#!/bin/sh -e
#
# 2020 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
#
# This file is part of cdist.
#
# cdist is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# cdist is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with cdist. If not, see <http://www.gnu.org/licenses/>.
#
# This explorer determines if the locale is defined on the target system.
# Will print nothing on error.
#
# Possible output:
#  present:
#    the main locale (and possibly aliases) is present
#  absent:
#    neither the main locale nor any aliases are present
#  alias-present:
#    the main locale is absent, but at least one of its aliases is present
#

# Hardcoded, create a pull request in case it is at another location for
# some other distro. (cf. gencode-remote)
aliasfile='/usr/share/locale/locale.alias'

command -v locale >/dev/null 2>&1 || exit 0

locales=$(locale -a)

parse_locale() {
	# This function will split locales into their parts. Locale strings are
	# usually of the form: [language[_territory][.codeset][@modifier]]
	# For simplicity, language and territory are not separated by this function.
	# Old Linux systems were also using "english" or "german" as locale strings.
	# Usage: parse_locale locale_str lang_var codeset_var modifier_var
	eval "${2:?}"="$(expr "$1" : '\([^.@]*\)')"
	eval "${3:?}"="$(expr "$1" : '[^.]*\.\([^@]*\)')"
	eval "${4:?}"="$(expr "$1" : '.*@\(.*\)$')"
}

format_locale() {
	# Usage: format_locale language codeset modifier
	printf '%s' "$1"
	test -z "$2" || printf '.%s' "$2"
	test -z "$3" || printf '@%s' "$3"
	printf '\n'
}

gnu_normalize_codeset() {
	# reimplementation of glibc/locale/programs/localedef.c normalize_codeset()
	echo "$*" | tr '[:upper:]' '[:lower:]' | tr -cd '[:alnum:]'
}

locale_available() (
	echo "${locales}" | grep -qxF "$1" || {
		# glibc uses "normalized" locale names in archives.
		# If a locale is stored in an archive, the normalized name will be
		# printed by locale, so that needs to be checked, too.
		localename=$(
			parse_locale "$1" _lang _codeset _modifier \
			&& format_locale "${_lang:?}" "$(gnu_normalize_codeset "${_codeset?}")" \
			   "${_modifier?}")
		echo "${locales}" | grep -qxF "${localename}"
	}
)

if locale_available "${__object_id:?}"
then
	echo present
else
	# NOTE: locale.alias can be symlinked.
	if test -e "${aliasfile}"
	then
		# Check if one of the aliases of the locale is defined
		baselocale=$(
			parse_locale "${__object_id:?}" _lang _codeset _modifiers \
			&& format_locale "${_lang}" "${_codeset}")
		while read -r _alias _localename
		do
			if test "${_localename}" = "${baselocale}" \
				&& echo "${locales}" | grep -qxF "${_alias}"
			then
				echo alias-present
				exit 0
			fi
		done <"${aliasfile}"
	fi

	echo absent
fi