#!/usr/bin/env bash
# author: joe.zheng
# version: 23.12.08

set -e

ADDR="localhost"
PORT=4400
BASE=0
COUNT=1

DRY_RUN="n"

function usage() {
  local self=`basename $0`
  local version="$(sed -n '1,4s/# version: \(.*\)/\1/p' $0)"

  cat <<EOF
Usage: $self [-a <addr>] [-p <port>] [-b <base>] [-n] [-h] [<count>]
  Stop a number of QEMU VMs through the QEMU monitor gently

  -a <addr>:  address of the QEMU monitor, default: $ADDR
  -p <port>:  base port of the QEMU monitor, default: $PORT
  -b <base>:  base index of the VM, default: $BASE
  -n:         dry run, print out information only, default: $DRY_RUN
  -h:         print the usage message

  <count>:    number of the VMs, default: $COUNT

  We assume the port number of the QEMU monitor for each VM is consecutive,
  e.g., if the base port is 4400, the ports of the 2 VMs should be 4400 and 4401
  
  You need to wait for a while to let the QEMU shutdown the VM gently,
  if you are impatient, access to the monitor by telnet and run commands:

  # check status
  info status
  # stop directly
  stop

Examples:
  # Check information before actual execution
  $self -n

  # Stop a VM via QEMU monitor at $ADDR:$PORT
  $self

  # Stop 2 VMs via QEMU monitor at 192.168.0.1, port: 4000, 4001 
  $self -a 192.168.0.1 -p 4000 2

Version: $version
EOF

}

while getopts ":a:b:hnp:" opt; do
  case $opt in
    a ) ADDR=$OPTARG;;
    b ) BASE=$OPTARG;;
    h ) usage && exit;;
    n ) DRY_RUN=y;;
    p ) PORT=$OPTARG;;
    * ) usage && exit 1;;
  esac
done

shift $((OPTIND-1))

if [[ -n $1 && $1 > 0 ]]; then
  COUNT=$1
fi

for ((i=BASE; i<BASE+COUNT; i++)); do
  host=$ADDR
  port=$(($PORT + $i))

  echo "connecting to the monitor $host:$port"
  name=$(echo "info name" | nc $host $port 2>/dev/null | head -n3 | tail -n1 | tr -d '\r\n')

  if [[ -n "$name" ]]; then
    echo "shutdown VM $name gently, wait for a while to finish"
    if [[ $DRY_RUN != "y" ]]; then
      echo "system_powerdown" | nc $host $port >/dev/null
    fi
    echo
  else
    echo "fail to connect" >&2
    exit 1
  fi
done