#!/bin/bash

exec_as() {
  local user="$1"
  shift

  if [ "$(whoami)" != "$user" ]; then
    exec sudo -u "$user" "$0" "$@"
  else
    cd
  fi
}

exec_as qemu "$@" || exit
PATH="./bin:${PATH}"

perror() {
  >&2 printf '\033[1;31mERROR:\033[0m \033[1m%s\033[0m\n' "$*"
}

public_help() {
  local name
  name="$(basename "$0")"
  cat << EOF
${name}: usage:
  ${name} start <VM name>  - start a VM
  ${name} watch <VM name>  - attach VM screen session
  ${name} active           - (default behaviour) list active VMs
  ${name} list             - list available VMs
  ${name} help             - show this help
EOF
}

error_usage() {
  perror "Invalid usage"
  >&2 public_help
  return 1
}

public_start() {
  local vm_name="$1"
  shift

  screen -d -m -S "$vm_name" "$vm_name" "$@"
}

public_watch() {
  screen -dr "$1"
}

public_list() {
  screen -ls
}

function="$1"
shift

if declare -F | cut -d \  -f 3- | grep '^public_' | sed 's/^public_//' | grep -q "^${function}$"; then
  "public_${function}" "$@"
else
  error_usage
fi