Ruby: Git statistics

git_stats.rb

#!/usr/bin/env ruby

require 'optparse'
require 'optparse/date'

options = {}

parser = OptionParser.new do |opts|
  opts.banner = 'Usage: git_stats.rb [options]'

  opts.on('-a', '--after [DATE]', Date, 'Get stats since given date') do |val|
    options[:after] = val
  end

  opts.on('-b', '--before [DATE]', Date, 'Get stats until given date') do |val|
    options[:before] = val
  end
end

begin
  parser.parse!
rescue OptionParser::InvalidArgument
  puts 'Error: Invalid date'
  exit
end


def date_param(date, param)
  date ? "--#{param} #{date}" : ''
end

def date_params(after, before)
  [date_param(after, :after), date_param(before, :before)].join(' ')
end

def git_authors(after, before)
  `git log --branches --remotes #{date_params(after, before)} --format='%aN' | sort -u`
end

# Git information containing commit hash and commit stats on separate lines
# Example:
# cd10440
# 3 files changed, 17 insertions(+), 1 deletion(-)
def git_log_stats(author, after, before)
  command = "git log --shortstat --pretty=format:\"%h\" --branches --remotes"
  `#{command} --author=\"#{author}\" #{date_params(after, before)}`
end

def str_with_stats?(str)
  str.split(' ').count > 1
end

def parse_count(str, substr)
  str.scan(/(\d+) #{substr}/).flatten.first.to_i
end

def count_stats(data)
  commits = files_changed = insertions = deletions = 0

  data.split("\n").each do |row|
    row.chomp!
    next if row.empty?

    if str_with_stats?(row)
      files_changed += parse_count(row, 'file')
      insertions += parse_count(row, 'insert')
      deletions += parse_count(row, 'del')
    else
      commits += 1
    end
  end

  { commits: commits,
    files_changed: files_changed,
    insertions: insertions,
    deletions: deletions }
end


authors = git_authors(options[:after], options[:before])

authors.split("\n").each do |author|
  raw_data = git_log_stats(author, options[:after], options[:before])
  stats = count_stats(raw_data)

  puts author
  puts "#{stats[:commits]} commits"
  puts "#{stats[:files_changed]} files changed"
  puts "#{stats[:insertions]} insertions(+)"
  puts "#{stats[:deletions]} deletions(-)"
  puts
end