# db8_update - updates given db with minimal changes
# Usage: db8_update($strOrFile, $db)
# 2013-2017 Vlado Keselj, version 1.4; documentation in DB822.txt
sub db8_update {
  my $arg = shift; my $db=shift; my $file='';
  if ($arg =~ /^file=/) {
    $file = $'; die "file=''!?" if $file eq '';
    local $F; open(F, $file) or die "cannot open $file:$!";
    $arg = join('', <F>);
    close(F);
  }
  
  my $arg_save = $arg; my $dbi = 0; my $argcopy = '';
  while ($arg) {
    # allow comments and space betwen records
    if ($arg =~ /^(\s*\n|[ \t]*#.*\n)*/) { $argcopy.=$&; $arg = $'; }
    my $record;
    if ($arg =~ /\n(\n+)/) { $record = "$`\n"; $arg = $1.$'; }
    else { $record = $arg; $arg = ''; }
    if ($dbi > $#{$db}) { last }
    my $r = {}; my %savedkeys = ();
    while ($record) {
      my $avpair = '';
      if ($record =~ /^.*/) { $avpair = $& }
      while ($record =~ /^(.*)(\\\n|\n[ \t]+)(.*)/)
	{ $record = "$1 $3$'"; $avpair.= $2.$3; }
      $record =~ /^([^\n:]*):(.*)\n/ or die;
      my $k = $1; my $v = $2; $record = $';
      $avpair .= "\n";
      if (exists($r->{$k})) {
	my $c = 0;
	while (exists($r->{"$k-$c"})) { ++$c }
	$k = "$k-$c";
      }
      $r->{$k} = $v;
      if (exists($db->[$dbi]->{$k}) && $db->[$dbi]->{$k} eq $v)
	{ $argcopy .= $avpair }
      elsif (exists($db->[$dbi]->{$k})) {
	my $newv = $db->[$dbi]->{$k}; $newv =~ s/\s/ /g; #to be improved
	$argcopy .= "$k:$newv\n";
      } # else skip it
      $savedkeys{$k} = 1;
    }
    for my $k (keys %{ $db->[$dbi] }) {
      if (!exists($savedkeys{$k})) {
	my $newv = $db->[$dbi]->{$k}; $newv =~ s/\s/ /g; #to be improved
	$argcopy .= "$k:$newv\n";
      }
    }
    ++$dbi;
 }

 while ($dbi <= $#{$db}) {
   $argcopy .= "\n";
   for my $k (sort(keys(%{ $db->[$dbi] }))) {
     my $newv = $db->[$dbi]->{$k}; $newv =~ s/\s/ /g; #to be improved
     $argcopy .= "$k:$newv\n";
   }
   ++$dbi;
 }

 if ($file ne '') {
   if ($argcopy ne $arg_save) {
     rename($file, "$file.bak");
     local $F; open(F,">$file"); print F $argcopy; close(F);
   }
   return;
 } else { return $argcopy }
} # end of db8_update