#!/usr/bin/perl
use warnings;
use strict;

# Imports for certain functions
use POSIX;
use Fcntl ':mode';


if( $#ARGV == -1)
{
   print STDERR "Usage: $0 <eintrag1> <wert1>.. :\n";
   exit 1;
}

my $eintrag1  = $ARGV[0] or die "definieren eintrag1.\n";
my $wert1     = $ARGV[1] or die "definiieren wert1 .\n";
my $eintrag2  = $ARGV[2] or die "definieren eintrag2.\n";
my $wert2     = $ARGV[3] or die "definieren wert2 .\n";
my $file      = $ARGV[4] or die "definieren file .\n";

#my $file = 'datei';
#my $tmpfile = "$file.tmp";

my $tmpfile = "";
my $file_typ = "";
my $real_filename = "";

my %changes = (
    #'eintrag1' => 'XXXX',
    $eintrag1 => $wert1,
    #'eintrag2' => 'foo',
    $eintrag2 => $wert2,
    # etc.
);

$file_typ = get_file_typ ($file);

if ( $file_typ eq '-1' || $file_typ eq '-2' )
{
  print STDERR "Fehler bei Ermitteln File_Typ\n";
}
elsif ( $file_typ eq 'l' )
{
  $real_filename = readlink_2_get_file ($file);
}
else
{
  $real_filename = $file;
}

$tmpfile = "$file.tmp";
  
open(my $fh, '<', $real_filename) or die $!;
open(my $th, '>', $tmpfile) or die $!;

LINE:
while (my $line = <$fh>) {
    #KEY;
    for my $key (keys %changes) {
        if ($line =~ s/($key\s*=\s*)[^#\s]+/$1$changes{$key}/) {
            print $th $line;
            next LINE;
        }
    }
    print $th $line;  # kein Match
}

close($fh) or die $!;
close($th) or die $!;
unlink $file;          # oder als Backup speichern
rename $tmpfile, $file;

exit 0;

#### Exportable Functions

sub get_file_typ {
    my $ofile = shift;

    my ( $mode, $type, $return_file_typ );

    if ( $ofile ne "" ) {
        if ( -e $ofile ) {
          # note: if the file is a symlink (type "l"), you might
          # want to use lstat() instead of stat()
          # note: "use POSIX" doesn't seem to provide constants for types
          # "n" "s" or "l"
  
          $mode = ( lstat $ofile )[2];
  
          $type = "b" if ( S_ISBLK($mode) );
          $type = "c" if ( S_ISCHR($mode) );
          $type = "d" if ( S_ISDIR($mode) );
          $type = "p" if ( S_ISFIFO($mode) );
          $type = "s" if ( S_ISSOCK($mode) );
          $type = "l" if ( S_ISLNK($mode) );
          $type = "f" if ( S_ISREG($mode) );
  
          $return_file_typ = $type;
        }
        else 
	{
          # file not found
          $return_file_typ = "-1";
        }
    } else {
        # no ARGV
        $return_file_typ = "-2";
    }
    return ($return_file_typ); 
}

sub readlink_2_get_file {
    my $ofile = shift;

    my ( $return_readlink );

    if ( $ofile ne "" ) {
       if ( -l $ofile ) {
        $return_readlink = readlink( $ofile );
       }
       else {
        # link not found
        $return_readlink = "-1";
       }
    } else {
        # no ARGV[0]
        $return_readlink = "-2";
    }
}