module BlameHelper
  def age_map_duration(blame_groups, project)
    now = Time.zone.now
    start_date = blame_groups.map { |blame_group| blame_group[:commit].committed_date }
      .append(project.created_at).min

    {
      now: now,
      started_days_ago: (now - start_date).to_i / 1.day
    }
  end

  def age_map_class(commit_date, duration)
    if duration[:started_days_ago] == 0
      "blame-commit-age-0"
    else
      commit_date_days_ago = (duration[:now] - commit_date).to_i / 1.day
      # Numbers 0 to 10 come from this calculation, but only commits on the oldest
      # day get number 10 (all other numbers can be multiple days), so the range
      # is normalized to 0-9
      age_group = [(10 * commit_date_days_ago) / duration[:started_days_ago], 9].min
      "blame-commit-age-#{age_group}"
    end
  end
end