Doomsday Calculator

# Doomsday calculator - coded by CMHammond

from random import randint

# date = [2018, 12, 11]
DAYS_OF_WEEK = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"]

def is_leap_year(year):
    # Divisible by 4/100/400?
    if year % 4 == 0:
        if not year % 100 == 0:
            return True
        elif year % 400 == 0:
            return True

    # If the year is divisble by 4 and 100, but not 400.
    # OR not divisible by 4 at all.
    return False


def random_date():
    # The Gregorian calendar was introduced in October 1582 by Pope Gregory XIII.
    # Although, it took time for all of Europe to adopt it, with Greece being the last in 1923.
    date = [randint(1583, 2100)]
    date.append(randint(1, 12))

    # ________________________________________________________
    if date[1] in [1, 3, 5, 7, 8, 10, 12]:
        dayLimit = 31

    elif date[1] in [4, 6, 9, 11]:
        dayLimit = 30

    else:
        # Dealing with leap years, if the month is February.
        if is_leap_year(date[0]) == False:
            dayLimit = 28

        else:
            dayLimit = 29
    # ________________________________________________________

    date.append(randint(1, dayLimit))

    # [YYYY, MM, DD]
    return date


def display_date(date):
    months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October",
              "November", "December"]

    suffix = "th"

    if date[2] in [1, 21, 31]:
        suffix = "st"
    elif date[2] in [2, 22]:
        suffix = "nd"
    elif date[2] in [3, 23]:
        suffix = "rd"

    month = months[date[1] - 1]

    return "The %d%s of %s %d" % (date[2], suffix, month, date[0])


def doomsday(date):
    dDays = {"1": 3, "2": 28, "3": 0, "4": 4, "5": 9, "6": 6, "7": 11, "8": 8, "9": 5, "10": 10, "11": 7,
             "12": 12}

    if is_leap_year(date[0]) and (date[1] in ["01", "02", 1, 2]):
        days = (date[2] - (dDays[ str( date[1] ) + 1] )) % 7
    else:
        days = (date[2] - dDays[ str(date[1]) ] ) % 7

        # Returns a 5, 3, 2 or 0. Works out the century code. 21st century counts as 20 or 2/Tuesday.
        fwts = [0, 5, 3, 2, 0, 5, 3]
        century = date[0] / 100

        # This needs to be improved, not sure how. abs() maybe?
        if century >= 20:
            anchor = fwts[3 + ((century - 20) % 4)]
        else:
            anchor = fwts[3 - ((20 - century) % 4)]

        yearDigits = int(str(date[0])[2:])

        # The actual calculation.
        a = yearDigits / 12
        b = yearDigits % 12
        c = b / 4

    result = (days + anchor + a + b + c) % 7

    return [result, days, anchor, a, b, c]


# Anchor point (Friday, Wednesday, Tuesday, Sunday) or (5, 3, 2, 0) [%4]
# Last two digits / 12 = A (Integer) and remainder is B
# B / 4 = C (Integer)
# (Days + Anchor + A + B + C) % 7 = Your answer

# Allow for infinitely large years, ie: 2'909'034. You need to check digits [:len(year - 2)] or 2909000 and the last two.
# User can enter RANDOM or R, instead of DDMMYYYY
# Menu has in-depth, step-by-step, quick answer and random date
# Menu will also allow date to have step-by-step/in-depth or quick answer afterwards.


def usable_input(date):
    # Turns DDMMYYYY into a list of YYYY, MM, DD.

    dateList = [int(date[4:])]
    dateList.append(int(date[2:4]))
    dateList.append(int(date[:2]))

    # [YYYY, MM, DD]
    return dateList


def date_check(date):
    if len(date) < 5:
        print "ERROR - Date is invalid.\n"
        menu_answer()
        return

    # Remove seperators (if correctly placed)
    if str(date[2]) in [".", "-", "/"] and str(date[5]) in [".", "-", "/"]:
        date = date[:2] + date[3:5] + date[6:]

    # Testing if the date is valid, even if the user puts a "-" at the start.
    try:
        int(date) and int(date[0])
    except ValueError:
        print "ERROR - Date is invalid.\n"
        menu_answer()
        return

    return usable_input(date)



def programHeader():
    print "_" * 195
    print " :::::::-.      ...         ...     .        :   .::::::.:::::::-.    :::.  .-:.     ::-.    .,-:::::   :::.      :::       .,-:::::  ...    ::: :::      :::. ::::::::::::   ...    :::::::..   "
    print "  ;;,   `';, .;;;;;;;.   .;;;;;;;.  ;;,.    ;;; ;;;`    ` ;;,   `';,  ;;`;;  ';;.   ;;;;'  ,;;;'````'   ;;`;;     ;;;     ,;;;'````'  ;;     ;;; ;;;      ;;`;;;;;;;;;;''''.;;;;;;;. ;;;;``;;;;"
    print "  `[[     [[,[[     \[[,,[[     \[[,[[[[, ,[[[[,'[==/[[[[,`[[     [[ ,[[ '[[,  '[[,[[['    [[[         ,[[ '[[,   [[[     [[[        [['     [[[ [[[     ,[[ '[[,   [[    ,[[     \[[,[[[,/[[['  "
    print "   $$,    $$$$$,     $$$$$$,     $$$$$$$$$$$\"$$$  '''    $ $$,    $$c$$$cc$$$c   c$$\"      $$$        c$$$cc$$$c  $$'     $$$        $$      $$$ $$'    c$$$cc$$$c  $$    $$$,     $$$$$$$$$c    "
    print "   888_,o8P'\"888,_ _,88P\"888,_ _,88P888 Y88\" 888o88b    dP 888_,o8P' 888   888,,8P\"`       `88bo,__,o, 888   888,o88oo,.__`88bo,__,o,88    .d888o88oo,.__888   888, 88,   \"888,_ _,88P888b \"88bo,"
    print "   MMMMP\"`    \"YMMMMMP\"   \"YMMMMMP\" MMM  M'  \"MMM \"YMmMY\"  MMMMP\"`   YMM   \"\"`mM\"            \"YUMMMMMP\"YMM   \"\"` \"\"\"\"YUMMM  \"YUMMMMMP\"\"YmmMMMM\"\"\"\"\"\"YUMMMYMM   \"\"`  MMM     \"YMMMMMP\" MMMM   \"W\""
    print "_" * 195
    print


def displayMenu():
    print
    print "_" * 60
    print "Choices: (A)nswer, (R)andom, (S)tep-by-step, (I)n-depth"



def menu_answer():
    date = raw_input("Please enter a date (DDMMYYY): ")

    if date.lower() in ["menu", "m"]:
        menu()
        return

    if date.lower() in ["random", "r"]:
        date = random_date()
        print "Random date chosen:", display_date(date), "\n"
        print DAYS_OF_WEEK[doomsday(date)[0]], display_date(date)

    else:
        date = date_check(date)
        if not date == None:
            print display_date(date), "was a", DAYS_OF_WEEK[doomsday(date)[0]].upper()

def menu():

    programHeader()
    i = None
    while i not in ["quit", "q", "exit", "e"]:
        displayMenu()
        i = raw_input("> ")

        if i.lower() in ["random", "r"]:
            date = random_date()
            print "Random date chosen:", display_date(date)
            raw_input("\nPress ENTER to show answer\n")
            print display_date(date), "was a", DAYS_OF_WEEK[doomsday(date)[0]].upper()

        elif i.lower() in ["answer", "a"]:
            menu_answer()

        elif i not in ["quit", "q", "exit", "e"]:
            print "Please enter a valid option."

    print "Program terminated."
    exit()


menu()