Tell whether Mercury is retrograde (astrologically bad for computer networks)

retrograde_mercury.py

#!/usr/bin/env python2.6
# -*- coding: utf-8 -*-

from datetime import *
import argparse
import sys

# this script has no actual code to calculate retrograde motion. sorry!

CSI = '['
RED = CSI + '31' + 'm'
BLACK = CSI + '30' + 'm'
YELLOW = CSI + '33' + 'm'
BLUE = CSI + '34' + 'm'

DEFCOLOR = CSI + '39' + 'm'
BOLD = CSI + '1' + 'm'
NOBOLD = CSI + '22' + 'm'

def bold(s):
    return BOLD + s + NOBOLD
def red(s):
    return RED + s + DEFCOLOR
def blue(s):
    return BLUE + s + DEFCOLOR
def yellow(s):
    return YELLOW + s + DEFCOLOR
def gray(s):
    return bold(BLACK + s + DEFCOLOR)

    

dateranges=(
    ((2012,7,14), (2012,8,7)),
    ((2012,11,6), (2012,11,26)),
    ((2013,2,23), (2013,3,17)),
    ((2013,6,26), (2013,7,20)),
    ((2013,10,21), (2013,11,10)),
    ((2014,2,6), (2014,2,28)),
    ((2014,6,7), (2014,7,1)),
    ((2014,10,4), (2014,10,25)),
    ((2015,1,21), (2015,2,11)),
    ((2015,5,18), (2015,6,11)),
    ((2015,9,17), (2015,10,9)),
    ((2016,1,5), (2016,1,25)),
    ((2016,4,28), (2016,5,22)),
    ((2016,8,30), (2016,9,21)),
    ((2016,12,19), (2017,1,8)),
    ((2017,4,9), (2017,5,3)),
    ((2017,8,12), (2017,9,5)),
    ((2017,12,2), (2017,12,22)),
    ((2018,3,22), (2018,4,15)),
    ((2018,7,25), (2018,8,18)),
    ((2018,11,16), (2018,12,6)),
    ((2019,3,5), (2019,3,28)),
    ((2019,7,7), (2019,7,31)),
    ((2019,10,31), (2019,11,20)),
    ((2020,2,16), (2020,3,9)),
    ((2020,6,17), (2020,7,12)),
    ((2020,10,13), (2020,11,3)),
    ((2021,1,30), (2021,2,20)),
    ((2021,5,29), (2021,6,22)),
    ((2021,9,26), (2021,10,18)),
    ((2022,1,14), (2022,2,3)),
    ((2022,5,10), (2022,6,3)),
    ((2022,9,9), (2022,10,2)),
    ((2022,12,29), (2023,1,18)),
    )

dates=[]
for r in dateranges:
    dates.append( ( date(r[0][0], r[0][1], r[0][2]) , 
                    date(r[1][0], r[1][1], r[1][2]) ))

today=date.today()
retro=False
for (start, end) in dates:
    if (today >= start) and (today <= end):
        retro=True
        break

parser = argparse.ArgumentParser(description='Show whether Mercury motion is retrograde.')
parser.add_argument('-c', '--chart', dest='chart', action='store_true',
                   help='also show a chart of retrograde dates')
args = parser.parse_args()

if retro:
    print bold(red('℞☿ Be careful!')) + ' Retrograde mercury today.'
else:
    print bold(blue('☿')) + ' Mercury is prograde today.'


if args.chart:
    print
    print 'Calendar of retrograde dates:'

    nextdue_done=False

    for (start, end) in dates:
        s = start.strftime('%Y-%m-%d')
        e = end.strftime('%Y-%m-%d')
        fmt = '%s\tto\t%s' % (s, e)

        if (today > end):
            print gray(fmt)
        elif (today >= start) and (today <= end):
            print bold(red(fmt + '←'))
        elif not nextdue_done:
            print bold(yellow(fmt + '*'))
            nextdue_done=True
        else:
            print fmt

if retro:
    sys.exit(1)
else:
    sys.exit(0)