#!/usr/bin/env bash

set -eo pipefail

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" > /dev/null && pwd )"
ORIG_DISK_IMAGE=$1

function usage {
  cat<<EOF
  Usage: $0 </chemin/vers/image_disque>
  Éxecute l'image disque donnée avec Qemu
EOF
  exit 1
}

function find_available_port {
 read lower_port upper_port < /proc/sys/net/ipv4/ip_local_port_range
 while :; do
   for (( port = lower_port ; port <= upper_port ; port++ )); do
   (echo > /dev/tcp/0.0.0.0/$port) 2>/dev/null >/dev/null
   if [ $? -ne 0 ]; then
     echo $port
     return
   fi
   done
 done
}

[ -z "$ORIG_DISK_IMAGE" ] && usage

DISK_IMAGE_DIR="$DIR/../.run/$(dirname $ORIG_DISK_IMAGE)"
ORIG_DISK_IMAGE=$(readlink -f "$ORIG_DISK_IMAGE")
DISK_IMAGE_NAME=$(date -r "$ORIG_DISK_IMAGE" | shasum - | cut -f1 -d ' ').img
DISK_IMAGE="$DISK_IMAGE_DIR/$DISK_IMAGE_NAME"

if [ -f "$DISK_IMAGE" ]; then
  echo "Using existing qcow2 image '$DISK_IMAGE'..."
else
  mkdir -p "$(dirname $DISK_IMAGE)"
  rm -f "$DISK_IMAGE_DIR"/*.img
  cd "$(dirname $DISK_IMAGE)"
  echo "Generating qcow2 image '$DISK_IMAGE'..."
  qemu-img create -f qcow2 -b "$ORIG_DISK_IMAGE" "$(basename $DISK_IMAGE)"
  cd -
fi

SSH_PORT=$(find_available_port)
echo "Starting VM... SSH will be available on '127.0.0.1:${SSH_PORT}'"

qemu-system-x86_64 -boot once=d \
  -device virtio-net,netdev=user.0 \
  -m 1024M -machine type=pc,accel=kvm \
  -display sdl \
  -hda "${DISK_IMAGE}" \
  -netdev user,id=user.0,hostfwd=tcp::${SSH_PORT}-:22