#!/bin/bash
#
# Wrapper around ssh and vncviewer
#

# Parameters
BASENAME="`basename $0`"
SERVER="$1"
REMOTEUSER="$2"
LOCALPORT="${3:-5901}"
REMOTEPORT="${4:-5901}"

# Clipboard options
# In practice, clipboard limitations are not working as expected
# So please do not use this script if you don't want to automatically share clipboard with the remote system
# This is probably a bug on xtigervncviewer
VIEWER_OPTS="-AcceptClipboard=off -SendClipboard=off -SetPrimary=off -SendPrimary=off"

function usage {
  echo "usage: $BASENAME <server> [user] [localport] [remoteport]"
  cat <<EOF

setup instructions
==================

* in the remote:

  sudo apt install tigervnc-standalone-server # install in the remote server
  vncpasswd                                   # generate a ~/.vnc/passwd in the remote server

* in the local box:

  scp <server>:~/.vnc/passwd ~/.vnc/<server>.passwd # copy the secret
  $BASENAME <server>                                      # use our magic script to do everything else

EOF

  exit 1
}

# Usage
if [ "$1" == "--help" ]; then
  usage
fi

# Set user
if [ -z "$REMOTEUSER" ]; then
  REMOTEUSER="`whoami`"
fi

# Set config
if [ -z "$SERVER" ]; then
  if [ -h "$HOME/.vnc/$REMOTEUSER@default.passwd" ]; then
    SERVER="$(basename `readlink $HOME/.vnc/$REMOTEUSER@default.passwd` .passwd)"
  elif [ -h "$HOME/.vnc/default.passwd" ]; then
    SERVER="$(basename `readlink $HOME/.vnc/default.passwd` .passwd)"
  else
    usage
  fi
fi

# Check if vncserver is running in the remote server and start otherwise
ssh $REMOTEUSER@$SERVER <<EOF
  HOSTNAME="\$(cat /etc/hostname)"

  if [ -e "\$HOME/.vnc/\$HOSTNAME:1.pid" ]; then
    PID="\$(cat \$HOME/.vnc/\$HOSTNAME:1.pid)"

    if ! ps \$PID &> /dev/null; then
      /usr/bin/vncserver -alwaysshared -dpi 96 -localhost :1
    fi
  else
    /usr/bin/vncserver -alwaysshared -dpi 96 -localhost :1
  fi
EOF

# See http://www.g-loaded.eu/2006/11/24/auto-closing-ssh-tunnels/
# Optional SSH compression
#ssh -C -c blowfish -f -L 5901:127.0.0.1:5901 $SERVER sleep 10
ssh -f -L $LOCALPORT:127.0.0.1:$REMOTEPORT $REMOTEUSER@$SERVER sleep 10

# Run VNC client
# Copy $SERVER:~/.vnc/passwd into $HOME/.vnc/$SERVER.passwd for passwordless login
if [ -e "$HOME/.vnc/$REMOTEUSER@$SERVER.passwd" ]; then
  vncviewer $VIEWER_OPTS -passwd $HOME/.vnc/$REMOTEUSER@$SERVER.passwd localhost:$LOCALPORT
else
  vncviewer $VIEWER_OPTS localhost:$LOCALPORT
fi