Script to copy custom Slack index.js when it gets updated and changes overridden

slack-dark.rb

#!/usr/bin/env ruby

require 'active_support'
require 'active_support/core_ext'
require 'thor'

# Usage:
# ./slack-dark.rb
# ./slack-dark.rb [NEW_INDEX_FILE]
#
# ruby slack-dark.rb # may work as an alternative, depending on permissions

class SlackDark < Thor
  SLACK_ORIG_INDEX_DIR = '/Applications/Slack.app/Contents/Resources/app.asar.unpacked/src/static/'.freeze
  SLACK_ORIG_INDEX = File.join(SLACK_ORIG_INDEX_DIR, 'index.js').freeze
  SLACK_DEFAULT_OVERRIDE_INDEX = File.join('.', 'slack-dark-index.js').freeze

  desc 'override [INDEX.js OVERRIDE LOCATION]', "overrides Slack's index.js with given override index.js"
  def override(new_index = SLACK_DEFAULT_OVERRIDE_INDEX)
    diff = `git diff --no-index #{new_index} #{SLACK_ORIG_INDEX}`

    if diff.present?
      display_diff(new_index)
      override_index!(new_index) if confirm_diff?
    else
      puts 'No diff, no need to override'
    end

    puts 'laterzzz'
  end
  default_task :override

  private

  def display_diff(new_index)
    system("git diff --no-index #{new_index} #{SLACK_ORIG_INDEX}")
  end

  def confirm_diff?
    puts 'After viewing diff, confirm override? (y/Y to confirm)'
    response = $stdin.gets.chomp.chr.downcase

    response == 'y'
  end

  def override_index!(new_index)
    system("mv #{SLACK_ORIG_INDEX} #{SLACK_ORIG_INDEX}.bak")
    puts "Orig index.js backed up to .bak"

    system("cp #{new_index} #{File.join(SLACK_ORIG_INDEX_DIR, 'index.js')}")
    puts "New index.js copied"
  end
end

SlackDark.start(ARGV)