#!/usr/bin/ruby

=begin
= manued diff
* copyright (c) 2002 Kazuhiro NISHIYAMA.
= about manued
* see ((<URL:http://www.archi.is.tohoku.ac.jp/~yamauchi/projects/manued/index.shtml>))
  or ((<URL:http://www.archi.is.tohoku.ac.jp/~yamauchi/projects/manued/index-j.shtml>))
=end

begin
  require 'diff'
rescue LoadError
  STDERR.puts "get from http://www.ruby-lang.org/en/raa-list.rhtml?name=diff.rb"
  raise
end

class Manuediff
  def initialize(a, b, options=Hash.new)
    @a = a
    @b = b
    @options = options
    options[:left_paren] ||= '['
    options[:right_paren] ||= ']'
    options[:delete] ||= '/'
    options[:swap] ||= '|'
    options[:comment] ||= ';'
    options[:escape] ||= '~'
    @need_quote_in_text = Regexp.new([
                                       options[:left_paren],
                                       options[:escape],
                                     ].collect{|x| Regexp.quote x}.join('|'))
    @need_quote_in_paren = Regexp.new([
                                        options[:left_paren],
                                        options[:right_paren],
                                        options[:delete],
                                        options[:swap],
                                        options[:comment],
                                        options[:escape],
                                      ].collect{|x| Regexp.quote x}.join('|'))
    @diffs = nil
  end

  def compactdiffs
    @diffs ||= Diff.new(@a,@b).compactdiffs
  end
  private :compactdiffs

  def manued_header
    result = "defparentheses  #{@options[:left_paren]} #{@options[:right_paren]}\n"
    result << "defdelete       #{@options[:delete]}\n"
    result << "defswap         #{@options[:swap]}\n"
    result << "defcomment      #{@options[:comment]}\n"
    result << "defescape       #{@options[:escape]}\n"
    result << "deforder        newer-last\n"
    result << "defversion      0.9.3\n"
  end

  def manued(header=nil)
    result = header || manued_header
    ai = bi = 0
    compactdiffs.each do |chunk|
      left_paren_inserted = false
      delete_inserted = false
      chunk.each do |sign, index, text|
        text = text.collect{|s|s.chr}.join('')
        case sign
        when '-'
          len = index - ai
          result << @a[ai,len].gsub(@need_quote_in_text, "#{@options[:escape]}\\&")
          ai += len
          bi += len
          unless left_paren_inserted
            left_paren_inserted = true
            result << @options[:left_paren]
          end
          result << text.gsub(@need_quote_in_paren, "#{@options[:escape]}\\&")
          ai += text.length
        when '+'
          len = index - bi
          result << @a[ai, len].gsub(@need_quote_in_paren, "#{@options[:escape]}\\&")
          ai += len
          bi += len
          unless left_paren_inserted
            left_paren_inserted = true
            result << @options[:left_paren]
          end
          unless delete_inserted
            delete_inserted = true
            result << @options[:delete]
          end
          result << text.gsub(@need_quote_in_paren, "#{@options[:escape]}\\&")
          bi += text.length
	else
	  raise "Unknown diff action"
        end
      end
      result << @options[:delete] unless delete_inserted
      result << @options[:right_paren]
    end
    result << @a[ai..-1].gsub(@need_quote_in_text, "#{@options[:escape]}\\&")
  end
end

if __FILE__ == $0
  if ARGV.size != 2
    STDERR.puts "usage: #{File.basename $0} old new"
  end

  a = File.readlines(ARGV[0]).join('')
  b = File.readlines(ARGV[1]).join('')
  md = Manuediff.new(a,b)
  puts md.manued
end