# Copyright 2005-2011 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Id: $
#
# DOCUMENTATION
# Following actions possible
# * show		do_show()
# * list		do_list()
# * set			do_set()
# * update		do_update()
# * clean       do_clean()
#
# Behaviour:
# do_show():
#	Checks if /usr/bin/guile is a link and if the target exists,
#	if yes, it outputs the currently linked Guile version.
#	If it is no symlink, the user is told so, the same if there is
#	no /usr/bin/guile or the target does not exist.
# do_list(): List all available versions of GNU Guile
# do_set(): Set a version to be target of the symlink.
# do_update(): Set the target to the highest version available
#	(optionally: only if not set)
# do_clean(): Remove all set symlinks (for pkg_prerm)

DESCRIPTION="Manage /usr/bin/guile* versions"
MAINTAINER="scheme@gentoo.org"
SVN_DATE='$Date: $'
VERSION=$(svn_date_to_version "${SVN_DATE}")

BINARYLIST="guile-snarf guile-config guile-tools guile"
MANPAGELIST="guile"

find_targets() {
	# Return the list of available Guile binaries
	local j
	for j in "${EROOT}"/usr/bin/guile-[0-9]*; do
		[[ -f ${j} ]] && basename ${j}
	done
}

remove_envfile() {
	# When cleaning symlinks this takes care of the info documentation settings
	rm -f "${EROOT}/etc/env.d/50guile"
}

# Define GUILE_LOAD_PATH environment variable in env file
set_envfile() {
	echo "GUILE_LOAD_PATH=${EPREFIX}/usr/share/guile/$1" >"${EROOT}/etc/env.d/50guile"
	[[ -d ${EROOT}/usr/share/info/guile-$1 ]] || return 1
	echo "INFOPATH=${EPREFIX}/usr/share/info/guile-$1" >>"${EROOT}/etc/env.d/50guile"
}

remove_symlinks() {
	# Remove existing symlinks to binaries, man pages,
	# m4 file, and the env file (own function)
	local f
	for f in ${BINARYLIST}; do
		rm -f "${EROOT}/usr/bin/${f}"
	done
	for f in ${MANPAGELIST}; do
		rm -f "${EROOT}"/usr/share/man/man1/${f}.1*
	done
	rm -f "${EROOT}"/usr/share/aclocal/guile.m4
	remove_envfile
}

set_bin_symlinks() {
	# Set symlinks to binaries in /usr/bin/
	local target=${1} f
	for f in ${BINARYLIST}; do
		# set symlink only if target binary actually exists
		if [[ -f ${EROOT}/usr/bin/${f}-${target} ]]; then
			ln -s "${f}-${target}" "${EROOT}/usr/bin/${f}" || die \
				"Couldn't set ${f}-${target} ${EROOT}/usr/bin/${f} symlink"
		fi
	done
}

set_m4_symlinks() {
	# Set symlink to guile.m4
	local target=${1}
	if [[ -f ${EROOT}/usr/share/aclocal/guile-${target}.m4 ]]; then
		ln -s "guile-${target}.m4" "${EROOT}"/usr/share/aclocal/guile.m4 \
			|| die "Couldn't set guile-${target}.m4 guile.m4 symlink"
	fi
}

set_man_symlinks() {
	# Set symlinks to man pages
	local target=${1} extension f i
	for f in ${MANPAGELIST}; do
		for i in "${EROOT}"/usr/share/man/man1/${f}-${target}.1*; do
			if [[ -f ${i} ]]; then
				# target file exists; determine compress extension
				extension=${i##*/${f}-${target}.1}
				ln -s "${f}-${target}.1${extension}" \
					"${EROOT}/usr/share/man/man1/${f}.1${extension}"
			fi
		done
	done
}

set_symlinks() {
	# Set symlinks to binaries and man pages, update info path
	local target=$1 targets major
	# target may be specified by its name or its index
	if is_number "${target}"; then
		# numeric index, find the target's name
		targets=( $(find_targets) )
		[[ ${target} -ge 1 && ${target} -le ${#targets[@]} ]] \
			|| die -q "Number out of range: ${1}"
		target=${targets[target-1]}
	fi

