#!/bin/sh
# Purpose {{{
## Create a temp file (to monitor) if an upgrade is available for GLPI Agent
## project on Github − https://github.com/glpi-project/glpi-agent/releases
## It's based on .deb package installation to check the current version.
## It can also compare the current available version in APT repositories
##   if "--repo" option is given.
## How-to use {{{
### 1. Needs releasetags script, in the same directory
### cf. https://git.ipr.univ-rennes1.fr/cellinfo/scripts/src/master/github/releasetags
# wget https://git.ipr.univ-rennes1.fr/cellinfo/scripts/raw/master/github/releasetags
### 2. Create a cron job, eg :
#00 20 * * * root /opt/repos/ipr.scripts/github/check.glpi-agent.update
### 2-1 Create a cron job to compare the version available in a Debian repository :
#00 20 * * * root /opt/repos/ipr.scripts/github/check.glpi-agent.update --repo
### 3. Monitor the temp file : /tmp/.github.glpi-agent.upgrade
# Or enable MAILTO in cronjob and edit the script to print a message.
# Or send a mail.
# …
## }}}
# }}}

# 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
### Don't use APT repository by default
readonly REPOSITORY_MODE_DEFAULT=1

readonly GLPI_AGENT_REPO_URL="https://github.com/glpi-project/glpi-agent"
readonly GLPI_AGENT_NEW_VERSION_FILE="/tmp/.github.glpi-agent.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|-r]

Compare GLPI Agent installed version and latest one.

EXAMPLES :
    - Compare the current version installed from .deb file
        ${PROGNAME}

    - Compare the current version from apt's repository
        ${PROGNAME} --repo

OPTIONS :
    -d,--debug
        Enable debug messages.

    -h,--help
        Print this help message.

    -r,--repo,--repository
        Use GLPI Agent version from APT repository.
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}"

	unset local_error_message

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

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

	unset local_total_var
	unset loop_count_var_empty

	return "${return_var_empty}"
}
# }}}

main() {                                                        # {{{

	## Define all vars
	define_vars

  ## Get current version from APT repository or from .deb package {{{

	if [ "${repository_mode}" -eq "0" ]; then
		debug_message "--- MAIN Check current version from ${RED}APT repositories${COLOR_DEBUG}."
		glpi_agent_current_version=$(apt-cache policy glpi-agent \
			| awk '/Candidate:/ {print $2}' \
			| sed 's/.:\(.*\)-.*/\1/')
	else
		debug_message "--- MAIN Check current version from ${RED}manually installed .deb package${COLOR_DEBUG}."
		glpi_agent_current_version=$(dpkg -l glpi-agent \
			| awk '/^ii.*glpi-agent/ {print $3}' \
			| sed 's/.:\(.*\)-.*/\1/')
	fi
	## }}}
	## Get latest version from project repository {{{
	### OR Exit with error message
		debug_message "--- MAIN Check latest version from project repository (${RED}${GLPI_AGENT_REPO_URL}${COLOR_DEBUG})."
	glpi_agent_latest_version=$("${PROGDIR}/releasetags" "${GLPI_AGENT_REPO_URL}" | head --lines=1 \
		|| error_message "Can't get latest GLPI Agent version from repository (${GLPI_AGENT_REPO_URL})." 02 )
	## }}}

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

	# Check if the current version is the last one {{{
	## If the two versions are the same {{{
	if [ "${glpi_agent_current_version}" = "${glpi_agent_latest_version}" ]; then
		debug_message "Test version − \
The current GLPI Agent version (${RED}${glpi_agent_current_version}${COLOR_DEBUG}) is up-to-date."

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

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

		## Create a temp file to monitor
		touch -- "${GLPI_AGENT_NEW_VERSION_FILE}"
		debug_message "An upgrade is available for GLPI Agent (current : ${glpi_agent_current_version}) : ${glpi_agent_latest_version}." >> "${GLPI_AGENT_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 "${1}" in
		--debug )                             ## debug
			DEBUG=0
			debug_message "--- Manage argument BEGIN"
			;;
		-h|--help )                           ## help
			usage
			## Exit after help informations
			exit 0
			;;
		-r|--repo|--repository )              ## Set repository_mode
			repository_mode=0
			;;
		* )                                   ## unknow option
			printf '%b\n' "${RED}Invalid option: ${1}${RESET}"
			printf '%b\n' "---"
			usage
			exit 1
			;;
	esac

	debug_message "| ${RED}${1}${COLOR_DEBUG} option managed."

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

	done

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

	debug_message "--- Manage argument END"
# }}}

main

exit 255