Rake tasks for generating changes made by author

changes.rake

# Taken from http://stackoverflow.com/a/9782550

namespace :git do
  desc "Analytics of changes made by author"
  task :changes do
    git_changes_by_author.sort_by { |a,h| -h[:total] }.each do |author, changes|
      puts "#{author}: #{changes[:total]} (#{changes[:insertions]} insertions, #{changes[:deletions]} deletions)"
    end
  end
end

def git_changes_by_author
  changes = {}

  IO.popen("git log --pretty=format:\"%an\" --shortstat") do |f|
    prev_line = ''
    while line = f.gets
      matches = /(\d+) insertions.* (\d+) deletions/.match(line)

      if matches
        changes[prev_line] ||= { :total => 0, :insertions => 0, :deletions => 0 }
        changes[prev_line][:total]      += matches[1].to_i + matches[2].to_i
        changes[prev_line][:insertions] += matches[1].to_i
        changes[prev_line][:deletions]  += matches[2].to_i
      end

      # Names are on a line of their own, just before the stats
      prev_line = line.strip
    end
  end

  changes
end