#!/usr/bin/env bash
#
#    Copyright (C) 2020 Santiago Piccinini <spiccinini@altermundi.net>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
# ARG_OPTIONAL_SINGLE([libremesh-workdir],[],[Optional path to a libremesh working directory to include it as a layer over the rootfs.])
# ARG_OPTIONAL_SINGLE([node-id],[],[An ID number from 0 to 99. Use this when running multiple qemu nodes, each node must have a different ID.],[0])
# ARG_OPTIONAL_SINGLE([enable-wan],[],[Provide the node with NATed access to the local netork. An ifc must be provided, eg wlan0. Needs dnsmasq installed.])
# ARG_OPTIONAL_SINGLE([eth0],[],[Optionally specify ifname of tap to use (need to create it yourself)])
# ARG_OPTIONAL_SINGLE([eth2],[],[Optionally specify ifname of tap to use (need to create it yourself)])
# ARG_OPTIONAL_BOOLEAN([verbose],[],[Turn on verbose mode],[])
# ARG_POSITIONAL_SINGLE([rootfs],[Path to a x86-64-generic-rootfs.tar.gz],[])
# ARG_POSITIONAL_SINGLE([ramfs],[Path to a x86-64-ramfs.bzImage],[])
# ARG_HELP([Helper to run libremesh in a qemu x86_64 for development purposes])
# ARGBASH_GO()
# needed because of Argbash --> m4_ignore([
### START OF CODE GENERATED BY Argbash v2.9.0 one line above ###
# Argbash is a bash code generator used to get arguments parsing right.
# Argbash is FREE SOFTWARE, see https://argbash.io for more info
# Generated online by https://argbash.io/generate


die()
{
	local _ret="${2:-1}"
	test "${_PRINT_HELP:-no}" = yes && print_help >&2
	echo "$1" >&2
	exit "${_ret}"
}


begins_with_short_option()
{
	local first_option all_short_options='h'
	first_option="${1:0:1}"
	test "$all_short_options" = "${all_short_options/$first_option/}" && return 1 || return 0
}

# THE DEFAULTS INITIALIZATION - POSITIONALS
_positionals=()
# THE DEFAULTS INITIALIZATION - OPTIONALS
_arg_libremesh_workdir=
_arg_node_id="0"
_arg_enable_wan=
_arg_eth0=
_arg_eth2=
_arg_verbose="off"


print_help()
{
	printf '%s\n' "Helper to run libremesh in a qemu x86_64 for development purposes"
	printf 'Usage: %s [--libremesh-workdir <arg>] [--node-id <arg>] [--enable-wan <arg>] [--eth0 <arg>] [--eth2 <arg>] [--(no-)verbose] [-h|--help] <rootfs> <ramfs>\n' "$0"
	printf '\t%s\n' "<rootfs>: Path to a x86-64-generic-rootfs.tar.gz"
	printf '\t%s\n' "<ramfs>: Path to a x86-64-ramfs.bzImage"
	printf '\t%s\n' "--libremesh-workdir: Optional path to a libremesh working directory to include it as a layer over the rootfs. (no default)"
	printf '\t%s\n' "--node-id: An ID number from 0 to 99. Use this when running multiple qemu nodes, each node must have a different ID. (default: '0')"
	printf '\t%s\n' "--enable-wan: Provide the node with NATed access to the local netork. An ifc must be provided, eg wlan0. Needs dnsmasq installed. (no default)"
	printf '\t%s\n' "--eth0: Optionally specify ifname of tap to use (need to create it yourself) (no default)"
	printf '\t%s\n' "--eth2: Optionally specify ifname of tap to use (need to create it yourself) (no default)"
	printf '\t%s\n' "--verbose, --no-verbose: Turn on verbose mode (off by default)"
	printf '\t%s\n' "-h, --help: Prints help"
}


parse_commandline()
{
	_positionals_count=0
	while test $# -gt 0
	do
		_key="$1"
		case "$_key" in
			--libremesh-workdir)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_libremesh_workdir="$2"
				shift
				;;
			--libremesh-workdir=*)
				_arg_libremesh_workdir="${_key##--libremesh-workdir=}"
				;;
			--node-id)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_node_id="$2"
				shift
				;;
			--node-id=*)
				_arg_node_id="${_key##--node-id=}"
				;;
			--enable-wan)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_enable_wan="$2"
				shift
				;;
			--enable-wan=*)
				_arg_enable_wan="${_key##--enable-wan=}"
				;;
			--eth0)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_eth0="$2"
				shift
				;;
			--eth0=*)
				_arg_eth0="${_key##--eth0=}"
				;;
			--eth2)
				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
				_arg_eth2="$2"
				shift
				;;
			--eth2=*)
				_arg_eth2="${_key##--eth2=}"
				;;
			--no-verbose|--verbose)
				_arg_verbose="on"
				test "${1:0:5}" = "--no-" && _arg_verbose="off"
				;;
			-h|--help)
				print_help
				exit 0
				;;
			-h*)
				print_help
				exit 0
				;;
			*)
				_last_positional="$1"
				_positionals+=("$_last_positional")
				_positionals_count=$((_positionals_count + 1))
				;;
		esac
		shift
	done
}


handle_passed_args_count()
{
	local _required_args_string="'rootfs' and 'ramfs'"
	test "${_positionals_count}" -ge 2 || _PRINT_HELP=yes die "FATAL ERROR: Not enough positional arguments - we require exactly 2 (namely: $_required_args_string), but got only ${_positionals_count}." 1
	test "${_positionals_count}" -le 2 || _PRINT_HELP=yes die "FATAL ERROR: There were spurious positional arguments --- we expect exactly 2 (namely: $_required_args_string), but got ${_positionals_count} (the last one was: '${_last_positional}')." 1
}


assign_positional_args()
{
	local _positional_name _shift_for=$1
	_positional_names="_arg_rootfs _arg_ramfs "

	shift "$_shift_for"
	for _positional_name in ${_positional_names}
	do
		test $# -gt 0 || break
		eval "$_positional_name=\${1}" || die "Error during argument parsing, possibly an Argbash bug." 1
		shift
	done
}

parse_commandline "$@"
handle_passed_args_count
assign_positional_args 1 "${_positionals[@]}"

