Day 21

Mix.install([
  {:kino, "~> 0.7.0"}
])

IEx.Helpers.c("/Users/johnb/dev/2023adventOfCode/advent_of_code.ex")
alias AdventOfCode, as: AOC
alias Kino.Input

# Note: when making the next template, something like this works well:
#   `cat day04.livemd | sed 's/03/04/' > day04.livemd`
#

Installation and Data

input_p1example = Kino.Input.textarea("Example Data")

input_p1puzzleInput = Kino.Input.textarea("Puzzle Input")

input_source_select =
  Kino.Input.select("Source", [{:example, "example"}, {:puzzle_input, "puzzle input"}])

p1data = fn ->
  (Kino.Input.read(input_source_select) == :example &&
     Kino.Input.read(input_p1example)) ||
    Kino.Input.read(input_p1puzzleInput)
end

Part 1

defmodule Day21 do
  @directions [:north, :south, :east, :west]
  @start "S"
  @rock "#"
  # @garden "."
  @part_1_steps 64

  def mark_neighbors(%{grid: grid, steps: cell_ids}, step_number) do
    compass = AOC.build_compass(grid)
    possible_steps = for direction <- @directions, cell_id <- cell_ids, do: {direction, cell_id}

    next_steps =
      possible_steps
      |> Enum.reduce([], fn {direction, cell_id}, acc ->
        potential_cell = cell_id + compass[direction]

        if AOC.on_edge_of_board?(grid, cell_id, direction) ||
             grid[potential_cell] == @rock do
          acc
        else
          [potential_cell | acc]
        end
      end)
      |> Enum.uniq()

    # |> Enum.sort()

    IO.puts("#{step_number}: #{Enum.count(next_steps)}")

    grid =
      next_steps
      |> Enum.reduce(grid, fn cell_id, acc ->
        Map.put(acc, cell_id, step_number)
      end)

    # |> AOC.display_grid()

    %{grid: grid, steps: next_steps}
  end

  def solve(text) do
    grid = AOC.as_grid(text)
    IO.inspect([grid.grid_width, grid.grid_height], label: "dimensions")

    start =
      grid
      |> AOC.grid_cells()
      |> Enum.find(fn x -> grid[x] == @start end)

    IO.inspect(String.length("oOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoO"),
      label: "is it 64?"
    )

    # (1..@part_1_steps)
    "oOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoO"
    |> String.split("", trim: true)
    |> Enum.reduce(
      %{grid: grid, steps: [start]},
      fn step_number, acc ->
        mark_neighbors(acc, step_number)
      end
    )

    nil
  end

  def solve2(text) do
    text
  end
end

p1data.()
|> Day21.solve()
|> IO.inspect(label: "\n*** Part 1 solution (example: )")

# 2331 is too low

# p1data.()
# |> Day21.solve2()
# |> IO.inspect(label: "\n*** Part 2 solution (example: )")

#