#!/bin/sh

# Manage virtual machines
#
# Prereq:
#  - curl
#  - cdrtools (isoinfo)
#  - expect
#  - qemu
#  - screen
#
# TODO:
#  - extract bzImage and initrd.gz with isoinfo
#  - ssh scripts to finish install (once ssh is ready)
#
# DONE:
#  - setup vde and networking
#  - setup ssh keys so it is possible to ssh in vm from host
#
unset CDPATH
export LC_ALL=C IFS=' 	
'

version='vm-0.1'

arch=$(uname -m)
sys=$(uname -s)
alpine_version='3.15.0'
pubkey=$HOME/.ssh/id_rsa.pub
dir="${VM_DIR:-$HOME/.vm}"

console() {
	usage 'console name' 'Attach a console to a virtual machine' && return
	[ "$1" ] || die "missing argument"
	is_running "$1" && screen -r "vm!$1!"
}

create() {
	usage 'create [-s size] name' 'Create an alpinelinux disk image' && return
	size=8g
	while getopts :s: opt; do
		case $opt in
		s) size=$OPTARG ;;
		*) Opth=2 create_alpine_image; return ;;
		esac
	done
	shift $((OPTIND - 1))
	[ -d "$dir/$1" ] && die "create failed: $dir/$1 already exists"
	mkdir "$dir/$1"
	cd "$dir/$1" || die "create failed: invalid directory $dir/$1"
	qemu-img create "$1.raw" "$size" || die "create failed"
	mac=$(new_macaddr)
	ip=$(new_ip)
	hdd="$1.raw"
	echo "hdd=$hdd
mac=$mac
ip=$ip" >> config

	# Before install do not use virtio, as devices may not recognized as bootable
	# TODO: alternate way: extract kernel and initrd files and pass them directly to qemu
	screen -S "vm!$1!" -d -m qemu-system-$arch -nographic \
		-cdrom ../alpine-iso/alpine-virt-$alpine_version-$arch.iso \
		-hdd "$hdd" -net nic,macaddr=$mac -net vde
	setup_alpine "$1"
	post_setup_alpine "$1"
}

die() { [ "$1" ] && echo "$0: $*" >&2; exit 1; }

help() {
	usage 'help' 'Print this help text' && return
        printf "$version\n  Manage virtual machines\n\nUsage: vm command [options] [args]\n"
        Opth=1; for c in $Cmdlist; do $c; done
}

init() {
	mkdir -p "$dir"
}

init_alpine_iso() {
	usage init_alpine_iso '' && return
	mkdir -p "$dir/alpine-iso"
	iso_url="https://dl-cdn.alpinelinux.org/alpine/v${alpine_version%.*}/releases/$arch"
	iso="alpine-virt-$alpine_version-$arch.iso"
	cd "$dir/alpine-iso" 
	[ -f "$iso" ] || curl -LO "$iso_url/$iso" || rm -f "$iso"
	echo "iso=$iso
" > config
	echo 10 > ../index
}

is_running() { screen -ls "vm!$1!" >/dev/null 2>&1; }

ls() {
	usage 'ls' 'list virtual machines' && return
	init && cd "$dir" || die "could not change dir to $dir"
	for i in */; do
		i=${i%/}
		[ "$i" = '*' ] && continue
		is_running "$i" && state=active || state=stopped
		printf "%-20s %s\n" "$i" "$state"
	done
}

new_ip() {
	read index < $dir/index
	index=$((index + 1))
	echo "$index" > $dir/index
	echo "10.0.2.$index/24"
}

new_macaddr() { printf 'de:ad:be:ef:%02x:%02x\n' $((RANDOM % 256)) $((RANDOM % 256)); }

pidof() {
	usage 'pidof name' 'print the PID of a virtual machine' && return
	p=$(screen -ls "vm!$1!" | awk 'NR==2 {print substr($1, 1, index($1, ".")-1)}')
	[ "$p" ] && pgrep -P $p
}

post_setup_alpine() {
	start "$1"
	read proto key id < "$pubkey"
	# echo '
	expect -c '
		set timeout -1
		spawn screen -x "vm!'$1'!"
		expect {
			" login: " { send "root\r"; exp_continue }
			"Password: " { send "root\r"; exp_continue }
			":~# "
		}
		send "mkdir -pm 0700 .ssh\r"
		expect ":~# "
		send "echo '$proto' '$key' '$id' >.ssh/authorized_keys\r"
		expect ":~# "
		send "exit\r"
	'
}

