soccer_rank.exs

input = System.argv()
  |> List.first()
if input != nil do
  lines = File.stream!(input)
  |> Stream.map(&String.trim/1)

  output = lines
  |> Enum.reduce(%{}, fn (line, result)->
      [_, team_a, score_a, team_b, score_b] = Regex.run(~r{^([\w\s]+)(\d+), ([\w\s]+)(\d+)$}, line)
      [team_a, team_b, score_a, score_b] = [String.trim(team_a), String.trim(team_b), String.to_integer(score_a), String.to_integer(score_b)]
      [point_a, point_b] =
        cond do
          score_a > score_b -> [3, 0]
          score_a < score_b -> [0, 3]
          true -> [1, 1]
        end

      result
      |> Map.put(team_a, Map.get(result, team_a, 0) + point_a)
      |> Map.put(team_b, Map.get(result, team_b, 0) + point_b)
    end)

  output
  |> Enum.sort(fn({a, point_a}, {b, point_b}) -> if(point_a == point_b, do: a < b, else: point_a > point_b) end)
  |> Enum.with_index(1) |> Enum.reduce({-1, 1}, fn ({{cur_team, cur_point}, index}, {prev_point, prev_pos}) ->
      cur_pos = if(prev_point != cur_point, do: index, else: prev_pos)
      IO.puts "#{cur_pos}. #{cur_team}, #{cur_point} pt#{if(cur_point != 1, do: "s", else: "")}"
      {cur_point, cur_pos}
  end)
else
  IO.puts "Missing filename."
end