###########################################################################################################################
sub date_() { return date(@_); }

sub date()
{
  my($ref,$pat)=@_; my $REF=$ref;

         $ref=~s/\s+/ /sg; 
         $ref=~s/^ | $//g;

  my @t=($ref=~s/(\d{4}-\d{2}-\d{2})//)? getYMD($1)
       :                                 getYMD(); 

     $t[0]+=-1                    if($ref=~s/last year//);
                                  # ($ref=~s/this year//);
     $t[0]+= 1                    if($ref=~s/next year//);

              $t[1] = 1           if($ref=~s/first month of//);
     $t[0]+=1,$t[1] =-1           if($ref=~s/last month of//);
              $t[1]+=-1           if($ref=~s/last month//);
                                  # ($ref=~s/this month//);
              $t[1]+= 1           if($ref=~s/next month//);

                        $t[2] = 1 if($ref=~s/first day of//);
              $t[1]+= 1,$t[2] =-1 if($ref=~s/last day of//);
                        $t[2]+=-1 if($ref=~s/last day|yesterday//);
                                  # ($ref=~s/this day|today|now//);
                        $t[2]+= 1 if($ref=~s/next day|tomorrow//);
  my @d=(0,0,0); 

     $d[0]+=  $1*($2?-1:1)        if($ref=~s/([+-]?\d+) years?( ago)?//);
     $d[1]+=  $1*($2?-1:1)        if($ref=~s/([+-]?\d+) months?( ago)?//);
     $d[2]+=7*$1*($2?-1:1)        if($ref=~s/([+-]?\d+) weeks?( ago)?//);
     $d[2]+=  $1*($2?-1:1)        if($ref=~s/([+-]?\d+) days?( ago)?//);

 # print ERR DJM(MJD($t[0]+$d[0],$t[1]+$d[1],$t[2]+$d[2])).' / '.qx(date -d "$REF" "+%Y-%m-%d").$REF."\n\n";

  return strfdate($pat,str2time($t[0]+$d[0]
                               ,$t[1]+$d[1]
                               ,$t[2]+$d[2])) if($pat=~/%/);

  return                DJM(MJD($t[0]+$d[0]
                               ,$t[1]+$d[1]
                               ,$t[2]+$d[2]));
}
###########################################################################################################################
sub str2time
{
 use integer; my $t=MJD(@_); $t-=MJD('19700101'); return $t*24*60*60;
}

sub strfdate
{    #   0        1          2           3           4         5        6
 @a=('Sonntag','Montag','Dienstag','Mittwoch','Donnerstag','Freitag','Samstag');
 @b=('','Jänner','Februar','März','April','Mai','Juni','Juli','August','September','Oktober','November','Dezember');

 my($r,$t,$o)=@_; $t||=time(); $o*=86400; # offset = Days

 my($S,$M,$H,$d,$m,$y,$w,$j)=localtime($t+$o); $m++;

 $r=~s/%R/%H:%M/g;
 $r=~s/%T/%H:%M:%S/g;
 $r=~s/%X/%H:%M:%S/g;
 $r=~s/%F/%Y-%m-%d/g;
 $r=~s/%x/%Y-%m-%d/g;
 $r=~s/%u/sprintf("%d",1+($w+6)%7);/ge; # Mo=1
 $r=~s/%w/sprintf("%d",  ($w+1)  );/ge; # So=1
 $r=~s/%a/i18n(substr($a[$w],0,2));/ge;
 $r=~s/%A/i18n(       $a[$w]     );/ge;
 $r=~s/%b/i18n(substr($b[$m],0,3));/ge;
 $r=~s/%B/i18n(       $b[$m]     );/ge;
 $r=~s/%Y/sprintf("%04d",$y+1900 );/ge;
 $r=~s/%y/sprintf("%04d",$y% 100 );/ge;
 $r=~s/%V/sprintf("%02d",weekOfYear($y+1900,$m,$d));/ge;
 $r=~s/%j/sprintf("%02d",$j);/ge;
 $r=~s/%m/sprintf("%02d",$m);/ge;
 $r=~s/%d/sprintf("%02d",$d);/ge;
 $r=~s/%e/sprintf("%2d" ,$d);/ge;
 $r=~s/%H/sprintf("%02d",$H);/ge;
 $r=~s/%k/sprintf("%2d", $H);/ge;
 $r=~s/%M/sprintf("%02d",$M);/ge;
 $r=~s/%S/sprintf("%02d",$S);/ge; return $r;
}

sub getYMD ### [now|yyyymmdd|yyyy-mm-dd|(yyyy,mm,dd)] => (y,m,d)
{
 my($y,$m,$d);

    if(@_==0) { (undef,undef,undef,$d,$m,$y)=localtime(); $y+=1900; $m++;  return ($y,$m,$d); }
 elsif(@_==1 && $_[0]=~/^(\d\d\d\d)(-?)(\d\d)\2(\d\d)/ )                 { return ($1,$3,$4); }
 elsif(@_==3
  && $_[0] =~ /^\d+$/
  && $_[1] =~ /^-?\d+$/
  && $_[2] =~ /^-?\d+$/)                                                 { return @_; }
}

sub MJD  ### [now|yyyymmdd|yyyy-mm-dd|(yyyy,mm,dd)] => julian
{
 use integer; my ($y,$m,$d)=getYMD(@_);

 while($m>12) { $m-=12; $y++ }
 while($m< 3) { $m+=12; $y-- } return $y*365+$y/4-$y/100+$y/400-306+($m+1)*306/10-122+$d-678576;
}

sub DJM  ### julian => yyyymmdd
{
 my $mjd=shift;
 my $jd =$mjd + 2400000.5;
 my $jd0=int($jd+0.5);
 my $b=int(($jd0-1867216.25)/36524.25);
 my $c=$jd0+($b-int($b/4))+1402;
 my $d=int(($c+0.9)/365.25);
 my $e=365*$d+int($d/4);
 my $f=int(($c-$e+123)/30.6001);

 my $day=$c-$e+123-int(30.6001*$f);
 my $month=($f-2)%12+1;
 my $year=$d-4716+($month<3); return sprintf("%d-%02d-%02d",$year,$month,$day);
}
###########################################################################################################################