gistfile1.rb

# Code based from Whenever::CommandLine removing the 'exit' calls and
# adding some helper methods like 'registerd?' and 'remove'
#
# Allows passing a string instead of a file as default.
#
# job = <<-JOB
#   set :environment, Rails.env
#   set :output, '/path/to/log'
#
#   every #{frequency}, :at => '#{time}' do
#     command ...
#     runner ...
#     rake ...
#   end
# JOB
#
# options = {:string => job, :update => true, :identifier => identifier}
# Whenever::Register.execute(options)
#
# Whenever::Register.registered(identifier)
# Whenever::Register.remove(identifier)
#
module Whenever
  class Register
    
    def self.execute(options={})
      new(options).run
    end
    
    def self.registered?(identifier, user=nil)
      new(:identifier => identifier, :user => user).exists?
    end
    
    def self.remove(identifier, user=nil)
      new(:identifier => identifier, :user => user).clear
    end
    
    def initialize(options={})
      @options = options
      
      unless @options[:identifier]
        raise '[fail] Identifier not setted.'
      end
    end
    
    def run
      if @options[:update]
        write_crontab(updated_crontab)
      else
        puts Whenever.cron(@options)
      end
    end
    
    def exists?
      read_crontab.index(comment_open) && read_crontab.index(comment_close) ? true : false
    end
    
    def clear
      return unless exists?
      contents = read_crontab.gsub(Regexp.new("#{comment_open}.+#{comment_close}", Regexp::MULTILINE), '').gsub(/\n{2,}/, "\n\n")
      write_crontab(contents)
    end
    
  protected
    def whenever_cron
      @whenever_cron ||= [comment_open, Whenever.cron(@options), comment_close].join("\n") + "\n"
    end
    
    def read_crontab
      return @current_crontab if @current_crontab
      
      command = ['crontab -l']
      command << "-u #{@options[:user]}" if @options[:user]
      
      command_results  = %x[#{command.join(' ')} 2> /dev/null]
      @current_crontab = $?.exitstatus.zero? ? command_results : ''
    end
    
    def write_crontab(contents)
      tmp_cron_file = Tempfile.new('whenever_tmp_cron').path
      File.open(tmp_cron_file, File::WRONLY | File::APPEND) do |file|
        file << contents
      end

      command = ['crontab']
      command << "-u #{@options[:user]}" if @options[:user]
      command << tmp_cron_file

      if system(command.join(' '))
        action = 'written' if @options[:write]
        action = 'updated' if @options[:update]
        puts "[write] crontab file #{action}"
      else
        raise "[fail] Couldn't write crontab; try running `whenever' with no options to ensure your schedule file is valid."
      end
    end
    
    def updated_crontab      
      # Check for unopened or unclosed identifier blocks
      if read_crontab.index(comment_open) && !read_crontab.index(comment_close)
        raise "[fail] Unclosed indentifier; Your crontab file contains '#{comment_open}', but no '#{comment_close}'"
      elsif !read_crontab.index(comment_open) && read_crontab.index(comment_close)
        raise "[fail] Unopened indentifier; Your crontab file contains '#{comment_close}', but no '#{comment_open}'"
      end
      
      # If an existing identier block is found, replace it with the new cron entries
      if read_crontab.index(comment_open) && read_crontab.index(comment_close)
        read_crontab.gsub(Regexp.new("#{comment_open}.+#{comment_close}", Regexp::MULTILINE), whenever_cron.chomp)
      else # Otherwise, append the new cron entries after any existing ones
        [read_crontab, whenever_cron].join("\n\n")
      end
    end
    
    def comment_base
      "Whenever generated tasks for: #{@options[:identifier]}"
    end
    
    def comment_open
      "# Begin #{comment_base}"
    end
    
    def comment_close
      "# End #{comment_base}"
    end
    
  end
end