#!/bin/bash
###############################################################################
#                                                                             #
# IPFire.org - A linux based firewall                                         #
# Copyright (C) 2017 IPFire Network Development Team                          #
#                                                                             #
# This program 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.                                         #
#                                                                             #
# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.       #
#                                                                             #
###############################################################################

editor_cleanup() {
	# Cleanup after a file was edited
	assert [ $# -eq 2 ]

	local file=${1}
	local temp_file=${2}

	lock_release "${file}.lock"
	rm -f ${temp_file}
}

editor_find_best() {
	# Open a file with the best available editor
	assert [ $# -eq 1 ]

	local file=${1}
	local ret

	for editor in ${EDITOR} vim vi; do
		${editor} "${file}"
		ret=${?}

		case "${ret}" in
			${EXIT_OK})
				return ${EXIT_OK}
				;;

			${EXIT_COMMAND_NOT_FOUND})
				continue
				;;

			*)
				return ${ret}
				;;
		esac
	done

	error "Unable to find a working editor"

	return ${EXIT_COMMAND_NOT_FOUND}
}

editor() {
	# This function open a file for editing and take care of all preperation and postprocessing
	assert [ $# -ge 1 ]

	local file=${1}
	if [ ! -f ${file} ] || [ ! -w ${file} ]; then
		error "${file} is not valid file or is not writeable"
		return ${EXIT_ERROR}
	fi

	local check_func=${2}

	# check if the file is locked
	if lock_exists "${file}.lock"; then
		error "Cannot edit ${file} because it is locked"
		return ${EXIT_ERROR}
	fi

	# lock the file
	if ! lock_acquire "${file}.lock"; then
		error "Cannot lock file ${file}"
		return ${EXIT_ERROR}
	fi

	# create a temporary file
	local temp_file=$(mktemp)

	if ! [ -f "${temp_file}" ]; then
		error "Cannot create temporary file"
	fi

	# copy the content into this temporary file
	cp -f "${file}" "${temp_file}"

	# edit the file
	if ! editor_find_best "${temp_file}"; then
		error "Could not edit ${file}"
		# cleanup
		editor_cleanup "${file}" "${temp_file}"
	fi

	# run the check if we have one
	if isset check_func && ! editor_check "${check_func}" "${temp_file}"; then
		return ${EXIT_ERROR}
	fi

	# copy the changes back
	cp -f "${temp_file}" "${file}"

	# cleanup
	editor_cleanup "${file}" "${temp_file}"

}

editor_check() {
	# Execute the check function to make sure that the changes does not break anything
	local check_func="${1}"
	shift

	# Execute the check function
	"${check_func}" "$@"
	local ret="${?}"

	case "${ret}" in
		# OK
		${EXIT_OK}|${EXIT_TRUE})
			log DEBUG "Check succeeded"
			return ${EXIT_TRUE}
			;;

		# Error
		${EXIT_ERROR}|${EXIT_FALSE})
			log CRITICAL "Check failed"
			return ${EXIT_FALSE}
			;;

		# Command not found
		${EXIT_COMMAND_NOT_FOUND})
			log CRITICAL "Check function '${check_func}' was not found"
			return ${EXIT_FALSE}
			;;
	esac

	log CRITICAL "Unhandled exit code for '${check_func}': ${ret}"
	return ${EXIT_ERROR}
}