class Delocalize::LocalizedDateTimeParser

def apply_regex(format)
  # maybe add other options as well
  format.gsub('%B', "(#{Date::MONTHNAMES.compact.join('|')})"). # long month name
    gsub('%b', "(#{Date::ABBR_MONTHNAMES.compact.join('|')})"). # short month name
    gsub('%m', "(\\d{2})").                                     # numeric month
    gsub('%A', "(#{Date::DAYNAMES.join('|')})").                # full day name
    gsub('%a', "(#{Date::ABBR_DAYNAMES.join('|')})").           # short day name
    gsub('%Y', "(\\d{4})").                                     # long year
    gsub('%y', "(\\d{2})").                                     # short year
    gsub('%e', "(\\w?\\d{1,2})").                               # short day
    gsub('%d', "(\\d{2})").                                     # full day
    gsub('%H', "(\\d{2})").                                     # hour (24)
    gsub('%M', "(\\d{2})").                                     # minute
    gsub('%S', "(\\d{2})")                                      # second
end

def default_parse(datetime, type)
  return if datetime.blank?
  begin
    today = Date.current
    parsed = Date._parse(datetime)
    return if parsed.empty? # the datetime value is invalid
    # set default year, month and day if not found
    parsed.reverse_merge!(:year => today.year, :mon => today.mon, :mday => today.mday)
    datetime = Time.zone.local(*parsed.values_at(:year, :mon, :mday, :hour, :min, :sec))
    Date == type ? datetime.to_date : datetime
  rescue
    datetime
  end
end

def input_formats(type)
  # Date uses date formats, all others use time formats
  type = type == Date ? :date : :time
  (@input_formats ||= {})[type] ||= I18n.t(:"#{type}.formats").slice(*I18n.t(:"#{type}.input.formats")).values
end

def parse(datetime, type)
  return unless datetime
  return datetime if datetime.respond_to?(:strftime) # already a Date/Time object -> no need to parse it
  translate_month_and_day_names(datetime)
  input_formats(type).each do |original_format|
    next unless datetime =~ /^#{apply_regex(original_format)}$/
    datetime = DateTime.strptime(datetime, original_format)
    return Date == type ?
      datetime.to_date :
      Time.zone.local(datetime.year, datetime.mon, datetime.mday, datetime.hour, datetime.min, datetime.sec)
  end
  default_parse(datetime, type)
end

def translate_month_and_day_names(datetime)
  translated = I18n.t([:month_names, :abbr_month_names, :day_names, :abbr_day_names], :scope => :date).flatten.compact
  original = (Date::MONTHNAMES + Date::ABBR_MONTHNAMES + Date::DAYNAMES + Date::ABBR_DAYNAMES).compact
  translated.each_with_index { |name, i| datetime.gsub!(name, original[i]) }
end