# we can set up the months as a dictionary so we can easily access extra data about them (like the month factor for calculating the start
# day of the month, and the number of days the month has in it)
months = {'jan':[31,0], 'feb':[28,3], 'mar':[31,3], 'apr':[30,6], 'may':[31,1], 'jun':[30,4], 'jul':[31,6], 'aug':[31,2], 'sept':[30,5], 'oct':[31,0], 'nov':[30,3], 'dec':[31,5]}


def getDOW(month):
    #this will get the day of the week the month starts on according to a quick google search leading to this website http://www.jimloy.com/math/day-week.htm
    #it only works for 2013 for now but can be expanded
    # this expects a list from the months dictionary
    centuryCode = 5
    y = 13
    m = month[1] # this will be the second element
    w = (centuryCode + y + (y//4)+1 + m + 1) % 7 # The final '1' is because the day factor needed is for the day the month will begin on
    return w #returns the day of week the first of the month will be on, 0 is sun, 6 is sat


def formatMonth(month):
# This just formats the month string to be capitalized
    m = month[0].upper() + month[1:] # uppercase the first element of the string and concatonate with the second element on
    return m

def formatCal(monthEnd, dayOfWeek):
# This formats the calendar for the user
# It takes a monthEnd which is the number of days the month has in it (can easily be extended for leap years)
# and the day of the week the first of the month is on 0 being sunday and 6 is saturday
    line = 'sun  mon  tue  wed  thu  fri  sat' # print the days
    line1 = list(range(1, 8-dayOfWeek)) # this creates a list of the days that will fit on the first row of the cal
    #These all take the ending date of the previous line e.g. 6 add 1 and create a list that will fit on that line i.e. equal to 7
    line2 = list(range(line1[-1]+1, line1[-1]+8))
    line3 = list(range(line2[-1]+1, line2[-1]+8))
    line4 = list(range(line3[-1]+1, line3[-1]+8))
    line5 = list(range(line4[-1]+1, monthEnd+1)) # this will end the month apropriatly
    # This is all formating junk not really inportant but you can see a few loops are used instead of typing it all out
    print(line)
    print('     '*(dayOfWeek), end=' ') #dayOfWeek can be zero
    for i in line1:
        print(i, end='    ')

    print('\n')

    for line in line2, line3, line4, line5: #this just loops over the lines/lists we described above
        for i in line: # for each element in the list print it with certian spaces according to one or two digits
            if i >= 9:
                print('',i , end='  ')

            else:
                print('',i , end='   ')
        print('\n') # throw a new line in to break them up

def main():
    month = input('What month? (three letter abbriviation only, q to quit): ') # get user input for three letter month

    while month != 'q': # make a little loop so that entering q will quit

        if month.lower() in months.keys(): # just check if the lowercase input is in the keys of the dict
            key = month.lower() # if it is then lets just use it
            DOW = getDOW(months[key]) # this calls the function returning the day (0-6) that the month starts on
            monthEnd = months[key][0] # gets the months end date 
            print('\n')
            print(formatMonth(key)) # prints the month capitolized
            print('------------------------------------')
            print(formatCal(monthEnd, DOW)) #print the calendar
            print('\n')
            month = input('What month? (q to quit): ') # ask for input again for the loop (q to quit)

        else:
            # this input was not int the dictionary keys so just ask again
            print('Only enter the three letter month abbriviation.')
            month = input('What month? (q to quit): ') # q to quit


if __name__ == '__main__':
    # Start the program
    main()