function restart_vnc_service {
  stop_service vncserver-x11-serviced.service
  disable_service vncserver-x11-serviced.service
  systemctl set-default multi-user.target

  enable_service vncserver-x11-serviced.service
  start_service vncserver-x11-serviced.service
  systemctl set-default graphical.target
  reboot_needed
}

function vnc {
  local option bootoptionstatus vncservicestatus xservicestatus ipaddress isgraphical
  checkroot
  checkargn $# 2
  option=$1
  auth=$2
  bootoptionstatus=$(systemctl is-enabled graphical.target)
  vncservicestatus=$(systemctl is-active vncserver-x11-serviced)
  xservicestatus=$(systemctl is-active lightdm)
  ipaddress=$(/usr/lib/vnc/get_primary_ip4)

  # Get the status of each VNC related service for status-service
  if [ "$bootoptionstatus" = "static" ]; then
    isgraphical="Console"
  elif [ "$bootoptionstatus" = "indirect" ]; then
    isgraphical="Desktop"
  fi

  # Checks whether we have the required package to run a VNC server
  if [ ! -d /usr/share/doc/realvnc-vnc-server ] ; then
    log_comment_and_exit1 "Error: the vnc server is not installed, to install it run:" "apt-get install realvnc-vnc-server"
  fi

  case "$option" in
    "")
      if [ "$bootoptionstatus" = "static" ] && [ "$vncservicestatus" = "inactive" ] && [ "$xservicestatus" = "inactive" ]; then
        echo "VNC is disabled."
        echo "To enable it, use $BASENAME vnc on"
      elif [ "$bootoptionstatus" = "indirect" ] && [ "$vncservicestatus" = "active" ] && [ "$xservicestatus" = "active" ]; then
        echo "You can now remotely access the system with a VNC client using the IP address: $ipaddress"
        echo "To disable it, use $BASENAME vnc off"
      elif [ "$bootoptionstatus" = "indirect" ] && [ "$vncservicestatus" = "active" ] && [ "$xservicestatus" = "failed" ]; then
        echo "Please reboot your system."
      elif [ "$bootoptionstatus" = "static" ] && [ "$vncservicestatus" = "inactive" ] && [ "$xservicestatus" = "active" ]; then
        echo "Please reboot your system."
      else
        echo "VNC server is not configured correctly. Please try $BASENAME vnc on to enable it, or $BASENAME vnc off to disable it."
        echo "Alternatively, you may try $BASENAME vnc info to verify the status of each specific required service."
      fi
      ;;
    "on")
      grep -qF 'hdmi_group=2' '/boot/config.txt' || echo 'hdmi_group=2' | tee -a '/boot/config.txt'
      grep -qF 'hdmi_mode=82' '/boot/config.txt' || echo 'hdmi_mode=82' | tee -a '/boot/config.txt'
      sed -i 's/#hdmi_force_hotplug=1/hdmi_force_hotplug=1/' /boot/config.txt
      enable_service vncserver-x11-serviced.service
      start_service vncserver-x11-serviced.service
      systemctl set-default graphical.target
      reboot_needed
      echo "Success: the vnc service has been started and enabled when the system boots."
      echo "Please reboot the system for changes to take effect."
      echo "You can then remotely access the system with a VNC client using the IP address: $ipaddress"
      ;;
    "off")
      sed -i '/hdmi_group=2/d' /boot/config.txt
      sed -i '/hdmi_mode=82/d' /boot/config.txt
      sed -i 's/hdmi_force_hotplug=1/#hdmi_force_hotplug=1/' /boot/config.txt
      stop_service vncserver-x11-serviced.service
      disable_service vncserver-x11-serviced.service
      systemctl set-default multi-user.target
      reboot_needed
      echo "Success: the vnc service has been stopped and disabled when the system boots."
      echo "Please reboot the system for changes to take effect."
      ;;
    "info")
      echo "The system boots into $isgraphical"
      echo "The VNC service is $vncservicestatus"
      echo "The X window service is $xservicestatus"
      echo "In order to access your desktop via a VNC viewer, the system needs to boot into Desktop, and VNC and X window services need to be running"
