#!/bin/bash

set -e

display=:10
interface=0.0.0.0
cert_group=ssl-cert
xstartup_script=~/.vnc/xstartup

declare -A all_desktop_environments=(
  [Cinnamon]=cinnamon-session
  [Mate]="XDG_CURRENT_DESKTOP=MATE dbus-launch --exit-with-session mate-session"
  [LXDE]=lxsession [Lxqt]=startlxqt
  [KDE]=startkde
  [Gnome]="XDG_CURRENT_DESKTOP=GNOME dbus-launch --exit-with-session /usr/bin/gnome-session"
  [XFCE]=xfce4-session)
detected_desktop_environments=()
declare -A numbered_desktop_environments

debug() {
  if [ -z "$debug" ]; then return; fi

  echo "$@"
}

print_detected_desktop_environments() {
  declare -i i=1

  echo "Please choose Desktop Environment to run:"
  for detected_de in "${detected_desktop_environments[@]}"; do
    echo "[$i] $detected_de"
    numbered_desktop_environments[$i]=$detected_de
    i+=1
  done
}

detect_desktop_environments() {
  for de_name in "${!all_desktop_environments[@]}"; do
    local executable=${all_desktop_environments[$de_name]}
    executable=($executable)
    executable=${executable[-1]}

    if detect_desktop_environment "$de_name" "$executable"; then
      detected_desktop_environments+=("$de_name")
    fi
  done
}

detect_desktop_environment() {
  local de_name="$1"
  local executable="$2"

  if command -v "$executable" &>/dev/null; then
    return 0
  fi

  return 1
}

de_cmd_from_name() {
  de_cmd=${all_desktop_environments[$de_name]}
}

de_name_from_number() {
  local de_number_to_run="$1"

  de_name=${numbered_desktop_environments[$de_number_to_run]}
}

generate_xstartup() {
  local de_name="$1"

  de_cmd_from_name

  cat <<-SCRIPT > "$xstartup_script"
    #!/bin/sh
    exec $de_cmd
SCRIPT
  chmod +x "$xstartup_script"
}

if [[ "$1" = "--help" ]]; then
  cat >&2 <<-USAGE
Usage: `basename $0` [options]
  -d     Debug output
  -kill  Kill vncserver
  --help show this help
USAGE
  exit
fi

if [[ "$1" = "-d" ]]; then
  debug=1
  log_option="-log *:stderr:100"
fi

action=start
if [[ "$1" = "-kill" ]]; then
  action=kill
fi

if groups | grep -qvw ssl-cert; then
  cat <<-EOF
    Can't access TLS certificate.
    Please add your user to $cert_group via 'addgroup <user> ssl-cert'
EOF
  exit 1
fi

if [[ "$action" = "kill" ]]; then
  vncserver -kill $display
  exit
fi

detect_desktop_environments
print_detected_desktop_environments
read -r de_number_to_run
de_name_from_number "$de_number_to_run"
debug "You selected $de_name desktop environment"
generate_xstartup "$de_name"

vncserver $display -interface $interface
vncserver -kill $display
vncserver $display -depth 24 -geometry 1280x1050 -websocketPort 8443 \
  -cert /etc/ssl/certs/ssl-cert-snakeoil.pem \
  -key /etc/ssl/private/ssl-cert-snakeoil.key -sslOnly -FrameRate=24 \
  -interface $interface -httpd /usr/share/kasmvnc/www $log_option