Complete day 6 part 2

Author: ctlevi

day6.exs

@@ -1,4 +1,4 @@
-defmodule Day6 do
+defmodule Day6.Part1 do
   @regex ~r/(?<command>\w*?\s?\w*) (?<top_x>\d*),(?<top_y>\d*) through (?<bottom_x>\d*),(?<bottom_y>\d*)/
 
   # Puts in instructions in the format {:command, {top_tuple}, {bottom_tuple}}
@@ -10,7 +10,11 @@ defmodule Day6 do
     end
   end
 
-  def follow_instructions(instructions) do
+  def total_on(instructions) do
+    follow_instructions(instructions) |> Dict.values |> Enum.filter(&(&1 == true)) |> Enum.count
+  end
+
+  defp follow_instructions(instructions) do
     coordinates = Enum.flat_map 0..999, fn x ->
       Enum.map 0..999, fn y -> {x, y} end
     end
@@ -37,10 +41,42 @@ defmodule Day6 do
   defp handle_instruction(:toggle, current), do: !current
 end
 
+defmodule Day6.Part2 do
+  def total_brightness(instructions) do
+    follow_instructions(instructions) |> Dict.values |> Enum.sum
+  end
+
+  defp follow_instructions(instructions) do
+    coordinates = Enum.flat_map 0..999, fn x ->
+      Enum.map 0..999, fn y -> {x, y} end
+    end
+    lights = Enum.reduce coordinates, HashDict.new, fn coordinate, acc ->
+      Dict.put(acc, coordinate, 0)
+    end
+
+    Enum.reduce instructions, lights, fn {instruction, top, bottom}, lights ->
+      change_lights(lights, instruction, top, bottom)
+    end
+  end
+
+  defp change_lights(lights, instruction, {top_x, top_y}, {bottom_x, bottom_y}) do
+    coordinates = Enum.flat_map top_x..bottom_x, fn x ->
+      Enum.map top_y..bottom_y, fn y -> {x, y} end
+    end
+    Enum.reduce coordinates, lights, fn coordinate, lights ->
+      Dict.update!(lights, coordinate, fn current -> handle_instruction(instruction, current) end)
+    end
+  end
+
+  defp handle_instruction(:turn_on, current), do: current + 1
+  defp handle_instruction(:turn_off, current), do: max(0, current - 1)
+  defp handle_instruction(:toggle, current), do: current + 2
+end
+
 {:ok, input} = File.read("input/day6.txt")
 parsed_instructions = input
   |> String.split("\n")
-  |> Day6.parse_instructions
+  |> Day6.Part1.parse_instructions
 
-#val = Day6.start([{:turn_on, {0, 0}, {999, 999}}])
-IO.inspect(Day6.follow_instructions(parsed_instructions) |> Dict.values |> Enum.filter(&(&1 == true)) |> Enum.count)
+IO.inspect Day6.Part1.total_on(parsed_instructions)
+IO.inspect Day6.Part2.total_brightness(parsed_instructions)