#!/usr/bin/perl

use strict;
use warnings;

our $server_dir = '/var/pgen';
use File::Which;

if (scalar(@ARGV) != 1) {
        usage("Requires exactly 1 argument:");
} elsif ($ARGV[0] eq '-h' || $ARGV[0] eq '--help') {
        usage("Usage:  $0 <option>");
} elsif ($ARGV[0] eq 'server') {
        if (-d $server_dir) {
                print("Installation appears to already exist. Would you like it to be removed and
replaced? All existing password information will be lost. You should back up
/var/pgen/data if you would like to maintain your passwords.");
                my $selection;
                do {
                        print("[y/N]? ");
                        $selection = <STDIN>;
                        chomp($selection);
                } while (!defined($selection) || $selection !~ m/^[yYnN]?$/);
                unless ($selection eq 'y' || $selection eq 'Y') {
                        die("Abandoning installation\n");
                }
                remove_server();
        }
        install_server();
} elsif ($ARGV[0] eq 'client') {
        install_client();
} elsif ($ARGV[0] eq 'remove') {
        my %removed = (
                'server'        => undef,
                'client'        => undef
        );
        if (detect_server()) {
                $removed{'server'} = remove_server();
                print("Reloading SSH Daemon\n");
                system('systemctl restart sshd');
        }
        if (detect_client()) {
                $removed{'client'} = remove_client();
        }
        foreach (keys(%removed)) {
                if (defined($removed{$_})) {
                        if ($removed{$_}) {
                                print("Received error '$removed{$_}' while removing $_\n");
                        } else {
                                print("Successfully removed $_\n");
                        }
                }
        }
} elsif ($ARGV[0] eq 'add') {
        add_key();
} else {
        usage("Invalid argument '$ARGV[0]'. Requires one of:");
}

exit(0);

sub detect_server
{
        my $dir = (getpwnam('pgen'))[7] || return undef;
        if (-d $dir) {
                return($dir);
        }
        return(undef);

}

sub detect_client
{
        return(which('pgen'));
}

sub install_server
{
        my $perl = which('perl') || die "Missing dependency: perl\n";
        chomp($perl);
        my ($perl_dir) = $perl =~ m/^((?:\/[^\/]*)*)\/perl$/;
        my @perl_path = ( $server_dir );
        foreach (split('/',$perl_dir)) {
                unless($_ eq '') {
                        if (scalar(@perl_path)) {
                                $_ = $perl_path[scalar(@perl_path)-1].'/'.$_;
                        }
                        push(@perl_path,$_);
                }
        }
        foreach (@perl_path, $server_dir."/.ssh", $server_dir."/bin", $server_dir."/lib", $server_dir."/lib64") {
                print "Creating directory '$_'\n";
                mkdir($_) || die "Failed to mkdir '$_': $!\n";
        }
        use File::Copy;
        print("Installing Perl...\n");
        copy($perl,"${server_dir}${perl}");
        chmod(0755, "${server_dir}${perl}");
        my $libs = `ldd ${server_dir}${perl}`;
        foreach (split("\n",$libs)) {
                if ($_ =~ m#^\s+([^\ ]+)\ =>\ (\/[^\/]+)((?:\/[^\/]*)*)\/([^\/]+) \(.*#) {
                        print "Copying ${2}${3}/${4} to ${server_dir}${2}/${4}\n";
                        copy("${2}${3}/${4}","${server_dir}${2}/${4}");
                        chmod(0755, "${server_dir}${2}/${4}");
                } elsif ($_ =~ m#^\s+(\/[^\/]+)((?:\/[^\/]*)*)\/([^\/]+) \(.*#) {
                        print "Copying ${1}${2}/${3} to ${server_dir}${1}/${3}\n";
                        copy("${1}${2}/${3}","${server_dir}${1}/${3}");
                        chmod(0755, "${server_dir}${1}/${3}");
                } else {
                        print "skipping $_\n";
                }
        }
        my $src = $0;
        $src =~ s/(.*)\/([^\/]*)/$1\/bin\/pgen-server/;
        print("Installing $src to ${server_dir}/bin/pgen\n");
        copy($src,"${server_dir}/bin/pgen") || die("Failed to install: $!\n");
        chmod(0755, "${server_dir}/bin/pgen");
        print("Configuring user 'pgen'\n");
        system("useradd -d $server_dir pgen");
        system("usermod -s /bin/pgen pgen");
        add_key();
        unless(-e '/etc/ssh/sshd_config.d') {
                mkdir('/etc/ssh/sshd_config.d');
        }
        if (open(my $fh, '>', '/etc/ssh/sshd_config.d/pgen.conf')) {
                print($fh "Match user pgen
ChrootDirectory ${server_dir}\n");
                close($fh);
                print("Reloading SSH Daemon\n");
                system("systemctl restart sshd");
        } else {
                print("Failed to add SSH Daemon rules. You need to add the following:
  Match user pgen
  ChrootDirectory ${server_dir}");
        }
        print("Server installation complete\n");
}

