#!/bin/sh
#
# Purpose {{{
# This script will :
#   1. Get Etherpad version from current installation (from directory)
#   2. Get latest Etherpad version from Github.
#   3. Compare installed and latest version.
#   4. Create a temp file (to monitor) if versions mismatch.
#
## How-to use {{{
### 1. Needs releasetags script, in the same directory
### cf. https://git.ipr.univ-rennes.fr/cellinfo/scripts/src/master/github/releasetags
# wget https://git.ipr.univ-rennes.fr/cellinfo/scripts/raw/master/github/releasetags
### 2. Create a cron job with Etherpad directory as argument, eg.
#00 20 * * * root /opt/repos/ipr.scripts/github/check_cachet_update --directory /srv/www/etherpad-lite
### 3. Monitor the temp file : /tmp/.github.etherpad.upgrade
### 3.b Or enable MAILTO in cronjob and edit the script to print a message.
## }}}
#
# 2022-08-25
# }}}
# Vars {{{
PROGNAME=$(basename "${0}"); readonly PROGNAME
PROGDIR=$(readlink -m $(dirname "${0}")); readonly PROGDIR
ARGS="${*}"; readonly ARGS
readonly NBARGS="${#}"
[ -z "${DEBUG}" ] && DEBUG=1
## Export DEBUG for sub-script
export DEBUG

## Default values for some vars
readonly ETHERPAD_INSTALL_DIR_DEFAULT="/srv/www/etherpad-lite"
readonly ETHERPAD_REPO_URL="https://github.com/ether/etherpad-lite"
readonly ETHERPAD_NEW_VERSION_FILE="/tmp/.github.etherpad.upgrade"

## Colors
readonly PURPLE='\033[1;35m'
readonly RED='\033[0;31m'
readonly RESET='\033[0m'
readonly COLOR_DEBUG="${PURPLE}"
# }}}
usage() {                                                       # {{{

	cat <<- HELP
usage: $PROGNAME [-d|-h]

Compare Etherpad installed version and latest one.

EXAMPLES :
    - Check Etherpad version from default directory (${ETHERPAD_INSTALL_DIR_DEFAULT})
        ${PROGNAME}

    - Check Etherpad version from a specific location
        ${PROGNAME} --directory /srv/www/my_etherpad

OPTIONS :
    --debug
        Enable debug messages.

    -d,--dir,--directory
        Etherppad installation directory.
        (default: ${ETHERPAD_INSTALL_DIR_DEFAULT}).

    -h,--help
        Print this help message.
HELP

}
# }}}
debug_message() {                                               # {{{

	local_debug_message="${1}"

	## Print message if DEBUG is enable (=0)
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6b\e[m\n' "DEBUG − ${PROGNAME} : ${local_debug_message}"

	unset local_debug_message

	return 0
}
# }}}
error_message() {                                               # {{{

	local_error_message="${1}"
	local_error_code="${2}"

	## Print message
	printf '%b\n' "ERROR − ${PROGNAME} : ${RED}${local_error_message}${RESET}"

	exit "${local_error_code:=66}"
}
# }}}
define_vars() {                                                 # {{{

	## If etherpad_install_dir wasn't defined (argument) {{{
	if [ -z "${etherpad_install_dir}" ]; then
		## Use default value
		readonly etherpad_install_dir="${ETHERPAD_INSTALL_DIR_DEFAULT}"
	fi
	## }}}

}
# }}}
is_var_empty() {                                                # {{{

	## Return False by default
	return_var_empty="1"
	## Total number of variables to test
	local_total_var="${#}"

	loop_count_var_empty="0"

	## While it remains a variable to test
	while [ "${local_total_var}" -gt "${loop_count_var_empty}" ]; do
		debug_message "is_var_empty − \
Test var: ${1}."
		### Test if this is empty and set return value to True
		[ -z "${1}" ] && return_var_empty="0"

		### Increase the number of tested variables
		loop_count_var_empty=$((loop_count_var_empty+1))

		### Shift to the next variable
		shift
	done

	return "${return_var_empty}"

