#!/usr/bin/perl -w

# rundos.pl
#
# This program modifies the dosbox configuration file so that when you type 'dosbox' in the
# terminal, it automatically launches a program. Usage: perl rundos.pl <workdir> <dosprogram>
# The workdir must be a full path using backslash as the separator and must be enclosed with
# double quotes. The dos program must include the full location of the program and the
# program name the same way.. Make sure that the path includes only 8+3 filenames and the
# program itself also has a name that is 8+3 length. (Here "8+3" means the file name is
# max 8 letters long, and the extension is 3 max letters long.)
#
# It does not matter whether the first and second arguments are in uppercase or lowercase,
# because these will be used inside dosbox. In a dos environment, the directory and program
# names can be in upper or lower case, and it's all the same. But it is important to always
# enclose the first and second arguments with double quotes.
#
# When you run this program without any arguments, "perl rundos.pl" it will remove the program
# launcher from the dosbox config file, so when you type "dosbox" in the terminal,
# it will let you decide what you want to do...
#
# When you run this program with just one argument, "perl rundos.pl \home\owner\dos" it
# will launch dosbox in that directory.
#
# Example for running with two arguments:
#    perl rundos.pl "\home\owner\dos" "\home\owner\dos\qbasic.exe"

use strict;
use warnings;

-e '/usr/bin/dosbox' or die "\nError: /usr/bin/dosbox is not found. Please install it.\n";

my $WORKDIR = (@ARGV > 0) ? $ARGV[0] : '';
my $DOSPROG = (@ARGV > 1) ? $ARGV[1] : '';
my $HOMEDIR = $ENV{HOME};

# Read this file:
my $F = $HOMEDIR . '/.dosbox/dosbox-0.74-3.conf';
-f $F or die "\nError: Dosbox configuration file not found - $F !!!\n\n";

# Read the config file's contents:
@ARGV = ($F);
my @LINES = <>;

# Find the line that begins with [autoexec]
my $FOUND = 0;
for (my $i = 0; $i < @LINES; $i++)
{
  $LINES[$i] =~ tr|\r\n||d;
  if ($FOUND) { $LINES[$i] = ''; }
  if (index($LINES[$i], '[autoexec]') >= 0) { $FOUND = $i; }
}
if ($FOUND) { splice(@LINES, $FOUND); }   # Delete it and everything that follows...
else { die "\nError: Dosbox config file doesn't contain [autoexec] section.\n"; }

if (length($WORKDIR) && length($DOSPROG))
{
  push(@LINES, '[autoexec]');
  push(@LINES, 'mount c /');
  push(@LINES, 'c:');
  push(@LINES, "cd $WORKDIR");
  push(@LINES, 'cls');
  push(@LINES, $DOSPROG);
  push(@LINES, 'exit');
}
elsif (length($WORKDIR))
{
  push(@LINES, '[autoexec]');
  push(@LINES, 'mount c /');
  push(@LINES, 'c:');
  push(@LINES, 'cd ' . $WORKDIR);
  push(@LINES, 'dir /w');
}
else
{
  push(@LINES, '[autoexec]');
  push(@LINES, 'ver');
}

# Save modified config file.
open my $fh, '>', $F or die "\nError: Cannot update to $F !!!\n\n";
print $fh join("\n", @LINES), "\n";
close $fh;

# Launch dosbox.
exec('dosbox');