source: inundation/ga/storm_surge/pyvolution/normalDate.py @ 1454

#!/usr/bin/env python
# normalDate.py - version 1.3 - 2002/05/24
# Author: Jeff Bauer, Rubicon Research - jbauer@rubic.com
# License: Same as Python 2.1 or later

import time
from types import IntType, ListType, StringType, TupleType

_bigBangScalar = -4345732  # based on (-9999, 1, 1) BC/BCE minimum
_bigCrunchScalar = 2958463  # based on (9999,12,31) AD/CE maximum
_daysInMonthNormal = [31,28,31,30,31,30,31,31,30,31,30,31]
_daysInMonthLeapYear = [31,29,31,30,31,30,31,31,30,31,30,31]
_dayOfWeekName = ['Monday', 'Tuesday', 'Wednesday', 'Thursday',
                  'Friday', 'Saturday', 'Sunday']
_monthName = ['January', 'February', 'March', 'April', 'May', 'June',
              'July','August','September','October','November','December']

class NormalDateException(Exception):
    """Exception class for NormalDate"""
    pass

class NormalDate:
    """
    NormalDate is a specialized class to handle dates without
    all the excess baggage (time zones, daylight savings, leap
    seconds, etc.) of other date structures.  The minimalist
    strategy greatly simplifies its implementation and use.

    Internally, NormalDate is stored as an integer with values
    in a discontinuous range of -99990101 to 99991231.  The
    integer value is used principally for storage and to simplify
    the user interface.  Internal calculations are performed by
    a scalar based on Jan 1, 1900.

    Valid NormalDate ranges include (-9999,1,1) B.C.E. through
    (9999,12,31) C.E./A.D.

    1.3 - Added weekOfYear() method submitted by Harri Pasanen.
    1.2 - Bugfix for Python2.2, which changed localtime's type
          to time.struct_time rather than a tuple.  Thanks to
          Paul Weimer for reporting this problem.  Added some,
          but not all, of Robin Becker's ideas he incorporated
          into ReportLab's version of normalDate.
    1.1 - Added exception in setNormalDate for bad integer;
          range() returns a list of normalDates rather than
          a list of integers.
    1.0 - No changes, except the version number.  After 3 years of use
            by various parties I think we can consider it stable.
    0.8 - added Prof. Stephen Walton's suggestion for a range method 
            - module author resisted the temptation to use lambda <0.5 wink>
    0.7 - added Dan Winkler's suggestions for __add__, __sub__ methods
    0.6 - modifications suggested by Kevin Digweed to fix:
            - dayOfWeek, dayOfWeekAbbrev, clone methods
            - permit NormalDate to be a better behaved superclass
    0.5 - minor tweaking
    0.4 - added methods __cmp__, __hash__
        - added Epoch variable, scoped to the module
        - added setDay, setMonth, setYear methods
    0.3 - minor touch-ups
    0.2 - fixed bug for certain B.C.E leap years
        - added Jim Fulton's suggestions for short alias class name =ND
          and __getstate__, __setstate__ methods

    Special thanks for ideas and suggestions:  
        Jim Fulton
        Kevin Digweed
        Paul Weimer
        Robin Becker
        Roedy Green
        Stephen Walton
    """
    def __init__(self, normalDate=None):
        """
        Accept 1 of 4 values to initialize a NormalDate:
            1. None - creates a NormalDate for the current day
            2. integer in yyyymmdd format
            3. string in yyyymmdd format
            4. tuple in (yyyy, mm, dd) - localtime/gmtime can also be used
        """
        if normalDate is None:
            self.setNormalDate(time.localtime(time.time()))
        else:
            self.setNormalDate(normalDate)

    def add(self, days):
        """add days to date; use negative integers to subtract"""
        if not type(days) is IntType:
            raise NormalDateException( \
                'add method parameter must be integer type')
        self.normalize(self.scalar() + days)

    def __add__(self, days):
        """add integer to normalDate and return a new, calculated value"""
        if not type(days) is IntType:
            raise NormalDateException( \
                '__add__ parameter must be integer type')
        cloned = self.clone()
        cloned.add(days)
        return cloned

    def clone(self):
        """return a cloned instance of this normalDate"""
        return self.__class__(self.normalDate)