#####################


if [[ "$_arg_verbose" == "on" ]]; then
    set -x
fi

BRIDGE_IFC="lime_br0"
NODE_ID="${_arg_node_id}"
[ ${#NODE_ID} == 1 ] && NODE_ID=0${NODE_ID} # Pad with leading zero
LAN_MAC="52:00:00:ab:c0:${NODE_ID}"
WAN_MAC="52:00:00:ab:c1:${NODE_ID}"
ETH2_MAC="52:00:00:ab:c2:${NODE_ID}"
LAN_IFC="lime_tap${NODE_ID}_0"
WAN_IFC="lime_tap${NODE_ID}_1"
ETH2_IFC="lime_tap${NODE_ID}_2"
OWN_LAN_IP="10.13.0.2/16"

[ -n "${_arg_eth0}" ] && LAN_IFC="${_arg_eth0}"
[ -n "${_arg_eth2}" ] && ETH2_IFC="${_arg_eth2}"

if [[ -z "$_arg_eth0" ]]; then
    if [ ! -e "/sys/class/net/$BRIDGE_IFC" ]; then
        ip link add name "$BRIDGE_IFC" type bridge
        ip link set "$BRIDGE_IFC" up
        ip addr add "$OWN_LAN_IP" dev "$BRIDGE_IFC"
    fi

    if [ ! -e "/sys/class/net/$LAN_IFC" ]; then
        # No IP for the tap LAN ifc
        ip tuntap add name "$LAN_IFC" mode tap
        ip link set "$LAN_IFC" up
        ip link set "$LAN_IFC" master "$BRIDGE_IFC"
    fi
fi

if [ -n "$_arg_enable_wan" ]; then
    # WAN ifc
    if [ ! -e "/sys/class/net/$WAN_IFC" ]; then
        ip tuntap add name "$WAN_IFC" mode tap
        ip addr add 172.99.0.1/24 dev "$WAN_IFC"
        ip link set "$WAN_IFC" up
    fi

    # DHCP server for WAN ifc
    dnsmasq -F 172.99.0.100,172.99.0.100 --dhcp-option=3,172.99.0.1 -i "$WAN_IFC" --dhcp-authoritative --log-dhcp

    # enable forwarding and NAT
    echo 1 > /proc/sys/net/ipv4/ip_forward
    iptables -t nat -A POSTROUTING -o "$_arg_enable_wan" -j MASQUERADE
    iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
    iptables -A FORWARD -i  "$WAN_IFC"  -o "$_arg_enable_wan" -j ACCEPT
fi

# Convert the rootfs.tar.gz into a cpio file
# We are using cpio rootfs so we can change the files before booting
temp_dir=/tmp/lime_rootfs_${NODE_ID}
rm -rf $temp_dir
mkdir -p $temp_dir
tar xf "${_arg_rootfs}" -C $temp_dir

# if a libremesh workdir is specified then we copy the files from the workdir
# into the rootfs
if [ "$_arg_libremesh_workdir" ]; then
    # Copying the new lime overlay here
    for package in "${_arg_libremesh_workdir}"/packages/*/files/*; do
        cp -r "${package}" $temp_dir
    done
fi

# quick hack used by qemu_cloud_start.yml ansible playbook
[ -e /tmp/lime_node_${NODE_ID} ] && mv /tmp/lime_node_${NODE_ID} ${temp_dir}/etc/config/lime-node

# build the cpio
( cd /tmp/lime_rootfs_${NODE_ID} && find . | cpio --quiet -o -H newc  > /tmp/lime_rootfs_${NODE_ID}.cpio )

MONITOR_PORT="454${NODE_ID}"

qemu-system-x86_64 \
-m 128 \
-smp 1,sockets=1,cores=1,threads=1 \
-no-user-config \
-enable-kvm \
-nographic \
-nodefaults \
-no-reboot \
-kernel "${_arg_ramfs}" \
-initrd /tmp/lime_rootfs_${NODE_ID}.cpio \
-serial mon:stdio \
-monitor "telnet::${MONITOR_PORT},server,nowait" \
-netdev tap,id=hostnet0,ifname="${LAN_IFC}",script=no,downscript=no \
-device e1000,netdev=hostnet0,id=net0,mac="${LAN_MAC}",bus=pci.0,addr=0x3 \
-netdev tap,id=hostnet1,ifname="${WAN_IFC}",script=no,downscript=no \
-device e1000,netdev=hostnet1,id=net1,mac="${WAN_MAC}",bus=pci.0,addr=0x4 \
-netdev tap,id=hostnet2,ifname="${ETH2_IFC}",script=no,downscript=no \
-device e1000,netdev=hostnet2,id=net2,mac="${ETH2_MAC}",bus=pci.0,addr=0x5


# cleanup
if [[ -z "$_arg_eth0" ]]; then
    ip tuntap del name ${LAN_IFC} mode tap
fi

if [ -n "$_arg_enable_wan" ]; then

    ip tuntap del name "${WAN_IFC}" mode tap

    # End dnsmasaq
    kill -TERM `cat /var/run/dnsmasq.pid`

fi