# -*-eselect-*-  vim: ft=eselect
# Copyright 2005-2021 Gentoo Authors
# Distributed under the terms of the GNU GPL version 2 or later

inherit package-manager

DESCRIPTION="Manage the iptables/arptables/ebtables symlinks"
MAINTAINER="base-system@gentoo.org"
VERSION="20200508"

# a simple list of symlinks does for iptables
IPTABLES_SYMLINKS=(
	"iptables-xml"
	"iptables" "iptables-restore" "iptables-save"
)
IP6TABLES_SYMLINKS=(
	"ip6tables" "ip6tables-restore" "ip6tables-save"
)

# for arptables and ebtables we map names to legacy targets
ARPTABLES_TARGETS=(
	"arptables-legacy"
	"xtables-nft-multi"
)
declare -A ARPTABLES_SYMLINKS=(
	[arptables]="arptables-legacy"
)

EBTABLES_TARGETS=(
	"ebtables-legacy"
	"xtables-nft-multi"
)
declare -A EBTABLES_SYMLINKS=(
	[ebtables]="ebtables-legacy"
	[ebtables-restore]="ebtables-legacy-restore"
	[ebtables-save]="ebtables-legacy-save"
)

# get which module is running
get_module() {
	local module
	module="${BASH_SOURCE[0]##*/}"

	printf -- '%s\n' "${module%.eselect}"
}

# find a list of symlink targets for the current module
find_targets() {
	local module target

	module="$(get_module)"
	case "${module}" in
		iptables)
			for target in "${EROOT}"/sbin/xtables-*-multi; do
				[[ -x ${target} ]] && printf -- '%s\n' "${target##*/}"
			done
		;;
		arptables)
			for target in "${ARPTABLES_TARGETS[@]}"; do
				[[ -x ${EROOT}/sbin/${target} ]] && printf -- '%s\n' "${target}"
			done
		;;
		ebtables)
			for target in "${EBTABLES_TARGETS[@]}"; do
				[[ -x ${EROOT}/sbin/${target} ]] && printf -- '%s\n' "${target}"
			done
		;;
		*) die "Invalid module name ${module}"
	esac
}

# get the list of symlinks for the current module
get_symlinks_list() {
	local module
	module="$(get_module)"

	case "${module}" in
		iptables)
			printf -- '%s\n' "${IPTABLES_SYMLINKS[@]}"

			if [[ ${1} == -a ]] || has_version 'net-firewall/iptables[ipv6]'
			then
				printf -- '%s\n' "${IP6TABLES_SYMLINKS[@]}"
			fi
		;;
		arptables) printf -- '%s\n' "${!ARPTABLES_SYMLINKS[@]}";;
		ebtables) printf -- '%s\n' "${!EBTABLES_SYMLINKS[@]}";;
		*) die "Invalid module name ${module}"
	esac
}

# get the symlink target given a symlink name and the target implementation
get_symlink_target() {	
	local link="${1}" target="${2}" module
	module="$(get_module)"

	case "${module}" in
		iptables) printf -- '%s\n' "${target}";;
		arptables)
			if [[ ${target} == *-legacy ]]; then
				printf -- '%s\n' "${ARPTABLES_SYMLINKS[${link}]}"
			else
				printf -- '%s\n' "${target}"
			fi
		;;
		ebtables)
			if [[ ${target} == *-legacy ]]; then
				printf -- '%s\n' "${EBTABLES_SYMLINKS[${link}]}"
			else
				printf -- '%s\n' "${target}"
			fi
		;;
		*) die "Invalid module name ${module}"
	esac
}

# set the symlinks for the current target
set_symlinks() {
	local target="${1}"
	local retval=0

	if is_number "${target}" && [[ ${target} -ge 1 ]]; then
		local -a targets
		readarray -t targets < <(find_targets)
		target=${targets[$((target-1))]}
	fi

	if [[ -z ${target} || ! -f ${EROOT}/sbin/${target} ]]; then
		die -q "Target \"${target}\" doesn't appear to be valid!"
	fi

