#!/bin/sh
# Purpose {{{
## Create a temp file (to monitor) if an upgrade is available for Gitea
## project on dl.gitea.io/Github.
## It based on gitea's binary available in $PATH or give as first argument.
## 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, eg.
#00 20 * * * root /opt/repos/ipr.scripts/github/check_gitea_update
### 2-1 Create a cron job with a specific path for gitea bin, eg.
#00 20 * * * root /opt/repos/ipr.scripts/github/check_gitea_update /srv/bin/gitea
### 3. Monitor the temp file : /tmp/.github.gitea.upgrade
# Or enable MAILTO in cronjob and edit the script to print a message.
# Or send a mail.
# …
## }}}
# }}}

# Vars {{{
readonly PROGNAME=$(basename "${0}")
readonly PROGDIR=$(readlink -m $(dirname "${0}"))
readonly ARGS="${*}"
readonly NBARGS="${#}"
## Test if DEBUG is already defined (by parent script,…)
[ -z "${DEBUG}" ] && DEBUG=1

## Default values for some vars
GITEA_BIN_PATH_DEFAULT="$(command -v gitea)"
GITEA_DOWNLOAD_DEFAULT=1
gitea_download_github=1

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

usage() {                                                       # {{{

	cat << HELP

usage: $PROGNAME (/path/to/gitea) [-b|-p|-d|-h]

Compare current version of an installed Gitea and the last available.

EXAMPLES :
    - Compare the current version of Gitea with bin available in \$PATH
        ${PROGNAME}

    - Compare the current version of Gitea at a specific place
        ${PROGNAME} /srv/bin/gitea
        ${PROGNAME} --path /srv/bin/gitea

    - Compare version and try to download the new version if require,
      next to current bin with '.to.upgrade.vX.YY.ZZ' suffix.
        ${PROGNAME} --download
        ${PROGNAME} --path /srv/bin/gitea --download

    - Compare version and try to download the new version from github.
        ${PROGNAME} --download --github

OPTIONS :
    -b,--bin,-p,--path
        Set the Gitea's path to use.

    --download
        Try to download the new release if available.

    --github
        Download new version from Github repository
        (dl.gitea.io is used by default).

    -d,--debug
        Enable debug messages.

    -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}"
}
# }}}
is_var_empty() {                                                # {{{

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

	loop_count_var_empty="0"

	## While it remains a variable to test
	while [ "${local_total_var_empty}" -gt "${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_empty
	unset loop_count_var_empty

	return "${return_var_empty}"
}
# }}}
is_file_empty() {                                               # {{{

	local_file="${1}"

	## File is empty by default
	return_is_file_empty="0"

	### Check if the file is empty
	if [ ! -s "${local_file}" ]; then
		return_is_file_empty="0"
		debug_message "is_file_empty − \
The file ${RED}${local_file}${COLOR_DEBUG} is empty or doesn't exists."
	else
		return_is_file_empty="1"
		debug_message "is_file_empty − \
The file ${RED}${local_file}${COLOR_DEBUG} exists and has a size greater than zero."
	fi

	return "${return_is_file_empty}"

}
# }}}
define_vars() {                                                 # {{{

	## If gitea_bin_path wasn't defined (argument) {{{
	## Use default value
	is_var_empty "${gitea_bin_path}" \
		&& gitea_bin_path="${GITEA_BIN_PATH_DEFAULT}"
	## }}}
	## If gitea_download wasn't defined (argument) {{{
	## Use default value
	is_var_empty "${gitea_download}" \
		&& gitea_download="${GITEA_DOWNLOAD_DEFAULT}"
	## }}}

	## Directory where is current Gitea bin
	gitea_bin_dir=$(readlink -m $(dirname "${gitea_bin_path}"))

	## Main Gitea repo's URL
	gitea_repo_url="https://github.com/go-gitea/gitea"

	## Gitea's versions
	gitea_current_version=$("${gitea_bin_path}" --version | cut --delimiter=' ' --fields=3)
	gitea_new_version=$("${PROGDIR}"/releasetags "${gitea_repo_url}" | grep --invert-match --extended-regexp -- '(dev|rc|^$)' | head --lines=1 | sed 's/v//')

