#!/usr/bin/env ruby

require 'algorithm/diff'

# TODO: parameters

def loadfile(filename)
  lines = nil
  File.open(filename, "r") { |f|
    lines = f.readlines
  }
  return lines
end

def diffrange(a, b)
  if (a == b)
    "#{a}"
  else
    "#{a},#{b}"
  end
end

class Diff2
  def initialize(a,b)
    @diffs = Diff::diff(a,b)
  end

  def to_diff(io = $defout)
    offset = 0
    return if @diffs.empty?
    p @diffs
    #@diffs.each { |b|
    first = @diffs[0][1]
      length = @diffs.length
      action = @diffs[0][0]
      addcount = 0
      remcount = 0
      @diffs.each { |l| 
        if l[0] == :+
          addcount += 1
        elsif l[0] == :-
          remcount += 1
        end
      }
      if addcount == 0
        puts "#{diffrange(first+1, first+remcount)}d#{first+offset}"
      elsif remcount == 0
        puts "#{first-offset}a#{diffrange(first+1, first+addcount)}"
      else
        puts "#{diffrange(first+1, first+remcount)}c#{diffrange(first+offset+1, first+offset+addcount)}"
      end
      lastdel = (@diffs[0][0] == :-)
      @diffs.each { |l|
        if l[0] == :- 
          offset -= 1
          print "< "
        elsif l[0] == :+
          offset += 1
	  if lastdel
	    lastdel = false
            puts "---"
          end
          print "> "
        end
	print l[2]
      }
  #}
  end
end

if $0 == __FILE__

  file1 = ARGV.shift
  file2 = ARGV.shift

  ary1 = loadfile file1
  ary2 = loadfile file2

  diff = Diff2.new(ary1, ary2)
  diff.to_diff

end