Control Elgato Air Light from shell

elgato-air-light

#!/usr/bin/env bash
set -euo pipefail

# USAGE
# elgato-air-light IP ON BRIGHTNESS TEMPERATURE
#
# ON can be 0 or 1
# BRIGTHNESS can be 0-100
# TEMPERATURE can be 0-100
#
# e.g. to have it on with half brightnesss and half temperature
# elgato-air-light 192.168.1.11 1 50 50
#
# DEPS
# bash
# curl
# jq

function main() {
    local IP=$1
    local ON=$2
    local BRIGHTNESS=$3
    local TEMPERATURE=$4

    [[ -z "${TEMPERATURE}" ]] || TEMPERATURE=$((${TEMPERATURE} * 2 + 143))

    local URL="http://${IP}:9123/elgato/lights"

    local STATE=$(curl "${URL}" 2>/dev/null)

    [[ -n "${ON}${BRIGHTNESS}${TEMPERATURE}" ]] || {
        echo "${STATE}" | jq
        return 0
    }

    [[ -n "${ON}" ]] || ON=$(echo "${STATE}" | jq -r ".lights[0].on")
    [[ -n "${BRIGHTNESS}" ]] || BRIGHTNESS=$(echo "${STATE}" | jq -r ".lights[0].brightness")
    [[ -n "${TEMPERATURE}" ]] || TEMPERATURE=$(echo "${STATE}" | jq -r ".lights[0].temperature")

    cat <<EOF | jq --compact-output | curl -XPUT -d @- "${URL}"
{
  "lights": [{
    "on": ${ON},
    "brightness": ${BRIGHTNESS},
    "temperature": ${TEMPERATURE}
  }]
}
EOF
}

main "$@"