class Circle
  def initialize(x, y, r)
    @x, @y, @r = [x, y, r].map(&:to_f)
  end
  attr_reader :x, :y, :r

  def self.apollonius(c1, c2, c3, s1=1, s2=1, s3=1)
    x1, y1, r1 = c1.x, c1.y, c1.r
    x2, y2, r2 = c2.x, c2.y, c2.r
    x3, y3, r3 = c3.x, c3.y, c3.r

    v11 = 2*x2 - 2*x1
    v12 = 2*y2 - 2*y1
    v13 = x1**2 - x2**2 + y1**2 - y2**2 - r1**2 + r2**2
    v14 = 2*s2*r2 - 2*s1*r1

    v21 = 2*x3 - 2*x2
    v22 = 2*y3 - 2*y2
    v23 = x2**2 - x3**2 + y2**2 - y3**2 - r2**2 + r3**2
    v24 = 2*s3*r3 - 2*s2*r2

    w12 = v12/v11
    w13 = v13/v11
    w14 = v14/v11

    w22 = v22/v21 - w12
    w23 = v23/v21 - w13
    w24 = v24/v21 - w14

    p = -w23/w22
    q = w24/w22
    m = -w12*p - w13
    n = w14 - w12*q

    a = n**2 + q**2 - 1
    b = 2*m*n - 2*n*x1 + 2*p*q - 2*q*y1 + 2*s1*r1
    c = x1**2 + m**2 - 2*m*x1 + p**2 + y1**2 - 2*p*y1 - r1**2

    d = b**2 - 4*a*c
    rs = (-b - Math.sqrt(d)) / (2*a)
    xs = m + n*rs
    ys = p + q*rs

    self.new(xs, ys, rs)
  end

  def to_s
    
  end
end

puts c1 = Circle.new(0, 0, 1)
puts c2 = Circle.new(2, 4, 2)
puts c3 = Circle.new(4, 0, 1)

puts Circle.apollonius(c1, c2, c3)
puts Circle.apollonius(c1, c2, c3, -1, -1, -1)