#!/usr/bin/perl
#
#  NAME OF SCRIPT FILE:
#   day1900
#
#  DESCRIPTION
#   Converts a date to the day number from 1900-01-00.
#   If one parameter is specified, it should be in form YYMMDD or YYYY-MM-DD.
#   If three parameters are specified they should be in order of year,
#   month, day.  Year can be 19YY or YY.  Month should be month number or
#   3 letter abbreviation. Uses today if no date is specified.
#
#  USAGE:
#   day1900 YYMMDD
#   day1900 YYYY-MM-DD
#   day1900 (YY|19YY) (MM|mmm) DD
#
#  HISTORY:
#   nash 921027 written
#   nash 950811 added YYYY-MM-DD processing, cleaned up code
#   $Header: /var/local/src/tmp/day1900,v 1.4 1995/08/11 21:28:12 root Exp $
#

# use today as default
  if  (!@ARGV)
  { ($dy,$dy,$dy,$dy,$mo,$yr,@junk) = localtime(time);   
    $mo++;
  }

# get year, month, and day from full date
  elsif  ($#ARGV == 0)
  { $date = shift;
    if  ($date =~ /-+/) { ($yr,$mo,$dy) = ($date =~ /\D*(\d+)-(\w+)-(\d+)/); }
    else { ($yr,$mo,$dy) = ($date =~ /\D*(\d+)(\d\d)(\d\d)/); }
  }

# get year, month, and day from separate parameters
  elsif  ($#ARGV == 2)
  { $yr = shift;
    $mo = shift;
    $dy = shift;
 }

# bad number of parameters
  else { die "Incorrect number of parameters: must be 0, 1, or 3\n"; }

# month given as characters
  if  (length($mo) eq 3)
  { $mo =~ tr/[A-Z]/[a-z]/;
    @mlist{'jan','feb','mar','apr','may','jun','jul','aug','sep','oct','nov',
      'dec'} = (1,2,3,4,5,6,7,8,9,10,11,12);
    ($mo = $mlist{$mo}) || die "Month is incorrectly specified\n";
  } 
# check ranges
  if  ($yr > 1899) { $yr = $yr-1900; }
  if  ($yr < 0)  { $yr = 0; }
  if  ($mo < 1)  { $mo = 1; }
  if  ($mo > 12)  { $mo = 12; }
  $mo--;
  if  ($dy < 1)  { $dy = 1; }
  @mlist = (0,31,59,90,120,151,181,212,243,273,304,334,365);
  @difflist = (31,28,31,30,31,30,31,31,30,31,30,31);

# leap year
  $leap = (($yr-int($yr/4)*4) == 0);
  $leap = ($leap & ($yr != 0));
  $dmax = $difflist[$mo]+($leap & ($mo == 1));
  if  ($dy > $dmax)  { $dy = $dmax; }
  $yrmod = ($mo+1)*100+$dy;

# result
  print $yr*365+int(($yr-1)/4)+(($yrmod > 300) & $leap)+$mlist[$mo]+$dy,"\n";
exit;