Implementation of DIscord Rich presence in posix shell script, not depenedent upon python or any other programming language

presence.sh

#!/bin/sh

### Posix compliant script for Discord Rich presence (no need to have python and pypresence) ###

#encode opcode and payload length in little-endian format and prepend it with payload
encode_data() {
	op=$1
	datalen=${#2}
	for i in $(seq 0 3); do
		byte=$(((op >> (i * 8)) & 255))
		#shellcheck disable=SC2059
		printf "\\$(printf "%03o" "$byte")"
	done
	for i in $(seq 0 3); do
		byte=$(((datalen >> (i * 8)) & 255))
		#shellcheck disable=SC2059
		printf "\\$(printf "%03o" "$byte")"
	done
	printf "%s" "$2"
}

#this do the handshake as well as set_activity
set_activity() {
	#handshake
	encode_data "0" '{"v":1,"client_id":"'$presence_client_id'"}'
	#send activity
	encode_data "1" "$1"
}

#main
presence_client_id="<your_client_id>"
discord_ipc="${XDG_RUNTIME_DIR}/discord-ipc-0"


# - need to write both inside a function since I want to send them at same time to netcat
# - activity will be shown as long as this running, if you do ctrl-c it "activity" will be disappeard
# - netcat should be bsd version, not gnu for this to work
# - $1 is actually payload json, atleast figure that out from internet
set_activity "$1" | nc -U "$discord_ipc"