instructions = File.stream!("inputs/day6.txt")

regex = ~r/(toggle|turn off|turn on) ([0-9]+),([0-9]+) through ([0-9]+),([0-9]+)/

endLights1 =
  Enum.reduce(instructions, MapSet.new(), fn instruction, acc ->
    [_, action, x1, y1, x2, y2] = Regex.run(regex, instruction)
    {x1, ""} = Integer.parse(x1)
    {x2, ""} = Integer.parse(x2)
    {y1, ""} = Integer.parse(y1)
    {y2, ""} = Integer.parse(y2)

    case action do
      "toggle" ->
        for x <- x1..x2, y <- y1..y2, reduce: acc do
          acc ->
            if MapSet.member?(acc, {x, y}) do
              MapSet.delete(acc, {x, y})
            else
              MapSet.put(acc, {x, y})
            end
        end

      "turn off" ->
        for x <- x1..x2, y <- y1..y2, reduce: acc do
          acc -> MapSet.delete(acc, {x, y})
        end

      "turn on" ->
        for x <- x1..x2, y <- y1..y2, reduce: acc do
          acc -> MapSet.put(acc, {x, y})
        end
    end
  end)

litLights1 = MapSet.size(endLights1)

IO.puts("Lit lights count 1: #{litLights1}")

min = 0
max = 999

startLights2 =
  for x <- min..max, y <- min..max, reduce: Map.new() do
    acc -> Map.put(acc, {x, y}, 0)
  end

endLights2 =
  Enum.reduce(instructions, startLights2, fn instruction, acc ->
    [_, action, x1, y1, x2, y2] = Regex.run(regex, instruction)
    {x1, ""} = Integer.parse(x1)
    {x2, ""} = Integer.parse(x2)
    {y1, ""} = Integer.parse(y1)
    {y2, ""} = Integer.parse(y2)

    case action do
      "toggle" ->
        for x <- x1..x2, y <- y1..y2, reduce: acc do
          acc ->
            {_, acc} = Map.get_and_update!(acc, {x, y}, fn i -> {i, i + 2} end)
            acc
        end

      "turn off" ->
        for x <- x1..x2, y <- y1..y2, reduce: acc do
          acc ->
            {_, acc} =
              Map.get_and_update!(acc, {x, y}, fn
                0 -> {0, 0}
                i -> {i, i - 1}
              end)

            acc
        end

      "turn on" ->
        for x <- x1..x2, y <- y1..y2, reduce: acc do
          acc ->
            {_, acc} = Map.get_and_update!(acc, {x, y}, fn i -> {i, i + 1} end)
            acc
        end
    end
  end)

lightIntensity2 = Map.values(endLights2) |> Enum.sum()

IO.puts("Lit lights intensity 2: #{lightIntensity2}")