# -*-eselect-*-  vim: ft=eselect
# Copyright 2005-2012 Gentoo Foundation
# Distributed under the terms of the GNU GPL version 2 or later

DESCRIPTION="Manage the /usr/src/linux symlink"
MAINTAINER="eselect@gentoo.org"

# sort function for kernel versions, to be used in a pipe
sort_kernel_versions() {
	local vsort="sort --version-sort"
	# Test if our sort supports the --version-sort option
	# (should be GNU sort, since the kernel module is GNU/Linux specific)
	${vsort} </dev/null &>/dev/null || vsort=sort

	# We sort kernel versions as follows:
	# 1. Run sed to prepend the version string by the numeric version
	#    and an additional rank indicator that is 0 for release candidates
	#    or 1 otherwise. After this step we have, for example:
	#      2.6.29 1 linux-2.6.29
	#      2.6.29 0 linux-2.6.29-rc8
	# 2. sort --version-sort
	# 3. Run sed again to remove the prepended keys from step 1.
	sed -e 's/^\(linux-\)\?\([[:digit:].]\+\)[-_]rc/\2 0 &/' \
		-e 't;s/^\(linux-\)\?\([[:digit:].]\+\)/\2 1 &/' \
		| LC_ALL=C ${vsort} | sed 's/.* //'
}

# find a list of kernel symlink targets
find_targets() {
	local f
	for f in "${EROOT}"/usr/src/linux-[[:digit:]]*; do
		[[ -d ${f} ]] && basename "${f}"
	done | sort_kernel_versions
}

# remove the kernel symlink
remove_symlink() {
	rm "${EROOT}/usr/src/linux"
}

# set the kernel symlink
set_symlink() {
	local target=$1

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

	if [[ -z ${target} ]]; then
		die -q "Target \"$1\" doesn't appear to be valid!"
	elif [[ -d ${EROOT}/usr/src/${target} ]]; then
		ln -s "${target}" "${EROOT}/usr/src/linux"
	elif [[ -d ${EROOT}/usr/src/linux-${target} ]]; then
		ln -s "linux-${target}" "${EROOT}/usr/src/linux"
	else
		die -q "Target \"$1\" doesn't appear to be valid!"
	fi
}

### show action ###

describe_show() {
	echo "Show the current kernel symlink"
}

do_show() {
	write_list_start "Current kernel symlink:"
	if [[ -L ${EROOT}/usr/src/linux ]]; then
		local kernel=$(canonicalise "${EROOT}/usr/src/linux")
		write_kv_list_entry "${kernel%/}" ""
	else
		write_kv_list_entry "(unset)" ""
	fi
}

### list action ###

describe_list() {
	echo "List available kernel symlink targets"
}

do_list() {
	local i targets=( $(find_targets) )

	write_list_start "Available kernel symlink targets:"
	for (( i = 0; i < ${#targets[@]}; i++ )); do
		[[ ${targets[i]} = \
			$(basename "$(canonicalise "${EROOT}/usr/src/linux")") ]] \
			&& targets[i]=$(highlight_marker "${targets[i]}")
	done
	write_numbered_list -m "(none found)" "${targets[@]}"
}

### set action ###

describe_set() {
	echo "Set a new kernel symlink target"
}

describe_set_parameters() {
	echo "<target>"
}

describe_set_options() {
	echo "target : Target name or number (from 'list' action)"
}

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

	if [[ -L ${EROOT}/usr/src/linux ]]; then
		# existing symlink
		remove_symlink || die -q "Couldn't remove existing symlink"
		set_symlink "$1" || die -q "Couldn't set a new symlink"
	elif [[ -e ${EROOT}/usr/src/linux ]]; then
		# we have something strange
		die -q "${EROOT}/usr/src/linux exists but is not a symlink"
	else
		set_symlink "$1" || die -q "Couldn't set a new symlink"
	fi
}