require "./common.cr"

lines = File.read("day10_input").split "\n"
lines.pop

points = [] of Tuple(Int64, Int64, Int64, Int64)

REGEX = /position=<\s*(-?\d+),\s*(-?\d+)> velocity=<\s*(-?\d+), \s*(-?\d+)>/
lines.map(&.match(REGEX)).each do |match|
  match = match.not_nil!
  points << { match[1].to_i64, match[2].to_i64, match[3].to_i64, match[4].to_i64 }  
end

def max_distance(points)
  points.product(points).max_of do |left, right|
    (left[0] - right[0]).abs + (left[1] - right[1]).abs
  end
end

def simulate(points, multiplier = 1)
  points.size.times do |index|
    old = points[index]
    points[index] = { old[0] + multiplier * old[2], old[1] + multiplier * old[3], old[2], old[3] }
  end
end

def print_message(points)
  max_x = points.max_of &.[0]
  min_x = points.min_of &.[0]
  max_y = points.max_of &.[1]
  min_y = points.min_of &.[1]

  (max_y - min_y + 2).times do |yoff|
    (max_x - min_x + 2).times do |xoff|
      x = min_x + xoff - 1
      y = min_y + yoff - 1
      if points.any? { |point| (point[0] == x) && (point[1] == y) }
        STDOUT << '▩'
      else
        STDOUT << '.'
      end
    end
    puts
  end
end

d1 = max_distance(points)
simulate(points)
d2 = max_distance(points)
times = (d2 / (d2 - d1)).abs - 10
simulate(points, times)

20.times do |i|
  simulate(points, multiplier = 1)
  print_message(points)
  puts "^ #{times + 1 + i + 1}"
end