#! /usr/bin/env python3
#
def timestamp ( ):

#*****************************************************************************80
#
## timestamp() prints the date as a timestamp.
#
#  Licensing:
#
#    This code is distributed under the MIT license. 
#
#  Modified:
#
#    06 April 2013
#
#  Author:
#
#    John Burkardt
#
  import time

  t = time.time ( )
  print ( time.ctime ( t ) )

  return

def weekday_gregorian ( y, m, d ):

#*****************************************************************************80
#
## weekday_gregorian() returns the weekday of a Y/M/D Gregorian date.
#
#  Discussion:
#
#    This function uses Zeller's congruence.
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    06 November 2019
#
#  Author:
#
#    John Burkardt
#
#  Input:
#
#    integer Y, M, D: the YMD date.
#
#  Output:
#
#    integer W: the week day number of the date, with
#    1 for Sunday, through 7 for Saturday.
#
  import numpy as np

  if ( m < 3 ):
    m = m + 12
    y = y - 1
 
  w = ( ( \
     d \
     + np.floor ( ( ( m + 1 ) * 13 ) / 5 ) \
     + y \
     + np.floor ( y / 4 ) \
     - np.floor ( y / 100 ) \
     + np.floor ( y / 400 ) - 1 ) \
     % 7 ) + 1
			
  return w

def weekday_gregorian_test ( ):

#*****************************************************************************80
#
## weekday_gregorian_test() tests weekday_gregorian().
#
#  Licensing:
#
#    This code is distributed under the MIT license. 
#
#  Modified:
#
#    06 November 2019
#
#  Author:
#
#    John Burkardt
#
  print ( '' )
  print ( 'weekday_gregorian_test' )
  print ( '  weekday_gregorian returns the day of the week' )
  print ( '  for Y/M/D dates in the Gregorian calendar.' )
  print ( '' )
  print ( '  YYYY  MM  DD  Weekday    Weekday' )
  print ( '                Tabulated  Computed' )
  print ( '' )

  n_data = 0

  while ( True ):

    n_data, y, m, d, w1 = weekday_values ( n_data )

    if ( n_data == 0 ):
      break

    if ( y <= 1582 ):
      continue

    w2 = weekday_gregorian ( y, m, d );

    s1 = weekday_to_name_common ( w1 );
    s2 = weekday_to_name_common ( w2 );

    print ( '  %4d  %2d  %2d  %10s  %10s' % ( y, m, d, s1, s2 ) )

  return

def weekday_julian ( y, m, d ):

#*****************************************************************************80
#
## weekday_julian() returns the weekday of a Y/M/D Julian date.
#
#  Discussion:
#
#    This function uses Zeller's congruence.
#
#    We assume that the year before 1 was -1.
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    06 November 2019
#
#  Author:
#
#    John Burkardt
#
#  Input:
#
#    integer Y, M, D: the YMD date.
#
#  Output:
#
#    integer W: the week day number of the date, with
#    1 for Sunday, through 7 for Saturday.
#
  import numpy as np

  if ( m < 3 ):
    m = m + 12
    y = y - 1

  if ( y < 1 ):
    y = y + 1
    k = np.floor ( ( - y ) / 28 ) + 1
    y = y + 28 * k
 
  w = ( ( \
     d \
     + np.floor ( ( ( m + 1 ) * 13 ) / 5 ) \
     + y \
     + np.floor ( y / 4 ) + 4 ) \
     % 7 ) + 1
			
  return w

def weekday_julian_test ( ):

#*****************************************************************************80
#
## weekday_julian_test() tests weekday_julian().
#
#  Licensing:
#
#    This code is distributed under the MIT license. 
#
#  Modified:
#
#    06 November 2019
#
#  Author:
#
#    John Burkardt
#
  print ( '' )
  print ( 'weekday_julian_test' )
  print ( '  weekday_julian returns the day of the week' )
  print ( '  for Y/M/D dates in the Julian calendar.' )
  print ( '' )
  print ( '  YYYY  MM  DD  Weekday    Weekday' )
  print ( '                Tabulated  Computed' )
  print ( '' )

  n_data = 0

  while ( True ):

    n_data, y, m, d, w1 = weekday_values ( n_data )

    if ( n_data == 0 ):
      break

    if ( 1582 <= y ):
      continue

    w2 = weekday_julian ( y, m, d );

    s1 = weekday_to_name_common ( w1 );
    s2 = weekday_to_name_common ( w2 );

    print ( '  %4d  %2d  %2d  %10s  %10s' % ( y, m, d, s1, s2 ) )

  return

def weekday_to_name_common ( w ):

#*****************************************************************************80
#
## weekday_to_name_common() returns the name of a Common weekday.
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    28 August 1999
#
#  Author:
#
#    John Burkardt
#
#  Input:
#
#    integer W, the weekday index.
#
#  Output:
#
#    string S, the weekday name.
#  
  if ( w == 1 ):
    s = 'Sunday'
  elif ( w == 2 ):
    s = 'Monday'
  elif ( w == 3 ):
    s = 'Tuesday'
  elif ( w == 4 ):
    s = 'Wednesday'
  elif ( w == 5 ):
    s = 'Thursday'
  elif ( w == 6 ):
    s = 'Friday'
  elif ( w == 7 ):
    s = 'Saturday'
  else:
    print ( '' )
    print ( 'weekday_to_name_common - Fatal error!' )
    print ( '  Index W must be between 1 and 7.' )
    raise Exception ( 'weekday_to_name_common - Fatal error!' )

  return s

def weekday_to_name_common_test ( ):

