#!/usr/bin/perl

sub translate_date_format
{ 
  my @tr = ( 'yyyy' => '%Y',
             'yy'   => '%y',
             'mmmm' => '%B',
             'mmm'  => '%b',
             'mm'   => '%m',
             'dddd' => '%A',
             'ddd'  => '%a',
             'dd'   => '%d',
             'd'    => '%e',
             'HH'   => '%H', #(%I if am/pm is specified)
             'H'    => '%k', #(%l if am/pm is specified)
             'MM'   => '%M',
             'AM'   => '%p',
             'PM'   => '%p',
             'am'   => '%P',
             'pm'   => '%P',
             'SS'   => '%S',
           );

  local $_ = shift;
  
  for ( my $i = 0; $i <= $#tr; $i += 2 ) { s/(?<!%)$tr[$i]/$tr[$i+1]/g; }
  s/%H(.*?%[pP])/%I$1/g; s/%k(.*?%[pP])/%l$1/g;

  return ( $_ );
}

### Test ######################################################################

use POSIX;
use Time::Piece;

my @test = ( 'yyyy-mm-dd',
             'd/mm/yy',
             'H:MM:SSAM',
             'HH:MM:SSpm',
             'mmm ddd, yy',
             'dddd, mmmm dd, yyyy HH:MM:SS',
           );

foreach ( @test )
{
  my $tdf = translate_date_format ( $_ );
  print "$_ => $tdf\n";

  my $date = POSIX::strftime ( $tdf, localtime() );
  print "  POSIX: $date\n";

  my $t = localtime();
  my $date = $t->strftime ( $tdf );
  print "  Time::Piece: $date";
  $date = $t->strptime ( $date, $tdf );
  print " => $date\n";
}