#!/usr/local/bin/perl
# -*- Perl -*-

# written by jason steiner, jsteiner@anwsun.phya.utoledo.edu, Jan 1993
#
# if you use or make improvements to this program i would appreciate
# copies of your modifications & your PGP public key.
#

# Modified by Greg Spencer, greg@graphics.cornell.edu, May 1994
# Mostly just cleaned up things and added stuff like automatic
# addition and detection (and ignoring) of keys to be added to keyring,
# and signal catching, as well as environment variable control of
# most site-specific stuff.
#
# Must set the following environment variables:
#
# EDITOR or VISUAL set to editor of choice
#
# PGPCOMMAND set to the pgp decryption command
#
# PGPID or SIGNATURE set to the id you wish to
# have used for your pgp signatures, etc.
#
# PREFIX set to the forwarded message prefix that you use
#

# setup some variables
($visual = $ENV{'EDITOR'}) || ($visual = $ENV{'VISUAL'}) || ($visual = '/usr/local/bin/joe');
($pgpcommand = $ENV{'PGPCOMMAND'}) || ($pgpcommand = "/usr/local/bin/pgp");
#($myname = $ENV{'PGPID'}) || ($myname = $ENV{'SIGNATURE'});
($prefix = $ENV{'PREFIX'}) || ($prefix = "> ");
$topgp = 0;
$blanks = 0;
$paragraphs = 1;
$blankcompress = 1;
$name=@ARGV[$#ARGV];

#temporary file names
$rplyfile = "$name.rply";
$pgpfile  = "$name.pgp";
$ascfile  = "$name.asc";
$clrfile  = "$name.clr";

# trap signals so we don't leave
# (possibly sensitive!) garbage around
sub catcher {
	local($sig) = @_;

	print "Caught a SIG$sig -- exiting\n";
	close (OUTPUT);
	close (PGPFILE);
	close (CLEAR);
	close (INPUT);
	unlink ("$pgpfile");
	unlink ("$rplyfile");
	unlink ("$clrfile");
	unlink ("$ascfile");
}

$SIG{'INT'}  = 'catcher';
$SIG{'QUIT'} = 'catcher';
$SIG{'HUP'}  = 'catcher';
$SIG{'KILL'} = 'catcher';

# parse the input file to see if we're replying to an encrypted message
# user may need to type in pass phrase to decode
umask (077);
open (INPUT, "<$name");
open (OUTPUT, ">$rplyfile") || die "Cannot open $rplyfile for output.\n";
while (<INPUT>) {
	# make sure to allow printing of key blocks
	if (!$topgp && (!m/^$prefix-----BEGIN PGP .*-----/ || m/^$prefix-----BEGIN PGP PUBLIC KEY BLOCK-----/)) {
		if (m/^$prefix*$/) {
			if ($paragraphs) {
				if ($blankcompress) {
					if ($blanks == 0) {
						print OUTPUT "\n";
						$blanks = 1;
					}
				} else {
					print OUTPUT "\n";
				}
			} else {
				print OUTPUT;
			}
		} elsif (m/^[ \t\r]*$/) {
			if ($blankcompress) {
				if ($blanks == 0) {
					print OUTPUT "\n";
					$blanks = 1;
				}
			} else {
				print OUTPUT;
			}
		} else {
			print OUTPUT;
			if ($. == 1 && !m/^$prefix/) {
				print OUTPUT "\n";
				$blanks = 1;
			} else {
				$blanks = 0;
			}
		}
	}
	# make sure to skip key blocks because we already did 'em in morepgp
	if (!$topgp && m/^$prefix-----BEGIN PGP .*-----/ && !m/^$prefix-----BEGIN PGP PUBLIC KEY BLOCK-----/ ) {
		$topgp = 1;
		unlink ($pgpfile);
		open (PGPFILE, ">$pgpfile") || die "Cannot open $pgpfile for output.\n";
	}
	if ($topgp) {
		$_ =~ s/^$prefix//;
		print PGPFILE $_;
		# make sure to skip key blocks because we already did 'em in morepgp
		if (m/^-----END PGP .*-----/ && !m/^-----END PGP PUBLIC KEY BLOCK-----/) {
			$blocktype = $_;
			$blocktype =~ s/^-----END (PGP .*)-----/$1/;
			$blocktype =~ s/PGP MESSAGE/DECRYPTED MESSAGE/;
			$blocktype =~ s/PGP SIGNATURE/SIGNED MESSAGE/;
			chop ($blocktype);
			$topgp = 0;
			close (PGPFILE);
			system ("$pgpcommand $pgpfile -o $clrfile > /dev/tty 2>&1");
			open (CLEAR, "<$clrfile") || die "Cannot open $clrfile for input.\n";
			print OUTPUT "$prefix-----BEGIN $blocktype-----\n> \n";
			$blanks = 0;
			while (<CLEAR>) {
				if (m/^[ \t\r]*$/) {
					if ($paragraphs) {
						if ($blankcompress) {
							if ($blanks == 0) {
								print OUTPUT "\n";
								$blanks = 1;
							}
						} else {
							print OUTPUT "\n";
						}
					} else {
						print OUTPUT "$prefix\n";
					}
				} else {
					print OUTPUT "$prefix";
					print OUTPUT;
					$blanks = 0;
				}
			}
			close (CLEAR);
			unlink ($clrfile);
			unlink ($pgpfile);
			print OUTPUT "$prefix-----END $blocktype-----\n\n";
		}
	}
}
close OUTPUT;
close INPUT;
unlink ($name);
rename ("$rplyfile", "$name");

system ($visual, @ARGV);

while (!$q) {
	print "\nSign this message? [Y]: ";
	$q = <STDIN>;
	$q =~ s/[ \t\n]//g;
	$q = substr ($q, 0, 1);
	if (($q eq 'Y') || ($q eq 'y') || ($q eq '')) {
		push (@opts, '-st', '+clearsig=on');
		$q = "y";
	} elsif (($q ne 'N') && ($q ne 'n')) {
		$q = '';
	}
}

# note that it is the default to NOT encrypt,
# simply because not everyone has PGP (unfortunately :-)
$q='';
while (!$q) {
	print "Encrypt this message? [N]: ";
	$q = <STDIN>;
	$q =~ s/[ \t\n]//g;
	$q = substr ($q, 0, 1);
	if (($q eq 'Y') || ($q eq 'y')) {
		push (@opts, '-e');
		$q = "y";
	} elsif (($q eq 'N') || ($q eq 'n') || ($q eq '')) {
		$q = "n";
	} else {
		$q = '';
	}
}

if (@opts) {
	if ($q eq 'y') {
		print "Enter receipients, each on a separate line, terminate with EOF or a single `.':\n";
		{
			print "> ";
			if ($_ = <STDIN>) {
				chop;
				last if ("$_" eq '.');
				push (@receipients, "$_");
				redo;
			}
			last;
		}
	}
	system ($pgpcommand, '-a', @opts, "$name", @receipients);
	if ($? == 0) {
		unlink ($name);
		rename ("$ascfile", "$name");
	}
}