vaportrails.rb

# Print the vaportrail of a ruby file in a git repo, i.e.,
# the complexity level at each commit.
#
# Requires: >= bash ?.?
#           >= git 1.7.1
#           >= ruby 1.9.2
#           >= flog 2.5.0
#           >= gruff 0.3.6
#

require 'rubygems'
require 'flog'
require 'time'
require 'gruff'

TEMP_FILE = "/tmp/vaportrail_junk.rb"

class VaporTrail

  class Reporter < ::StringIO
    # borrowed from Chad Fowler
    SCORE_LINE_DETECTOR = /^\s+([^:]+).*flog total$/
      def score
        Float(string.scan(SCORE_LINE_DETECTOR).flatten.first)
      end
  end

  def self.trail_for(filename)
    trail = new(filename).generate_datestamped_complexities.sort
    trail
  end

  def initialize(filename)
    @filename = filename
  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
    reporter = Reporter.new
    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_columm = 1] }
  end


end

def create_graph(trail)
  dates, flog_values = trail.transpose

  g = Gruff::Line.new
  g.title = "Flog Vs. Date"

  g.data("Flog", flog_values)

  labels = {}
  dates.each_index { |i| labels[i] = dates[i] }
  g.labels = labels

  g.write('flog.png')
end

if ARGV.size != 1
  puts "help: vaportrail <rubyfilename>"
  puts "      run in the folder of a git repo"
  exit
end

trail = VaporTrail.trail_for(ARGV[0])
create_graph(trail)
puts trail

The axis with the dates looks pretty terrible when there are more than a few commits, maybe I'll fix that tomorrow.