vaportrails.rb

#!/usr/bin/env ruby

# 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
#

require 'flog'
require 'time'

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)
    new(filename).generate_datestamped_complexities.sort
  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

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

p VaporTrail.trail_for(ARGV[0])