mpv-get-property

#!/usr/bin/env bash
# Sends commands to an mpv socket using socat
# First argument: mpv socket
# Second argument: mpv property to get from the socket

SOCKET="${1:?Must provide socket as first argument}"
if [[ -e "${SOCKET}" ]]; then
	if [[ ! -S "${SOCKET}" ]]; then
		echo "Path is not a socket: ${SOCKET}" >&2
		exit 2
	fi
else
	echo "Path doesn't exist: ${SOCKET}" >&2
	exit 2
fi
PROPERTY="${2:?Must provide property as second argument}"
readonly SOCKET PROPERTY

# interpolate the property and capture the response
MPV_RESP="$(printf '{ "command": ["get_property", "%s" ] }\n' "${PROPERTY}" | socat - "${SOCKET}")"

# to reduce overhead from multiple jq calls -- try the common case first
# select (filter) and extract data if it succeeded
DATA="$(jq -r 'select(.error == "success") | .data' <<<"$MPV_RESP")"
if [[ -z "$DATA" ]]; then
	# was empty, so extract/dump error
	err="$(echo "${MPV_RESP}" | jq -r '.error')"
	echo -e "Error: ${err}\nResponse:" >&2
	jq <<<"${MPV_RESP}" >&2
	exit 1
fi
# data wasn't empty; succeeded
echo "${DATA}"