# Moving a turtle with a Logo program
#
# See Part 2.
module turtle

import logo

# A oriented cursor on a plane
class Turtle
	# x coordinate
	var x = 0.0 is writable

	# y coordinate
	var y = 0.0 is writable

	# angle in degree
	var angle = 0.0 is writable

	redef fun to_s do return "({x},{y};{angle})"

	# Move the turtle forward
	fun fd(distance: Int) do
		var angle_rad = angle * pi / 180.0
		x += distance.to_f * angle_rad.cos
		y += distance.to_f * angle_rad.sin
	end

	# Turn the turtle right
	fun rt(angle: Int) do
		self.angle += angle.to_f
		while self.angle >= 360.0 do self.angle -= 360.0
		while self.angle < 0.0 do self.angle += 360.0
	end
end

redef class Logo
	# Apply the instruction on the turtle
	fun apply(turtle: Turtle) is abstract
end

# TODO

var t

t = new Turtle
logo.fd(50).main.apply(t)
print t

t = new Turtle
logo.fd(10).rt(90).fd(20).main.apply(t)
print t

t = new Turtle
logo.repeat(6).fd(5).repeat(5).fd(10).fini.rt(90).main.apply(t)
print t