# setup_alpine automates alpine installation from iso to image.
# When done, base image system is ready, with storage and network up.
# No user nor ssh access configured yet.
# TODO: custom network (in case of no dhcp).
setup_alpine() {
	usage 'setup_alpine' && return
	expect -c '
		set timeout -1
		spawn screen -x "vm!'$1'!"
		expect {
			"localhost login: "                     { send "root\r"; exp_continue }
			"localhost:~# "                         { send "SWAP_SIZE=0 setup-alpine\r"; exp_continue }
			"Select keyboard layout: "              { send "\r"; exp_continue }
			"Enter system hostname"                 { send "'$1'\r"; exp_continue }
			"Which one do you want to initialize?"  { send "\r"; exp_continue }
			"Ip address for eth0?"                  { send "'$ip'\r"; exp_continue }
			"Gateway?"                              { send "10.0.2.2\r"; exp_continue }
			"manual network configuration?"         { send "\r"; exp_continue }
			"DNS domain name?"                      { send "lan\r"; exp_continue }
			"DNS nameserver(s)?"                    { send "10.0.2.2 1.1.1.1\r"; exp_continue }
			"New password:"                         { send "root\r"; exp_continue }
			"Retype password:"                      { send "root\r"; exp_continue }
			"Which timezone are you in?"            { send "\r"; exp_continue }
			"HTTP/FTP proxy URL?"                   { send "\r"; exp_continue }
			"Enter mirror number "                  { send "\r"; exp_continue }
			"Which SSH server?"                     { send "\r"; exp_continue }
			"Which disk(s) would you like to use?"  { send "sda\r"; exp_continue }
			"How would you like to use it?"         { send "sys\r"; exp_continue }
			"Erase the above disk(s) and continue?" { send "y\r"; exp_continue }
			"Installation is complete"              { send "poweroff\r" }
		}
		interact
	'
}

start_vde() {
	usage start_vde && return
	sudo sh <<- EOT
		vde_switch -tap tap0 -sock /tmp/vde.ctl -daemon -mod 666
		sleep 1
		ip address add 10.0.2.2/24 dev tap0
		ip link set tap0 up
		echo 1 > /proc/sys/net/ipv4/ip_forward
		iptables -t nat -A POSTROUTING -s 10.0.2.0/24 -o eth0 -j MASQUERADE
		iptables -t nat -A POSTROUTING -s 10.0.2.0/24 -o wlan0 -j MASQUERADE
	EOT
	#slirpvde --dhcp --daemon
}

stop_vde() {
	# killall slirpvde
	sudo sh <<- EOT
		iptables -t nat -D POSTROUTING -s 10.0.2.0/24 -o eth0 -j MASQUERADE
		iptables -t nat -D POSTROUTING -s 10.0.2.0/24 -o wlan0 -j MASQUERADE
		ip link set tap0 down
		killall vde_switch
	EOT
}

start() {
	usage 'start [-acd] name' 'start a virtual machine' && return
	while getopts :acd opt; do
		case $opt in
		a) opta=1 ;;
		c) boot=c ;;
		d) boot=d ;;
		esac
	done
	shift $((OPTIND -1))
	[ "$1" ] || die 'start failed: name missing'
	cd "$dir/$1" || die "start failed: invalid directory $dir/$1"
	is_running "$1" || start_qemu "$1"
	[ "$opta" ] && console "$1"
}

start_qemu() (
	opt='-nographic -cpu max'
	[ "$sys" = Linux ] && opt="$opt -enable-kvm"
	. ./config || die "could not source $PWD/config"
	exec 1>>qemu.log 2>&1
	date +%F_%T
	set -x
	screen -S "vm!$1!" -d -m qemu-system-$arch $opt \
		${smp+-smp $smp} \
		${ram+-m $ram} \
		${mac+-net nic,macaddr=$mac,model=virtio-net-pci} -net vde \
		${hdd+-drive file="$hdd",if=virtio,media=disk,format=raw} \
		${iso+-drive file="$iso",if=virtio,media=cdrom,format=raw} \
		${boot+-boot $boot}
)

stop() {
	usage 'stop name' 'stop a virtual machine' && return
	is_running "$1" && kill "$(pidof "$1")"
}

usage() {
	case $Opth in
	1) printf " %-34s %s\n" "$1" "$2" ;;
	2) printf "$0 $1\n\t$2\n" ;;
	*) return 1 ;;
	esac
}

version() {
	usage 'version' 'Print version' && return
	echo "$version"
}

Cmdlist='console create help init_alpine_iso ls pidof setup_alpine start start_vde stop version'
[ "$1" ] && C=$1 && shift 1 || { help; exit 1; }
#for c in $Cmdlist; do
#	case $c in
#	("$C")  cmd=$c; break ;;
#	("$C"*) [ "$cmd" ] && die "ambiguous command $C" || cmd=$c ;;
#	esac
#done
cmd=$C
[ "$cmd" ] || { help; exit 1; } && $cmd "$@"