"""Calendar printing functions

Note when comparing these calendars to the ones printed by cal(1): By
default, these calendars have Monday as the first day of the week, and
Sunday as the last (the European convention). Use setfirstweekday() to
set the first day of the week (0=Monday, 6=Sunday)."""

import sys
import datetime
import locale as _locale
from itertools import repeat

__all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday",
           "firstweekday", "isleap", "leapdays", "weekday", "monthrange",
           "monthcalendar", "prmonth", "month", "prcal", "calendar",
           "timegm", "month_name", "month_abbr", "day_name", "day_abbr",
           "Calendar", "TextCalendar", "HTMLCalendar", "LocaleTextCalendar",
           "LocaleHTMLCalendar", "weekheader"]

# Exception raised for bad input (with string parameter for details)
error = ValueError

# Exceptions raised for bad input
class IllegalMonthError(ValueError):
    def __init__(self, month):
        self.month = month
    def __str__(self):
        return "bad month number %r; must be 1-12" % self.month


class IllegalWeekdayError(ValueError):
    def __init__(self, weekday):
        self.weekday = weekday
    def __str__(self):
        return "bad weekday number %r; must be 0 (Monday) to 6 (Sunday)" % self.weekday


# Constants for months referenced later
January = 1
February = 2

# Number of days per month (except for February in leap years)
mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

# This module used to have hard-coded lists of day and month names, as
# English strings.  The classes following emulate a read-only version of
# that, but supply localized names.  Note that the values are computed
# fresh on each call, in case the user changes locale between calls.

class _localized_month:

    _months = [datetime.date(2001, i+1, 1).strftime for i in range(12)]
    _months.insert(0, lambda x: "")

    def __init__(self, format):
        self.format = format

    def __getitem__(self, i):
        funcs = self._months[i]
        if isinstance(i, slice):
            return [f(self.format) for f in funcs]
        else:
            return funcs(self.format)

    def __len__(self):
        return 13


class _localized_day:

    # January 1, 2001, was a Monday.
    _days = [datetime.date(2001, 1, i+1).strftime for i in range(7)]

    def __init__(self, format):
        self.format = format

    def __getitem__(self, i):
        funcs = self._days[i]
        if isinstance(i, slice):
            return [f(self.format) for f in funcs]
        else:
            return funcs(self.format)

    def __len__(self):
        return 7


# Full and abbreviated names of weekdays
day_name = _localized_day('%A')
day_abbr = _localized_day('%a')

# Full and abbreviated names of months (1-based arrays!!!)
month_name = _localized_month('%B')
month_abbr = _localized_month('%b')

# Constants for weekdays
(MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY) = range(7)


def isleap(year):
    """Return True for leap years, False for non-leap years."""
    return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)


def leapdays(y1, y2):
    """Return number of leap years in range [y1, y2).
       Assume y1 <= y2."""
    y1 -= 1
    y2 -= 1
    return (y2//4 - y1//4) - (y2//100 - y1//100) + (y2//400 - y1//400)


def weekday(year, month, day):
    """Return weekday (0-6 ~ Mon-Sun) for year (1970-...), month (1-12),
       day (1-31)."""
    return datetime.date(year, month, day).weekday()


def monthrange(year, month):
    """Return weekday (0-6 ~ Mon-Sun) and number of days (28-31) for
       year, month."""
    if not 1 <= month <= 12:
        raise IllegalMonthError(month)
    day1 = weekday(year, month, 1)
    ndays = mdays[month] + (month == February and isleap(year))
    return day1, ndays


class Calendar(object):
    """
    Base calendar class. This class doesn't do any formatting. It simply
    provides data to subclasses.
    """

    def __init__(self, firstweekday=0):
        self.firstweekday = firstweekday # 0 = Monday, 6 = Sunday

    def getfirstweekday(self):
        return self._firstweekday % 7

    def setfirstweekday(self, firstweekday):
        self._firstweekday = firstweekday

    firstweekday = property(getfirstweekday, setfirstweekday)

    def iterweekdays(self):
        """
        Return an iterator for one week of weekday numbers starting with the
        configured first one.
        """
        for i in range(self.firstweekday, self.firstweekday + 7):
            yield i%7

    def itermonthdates(self, year, month):
        """
        Return an iterator for one month. The iterator will yield datetime.date
        values and will always iterate through complete weeks, so it will yield
        dates outside the specified month.
        """
        date = datetime.date(year, month, 1)
        # Go back to the beginning of the week
        days = (date.weekday() - self.firstweekday) % 7
        date -= datetime.timedelta(days=days)
        oneday = datetime.timedelta(days=1)
        while True:
            yield date
            try:
                date += oneday
            except OverflowError:
                # Adding one day could fail after datetime.MAXYEAR
                break
            if date.month != month and date.weekday() == self.firstweekday:
                break

    def itermonthdays2(self, year, month):
        """
        Like itermonthdates(), but will yield (day number, weekday number)
        tuples. For days outside the specified month the day number is 0.
        """
        for i, d in enumerate(self.itermonthdays(year, month), self.firstweekday):
            yield d, i % 7