    def __cmp__(self, target):
        if target is None: 
            return 1
        elif not hasattr(target, 'normalDate'):
            return 1
        else:
            return cmp(self.normalDate, target.normalDate)

    def day(self):
        """return the day as integer 1-31"""
        return int(repr(self.normalDate)[-2:])

    def dayOfWeek(self):
        """return integer representing day of week, Mon=0, Tue=1, etc."""
        return apply(dayOfWeek, self.toTuple())

    def dayOfWeekAbbrev(self):
        """return day of week abbreviation for current date: Mon, Tue, etc."""
        return _dayOfWeekName[self.dayOfWeek()][:3]

    def dayOfWeekName(self):
        """return day of week name for current date: Monday, Tuesday, etc."""
        return _dayOfWeekName[self.dayOfWeek()]

    def dayOfYear(self):
        """day of year"""
        if self.isLeapYear():
            daysByMonth = _daysInMonthLeapYear
        else:
            daysByMonth = _daysInMonthNormal
        priorMonthDays = 0
        for m in xrange(self.month() - 1):
            priorMonthDays = priorMonthDays + daysByMonth[m]
        return self.day() + priorMonthDays

    def daysBetweenDates(self, normalDate):
        """
        return value may be negative, since calculation is 
        self.scalar() - arg
        """
        if type(normalDate) is _NormalDateType:
            return self.scalar() - normalDate.scalar()
        else:
            return self.scalar() - NormalDate(normalDate).scalar()

    def daysInMonth(self, month):
        """returns last day of the month as integer 28-31"""
        if self.isLeapYear():
            return _daysInMonthLeapYear[month - 1]
        else:
            return _daysInMonthNormal[month - 1]

    def equals(self, target):
        if type(target) is _NormalDateType:
            if target is None:
                return self.normalDate is None
            else:
                return self.normalDate == target.normalDate
        else:
            return 0

    def endOfMonth(self):
        """returns (cloned) last day of month"""
        return self.__class__(self.__repr__()[-8:-2] + \
                              str(self.lastDayOfMonth()))

    def firstDayOfMonth(self):
        """returns (cloned) first day of month"""
        return self.__class__(self.__repr__()[-8:-2] + "01")

    def formatUS(self):
        """return date as string in common US format: MM/DD/YY"""
        d = self.__repr__()
        return "%s/%s/%s" % (d[-4:-2], d[-2:], d[-6:-4])

    def formatUSCentury(self):
        """return date as string in 4-digit year US format: MM/DD/YYYY"""
        d = self.__repr__()
        return "%s/%s/%s" % (d[-4:-2], d[-2:], d[-8:-4])

    def __getstate__(self):
        """minimize persistent storage requirements"""
        return self.normalDate

    def __hash__(self):
        return hash(self.normalDate)

    def __int__(self):
        return self.normalDate

    def isLeapYear(self):
        """
        determine if specified year is leap year, returning true (1) or 
        false (0)
        """
        return isLeapYear(self.year())

    def _isValidNormalDate(self, normalDate):
        """checks for date validity in [-]yyyymmdd format"""
        if type(normalDate) is not IntType:
            return 0
        if len(repr(normalDate)) > 9:
            return 0
        if normalDate < 0:
            dateStr = "%09d" % normalDate
        else:
            dateStr = "%08d" % normalDate
        if len(dateStr) < 8:
            return 0
        elif len(dateStr) == 9:
            if (dateStr[0] != '-' and dateStr[0] != '+'):
                return 0
        year = int(dateStr[:-4])
        if year < -9999 or year > 9999 or year == 0:
            return 0    # note: zero (0) is not a valid year
        month = int(dateStr[-4:-2])
        if month < 1 or month > 12:
            return 0
        if isLeapYear(year):
            maxDay = _daysInMonthLeapYear[month - 1]
        else:
            maxDay = _daysInMonthNormal[month - 1]
        day = int(dateStr[-2:])
        if day < 1 or day > maxDay:
            return 0
        if year == 1582 and month == 10 and day > 4 and day < 15:
            return 0  # special case of 10 days dropped: Oct 5-14, 1582
        return 1

    def lastDayOfMonth(self):
        """returns last day of the month as integer 28-31"""
        if self.isLeapYear():
            return _daysInMonthLeapYear[self.month() - 1]
        else:
            return _daysInMonthNormal[self.month() - 1]

