app.asar.unpacked/src/static/'
target_css_file =  static_path + 'black.css'

File.open(target_css_file, 'w') {|f| f.write remote_css}
slack_pid = `ps -axcf -S -O%cpu | grep Slack | awk '{print $2}' | head -n 1`.strip
unless slack_pid.empty?
  `kill -9 #{slack_pid}`
end

js_code = <<-JS
document.addEventListener('DOMContentLoaded', async function() {
  const initTheme = themeCssUrl => new Promise(resolve => $.ajax({
    url: themeCssUrl,
    success: css => {
      const styleJqueryEl = $('<style>').html(css).appendTo('head')
      const styleElement = styleJqueryEl[0]
      resolve(styleElement)
    }
  }))
  initTheme("#{remote_repo}")
})
JS

@file_target = static_path + 'ssb-interop.js'
`cp #{@file_target} #{@file_target}.bak`
@current_file = File.read(@file_target)
@normal_mode = @day_mode_set ? @current_file : @current_file.split(js_code).first
@night_mode = @normal_mode + js_code

use_day_mode = ARGV[0] == '-d'
def set_mode(mode)
  if mode == 'd'
    File.open(@file_target, 'w'){|f| f.puts @normal_mode}
		puts "Slack Normal (day) mode has been set!"
  else
    File.open(@file_target, 'w'){|f| f.puts @night_mode}
		puts "Slack Normal night mode has been set!"
  end
end

use_day_mode ? set_mode('d') : set_mode('n')

`open -a "Slack"`

They changed their app bundle. In this repo they got it working: https://github.com/LanikSJ/slack-dark-mode/pull/77/files#diff-4e5b58d0c0e2e47e41878b4116e03b7f