# (c) Chui Tey 2007
# http://www.cognoware.com

# zellers formula
month_rel = {
    1   :   0,
    2   :   3,
    3   :   3,
    4   :   6,
    5   :   1,
    6   :   4,
    7   :   6,
    8   :   2,
    9   :   5,
   10   :   0,
   11   :   3,
   12   :   5,
}

# TODO: use localized days as in calendar.py
#       to get days of week and month names

dow_text = {
    0   :   'Su',
    1   :   'Mo',
    2   :   'Tu',
    3   :   'We',
    4   :   'Th',
    5   :   'Fr',
    6   :   'Sa',
}

mon_text = {
    1   :   'Jan',
    2   :   'Feb',
    3   :   'Mar',
    4   :   'Apr',
    5   :   'May',
    6   :   'Jun',
    7   :   'Jul',
    8   :   'Aug',
    9   :   'Sep',
    10  :   'Oct',
    11  :   'Nov',
    12  :   'Dec',
}

def is_leap(year):
    if divmod(year, 400)[1] == 0:
        return 1
    elif divmod(year, 100)[1] == 0:
        return 0
    elif divmod(year, 4)[1] == 0:
        return 1
    else:
        return 0

def dayofweek(year, month, day):
    if month in (1,2) and is_leap(year):
        mod, rem = divmod(year + year / 4 + month_rel[month] + day - 1 - 2, 7)
    else:    
        mod, rem = divmod(year + year / 4 + month_rel[month] + day - 0 - 2, 7)
    return rem

# print dayofweek(2006, 02, 15)

def dategrid(cols, rows):
    def date(i, j):
        d = i+j*cols+1
        if d <= 31:
            return '%2d' % d
        else:
            return '  '
            
    assert divmod(cols, 7)[1] == 0
    for j in range(rows):
        #line = " ".join(["%2d" % (divmod(i+j*cols, 31)[1]+1) for i in range(cols)])
        line = " ".join([date(i,j) for i in range(cols)])
        print "%12s %s" % ("", line)

def weekhead(year, cols):
    headers = {}
    for month in range(1, 13):
        dow = dayofweek(year, month, 1)
        line = " ".join(["%2s" % dow_text[divmod(dow+day,7)[1]] for day in range(cols)])
        if not headers.has_key(line): headers[line] = []
        headers[line].append(mon_text[month])    
    for line, months in headers.items():
        month_head = " ".join(months)
        print "%12s %s %-12s" % (month_head, line, month_head)

def weekhead2(year1, year2, cols):
    headers = {}
    for year in [year1, year2]:
        for month in range(1, 13):
            dow = dayofweek(year, month, 1)
            line = " ".join(["%2s" % dow_text[divmod(dow+day,7)[1]] for day in range(cols)])

            dow_key = (dow, line) # used for decorated sort of the week headers
            if not headers.has_key(dow_key): headers[dow_key] = []
            headers[dow_key].append((year, mon_text[month]))    
    
    weekdays = headers.keys()
    weekdays.sort()
    for (dow, line) in weekdays:
        yearmonths = headers[(dow, line)]
        month_head1 = " ".join([month for (year, month) in yearmonths if year == year1])
        month_head2 = " ".join([month for (year, month) in yearmonths if year == year2])
        print "%12s %s %-12s" % (month_head1, line, month_head2)

def pryear(year):
    dategrid(cols, rows)
    weekhead(year, cols)

def pryear2(year1, year2):

    dategrid(cols, rows)
    print "%12s %20s %-12s" % (year1, '', year2)
    weekhead2(year1, year2, cols)

# Usage:
cols, rows = 7, 5
#pryear(2008)
pryear2(2008, 2009)