# Copyright 1999-2021 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

DESCRIPTION="Manage /usr/bin/racket implementation"
MAINTAINER="tgbugs@gmail.com"
VERSION="0.1"

BINARYLIST="drracket
gracket
gracket-text
mred
mred-text
mzc
mzpp
mzscheme
mztext
pdf-slatex
plt-games
plt-help
plt-r5rs
plt-r6rs
plt-web-server
raco
scribble
setup-plt
slatex
slideshow
swindle"

find_targets() {
	# Return the list of available Racket binaries
	local j
	for j in "${EROOT}"/usr/bin/racket{cs,bc,cgc}; do
		[[ -f ${j} ]] && sed 's/racket//' <(basename ${j})
	done
}

remove_symlinks() {
	# Remove existing symlinks to binaries, man pages,
	# and the env file (own function)
	local f
	for f in racket ${BINARYLIST}; do
		rm -f "${EROOT}/usr/bin/${f}"
	done
}

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_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 Racket binary with this name exist?
	[[ -f ${EROOT}/usr/bin/racket${target} ]] \
		|| die -q "Target \"$1\" doesn't appear to be valid!"

	echo "Switching racket to ${target} ..."
	remove_symlinks || die -q "Couldn't remove existing symlink"
	# the main /usr/bin/racket symlink is only set for Racket binaries
	if [[ -z ${nomain} ]]; then
		ln -s "racket${target}" "${EROOT}/usr/bin/racket" \
			|| die "Couldn't set ${target} ${EROOT}/usr/bin/racket symlink"
	fi
	set_bin_symlinks "${target}"

	# 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 Racket symlink"
}

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

	write_list_start "Current target of Racket symlink:"
	if [[ -L ${EROOT}/usr/bin/racket && -e ${EROOT}/usr/bin/racket ]]; then
		write_kv_list_entry \
			"$(basename "$(readlink "${EROOT}/usr/bin/racket")")" ""
	elif [[ -e ${EROOT}/usr/bin/racket ]]; 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 Racket symlink targets"
}

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

	local i targets
	targets=( $(find_targets) )

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

### set action ###

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

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