require "advent"

struct Tuple(*T)
  def reduce_fraction
    gcd = (self[0].gcd self[1]).abs
    return self if gcd == 0
    {self[0] // gcd, self[1]//gcd}
  end
end

struct Tuple(*T)
  def -(other)
    {self[0]-other[0], self[1] - other[1]}
  end
end

input = input(2019, 10)
asteroids = Set({Int32, Int32}).new
input.lines.each_with_index do |l, y|
  l.chars.each_with_index do |c, x|
    next unless c == '#'
    asteroids << {x, y}
  end
end

p1 = asteroids.max_of do |a|
  angles = Set({Int32, Int32}).new
  asteroids.each do |b|
    next if a == b
    angles << (b-a).reduce_fraction
  end
  angles.size
end

puts p1

p2s = asteroids.max_by do |a|
  angles = Set({Int32, Int32}).new
  asteroids.each do |b|
    next if a == b
    angles << (b-a).reduce_fraction
  end
  angles.size
end

angle_groups = asteroids.group_by do |a|
  (a - p2s).reduce_fraction
end
angle_groups.delete({0,0})
angle_groups.each do |k, v|
  v.sort! do |a|
    (a - p2s).sum
  end
end

angles = angle_groups.keys.sort_by do |k|
  -Math.atan2(k[0].to_f32, k[1].to_f32)
end
i = 1
angles.cycle do |angle|
  next if angle_groups[angle].empty?
  asteroid = angle_groups[angle].delete_at(0)
  if i == 200
    puts asteroid[0] * 100 + asteroid[1]
    break
  end
  i += 1
end