use strict;
use warnings;
use Net::SSH2;
use Term::ReadLine;

my $host = 'hostname';
my $user = 'username';
my $pass = 'password';

my $ssh2 = Net::SSH2->new();
if ($ssh2->connect($host, 22)) {
    if ($ssh2->auth_password($user, $pass)) {

        my $chan = $ssh2->channel();
        $chan->blocking(0); # Needed on Windows
        $chan->shell();
        binmode($chan) # Seems to take care of both Unix SSH and Cisco servers
                       # Also set binmode in Net::Telnet::Cisco (\n vs \r\n)

        # Needed to "clear", flush() doesn't seem to work
        # Otherwise, first command does not work
        chan_read($chan);

        # START:  Interactive Mode
        my $prompt = "ssh> ";
        my $ssh = Term::ReadLine->new("SSH");
        $ssh->ornaments(0);

        # Main loop. This is inspired from the POD page of Term::Readline.
        while (defined (my $cmd = $ssh->readline($prompt))) {
            chomp $cmd;

            # nothing
            if ($cmd =~ /^\s*$/)        { next }
            # exit
            if ($cmd =~ /^\s*exit\s*$/) { last }
            cmd($chan, $cmd)
        }
        $chan->close
    } else {
        warn "Authentication failed\n"
    }
} else {
    warn "Unable to connect to host $host: $!\n"
}

sub cmd {
    my ($chan, $cmd) = @_;

    chomp $cmd;
    $chan->write("$cmd\n");
    select(undef,undef,undef,0.2); # or sleep 1
    my $ret = chan_read($chan, $cmd);
    print $ret
}

sub chan_read {
    my ($chan, $cmd) = @_;

    # need actual polling method rather than select or sleep to wait for a bit
    # example from the Net::SSH2 code, but doesn't seem to work:
    #
    # my @poll = ({handle => $chan, events => 'in'});
    # if($ssh2->poll(250, \@poll) && $poll[0]->{revents}->{in}) {
    #     print "HERE\n"
    # }
    #
    # or select():
    #
    # my ($rin, $rout, $ein, $eout) = ('', '', '', '');
    # vec($rin, $chan, 1) = 1; # tried $ssh2 and $chan, both "worked"
    #                          # should be: fileno($var)
    # if (select($rout=$rin, undef, $eout=$ein, 5000)) {
    #     print $buf while defined ($len = $chan->read($buf,512))
    # }
    my $DONE = 0;
    my $buffer;
    # Read until $DONE
    while (1) {
        last if $DONE;
        my $buf;
        # Read chunk
        while (defined (my $len = $chan->read($buf,512))) {
            # Found $PROMPT - then $DONE
            if ($buf =~ $PROMPT) {
                $buf =~ s/$PROMPT//;
                $DONE++;
            }
            $buffer .= $buf;
        }
    }
    # Remove $cmd from first line so no echo back
    if ((defined $cmd) and ($buffer =~ $cmd)) {
        $buffer =~ s/^$cmd\r\n//;
    }
    return $buffer
}