      if [ "$bootoptionstatus" = "indirect" ] && [ "$vncservicestatus" = "active" ] && [ "$xservicestatus" = "failed" ]; then
        echo "Please reboot your system."
      fi
      if [ "$bootoptionstatus" = "static" ] && [ "$vncservicestatus" = "inactive" ] && [ "$xservicestatus" = "active" ]; then
        echo "Please reboot your system."
      fi
      ;;
    "auth")
      case $auth in
        "system")
          echo "Changing VNC server authentication to system authentication way..."
          echo "Writing 'Authentication=SystemAuth' to config file"
          if [[ -f /root/.vnc/config.d/vncserver-x11 ]]
          then
            if grep -Fxq "Authentication" /root/.vnc/config.d/vncserver-x11
            then
              sed -i 's/VncAuth/SystemAuth/' /root/.vnc/config.d/vncserver-x11
            else
               echo "Authentication=SystemAuth" >> /root/.vnc/config.d/vncserver-x11
            fi
          else
            mkdir -p /root/.vnc/config.d
            echo "Authentication=SystemAuth" >> /root/.vnc/config.d/vncserver-x11
          fi
          restart_vnc_service > /dev/null 2>&1
          echo "Please reboot the system for changes to take effect."
          ;;
        "vnc")
          if [[ -f /root/.vnc/config.d/vncserver-x11 ]]
          then
            echo "Changing VNC server authentication to VNC password authentication way..."
            echo "Writing 'Authentication=VncAuth' to config file"
            if grep -Fxq "Authentication" /root/.vnc/config.d/vncserver-x11
            then
              sed -i 's/SystemAuth/VncAuth/' /root/.vnc/config.d/vncserver-x11
              echo "Please reboot the system for changes to take effect."
            else
              echo "Authentication=VncAuth" >> /root/.vnc/config.d/vncserver-x11
            fi
            restart_vnc_service > /dev/null 2>&1
            echo "Create your password, run 'treehouses vnc password'."
            echo "Please reboot the system for changes to take effect."
          else
            echo "Please create a password first, run 'treehouses vnc password'."
          fi
          ;;
        "info")
          if [[ -f /root/.vnc/config.d/vncserver-x11 ]]
          then
            if grep "VncAuth" < /root/.vnc/config.d/vncserver-x11
            then
              echo "You are running VNC password authentication."
            else
              echo "You are running system authentication."
            fi
          else
            echo "You are running system authentication."
          fi
          ;;
        *)
          echo "Error: only 'system', 'vnc', 'info' options are supported"
          ;;
      esac
      ;;
    "password")
      echo "Creating password of VNC service mode for VNC password authentication..."
      vncpasswd -service
      ;;
    *)
      log_and_exit1 "Error: only 'on', 'off', 'info', 'auth', 'password' options are supported"
      ;;
  esac
}

# Prints the options for the "vnc" command
function vnc_help {
  echo
  echo "Usage: $BASENAME vnc <on|off|info>"
  echo
  echo "Example:"
  echo "  $BASENAME vnc"
  echo "      Prints the status of the VNC server (enabled or disabled)."
  echo
  echo "  $BASENAME vnc on"
  echo "      The VNC service will be enabled. This will allow devices on your network to be able to connect to the raspberry pi using VNC viewer."
  echo "      This will disable html, if it is active."
  echo
  echo "  $BASENAME vnc off"
  echo "      VNC services will be disabled."
  echo
  echo "  $BASENAME vnc info"
  echo "      Prints a detailed configuration of each required component (boot option, vnc service, x service)."
  echo
  echo "  $BASENAME vnc auth <system|vnc|info>"
  echo "      Change the VNC server authentication way (system default or vnc password)."
  echo
  echo "  $BASENAME vnc password"
  echo "      Create password of VNC service mode for VNC password authentication."
  echo
}