#!/bin/sh
# Purpose {{{
## Create a temp file (to monitor) if an upgrade is available for  Discord client
## from official website − https://discord.com/download
## 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" is given as first argument.
## How-to use {{{
### 1. Create a cron job, eg :
#00 20 * * * root /opt/repos/ipr.scripts/app/check.discord.update
### 2-1 Create a cron job to compare the version available in an APT repository :
#00 20 * * * root /opt/repos/ipr.scripts/app/check.discord.update repo
### 2. Monitor the temp file : /tmp/.discord.upgrade
# Or enable MAILTO in cronjob and edit the script to print a message.
# Or send a mail.
# …
## }}}
# }}}

# Expect maximum 1 argument {{{
if [ $# -gt 1 ]
then
	cat << HELP

check.discord.update    --
Compare current version of an installed Discord client and the last available.

EXAMPLE :
    - Compare the current version installed from .deb file
        check.discord.update

    - Compare the current version from apt's repository
        check.discord.update repo

HELP

	exit 1
fi
# }}}

# Vars {{{
DEBUG=1

if [ $# -eq 1 ] && [ "${1}" = "repo" ]  ## If repository's version should be compared
then
	discord_current_version=$(apt-cache policy -- discord | awk '/Candidate:/ {print $2}' | sed 's/.:\(.*\)-.*/\1/')
else
	discord_current_version=$(dpkg --list -- discord | awk '/^ii *discord/ {print $3}' | sed 's/.:\(.*\)-.*/\1/')
fi

discord_new_version=$(curl -s 'https://discord.com/api/download?platform=linux&format=deb' --header 'User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36' | grep " href=\"https" | sed -e 's;.*.deb">.*/apps/linux/\(.*\)/discord.*.deb</a>.*;\1;')

discord_new_version_file="/tmp/.discord.upgrade"

discord_new_pkg_url=$(curl -s 'https://discord.com/api/download?platform=linux&format=deb' --header 'User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36' | grep " href=\"https" | sed -e 's;.*href="\(.*.deb\)">.*;\1;')
discord_new_pkg_path="/tmp/discord-${discord_new_version}.deb"
# }}}

# Check if the current version is the last one {{{
if [ "${discord_current_version}" != "${discord_new_version}" ]; then
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test version — Current version (${discord_current_version}) and new one (${discord_new_version}) seems to be different."

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

	## If it doesn't already exists, download this new package
	if [ ! -f "${discord_new_pkg_path}" ]; then
		[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Download .deb file from discord.com to ${discord_new_pkg_path} ."
		wget --quiet "${discord_new_pkg_url}" --output-document="${discord_new_pkg_path}"
	fi

else
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test version — The current version is up-to-date."
	## Ensure to remove any temp file and useless .deb file
	rm --force -- "${discord_new_version_file}" "${discord_new_pkg_path}"
fi
# }}}

exit 0