sub install_client
{
        if (detect_client()) {
                die("Client is already installed. If necessary, uninstall it with 'remove'\n");
        }
        print("TODO: Here I would install the client\n");
}

sub remove_server
{
        if (detect_server()) {
                system("userdel pgen");
        }
        my @paths;
        my $paths_ref = \@paths;
        dig_dirs($paths_ref, $server_dir);
        unless (scalar(@paths)) {
                die("No chroot installation present at $server_dir\n");
        }
        push(@paths, '/etc/ssh/sshd_config.d/pgen.conf');
        while (scalar(@paths)) {
                my $target = pop(@paths);
                print "Removing $target\n";
                if (-d $target && !-l $target) {
                        rmdir($target) || die("Failed to remove directory '$target': $!\n");
                } else {
                        unlink($target) || die("Failed to delete '$target': $!\n");
                }
        }
}

sub dig_dirs
{
        my $paths_ref = shift;
        my $path = shift;
        unless (-e $path) {
                return(undef);
        }
        if ($path =~ m/\/\.\.?$/) {
                return;
        }
        push(@$paths_ref, $path);
        foreach (glob("$path/*"), glob("$path/.*")) {
                if ($path =~ m/\/\.\.?$/) {
                        next();
                } elsif (-l $_) {
                        push(@$paths_ref, $_);
                } elsif (-d $_) {
                        dig_dirs($paths_ref,$_);
                } else {
                        push(@$paths_ref, $_);
                }
        }
}

sub remove_client
{
        unless (detect_client()) {
                return "Client is not installed.\n";
        }
        print("TODO: Here I would remove the client\n");
}

sub add_key
{
        unless (detect_server()) {
                die("This must be run on a host with the server installed");
        }
        my $file = "$server_dir/.ssh/authorized_keys";
        my $msg = "Paste the SSH public key of the user. 'Q' to";
        if (-e $file) {
                print("Adding new user. $msg abort ");
        } else {
                print("Initializing with first user. $msg skip ");
        }
        my $key;
        do {
                print("[<key>/Q]: ");
                $key = <STDIN>;
                chomp($key);
        } while (!defined($key) || ($key ne 'Q' && $key ne 'q' && $key !~ m/^ssh\-(dsa|ecdsa|ecdsa\sk|ed25519|ed25519-sk|rsa)\ [a-zA-Z0-9\+\/]{50,}/));
        open(my $fh, '>>', $file) || die("Failed to open '$file': $!\n");
        unless ($key eq 'Q' && $key ne 'q') {
                print $fh $key."\n";
        }
        close($fh);
}

sub usage
{
        my $error = shift;
        if (!defined($error)) {
                $error = "Unknown failure. Try running with one of these options:";
        }
        die($error . "
        server  - install server application
        client  - install client application
        remove  - uninstall client and server (as necessary)
        add     - add a user key (SSH public key)\n");
        exit(1);
}