change_exifs.rb

  # For mac XOS
  # dependent from SetFile
  # uses it like: SetFile -d '12/31/1999 23:59:59' photo.jpg in order to change 
  # the displayed creation date of a file
  # usage: enter directory with all directories with names, which are date-like
  # yyyymmdd - so y - year; m - month; d - day

  # 1. put file on the desktop
  # 2. enter irb
  # 3. write in console: load '~/Desktop/change_exifs.rb'
  # 4. ChangingPhotoHistory.new.replace_all_created_at_dates
  # 5. do nothing, it is done :-)

  # if something gets broken, no worries, the displayed on mac created at dates
  # are not the "true" one. You can recover them.

class ChangingPhotoHistory
  require 'shellwords'

  def initialize(main_directory=".")
    @main_directory = main_directory
  end

  def dir_name_to_date(dir_name)
    date = "#{dir_name[4..5]}/#{dir_name[6..7]}/#{dir_name[0..3]}"
    hour = "23:59:59"
    "#{date} #{hour}"
  end

  def escape_spaces(filename)
    Shellwords.shellescape(filename)
  end

  def replace_all_created_at_dates
    Dir.entries(@main_directory).each do |d|
      next if is_a_wrong_file?(d)
      Dir.entries(d).each do |inner_file|
        next if is_a_system_file?(inner_file)
        date = dir_name_to_date(d)
        file_with_path = d + "/" + inner_file
        command = "SetFile -d '" + date + "' "+ escape_spaces(file_with_path)
        puts command
        system command
      end
    end
  end

  def contains_eight_digits(file_name)
    file_name =~ /\d{8}/
  end

  def is_a_wrong_file?(file_name)
    file_name.size != 8 or !contains_eight_digits(file_name)
  end

  def is_a_system_file?(file_name)
    file_name == '.' or file_name == '..' or file_name == '.DS_Store'
  end
end