#!/bin/sh

# vm is a tool to manage and operate virtual machines.

vm_version='vm-0.1'

# TODO:
# - DONE: fetch, build and install vftool in .vm/vftool
# - setup a config file per VM
# - creation of hdd image
# - script install from CDROM iso:
#	- setup system, including static IP address
# 	- setup user account from host
# 	- setup ssh from host
# 	- time synchronization from host
#

unset CDPATH
export LC_ALL=C IFS=' 	
'

add() {
	usage 'add name' 'Add a new VM' && return
	[ -d "$dir/$1" ] && die "vm $1 already exists in $dir/$1"
	init_alpine || die "could not init alpine iso"
	mkdir -p "$dir/$1" && cd "$dir/$1" || die "add $1 failed"
	pwd
}

console() {
	usage 'console name' 'Attach a console to a VM' && return
	[ "$1" ] || die 'console: name is missing'
	cd "$dir/$1" || die 'console $1 failed'
	[ -f vftool.pid ] || die "vm $1 is not active"
	screen -r "$1"
}

del() {
	usage 'del name' 'Delete a VM' && return
	echo 'not implemented yet'
}

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

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

info() {
	usage 'info name' 'Print informations on a VM' && return
	echo 'not implemented yet'
}

# CAUTION: be careful to preserve tabs in the following Makefile template string.

alpine_makefile='# Generated by "vm". DO NOT EDIT.
# Check https://alpinelinux.org/downloads for possible upgrades
iso_url = https://dl-cdn.alpinelinux.org/alpine/v3.13/releases/aarch64/alpine-virt-3.13.2-aarch64.iso
iso = $(notdir $(iso_url))
isoinfo ?= /opt/homebrew/bin/isoinfo

all: initrd vmlinux

initrd: $(iso) $(isoinfo)
	isoinfo -i $(iso) -J -x /boot/initramfs-virt > $@

vmlinux: $(iso) $(isoinfo)
	isoinfo -i $(iso) -J -x /boot/vmlinuz-virt | gunzip > $@

$(iso):
	curl -LO $(iso_url) || { rm -f $@; false; }
	ln -sf $(iso) iso

$(isoinfo):
	brew install cdrtools
'

init_alpine() {
	mkdir -p "$dir/alpine-iso"  && cd "$dir/alpine-iso" || die 'init alpine failed'
	[ -f 'Makefile' ] || echo "$alpine_makefile" > Makefile
	make -s all
}

init_vftool() {
	[ -x "$dir/vftool" ] && return
	cd '/tmp' &&
	git clone --depth=1 'https://github.com/evansm7/vftool' &&
	cd 'vftool' &&
	make &&
	cp 'build/vftool' "$dir/vftool"
	rm -rf '/tmp/vftool'
}

log() {
	usage 'log name' 'print logs of a VM' && return
	[ "$1" ] || die "log failed: name missing"
	cd "$dir/$1" || die "log $1 failed"
	cat vftool.log.old vftool.log 2>/dev/null
}

ls() {
	usage 'ls' 'list VMs' && return
	[ -d "$dir" ] && cd "$dir" || return
	for i in */; do
		i=${i%/}
		[ -f "$i/vftool.pid" ] && state=active || state=stopped
		printf "%-20s %s\n" "$i" "$state"
	done
}

start() {
	usage 'start [-a][-c vm] name' 'Start a VM' && return
	while getopts :ac: opt; do
		case $opt in
		(a) attach=1 ;;
		(c) from=$OPTARG ;;
		(*) Opth=1 start; exit;;
		esac
	done
	shift $((OPTIND - 1))

	[ "$1" ] || die "start failed: name missing"
	init_vftool
	cd "$dir/$1" || die "start $1 failed"
	[ -f vftool.pid ] && die "Error: process $(cat vftool.pid) is active or $PWD/vftool.pid should be removed"
	start_vm &
}

start_vm() (
        trap 'rm -f vftool.pid' EXIT
        [ -f vftool.log ] && cat vftool.log >> vftool.log.old
        "$dir/vftool" -k vmlinux -i initrd -c iso >vftool.log 2>&1 & sleep 1
	exec 1>>vftool.log 2>&1
        echo "$!" >vftool.pid
        screen -S "${PWD##*/}" -d -m "$(grep -om 1 '\/dev\/tty.*' vftool.log)"
        wait
)

stop() {
	usage 'stop name' 'Stop a VM' && return
	[ "$1" ] || die 'stop: name missing'
	cd "$dir/$1" || die 'stop $1 failed'
	[ -f vftool.pid ] || die "stop: vm $1 is not active"
	kill $(cat vftool.pid)
}

usage() { [ "$Opth" ] && printf " %-34s %s\n" "$1" "$2"; }

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

# Main starts here.
dir="$HOME/.vm"
Cmdlist='add console del info help ls log start 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" ] || { help; exit 1; } && $cmd "$@"