advent9.exs

defmodule Advent9 do
  def count(input) do
    no_exclamations =
      input
      |> String.trim()
      |> String.replace("!!!!", "")
      |> String.replace("!!", "")
      |> String.replace(~r/!./, "")
      |> String.codepoints()

    removed_garbage =
      no_exclamations
      |> Enum.reduce(%{garbage_started: false, result: [], garbage_count: 0}, &remove_garbage/2)

    IO.inspect(count_groups(removed_garbage.result).sum)
    IO.inspect(Map.fetch!(removed_garbage, :garbage_count))
  end

  def remove_garbage("<", %{garbage_started: false} = acc),
    do: Map.put(acc, :garbage_started, true)

  def remove_garbage(">", acc), do: Map.put(acc, :garbage_started, false)

  def remove_garbage(_, %{garbage_started: true} = acc),
    do: Map.put(acc, :garbage_count, acc.garbage_count + 1)

  def remove_garbage(el, acc), do: Map.put(acc, :result, acc.result ++ [el])

  def count_groups(list), do: Enum.reduce(list, %{level: 0, sum: 0}, &add_current_element/2)

  def add_current_element("{", acc), do: Map.put(acc, :level, acc.level + 1)

  def add_current_element("}", acc) do
    map = Map.put(acc, :level, acc.level - 1)
    Map.put(map, :sum, acc.sum + acc.level)
  end

  def add_current_element(",", acc), do: acc
end

{:ok, input} = File.read("input9")
input |> Advent9.count()