defmodule Day25 do
  def run do
    %{locks: locks, keys: keys} = parse_input("data.txt")

    # compare every key against every lock
    good_keys =
      Enum.reduce(keys, 0, fn key, acc ->
        acc +
          Enum.reduce(locks, 0, fn lock, acc2 ->
            acc2 + if fits(lock, key), do: 1, else: 0
          end)
      end)

    dbg(good_keys)
  end

  defp fits(lock, key) do
    Enum.reduce(0..4, true, fn idx, acc ->
      acc and Enum.at(lock, idx) + Enum.at(key, idx) <= 5
    end)
  end

  defp parse_input(file) do
    File.read!(file)
    |> String.trim()
    |> String.split("\n\n")
    |> Enum.reduce(%{locks: [], keys: []}, fn el, %{locks: locks, keys: keys} = acc ->
      grid = String.split(el, "\n") |> Enum.map(&String.graphemes/1)
      is_lock = grid |> hd() |> hd() |> String.graphemes() |> Enum.all?(fn el -> el == "#" end)

      res =
        Enum.map(0..4, fn col ->
          Enum.reduce(0..6, 0, fn row, acc2 ->
            el = Enum.at(grid, row) |> Enum.at(col)

            case el do
              "#" -> acc2 + 1
              _ -> acc2
            end
          end) - 1
        end)

      case is_lock do
        true -> %{acc | locks: [res | locks]}
        false -> %{acc | keys: [res | keys]}
      end
    end)
  end
end

Day25.run()