	## Gitea new version's URL
	if [ "${gitea_download_github}" -eq "0" ]; then
		gitea_new_version_url="https://github.com/go-gitea/gitea/releases/download/v${gitea_new_version}/gitea-${gitea_new_version}-linux-amd64"
	else
		gitea_new_version_url="https://dl.gitea.io/gitea/${gitea_new_version}/gitea-${gitea_new_version}-linux-amd64"
	fi
	## Gitea new version's path
	gitea_new_bin_path="${gitea_bin_path}.to.upgrade.v${gitea_new_version}"

	## Temp file to monitor
	gitea_new_version_file="/tmp/.github.gitea.upgrade"
}
# }}}

main() {                                                        # {{{

	define_vars

	# If gitea_bin_path is empty {{{
	# Exit with error
	is_var_empty "${gitea_current_version}" \
		&& error_message "Can't get current version from Gitea's binary (${gitea_bin_path})." 1
	# }}}
	# If gitea_new_version is empty {{{
	# Exit with error
	is_var_empty "${gitea_new_version}" \
		&& error_message "Can't get new version (${gitea_new_version}) from Gitea's repository (${gitea_repo_url})." 1
	# }}}

	# If an update is available {{{
	if [ "${gitea_current_version}" != "${gitea_new_version}" ]; then
		debug_message "Test version − \
Current version (${RED}${gitea_current_version}${COLOR_DEBUG}) and new one (${RED}${gitea_new_version}${COLOR_DEBUG}) seems different."

		## Create a temp file to monitor
		touch -- "${gitea_new_version_file}"
		printf '\e[1;35m%-6s\e[m\n' "An upgrade is available for Gitea (current : ${gitea_current_version}) : ${gitea_new_version}." >> "${gitea_new_version_file}"

		## If new release should be downloaded
		if [ "${gitea_download}" -eq "0" ]; then
			### Download and prepare the new bin {{{
			debug_message "Test version − \
Download Gitea binary (from ${gitea_new_version_url} ) to ${RED}${gitea_new_bin_path}${COLOR_DEBUG} ."
			wget --quiet "${gitea_new_version_url}" --output-document="${gitea_new_bin_path}"
			### }}}
			### If the new binary file is empty {{{
			### Ensure to remove (don't want an empty upgrade file)
			### Exit with error
			is_file_empty "${gitea_new_bin_path}" \
				&& rm --force -- "${gitea_new_bin_path}" \
				&& error_message "New binary (${gitea_new_bin_path}) is empty or doesn't exists." 2
			### }}}
			chmod +x -- "${gitea_new_bin_path}"
		fi
	# }}}

	# Gitea is up-to-date {{{
	else
		debug_message "Test version − \
The current version (${RED}${gitea_current_version}${COLOR_DEBUG}) is up-to-date."

		debug_message "Test version − \
Ensure to remove temp file and any previous and unused releases."
		rm --force -- "${gitea_new_version_file}"
		find "${gitea_bin_dir}" -maxdepth 1 -type f -iname "gitea.to.upgrade*" -delete
	fi
	# }}}

}
# }}}

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

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

	manage_arg="0"

	## If the first argument is not an option
	if ! printf -- '%s' "${1}" | grep --quiet --extended-regexp -- "^-+";
	then
		## Consider it as the path to Gitea
		gitea_bin_path="${1}"
		## Move to the next argument
		shift
		manage_arg=$((manage_arg+1))
	fi

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

	case "${1}" in
		-b|--bin|-p|--path )   ## Define gitea_bin_path
			## Move to the next argument
			shift
			## Define var
			readonly gitea_bin_path="${1}"
			;;
		--download )           ## Enable download_mode
			## Try to download new release if available
			gitea_download=0
			;;
		--github )             ## Download new release from Github
			## Try to download new release from Github
			gitea_download_github=0
			;;
		-d|--debug )           ## debug
			DEBUG=0
			;;
		-h|--help )            ## help
			usage
			## Exit after help informations
			exit 0
			;;
		-- )                   ## End of options list
			## End the while loop
			break
			;;
		* )                    ## 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 0