ZeusWPI/gamification

# == Schema Information
#
# Table name: commits
#
#  id            :integer          not null, primary key
#  coder_id      :integer
#  repository_id :integer
#  sha           :string(255)      not null
#  additions     :integer          default(0), not null
#  deletions     :integer          default(0), not null
#  date          :datetime         not null
#  created_at    :datetime
#  updated_at    :datetime
#

class Commit < ActiveRecord::Base
  belongs_to :coder
  belongs_to :repository

  require 'rugged'

  scope :additions, -> { sum :additions }
  scope :deletions, -> { sum :deletions }

  def addition_score
    (Math.log(additions + 1) *
      Rails.application.config.addition_score_factor).round
  end

  def reward!
    coder.reward_commit!(self)
  end

  def self.register_from_sha(repo, sha, **opts)
    r_commit = repo.rugged_repo.lookup(sha)
    register_rugged(repo, r_commit, **opts)
  end

  def self.register_rugged(repo, r_commit, reward: true)
    # if committer can't be determined, fuck this shit
    committer = get_committer(repo, r_commit)
    return nil unless committer
    Commit.find_or_create_by(repository: repo,
                             sha: r_commit.oid,
                             coder: committer) do |commit|
      commit.initialize_from_rugged(r_commit)
      commit.reward! if reward
    end
  end

  def self.get_committer(repo, r_commit)
    identity = GitIdentity.find_by(name: r_commit.author[:name],
                                   email: r_commit.author[:email])
    unless identity
      coder = get_committer_from_github(repo, r_commit)
      return nil unless coder
      identity = GitIdentity.create(name:  r_commit.author[:name],
                                    email: r_commit.author[:email],
                                    coder: coder)
    end
    identity.coder
  end

  def self.get_committer_from_github(repo, r_commit)
    github = Rails.configuration.x.github
    commit = github.repos.commits.get(Rails.application.config.organisation,
                                      repo.name, r_commit.oid)
    if commit.author
      Coder.find_or_create_by_github_name(commit.author.login)
    end
  end

  def initialize_from_rugged(r_commit)
    self.date = r_commit.time
    set_stats(r_commit)
  end

  def github_url
    repository.github_url + "/commit/#{sha}"
  end

  private

  def set_stats(r_commit)  # rubocop:disable Style/AccessorMethodName
    if r_commit.parents.size >= 2
      # Do not reward merges
      self.additions = self.deletions = 0
    else
      if r_commit.parents.empty?
        # First commit
        diff = r_commit.diff
      else
        diff = r_commit.diff(r_commit.parents.first)
      end
      self.additions = diff.stat[2]
      self.deletions = diff.stat[1]
    end
  end
end