contributions.rb

require 'json'

module GitHelper
  def get_tag(steps: 1)
    tag = `git tag -l`.split("\n")[-steps]
  end

  def the_goods since: get_tag
    `git shortlog #{since}..HEAD`
  end

  def sanitize(steps: 1)
    tag = get_tag(steps: steps)
    goods = the_goods(since: tag)
    lines = goods.split("\n")
    lines.reject { |line| line.include?("Merge pull request") }
      .map { |line| line.author? ? line.mine_author : line }
  end

  def process(steps: 1)
    lines = sanitize(steps: steps)
    report = {}
    current_author = nil

    lines.each do |line|
      next if line.empty?
      if line.author?
        current_author = line.mine_author
      else
        report[current_author] ||= []
        report[current_author] << line.strip
      end
    end

    report
  end
end

class ScoreCard
  include GitHelper
  attr_accessor :players

  def initialize(innings: 1)
    score_game(innings)
  end

  def score_game(steps)
    @players ||= []
    replay = process steps: steps
    replay.each do |player, contributions|
      @players << Player.new(name: player, contributions: contributions)
    end
  end
end

class Player
  attr_accessor :name, :contributions

  def initialize(name: nil, contributions: nil)
    raise MissingArgumentsError unless name && contributions
    @name = name
    @contributions = contributions
  end

  def score
    contributions.count
  end
end

class String
  def commit?
    self[0] == ' '
  end

  def author?
    !empty? && self[0].match(/^[[:alpha:]]$/)
  end

  def mine_author
    self.sub /\s*\(\d+\)\:$/, ''
  end
end