    def localeFormat(self):
        """override this method to use your preferred locale format"""
        return self.formatUS()

    def month(self):
        """returns month as integer 1-12"""
        return int(repr(self.normalDate)[-4:-2])

    def monthAbbrev(self):
        """returns month as a 3-character abbreviation, i.e. Jan, Feb, etc."""
        return _monthName[self.month() - 1][:3]

    def monthName(self):
        """returns month name, i.e. January, February, etc."""
        return _monthName[self.month() - 1]

    def normalize(self, scalar):
        """convert scalar to normalDate"""
        if scalar < _bigBangScalar:
            msg = "normalize(%d): scalar below minimum" % \
                  _bigBangScalar
            raise NormalDateException(msg)
        if scalar > _bigCrunchScalar:
            msg = "normalize(%d): scalar exceeds maximum" % \
                  _bigCrunchScalar
            raise NormalDateException(msg)
        from math import floor
        if scalar >= -115860:
            year = 1600 + int(floor((scalar + 109573) / 365.2425))
        elif scalar >= -693597:
            year = 4 + int(floor((scalar + 692502) / 365.2425))
        else:
            year = -4 + int(floor((scalar + 695058) / 365.2425))
        days = scalar - firstDayOfYear(year) + 1
        if days <= 0:
            year = year - 1
            days = scalar - firstDayOfYear(year) + 1
        daysInYear = 365
        if isLeapYear(year):
            daysInYear = daysInYear + 1
        if days > daysInYear:
            year = year + 1
            days = scalar - firstDayOfYear(year) + 1
        # add 10 days if between Oct 15, 1582 and Dec 31, 1582
        if (scalar >= -115860 and scalar <= -115783):
            days = days + 10
        if isLeapYear(year):
            daysByMonth = _daysInMonthLeapYear
        else:
            daysByMonth = _daysInMonthNormal
        dc = 0; month = 12
        for m in xrange(len(daysByMonth)):
            dc = dc + daysByMonth[m]
            if dc >= days:
                month = m + 1
                break
        # add up the days in prior months
        priorMonthDays = 0
        for m in xrange(month - 1):
            priorMonthDays = priorMonthDays + daysByMonth[m]
        day = days - priorMonthDays
        self.setNormalDate((year, month, day))

        def __radd__(self,days):
                """for completeness"""
                return self.__add__(days)

    def range(self, days):
        """Return a range of normalDates as a list.  Parameter
        may be an int or normalDate."""
        if type(days) is not IntType:
            days = days - self  # if not int, assume arg is normalDate type
        r = []
        for i in range(days):
            r.append(self + i)
        return r

    def __repr__(self):
        """print format: [-]yyyymmdd"""
        # Note: When disassembling a NormalDate string, be sure to
        # count from the right, i.e. epochMonth = int(`Epoch`[-4:-2]),
        # or the slice won't work for dates B.C.
        if self.normalDate < 0:
            return "%09d" % self.normalDate
        else:
            return "%08d" % self.normalDate

        def __rsub__(self, v):
                if type(v) is IntType:
                        return NormalDate(v) - self
                else:
                        return v.scalar() - self.scalar()

    def scalar(self):
        """days since baseline date: Jan 1, 1900"""
        (year, month, day) = self.toTuple()
        days = firstDayOfYear(year) + day - 1
        if self.isLeapYear():
            for m in xrange(month - 1):
                days = days + _daysInMonthLeapYear[m]
        else:
            for m in xrange(month - 1):
                days = days + _daysInMonthNormal[m]
        if year == 1582:
            if month > 10 or (month == 10 and day > 4):
                days = days - 10
        return days

    def setDay(self, day):
        """set the day of the month"""
        maxDay = self.lastDayOfMonth()
        if day < 1 or day > maxDay:
            msg = "day is outside of range 1 to %d" % maxDay
            raise NormalDateException(msg)
        (y, m, d) = self.toTuple()
        self.setNormalDate((y, m, day))

    def setMonth(self, month):
        """set the month [1-12]"""
        if month < 1 or month > 12:
            raise NormalDateException('month is outside range 1 to 12')
        (y, m, d) = self.toTuple()
        self.setNormalDate((y, month, d))

