import math
import copy

class dimension:
	def __init__(self, a, b):
		self.a = a
		self.b = b

	def get_ratio(self):
		return self.a/self.b

	#scales this object so it fits into to_fit, maximizing size while keeping its ratio
	def scale_to_fit(self, to_fit):
		r = self.get_ratio()
		if r > to_fit.get_ratio():  # wider than to_fit -> fit width, scale height
			self.a, self.b = to_fit.a, to_fit.a/r
		else:  						# higher than to_fit -> fit height, scale width
			self.a, self.b = to_fit.b*r, to_fit.b

#for test runs of dim.scale_to_fit
def test(to_scale, to_fit):
	after_to_scale, after_to_fit = copy.copy(to_scale), copy.copy(to_fit)
	after_to_scale.scale_to_fit(after_to_fit)

	print("--- test run ---")
	print("to_fit dim: ", to_fit.a, to_fit.b)
	print("to_fit ratio:", to_fit.get_ratio())
	print("to_scale dim: ", to_scale.a, to_scale.b)
	print("to_scale ratio:", to_scale.get_ratio())

	print("new to_scale dim:", after_to_scale.a, after_to_scale.b)
	print("new to_scale ratio:", after_to_scale.get_ratio())

	assert to_fit.get_ratio() == to_fit.a / to_fit.b, "ratio calculation failed"
	assert after_to_fit.a == to_fit.a, "to_fit changed"
	assert after_to_fit.b == to_fit.b, "to_fit changed"
	assert math.isclose(after_to_scale.get_ratio(), to_scale.get_ratio(), rel_tol=1e-07), "to_scale ratio changed"

	if after_to_scale.get_ratio() > after_to_fit.get_ratio():
		assert after_to_scale.a == after_to_fit.a, "scaling failed"
		assert after_to_scale.b == after_to_fit.a / to_scale.get_ratio(), "scaling failed"
	else:
		assert after_to_scale.a == after_to_fit.b * to_scale.get_ratio(), "scaling failed"
		assert after_to_scale.b == after_to_fit.b, "scaling failed"


if __name__ == "__main__":
	test(dimension(1600, 900), dimension(10, 30))
	test(dimension(1600, 900), dimension(30, 30))
	test(dimension(30, 10), dimension(1600, 900))
	test(dimension(10, 30), dimension(1600, 900))