#!/usr/bin/env ruby

require "debug"
require "ostruct"

MOVES = 100

input = (if ARGV.first.nil?
  WIDTH = 11
  HEIGHT = 7

  DATA
else
  WIDTH = 101
  HEIGHT = 103

  ARGF
end)

def print_grid(grid)
  grid.each_with_index do |row, y|
    row.each_with_index do |val, x|
      if  val.size > 0
        print grid[y][x].size
      elsif x == WIDTH / 2 || y == HEIGHT / 2
        print " "
      else
        print " "
      end
    end
    puts
  end
  puts
  puts
end

def move(grid, ticks = 1)
  new_grid = Array.new(HEIGHT) { Array.new(WIDTH) { Array.new } }
  grid.each_with_index do |row, y|
    row.each_with_index do |val, x|
      movements = val.map do |robot|
        new_x = (x + robot.first * ticks) % WIDTH
        new_y = (y + robot.last * ticks) % HEIGHT

        new_grid[new_y][new_x] << robot
      end
    end
  end

  new_grid
end

def safety_factor(grid)
  [
    [[0, 0], [HEIGHT / 2 - 1, WIDTH / 2 - 1]],
    [[0, WIDTH / 2 + 1], [HEIGHT / 2 - 1, WIDTH - 1]],
    [[HEIGHT / 2 + 1, 0], [HEIGHT - 1, WIDTH / 2 - 1]],
    [[HEIGHT / 2 + 1, WIDTH / 2 + 1], [HEIGHT - 1, WIDTH - 1]],
  ].map do |(top_left, bottom_right)|
    (top_left.first..bottom_right.first).map do |y|
      (top_left.last..bottom_right.last).map do |x|
        grid[y][x].size
      end.sum
    end.sum
  end.inject(:*)
end

def count_top(grid)
  (0...HEIGHT / 2).map do |y|
    grid[y].select { !_1.empty? }.size
  end.sum
end

grid = Array.new(HEIGHT) { Array.new(WIDTH) { Array.new } }
input = input.readlines(chomp: true)
  .map do |line|
    x, y, vx, vy = line.scan(/(-?\d+)/).flatten.map(&:to_i)
    grid[y][x] << [vx, vy]
  end

new_grid = move(grid.clone.map(&:clone), MOVES)
part_1 = safety_factor(new_grid)

new_grid = grid.dup.map(&:dup)
candidates = (WIDTH * HEIGHT).times.map.with_index do |moves|
  new_grid = move(new_grid)

  [moves + 1, safety_factor(new_grid)]
end.sort_by(&:last)

part_2 = candidates.first.first

print_grid(move(grid, candidates.first.first))
p part_1
p part_2

__END__
p=0,4 v=3,-3
p=6,3 v=-1,-3
p=10,3 v=-1,2
p=2,0 v=2,-1
p=0,0 v=1,3
p=3,0 v=-2,-2
p=7,6 v=-1,-3
p=3,0 v=-1,-2
p=9,3 v=2,3
p=7,3 v=-1,2
p=2,4 v=2,-3
p=9,5 v=-3,-3