    def setNormalDate(self, normalDate):
        """
        accepts date as scalar string/integer (yyyymmdd) or tuple 
        (year, month, day, ...)"""
        _type = type(normalDate)
        if _type is IntType:
            self.normalDate = normalDate
        elif _type is StringType:
            try:
                self.normalDate = int(normalDate)
            except ValueError:
                raise NormalDateException("Bad integer: '%s'" % normalDate)
        elif _type in (TupleType, ListType) or _type is _TimeType:
            self.normalDate = int("%04d%02d%02d" % normalDate[:3])
        elif _type is _NormalDateType:
            self.normalDate = normalDate.normalDate
        if not self._isValidNormalDate(self.normalDate):
            msg = "unable to setNormalDate(%s)" % `normalDate`
            raise NormalDateException(msg)

    def setYear(self, year):
        if year == 0:
            raise NormalDateException('cannot set year to zero')
        elif year < -9999:
            raise NormalDateException('year cannot be less than -9999')
        elif year > 9999:
            raise NormalDateException('year cannot be greater than 9999')
        (y, m, d) = self.toTuple()
        self.setNormalDate((year, m, d))

    __setstate__ = setNormalDate

    def __sub__(self, v):
        if type(v) is IntType:
            return self.__add__(-v)
        return self.scalar() - v.scalar()

    def toTuple(self):
        """return date as (year, month, day) tuple"""
        return (self.year(), self.month(), self.day())

    def weekOfYear(self):
        """returns the week of the year: 1-52"""
        week = self.dayOfYear() / 7 + 1
        if week == 53:
            week = 1
        return week

    def year(self):
        """return year in yyyy format, negative values indicate B.C."""
        return int(repr(self.normalDate)[:-4])

#################  Utility functions  #################

def bigBang():
    """return lower boundary as a NormalDate"""
    return NormalDate((-9999, 1, 1))

def bigCrunch():
    """return upper boundary as a NormalDate"""
    return NormalDate((9999, 12, 31))

def dayOfWeek(y, m, d):
    """return integer representing day of week, Mon=0, Tue=1, etc."""
    if m == 1 or m == 2:
        m = m + 12
        y = y - 1
    return (d + 2*m + 3*(m+1)/5 + y + y/4 - y/100 + y/400) % 7

def firstDayOfYear(year):
    """number of days to the first of the year, relative to Jan 1, 1900"""
    if type(year) is not IntType:
        msg = "firstDayOfYear() expected integer, got %s" % type(year)
        raise NormalDateException(msg)
    if year == 0:
        raise NormalDateException('first day of year cannot be zero (0)')
    elif year < 0:  # BCE calculation
        firstDay = (year * 365) + int((year - 1) / 4) - 693596
    else:           # CE calculation
        leapAdjust = int((year + 3) / 4)
        if year > 1600:
            leapAdjust = leapAdjust - int((year + 99 - 1600) / 100) + \
                         int((year + 399 - 1600) / 400)
        firstDay = year * 365 + leapAdjust - 693963
        if year > 1582:
            firstDay = firstDay - 10
    return firstDay

def isLeapYear(year):
    """determine if specified year is leap year, returns Python boolean"""
    if year < 1600:
        if year % 4:
            return 0
        else:
            return 1
    elif year % 4 != 0:
        return 0
    elif year % 100 != 0:
        return 1
    elif year % 400 != 0:
        return 0
    else:
        return 1

ND=NormalDate
Epoch=bigBang()
_NormalDateType = type(Epoch)
_TimeType = type(time.localtime(time.time()))

if __name__ == '__main__':
    today = ND()
    print "NormalDate test:"
    print "  Today (%s) is: %s %s" % \
          (today, today.dayOfWeekAbbrev(), today.localeFormat())
    yesterday = today - 1
    print "  Yesterday was: %s %s" % \
          (yesterday.dayOfWeekAbbrev(), yesterday.localeFormat())
    tomorrow = today + 1
    print "  Tomorrow will be: %s %s" % \
          (tomorrow.dayOfWeekAbbrev(), tomorrow.localeFormat())
    print "  Days between tomorrow and yesterday: %d" % \
          (tomorrow - yesterday)