day_14.ex

defmodule AdventOfCode.Y2017.Day14 do
  @moduledoc """
  --- Day 14: Disk Defragmentation ---
  Problem Link: https://adventofcode.com/2017/day/14
  Difficulty: m
  Tags: not-fast-enough half-done hash
  """
  alias AdventOfCode.Helpers.{InputReader, Transformers}
  alias AdventOfCode.Y2017.Day10

  def input, do: InputReader.read_from_file(2017, 14)

  def run(input \\ input()) do
    squares = input |> parse() |> squares()

    {run_1(squares), run_2(squares)}
  end

  def parse(data \\ input()), do: hd(Transformers.lines(data))

  defp run_1(squares) do
    squares
    |> Enum.sum_by(&Enum.count(&1, fn i -> i == "1" end))
  end

  defp run_2(_squares) do
    {:todo, 2}
  end

  defp squares(input) do
    0..127
    |> Enum.map(fn key ->
      "#{input}-#{key}"
      |> Day10.compute_knot_hash()
      |> to_bits()
    end)
  end

  defp to_bits(hash) do
    hash
    |> String.graphemes()
    |> Enum.map_join(fn digit ->
      digit
      |> String.to_integer(16)
      |> Integer.to_string(2)
      |> String.pad_leading(4, "0")
    end)
    |> String.graphemes()
  end
end