#!/usr/bin/env python
"""
moonphase.py - Calculate Lunar Phase
Author: Sean B. Palmer, inamidst.com
Cf. http://en.wikipedia.org/wiki/Lunar_phase#Lunar_phase_calculation
"""

import math
import decimal
import datetime

dec = decimal.Decimal


def position(now=None):
    if now is None:
        now = datetime.datetime.now()

    diff = now - datetime.datetime(2001, 1, 1)
    days = dec(diff.days) + (dec(diff.seconds) / dec(86400))
    lunations = dec("0.20439731") + (days * dec("0.03386319269"))

    return lunations % dec(1)


def phase(pos):
    index = (pos * dec(8)) + dec("0.5")
    index = math.floor(index)
    return {
       0: "New Moon",
       1: "Waxing Crescent",
       2: "First Quarter",
       3: "Waxing Gibbous",
       4: "Full Moon",
       5: "Waning Gibbous",
       6: "Last Quarter",
       7: "Waning Crescent"
    }[int(index) & 7]


def main():
    pos = position()
    phasename = phase(pos)

    roundedpos = round(float(pos), 3)
    num_days = float(roundedpos * 29.6)
    simple_days = round(num_days, 1)
    print("%s days" % (simple_days))

if __name__=="__main__":
    main()