	# create an array of symlinks to be created, then create them
	# in a separate pass, it's done this way in an attempt to be atomic
	# either all symlinks get updated, or none
	local -a symlinks_list
	readarray -t symlinks_list < <(get_symlinks_list)

	local symlink
	local -A do_symlinks
	for symlink in "${symlinks_list[@]}"; do
		local symlink_path="${EROOT}/sbin/${symlink}"

		if [[ -L ${symlink_path} || ! -e ${symlink_path} ]]; then
			do_symlinks["${symlink_path}"]="$(get_symlink_target "${symlink}" "${target}")"
	
		else
			die -q "Could not create symlink at ${symlink_path}:" \
				"path exits and is not a symlink"
		fi
	done

	for symlink in "${!do_symlinks[@]}"; do
		if ! ln -sfn "${do_symlinks["${symlink}"]}" "${symlink}"; then
			write_error_message "Failed to create symlink at ${symlink}"
			retval=1
		fi
	done

	return "${retval}"
}

### show action ###

describe_show() {
	printf -- 'Show the current %s symlink\n' "$(get_module)"
}

do_show() {
	local -a symlinks_list
	readarray -t symlinks_list < <(get_symlinks_list)

	local all_unset=1 symlink
	write_list_start "Current $(get_module) symlinks:"
	for symlink in "${symlinks_list[@]}"; do
		symlink_path="${EROOT}/sbin/${symlink}"

		if [[ -L ${symlink_path} ]]; then
			local symlink_target
			symlink_target=$(canonicalise "${symlink_path}")
			write_kv_list_entry "${symlink}" "${symlink_target%/}"
			all_unset=0
		elif [[ ! -f ${symlink_path} ]]; then
			write_kv_list_entry "${symlink}" "(unset)"
	  fi
	done

	return "${all_unset}"
}
### list action ###

describe_list() {
	printf -- 'List available %s symlink targets\n' "$(get_module)"
}

do_list() {
	local module
	module="$(get_module)"

	local -a targets_list symlinks_list
	readarray -t targets_list < <(find_targets)
	readarray -t symlinks_list < <(get_symlinks_list)

	local -a targets_output

	write_list_start "Available ${module} symlink targets:"
	local symlink current_target
	for symlink in "${symlinks_list[@]}"; do
		local symlink_path="${EROOT}/sbin/${symlink}"
		local target
		for target in "${targets_list[@]}"; do
			local symlink_target resolved_target
			symlink_target="$(get_symlink_target "${symlink}" "${target}")"
			resolved_target="$(basename "$(canonicalise "${symlink_path}")")"

			if [[ ${resolved_target} == "${symlink_target}" ]]; then
				if [[ -z ${current_target} ]]; then
					current_target="${target}"
					break
				elif [[ ${current_target} != "${target}" ]]; then
					write_warning_msg "Target mismatch"
					unset current_target
					break 2
				fi
			fi
		done
	done
	for target in "${targets_list[@]}"; do
		if [[ ${target} == "${current_target}" ]]; then
			targets_output+=("$(highlight_marker "${target}")")
		else
			targets_output+=("${target}")
		fi
	done

	write_numbered_list -m "(none found)" "${targets_output[@]}"
}

### set action ###

describe_set() {
	printf "Set a new $(get_module) symlink target\\n"
}

describe_set_options() {
	printf -- "target : Target name or number (from 'list' action)\\n"
}

do_set() {
	local target="${1}"

	[[ -z ${target} ]] && die -q "You didn't tell me what to set the symlink to"
	[[ ${#} -gt 1 ]] && die -q "Too many parameters"

	set_symlinks "${target}" || die -q "Couldn't set symlinks"
}

### unset action ###

describe_unset() {
	printf -- 'Unset %s symlink targets\n' "$(get_module)"
}

do_unset() {
	local retval=0

	local -a symlinks_list
	readarray -t symlinks_list < <(get_symlinks_list -a)

	local symlink
	for symlink in "${symlinks_list[@]}"; do
		local symlink_path="${EROOT}/sbin/${symlink}"
		if [[ -L ${symlink_path} ]]; then
			unlink "${symlink_path}" || retval=${?}
		elif [[ -e ${symlink_path} ]]; then
			write_error_msg "Not removing non-symlink \"${symlink_path}\""
			retval=1
		fi
	done

	return ${retval}
}