# -*-eselect-*-  vim: ft=eselect
# Copyright 1999-2013 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2 or later
# $Id: $

DESCRIPTION="Switch between sysvinit implementations"
MAINTAINER="lxnay@gentoo.org"
VERSION="0.1"

# Directory where sysvinit implementations are supposed to be found.
# The directory name is going to become the target name.
INITS_DIR="${EROOT}/%INITS_DIR%"

# Directory where symlinks are created
INIT_DIR="${EROOT}/%INIT_DIR%"

# Executables expected to be found in ${INITS_DIR}/<target>/
INIT_PARTS=( %INIT_PARTS% )

# File that contains the name of the currently running
# sysvinit, that will be used by /sbin/init.d/exec.sh
# to redirect the command calls to the old sysvinit
# implementation (which is now in lame duck), after
# a successful set.
RUNNING_INIT="${EROOT}/run/running.sysvinit"


find_targets() {
	local d=
	local dname=
	local legit=
	for d in "${INITS_DIR}/"*; do
		[[ ! -d "${d}" ]] && continue
		legit=1
		for part in "${INIT_PARTS[@]}"; do
			[[ ! -x "${d}/${part}" ]] && {
				legit=0;
				break;
			}
		done
		[[ ${legit} == 0 ]] && continue
		dname=$(basename "${d}")
		echo "${dname}"
	done
}

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

	if is_number "${target}"; then
		local targets=( $(find_targets) )
		target=${targets[target-1]}
	fi
	local target_dir="${INITS_DIR}/${target}"

	[[ -z "${target}" || ! -d "${target_dir}" ]] \
		&& die -q "Target \"${target}\" doesn't appear to be valid!"

	if [ ! -e "${RUNNING_INIT}" ]; then
		echo "$(get_init)" > "${RUNNING_INIT}.tmp" || \
			die "Cannot create ${RUNNING_INIT}.tmp"
		mv -n "${RUNNING_INIT}.tmp" "${RUNNING_INIT}" || \
			die "Cannot create ${RUNNING_INIT}"
	fi

	echo "Setting the sysvinit implementation to ${target}"
	local s d part
	for part in "${INIT_PARTS[@]}"; do
		s="${target_dir}/${part}"
		d="${INIT_DIR}/${part}"
		ln -sf "${s#${INIT_DIR}/}" "${d}.tmp" || \
			{
				rm -f "${d}.tmp";
				die "Cannot create symlink: ${d}.tmp"
			}
		mv "${d}.tmp" "${d}" || die "Cannot mv symlink: ${d}.tmp"
	done
}

get_init() {
	local init=
	local init_link=
	local init_link_dir=
	local init_bn=

	init="${INIT_DIR}/${INIT_PARTS[0]}"
	[[ ! -L "${init}" ]] && return 1

	init_link=$(readlink "${init}")
	[[ -z "${init_link}" ]] && return 1

	init_link_dir=$(dirname "${init_link}")
	[[ -z "${init_link_dir}" ]] && return 1

	init_bn=$(basename "${init_link_dir}")
	echo ${init_bn}
}

describe_show() {
	echo "Show the current sysvinit implementation"
}

describe_show_options() {
	echo "--quiet  : only print the actual sysvinit implementation"
	echo "--silent : same as --quiet"
}

do_show() {
	local quiet=
	local init=

	while [[ $# -gt 0 ]]; do
		case ${1##--} in
			quiet|silent)
				quiet="1"
				;;
		esac
		shift
	done

	init=$(get_init)
	[[ -z "${quiet}" ]] && write_list_start "Current :"
	if [[ -n "${init}" ]]; then
		if [[ -n "${quiet}" ]]; then
			echo "${init}"
		else
			write_kv_list_entry "${init}" ""
		fi
	else
		if [[ -z "${quiet}" ]]; then
			write_kv_list_entry "(unset)" ""
		fi
	fi
}

### list action ###

describe_list() {
	echo "List available sysvinit implementations"
}

describe_list_options() {
	echo "--quiet  : only print the actual sysvinit implementation"
	echo "--silent : same as --quiet"
}

do_list() {
	local quiet=
	local i=
	local init=$(get_init)
	local targets=( $(find_targets) )

	while [[ $# -gt 0 ]]; do
		case ${1##--} in
			quiet|silent)
				quiet="1"
				;;
		esac
		shift
	done

	[[ -z "${quiet}" ]] && \
		write_list_start "Available sysvinit implementations:"
	for (( i = 0; i < ${#targets[@]}; i++ )); do
		if [[ -z "${quiet}" ]]; then
			[[ "${targets[i]}" == "${init}" ]] && \
				targets[i]=$(highlight_marker "${targets[i]}")
		else
			echo "${targets[i]}"
		fi
	done
	[[ -z "${quiet}" ]] && \
		write_numbered_list -m "(none found)" "${targets[@]}"
}

describe_set() {
	echo "Set a new sysvinit implementation"
}

describe_set_parameters() {
	echo "<target>"
}

describe_set_options() {
	echo "target : Target name or number (from 'list' action)"
	echo "--use-old : use the old value if target is already set"
}

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

	while [[ $# -gt 0 ]]; do
		case ${1##--} in
			use-old)
				use_old="1"
				;;
		esac
		shift
	done

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

	if [[ "${use_old}" = "1" ]]; then
	   old_target=$(get_init)
	   target="${old_target:-${target}}"
	fi

	set_init "${target}" || die -q "Couldn't set a new symlink"
}