#!/usr/bin/perl -w
use strict;

main( @ARGV );
exit( 0 );

sub main {
    my( $file )= @_;

    my $start= tell(DATA)
        or  die "Can't tell(DATA): $!";
    open DATA, "+< $0"  or  die "Can't read self ($0): $!\n";
    seek( DATA, $start, 0 )
        or  die "Can't fseek(DATA,$start,0): $!";
    die "Expected :endofperl after __END__ of $0.\n"
        unless  <DATA> =~ /^\s*:endofperl\s*$/i;

    open TEMP, "< $file"
        or  die "Can't read $file: $!\n";
    chomp( my @curr= <TEMP> );
    close TEMP;
    my %curr= map { ( split /=/, $_, 2 )[0,1] } @curr;

    system( ( $ENV{VISUAL} || "notepad" ), qq("$file") );

    open TEMP, "< $file"
        or  die "Can't reread $file: $!\n";
    chomp( my @user= <TEMP> );
    close TEMP;
    my %user= map { ( split /=/, $_, 2 )[0,1] } @user;

    for my $key (  keys %user  ) {
        if(  ! exists $curr{$key}  ) {
            next;
        } elsif(  $curr{$key} eq $user{$key}  ) {
            delete $user{$key};
        }
        delete $curr{$key};
    }
    seek( DATA, 0, 1 )
        or  die "Can't fseek(DATA,0,1): $!";
    for my $key (  keys %curr  ) {
        print DATA "set $key=\n";
    }
    for my $key (  keys %user  ) {
        print DATA qq{set $key=$user{$key}\n};
    }
    truncate DATA, tell(DATA);
}
__END__
:endofperl