}
# }}}

main() {                                                        # {{{

	## Define all vars
	define_vars

	## If Etherpad install dir doesn't exists {{{
	### AND Exit with error message
	! test -d ${etherpad_install_dir} \
		&& error_message "Etherpad installation directory (${etherpad_install_dir}) doesn't seem to exist." 01
	## }}}

	## Get current version from src/package.json file {{{
	### OR Exit with error message
	etherpad_current_version=$(sed --silent 's/.*"version": "\(.*\)".*/\1/p' "${etherpad_install_dir}"/src/package.json \
		|| error_message "Can't get current Etherpad version from file (${etherpad_install_dir}/src/package.json)." 02 )
		debug_message "main − Etherpad installed version : ${RED}${etherpad_current_version}${COLOR_DEBUG} (from ${etherpad_install_dir}/src/package.json file)."
	## }}}
	## Get latest version from project repository {{{
	### OR Exit with error message
	etherpad_latest_version=$("${PROGDIR}/releasetags" "${ETHERPAD_REPO_URL}" | head --lines=1 | sed 's/v//' \
		|| error_message "Can't get latest Etherpad version from repository (${ETHERPAD_REPO_URL})." 02 )
		debug_message "main − Etherpad available version : ${RED}${etherpad_latest_version}${COLOR_DEBUG} (from ${ETHERPAD_REPO_URL} project repository)."
	## }}}

	## If any of the two variables is empty {{{
	### OR Exit with error message
	### Double check :)
	is_var_empty "${etherpad_current_version}" "${etherpad_latest_version}" \
		&& error_message "At least one variable is empty (current version : ${etherpad_current_version}, latest version : ${etherpad_latest_version}) !" 04
	## }}}

	# Check if the current version is the last one {{{
	## If the two versions are the same {{{
	if [ "${etherpad_current_version}" = "${etherpad_latest_version}" ]; then
		debug_message "Test version − \
The current Etherpad version (${etherpad_current_version}) is up-to-date."

		### Ensure to remove any temp file
		rm --force -- "${ETHERPAD_NEW_VERSION_FILE}"

		exit 0
	## }}}
	## If the versions are different {{{
	else
		debug_message "Test version − \
Current version (${etherpad_current_version}) and latest one (${etherpad_latest_version}) seems to be different."

		## Create a temp file to monitor
		touch -- "${ETHERPAD_NEW_VERSION_FILE}"
		debug_message "An upgrade is available for Cachet (current : ${etherpad_current_version}) : ${etherpad_latest_version}." >> "${ETHERPAD_NEW_VERSION_FILE}"

		exit 0
	fi
	## }}}
	# }}}

}
# }}}

# Manage arguments                                                # {{{
# This code can't be in a function due to argument management

if [ ! "${NBARGS}" -eq "0" ]; then

	manage_arg="0"

	## If the first argument is not an option
	if ! printf -- '%s' "${1}" | grep -q -E -- "^-+";
	then
		## Print help message and exit
		printf '%b\n' "${RED}Invalid option: ${1}${RESET}"
		printf '%b\n' "---"
		usage

		exit 1
	fi

	# Parse all options (start with a "-") one by one
	while printf -- '%s' "${1}" | grep -q -E -- "^-+"; do

	case "${1}" in
		--debug )                             ## debug
			DEBUG=0
			;;
		-h|--help )                           ## help
			usage
			## Exit after help informations
			exit 0
			;;
		-d|--dir|--directory )                ## Define etherpad_install_dir with given arg
			### Move to the next argument
			shift
			### Define var
			readonly etherpad_install_dir="${1}"
			;;
		* )                                   ## unknow option
			printf '%b\n' "${RED}Invalid option: ${1}${RESET}"
			printf '%b\n' "---"
			usage
			exit 1
			;;
	esac

	debug_message "Arguments management − \
${RED}${1}${COLOR_DEBUG} option managed."

	## Move to the next argument
	shift
	manage_arg=$((manage_arg+1))

	done

	debug_message "Arguments management − \
${RED}${manage_arg}${COLOR_DEBUG} argument(s) successfully managed."
else
	debug_message "Arguments management − \
No arguments/options to manage."
fi

# }}}

main

exit 255