# -*-eselect-*-
# Copyright 2005-2014 Gentoo Authors
# Distributed under the terms of the GNU GPL version 2 or later
#
# DOCUMENTATION
# Following actions possible
# * show		do_show()
# * list		do_list()
# * set			do_set()
# * update		do_update()
#
# Behaviour:
# do_show():
#	Checks if /usr/bin/emacs is a link and if the target exists,
#	if yes, it outputs the currently linked Emacs version.
#	If it is no symlink, the user is told so, the same if there is
#	no /usr/bin/emacs or the target does not exist.
# do_list(): List all available versions of GNU Emacs
# 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)

DESCRIPTION="Manage /usr/bin/emacs version"
MAINTAINER="emacs@gentoo.org"
VERSION="1.18"

# ctags and etags are handled in their own module
BINARYLIST="emacsclient b2m ebrowse rcs-checkin grep-changelog"
MANPAGELIST="${BINARYLIST}"
HEADERLIST="emacs-module.h"

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

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

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

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

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

set_header_symlinks() {
	# Set symlinks to header files in /usr/include/
	local target=$1 f
	for f in ${HEADERLIST}; do
		if [[ -f ${EROOT}/usr/include/${target}/${f} ]]; then
			ln -s "${target}/${f}" "${EROOT}/usr/include/${f}" \
				|| die "Couldn't set ${EROOT}/usr/include/${f} symlink"
		fi
	done
}

set_symlinks() {
	# Set symlinks to binaries and man pages, update info path
	local target=$1 nomain=$2 targets suffix i
	# target may be specified by its name or its index
	if is_number "${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 an Emacs binary with this name exist?
	[[ -f ${EROOT}/usr/bin/${target} ]] \
		|| die -q "Target \"$1\" doesn't appear to be valid!"

	echo "Switching emacs to ${target} ..."
	remove_symlinks || die -q "Couldn't remove existing symlink"
	# the main /usr/bin/emacs symlink is only set for Emacs binaries
	# (but not for other providers of auxiliary programs, e.g., XEmacs)
	if [[ -z ${nomain} ]]; then
		ln -s "${target}" "${EROOT}/usr/bin/emacs" \
			|| die "Couldn't set ${target} ${EROOT}/usr/bin/emacs symlink"
		for i in "${EROOT}/usr/share/man/man1/${target}.1"*; do
			if [[ -f ${i} ]]; then
				suffix=${i##*/"${target}.1"}
				ln -s "${target}.1${suffix}" \
					"${EROOT}/usr/share/man/man1/emacs.1${suffix}"
			fi
		done
	fi
	set_bin_symlinks "${target}"
	set_man_symlinks "${target}"
	set_header_symlinks "${target}"
	set_infopath "${target}"

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

	return 0
}

xemacs_info() {
	# This is just informational to tell that XEmacs has been found,
	# a wish from graaff
	if [[ -e ${EROOT}/usr/bin/xemacs ]]; then
		echo
		write_list_start "XEmacs is also installed"
	fi
}

vim_info() {
	# Don't take this too serious
	if [[ -e ${EROOT}/usr/bin/vi ]]; then
		echo
		write_list_start "Vi found, your system is in real trouble now! ;)"
	fi
}

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 Emacs symlink"
}

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

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

	if ! is_output_mode brief; then
		xemacs_info
		#vim_info
	fi
}

### list action ###

describe_list() {
	echo "List available Emacs 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/emacs")")" ]] \
			&& targets[i]=$(highlight_marker "${targets[i]}")
	done
	write_list_start "Available Emacs symlink targets:"
	write_numbered_list -m "(none found)" "${targets[@]}"

	if ! is_output_mode brief; then
		xemacs_info
		#vim_info
	fi
}

### set action ###

describe_set() {
	echo "Set a new Emacs 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/emacs && ! -L ${EROOT}/usr/bin/emacs ]]; then
		die -q "${EROOT}/usr/bin/emacs exists but is not a symlink"
	fi

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

	# ctags symlinks are handled in an own module now
	do_action ctags update
}

### update action ###

describe_update() {
	echo "Automatically update the Emacs 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/emacs ]]; then
		if [[ $1 = *if*unset && -e ${EROOT}/usr/bin/emacs ]]; then
			do_action ctags update ifunset
			return
		fi
		# this is not redundant: "update" is called in pkg_postrm() of emacs
		# and should clean up any dead symlinks if no valid target exists
		remove_symlinks || die -q "Couldn't remove existing symlink"
	elif [[ -e ${EROOT}/usr/bin/emacs ]]; then
		die -q "${EROOT}/usr/bin/emacs 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"
	elif [[ -f ${EROOT}/usr/bin/xemacs ]]; then
		# no Emacs target found - link to XEmacs versions
		set_symlinks xemacs nomain
	fi

	# ctags and etags symlinks are handled in an own module
	do_action ctags update
}