#!/usr/bin/env python3
#
#       This program is free software; you can redistribute it and/or modify
#       it under the terms of the GNU General Public License as published by
#       the Free Software Foundation; either version 3 of the License, or
#       (at your option) any later version.
#
#       This program is distributed in the hope that it will be useful,
#       but WITHOUT ANY WARRANTY; without even the implied warranty of
#       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#       GNU General Public License for more details.
#
#       You should have received a copy of the GNU General Public License
#       along with this program; if not, write to the Free Software
#       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#       MA 02110-1301, USA.

def main():
    print("Find the reference angle of a given degree",
          "\nType only 'Enter' to quit")
    while True:
        degree = get_float("Degree? ")
        degree = return_positive(degree)
        quad = in_quad(degree)
        print_ref(degree, quad)

def get_float(msg):
    while True:
        i = input(msg)
        try:
            if i:
                return float(i)
            else:
                exit()
        except ValueError as err:
            print(err)
            continue

def return_positive(degree):
    if degree <= 360 and degree >=0:
        return degree
    while degree > 360:
        degree -= 360
        if degree < 360 and degree >= 0:
            return degree
    while degree < 360:
        degree += 360
        if degree < 360 and degree >= 0:
            return degree

def in_quad(degree):
    if degree <= 90:
        return "I"
    elif degree <= 180 and degree > 90:
        return "II"
    elif degree <= 270 and degree > 180:
        return "III"
    elif degree <= 360 and degree > 270:
        return "IV"

def print_ref(degree, quad):
    if quad == "I":
        ref = degree
    elif quad == "II":
        ref = 180 - degree
    elif quad == "III":
        ref = degree - 180
    elif quad == "IV":
        ref = 360 - degree
    print("Reference angle is: {0}\N{DEGREE SIGN}".format(ref))

if __name__ == "__main__":
    main()