Script to convert a Rails/Redmine plugin to a RubyGem without Jeweler

plugin_to_gem.rb

#!/usr/bin/env ruby
# Usage:
#  ruby plugin_to_gem.rb my_plugin_directory
require 'fileutils'
require 'uri'
require 'erb'

@plugin_dir = ARGV[0]

def gemspec_content
  description = 'TODO'
  authors = "'Nobody'"
  email = "'test@test.com'"
  homepage = nil
  summary = nil
  redmine_init_content = File.read('init.rb')
  if redmine_init_content.match(/description (.*$)/)
    description = $1.gsub("'",'').gsub('"','')
  end
  summary = description
  if redmine_init_content.match(/name (.*$)/)
    summary = $1.gsub("'",'').gsub('"','')
  end
  if redmine_init_content.match(/author (.*$)/)
    authors = $1.gsub("'",'').gsub('"','').split(',')
    authors = "'#{authors.join("', '")}'"
  end
  if redmine_init_content.match(/email (.*$)/)
    email = $1.gsub("'",'').gsub('"','').split(',')
    email = "'#{email.join("', '")}'"
  end
  if redmine_init_content.match(/url (.*$)/)
    url = $1.gsub("'",'').gsub('"','')
    unless (url =~ URI::regexp).nil?
      homepage = url
    end
  end

  content = ERB.new <<-EOF
# -*- encoding: utf-8 -*-
require File.join(File.dirname(__FILE__), 'VERSION.rb')

Gem::Specification.new do |s|
  s.name        = '<%= $plugin_name %>'
  s.version     = VERSION
  s.authors     = [<%= authors %>]
  s.email       = [<%= email %>]
  s.description = '<%= description %>'
  <% if homepage %>s.homepage    = '<%= homepage %>'<% end %>
  <% if summary %>s.summary     = '<%= summary %>'<% end %>

  s.rubyforge_project = "<%= $plugin_name %>" #TODO

  s.files         = `git ls-files`.split("\\n")
  s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\\n")
end

EOF
  content.result(binding)
end

FileUtils.cd(@plugin_dir, :verbose => true) do |dir|
  system('rake clean')
  system('git status')
  system('git checkout master')
  system('git merge origin/master')
  system('git checkout -b gem')
  
  redmine_init_content = File.read('init.rb')
  if redmine_init_content.match(/Redmine::Plugin.register :(.*) do/)
    $plugin_name = $1.strip()
  else
    $plugin_name = @plugin_dir
  end

  # Rakefile
  File.open('Rakefile','a') do |file|
    file.puts('require "bundler/gem_tasks"')
  end
  # Gemspec
  File.open("#{$plugin_name}.gemspec",'a') do |file|
    file.puts(gemspec_content)
  end
  system("git add Rakefile #{$plugin_name}.gemspec")
  system('git commit -m "Updated rakefile and added gemspec."')

  # VERSION
  File.open('VERSION.rb','w') do |version_file|
    version = "0.0.1"
    if redmine_init_content.match(/version (.*$)/)
      version = $1.gsub("'",'').gsub('"','')
    end
    version_file.puts("VERSION = '#{version}'")
  end
  system('git add VERSION.rb')
  system('git commit -am "Added Version file"')

  # Rails GemPlugin init.rb
  FileUtils.mkdir_p('rails')
  system('git mv init.rb rails/init.rb')
  File.open('init.rb','w') do |init_file|
    init_file.puts('require File.dirname(__FILE__) + "/rails/init"')
  end
  system('git add init.rb')
  system('git commit -am "Added init file for Rails GemPlugin"')

  # Install to test
  system('rake install')

  # Back to master to allow merging
  system('git checkout master')
end