get_title_and_rename.rb

# -*- coding: utf-8 -*-
require 'find'
require 'fileutils'
require 'minitest/autorun'

# USAGE: ruby -w script.rb inputfolder 
# change lines of *.txt 
# !! update filename in place !!
# files in inputfolder will be renamed accordingly

path = File.expand_path ARGV[0] if __FILE__ ==$0

def get_title_and_rename path
  Find.find(path) do |file|
    next if File.directory? file
    next unless file =~ /.txt$/i
    filepath = File.dirname file
    filename = File.basename(file, '.txt')
    File.open(file, 'r') do |l|
      title = l.gets # 默认第一行就是题目 且题目格式是 title: some title
      # The (?:…) construct provides grouping without capturing.
      #if m = title.match(/The Project Gutenberg (?:EBook|etext) of(.+)/i)
      $realtitle = title.iyc_get_title 
      if $realtitle # 也许有的文件就没有 title: some title 这行 必须得确认 #realtitle 不是 nil
        $realtitle = $realtitle.strip.tr(',;:', '').gsub(/\s+/, '_').gsub(/\n|\r/, '').downcase
      else
        $realtitle = '' 
      end
    end
    newfilename = filename.downcase + '_' + $realtitle + '.txt'
    newfilename = newfilename.gsub(/_+\./, '.') # handle "An_Essay_on_Profits_.txt"
    p "rename #{filename} to #{newfilename}"
    if filename + '.txt' != newfilename  # 如果将文件改名为它自身会报错，比如 mv file file 报错的
      FileUtils.mv(file, "#{filepath}/#{newfilename}") 
    end # can't get title for some files so newfilename would be equal to filename, skip those!
  end
end
get_title_and_rename path if __FILE__ == $0

class String
  def iyc_get_title
    self.split(':')[1..-1].join.strip
    # array[1..-1] to cater to special case Title: title with colon: a true story
  end
  def iyc_title_to_filename
    self.strip.tr(',;:!', '').gsub(/\s+/, '_').gsub(/\n|\r/, '').downcase
  end
end