methodshark.rb

#!/usr/bin/env ruby

# Print the complexity over time for a Ruby method in a
# git repository.
#
# Requires: >= bash ?.?
#           >= git 1.7.1
#           >= ruby 1.9.2
#           >= flog 2.5.0
#

require 'flog'
require 'time'

TEMP_FILE = "/tmp/methodshark_junk.rb"

class MethodShark

  class Reporter < ::StringIO
    def initialize(methodname)
      super()
      @detector = Regexp.new('\s+(\d+.\d+):\s+' + methodname)
    end

    def score
      text = string.scan(@detector).flatten.first
      text ? Float(text) : 0.0
    end
  end

  def self.trail_for(filename, methodname)
    new(filename, methodname).generate_datestamped_complexities.sort
  end

  def initialize(filename, methodname)
    @filename = filename
    @methodname = methodname
  end

  def generate_datestamped_complexities
    complexities = {}
    sha1s_of_commits.each do |sha1|
      complexities[commit_date_of(sha1)] = complexity_of(sha1)
    end
    complexities
  end

  def commit_date_of(sha1)
    Time.parse(`git show -s --format=%cd #{sha1}`).strftime("%D")
  end

  def complexity_of(sha1)
    `git show #{sha1}:#{@filename} > #{TEMP_FILE}`
    flogger = Flog.new({ :all => true })
    reporter = Reporter.new(@methodname)
    flogger.flog(TEMP_FILE)
    flogger.report(reporter)
    reporter.score
  end

  def sha1s_of_commits
    @commits ||= `git log #{@filename}| grep ^commit`.split(/\n/).map(&:split).map {|fields| fields[sha1_column = 1] }
  end
end

if ARGV.size != 2
  puts "help: methodshark <rubyfilename> <methodname>"
  puts ""
  puts "      Run in a git repository folder"
  puts ""
  puts "      Ex.  methodshark app/models/flubber.rb Foo#bar!"
  puts "           methodshark app/models/flubber.rb no_foo?"
  puts ""
  exit
end

MethodShark.trail_for(ARGV[0], ARGV[1]).each do |date,complexity|
  puts "#{date},#{complexity}"
end