	# is the target valid, i.e. does a Guile binary with this name exist?
	[[ -f ${EROOT}/usr/bin/${target} ]] \
		|| die -q "Target \"${1}\" doesn't appear to be valid!"

	echo "Switching guile to ${target} ..."
	remove_symlinks || die -q "Couldn't remove existing symlink"

	major=${target#guile-}
	set_bin_symlinks "${major}"
	set_m4_symlinks  "${major}"
	set_man_symlinks "${major}"
	set_envfile "${major}"

	# update /etc/profile.env from /etc/env.d files
	do_action env update noldconfig

	return 0
}

test_for_root() {
	# checks if the user has rights to modify /usr/bin/
	[[ -w ${EROOT}/usr/bin ]] || die -q "You need root privileges!"
}

### show action ###

describe_show() {
	echo "Show the current target of the Guile symlink"
}

do_show() {
	[[ $# -gt 0 ]] && die -q "Too many parameters"

	write_list_start "Current target of Guile symlink:"
	if [[ -L ${EROOT}/usr/bin/guile && -e ${EROOT}/usr/bin/guile ]]; then
		write_kv_list_entry \
			"$(basename "$(readlink "${EROOT}/usr/bin/guile")")" ""
	elif [[ -e ${EROOT}/usr/bin/guile ]]; then
		write_kv_list_entry \
			"(not a symlink or target of symlink does not exist)" ""
	else
		write_kv_list_entry "(unset)" ""
	fi
}

### list action ###

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

do_list() {
	[[ $# -gt 0 ]] && die -q "Too many parameters"

	local i targets
	targets=( $(find_targets) )

	for (( i = 0; i < ${#targets[@]}; i++ )); do
		# Highlight the currently chosen version
		[[ ${targets[i]} = \
			$(basename "$(readlink "${EROOT}/usr/bin/guile")") ]] \
			&& targets[i]=$(highlight_marker "${targets[i]}")
	done
	write_list_start "Available Guile symlink targets:"
	write_numbered_list -m "(none found)" "${targets[@]}"
}

### set action ###

describe_set() {
	echo "Set a new Guile symlink"
}

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

describe_set_parameters() {
	echo "<target>"
}

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

	if [[ -e ${EROOT}/usr/bin/guile && ! -L ${EROOT}/usr/bin/guile ]]; then
		die -q "${EROOT}/usr/bin/guile exists but is not a symlink"
	fi

	set_symlinks "${1}" || die -q "Couldn't set a new symlink"
}

### update action ###

describe_update() {
	echo "Automatically update the Guile symlink"
}

describe_update_options() {
	echo "ifunset : Do not override currently set version"
}

do_update() {
	[[ -z $1 || $1 = ifunset || $1 = --if-unset ]] || die -q "Usage error"
	[[ $# -gt 1 ]] && die -q "Too many parameters"
	test_for_root

	if [[ -L ${EROOT}/usr/bin/guile ]]; then
		# this is not redundant: "update" is called in pkg_postrm() of guile
		# and should clean up any dead symlinks if no valid target exists
		remove_symlinks || die -q "Couldn't remove existing symlink"
	elif [[ -e ${EROOT}/usr/bin/guile ]]; then
		die -q "${EROOT}/usr/bin/guile exists but is not a symlink"
	fi

	local targets=( $(find_targets) )
	if [[ ${#targets[@]} -gt 0 ]]; then
		set_symlinks "${targets[${#targets[@]}-1]}" \
			|| die -q "Couldn't set a new symlink"
	fi
}

### Clean action
describe_clean() {
	echo "Remove any existing symlinks"
}

do_clean() {
	remove_symlinks
}