#*****************************************************************************80
#
## weekday_to_name_common_test() tests weekday_to_name_common().
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    03 July 2017
#
#  Author:
#
#    John Burkardt
#
  import platform
  
  print ( '' )
  print ( 'weekday_to_name_common_test:' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  weekday_to_name_common is given a weekday index between 1 and 7' )
  print ( '  and returns the corresponding name of the weekday.' )
  print ( '' )
  print ( '  Index    Name' )
  print ( '' )
  
  for w in range ( 1, 8 ):
    s = weekday_to_name_common ( w )
    print ( '  %5d  %s' % ( w, s ) )
    
  return

def weekday_values ( n_data ):

#*****************************************************************************80
#
## weekday_values() returns the day of the week for various dates.
#
#  Discussion:
#
#    The CE or Common Era calendar is used, under the
#    hybrid Julian/Gregorian Calendar, with a transition from Julian
#    to Gregorian.  The day after 04 October 1582 was 15 October 1582.  
#
#    The year before 1 AD or CE is 1 BC or BCE.  In this data set,
#    years BC/BCE are indicated by a negative year value.  
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    22 February 2015
#
#  Author:
#
#    John Burkardt
#
#  Reference:
#
#    Edward Reingold, Nachum Dershowitz,
#    Calendrical Calculations: The Millennium Edition,
#    Cambridge University Press, 2001,
#    ISBN: 0 521 77752 6
#    LC: CE12.R45.
#
#  Input:
#
#    integer N_DATA.  The user sets N_DATA to 0 before the first call.  
#
#  Output:
#
#    integer N_DATA.  On each call, the routine increments N_DATA by 1,
#    and returns the corresponding data when there is no more data, the
#    output value of N_DATA will be 0 again.
#
#    integer Y, M, D, the Common Era date.
#
#    integer W, the day of the week.  Sunday = 1.
#
  import numpy as np

  n_max = 34

  d_vec = np.array ( ( \
    30, \
     8, \
    26, \
     3, \
     7, \
    18, \
     7, \
    19, \
    14, \
    18, \
    16, \
     3, \
    26, \
    20, \
     4, \
    25, \
    31, \
     9, \
    24, \
    10, \
    30, \
    24, \
    19, \
     2, \
    27, \
    19, \
    25, \
    29, \
    19, \
     7, \
    17, \
    25, \
    10, \
    18 ))

  m_vec = np.array ( ( \
     7, \
    12, \
     9, \
    10, \
     1, \
     5, \
    11, \
     4, \
    10, \
     5, \
     3, \
     3, \
     3, \
     4, \
     6, \
     1, \
     3, \
     9, \
     2, \
     6, \
     6, \
     7, \
     6, \
     8, \
     3, \
     4, \
     8, \
     9, \
     4, \
    10, \
     3, \
     2, \
    11, \
     7 ))

  w_vec = np.array ( ( \
    1, \
    4, \
    4, \
    1, \
    4, \
    2, \
    7, \
    1, \
    7, \
    1, \
    6, \
    7, \
    6, \
    1, \
    1, \
    4, \
    7, \
    7, \
    7, \
    4, \
    1, \
    6, \
    1, \
    2, \
    4, \
    1, \
    1, \
    2, \
    2, \
    5, \
    3, \
    1, \
    4, \
    1 ))

  y_vec = np.array ( ( \
    - 587, \
    - 169, \
       70, \
      135, \
      470, \
      576, \
      694, \
     1013, \
     1066, \
     1096, \
     1190, \
     1240, \
     1288, \
     1298, \
     1391, \
     1436, \
     1492, \
     1553, \
     1560, \
     1648, \
     1680, \
     1716, \
     1768, \
     1819, \
     1839, \
     1903, \
     1929, \
     1941, \
     1943, \
     1943, \
     1992, \
     1996, \
     2038, \
     2094 ))

  if ( n_data < 0 ):
    n_data = 0

  if ( n_max <= n_data ):
    n_data = 0
    y = 0
    m = 0
    d = 0
    w = 0
  else:
    y = y_vec[n_data]
    m = m_vec[n_data]
    d = d_vec[n_data]
    w = w_vec[n_data]
    n_data = n_data + 1

  return n_data, y, m, d, w

def weekday_values_test ( ):

#*****************************************************************************80
#
## weekday_values_test() tests weekday_values().
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    22 February 2015
#
#  Author:
#
#    John Burkardt
#
  import platform

  print ( '' )
  print ( 'weekday_values_test:' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  weekday_values stores values of' )
  print ( '  the weekday for a given Y/M/D date' )
  print ( '' )
  print ( '         Y       M       D           W' )
  print ( '' )

  n_data = 0

  while ( True ):

    n_data, y, m, d, w = weekday_values ( n_data )

    if ( n_data == 0 ):
      break

    print ( '  %6d  %6d  %6d  %6d' % ( y, m, d, w ) )
#
#  Terminate.
#
  print ( '' )
  print ( 'weekday_values_test:' )
  print ( '  Normal end of execution.' )
  return

def weekday_zeller_test ( ):

#*****************************************************************************80
#
## weekday_zeller_test() tests weekday_zeller().
#
#  Licensing:
#
#    This code is distributed under the MIT license. 
#
#  Modified:
#
#    06 November 2019
#
#  Author:
#
#    John Burkardt
#
  import platform
  
  print ( '' )
  print ( 'weekday_zeller_test():' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  Test weekday_zeller().' )

  weekday_gregorian_test ( )
  weekday_julian_test ( )
  weekday_to_name_common_test ( )
#
#  Terminate.
#
  print ( '' )
  print ( 'weekday_zeller_test():' )
  print ( '  Normal end of execution.' )
  return

if ( __name__ == '__main__' ):
  timestamp ( )
  weekday_zeller_test ( )
  timestamp ( )