    def itermonthdays(self, year, month):
        """
        Like itermonthdates(), but will yield day numbers. For days outside
        the specified month the day number is 0.
        """
        day1, ndays = monthrange(year, month)
        days_before = (day1 - self.firstweekday) % 7
        yield from repeat(0, days_before)
        yield from range(1, ndays + 1)
        days_after = (self.firstweekday - day1 - ndays) % 7
        yield from repeat(0, days_after)

    def monthdatescalendar(self, year, month):
        """
        Return a matrix (list of lists) representing a month's calendar.
        Each row represents a week; week entries are datetime.date values.
        """
        dates = list(self.itermonthdates(year, month))
        return [ dates[i:i+7] for i in range(0, len(dates), 7) ]

    def monthdays2calendar(self, year, month):
        """
        Return a matrix representing a month's calendar.
        Each row represents a week; week entries are
        (day number, weekday number) tuples. Day numbers outside this month
        are zero.
        """
        days = list(self.itermonthdays2(year, month))
        return [ days[i:i+7] for i in range(0, len(days), 7) ]

    def monthdayscalendar(self, year, month):
        """
        Return a matrix representing a month's calendar.
        Each row represents a week; days outside this month are zero.
        """
        days = list(self.itermonthdays(year, month))
        return [ days[i:i+7] for i in range(0, len(days), 7) ]

    def yeardatescalendar(self, year, width=3):
        """
        Return the data for the specified year ready for formatting. The return
        value is a list of month rows. Each month row contains up to width months.
        Each month contains between 4 and 6 weeks and each week contains 1-7
        days. Days are datetime.date objects.
        """
        months = [
            self.monthdatescalendar(year, i)
            for i in range(January, January+12)
        ]
        return [months[i:i+width] for i in range(0, len(months), width) ]

    def yeardays2calendar(self, year, width=3):
        """
        Return the data for the specified year ready for formatting (similar to
        yeardatescalendar()). Entries in the week lists are
        (day number, weekday number) tuples. Day numbers outside this month are
        zero.
        """
        months = [
            self.monthdays2calendar(year, i)
            for i in range(January, January+12)
        ]
        return [months[i:i+width] for i in range(0, len(months), width) ]

    def yeardayscalendar(self, year, width=3):
        """
        Return the data for the specified year ready for formatting (similar to
        yeardatescalendar()). Entries in the week lists are day numbers.
        Day numbers outside this month are zero.
        """
        months = [
            self.monthdayscalendar(year, i)
            for i in range(January, January+12)
        ]
        return [months[i:i+width] for i in range(0, len(months), width) ]


class TextCalendar(Calendar):
    """
    Subclass of Calendar that outputs a calendar as a simple plain text
    similar to the UNIX program cal.
    """

    def prweek(self, theweek, width):
        """
        Print a single week (no newline).
        """
        print(self.formatweek(theweek, width), end=' ')

    def formatday(self, day, weekday, width):
        """
        Returns a formatted day.
        """
        if day == 0:
            s = ''
        else:
            s = '%2i' % day             # right-align single-digit days
        return s.center(width)

    def formatweek(self, theweek, width):
        """
        Returns a single week in a string (no newline).
        """
        return ' '.join(self.formatday(d, wd, width) for (d, wd) in theweek)

    def formatweekday(self, day, width):
        """
        Returns a formatted week day name.
        """
        if width >= 9:
            names = day_name
        else:
            names = day_abbr
        return names[day][:width].center(width)

    def formatweekheader(self, width):
        """
        Return a header for a week.
        """
        return ' '.join(self.formatweekday(i, width) for i in self.iterweekdays())

    def formatmonthname(self, theyear, themonth, width, withyear=True):
        """
        Return a formatted month name.
        """
        s = month_name[themonth]
        if withyear:
            s = "%s %r" % (s, theyear)
        return s.center(width)

    def prmonth(self, theyear, themonth, w=0, l=0):
        """
        Print a month's calendar.
        """
        print(self.formatmonth(theyear, themonth, w, l), end='')

    def formatmonth(self, theyear, themonth, w=0, l=0):
        """
        Return a month's calendar string (multi-line).
        """
        w = max(2, w)
        l = max(1, l)
        s = self.formatmonthname(theyear, themonth, 7 * (w + 1) - 1)
        s = s.rstrip()
        s += '\n' * l
        s += self.formatweekheader(w).rstrip()
        s += '\n' * l
        for week in self.monthdays2calendar(theyear, themonth):
            s += self.formatweek(week, w).rstrip()
            s += '\n' * l
        return s

    def formatyear(self, theyear, w=2, l=1, c=6, m=3):
        """
        Returns a year's calendar as a multi-line string.
        """
        w = max(2, w)
        l = max(1, l)
        c = max(2, c)
        colwidth = (w + 1) * 7 - 1
        v = []
        a = v.append
        a(repr(theyear).center(colwidth*m+c*(m-1)).rstrip())