Acquire current UTC leap second from Internet sources

leapSecond.py

#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

import logging
import requests


log = logging.getLogger( __name__ )

offsetUrls = {
    'mil' : 'http://maia.usno.navy.mil/ser7/tai-utc.dat',
    'nasa' : 'http://cdf.gsfc.nasa.gov/html/CDFLeapSeconds.txt'
}


def parseNasa( ) :
    leapSecondColumn = 3

    r = requests.get( offsetUrls[ 'nasa' ] )

    tableData = r.text.split( '\n' )

    splitTable = [ ]
    for row in tableData :
        columns = row.split( )
        # Ignore blank lines and comment lines (begin with ';')
        if columns and (columns[ 0 ] != ';') :
            splitTable.append( columns )

    numberRows = len( splitTable )

    currentLeapSecond = splitTable[ numberRows - 1 ][ leapSecondColumn ]

    return currentLeapSecond


def parseMil( ) :
    leapSecondColumn = 6

    r = requests.get( offsetUrls[ 'mil' ] )

    tableData = r.text.split( '\n' )

    splitTable = [ ]
    for row in tableData :
        columns = row.split( )
        # Ignore blank lines
        if columns :
            splitTable.append( columns )

    numberRows = len( splitTable )

    currentLeapSecond = splitTable[ numberRows - 1 ][ leapSecondColumn ]

    return currentLeapSecond


def getCurrentOffset( ) :
    try :
        currentLeapSecond = parseMil( )
    except :
        # Try an alternative URL
        currentLeapSecond = parseNasa( )

    return currentLeapSecond


if __name__ == '__main__' :
    currentLeapSecond = getCurrentOffset( )

    log.info( 'Current leap second: ' + repr( currentLeapSecond ) )
    print( 'Current leap second: ' + repr( currentLeapSecond ) )