c4wled.sh/wled

#!/bin/sh
#
# Turn WLED installations in the C4 hackspace on/off, change brightness or
# switch between presets.
#
# Author: Shy
# License: CC0

NAME="wled.sh"
COMMAND="wled"
VERSION="0.1.1"

print_usage() {
    echo "\
Usage: $COMMAND -f(norcenter)|-w(wohnzimmer) [on|off]
       $COMMAND -f|-w [1-17|list]
       $COMMAND -f|-w -b [1-255]"
}

print_help() {
    print_usage
    echo "
host selection:
    -f,--fnordcenter        select fnordcenter
    -w,--wohnzimmer         select wohnzimmer

commands:
    on|off                  switch on/off
    [1-17]                  switch preset
    l, list                 list presets
    -b,--brightness [1-255] set brightness"
}

curl_cmd() {
    curl --silent --show-error --fail --ipv4 --max-filesize 32K "$@"
}

active_preset() {
    # Find number of active preset. API returns -1 if none is active, we return
    # an empty string.
    preset="$(curl_cmd "http://$1/json" | \
        # -1 will be a no-match.
        sed -n 's/.*"ps"[[:space:]]*:[[:space:]]*\(1\?[0-9]\).*/\1/p')"
    printf '%u' "$preset"
}

# Parse host argument.
case "$1" in
    ""|-h|--help) # Missing host parameter.
        print_help
        exit 0
    ;;
    -v|--version)
        echo "$NAME version $VERSION"
        exit 0
    ;;
    -f|--fnordcenter)
        wled_host='wled-fnordcenter.local'
    ;;
    -w|--wohnzimmer)
        wled_host='wled-wohnzimmer.local'
    ;;
    *) # Unknown host parameter.
        echo "Error: unknown host \"$1\"." >&2
        print_usage
        exit 1
    ;;
esac

# Parse and execute command argument.
case "$2" in
    on) # Switch on.
        api_resp=$(curl_cmd --json '{"on":true}' "http://$wled_host/json")
    ;;
    off) # Switch off.
        api_resp=$(curl_cmd --json '{"on":false}' "http://$wled_host/json")
    ;;
    -b|--brightness) # Set brightness.
        if test -z "$3"; then
            echo "Error: missing parameter for brightness." >&2
            exit 1
        fi
        # Try to convert 3rd parameter to an integer between 1 an 255.
        bright=$(printf '%u' "$3" 2>/dev/null)
        if test $? -gt 0; then # Conversion failed.
            echo "Error: unable to parse parameter for brightness." >&2
            exit 1
        elif test "$bright" -lt 1 -o "$bright" -gt 255; then
            echo "Error: parameter for brightness is out of range." >&2
            exit 1
        fi
        api_resp=$(curl_cmd --json "{'bri':$bright}" "http://$wled_host/json")
    ;;
    [1-9]|1[0-7]) # Switch to preset.
        api_resp=$(curl_cmd --json "{'ps':$2}" "http://$wled_host/json")
    ;;
    l|list) # List presets.
        printf "loading ...\r"
        active_ps=$(active_preset "$wled_host")
        curl_cmd "http://$wled_host/presets.json" | \
            # Split into lines - one line per preset.
            sed --sandbox 's/"1\?[0-9]"[[:space:]]*:/\n&/g' | \
            # Prepend description, extract number and name of every preset,
            # match active preset, right-align numbers and finally select
            # lines to print.
            sed --sandbox -n \
                -e "1i\\Presets on $wled_host:" \
                -e 's/^"\(1\?[0-9]\)"[[:space:]]*:.*"n"[[:space:]]*:[[:space:]]*"\([[:print:]]*\)".*$/\1: \2/' \
                -e "s/^$active_ps:.*/& */" \
                -e 's/^[0-9]:/ &/' \
                -e '/^[1 ]\?[0-9]: [[:print:]]\+/p' | \
            # Sort.
            sort -b -n
        exit $?
    ;;
    dump) # Dump JSON response from API.
        curl_cmd -w '\n' "http://$wled_host/json"
        exit 0
    ;;
    "") # Missing command.
        echo "Error: missing command." >&2
        print_usage
        exit 1
    ;;
    *) # Unknown command.
        echo "Error: unknown command \"$2\"." >&2
        print_usage
        exit 1
    ;;
esac

# Check curl exit status
curl_exit=$?
if test $curl_exit -ne 0; then
    echo "Error: curl exited with exit code $curl_exit." >&2
    exit 1
fi

# Check API responce.
if echo "$api_resp" | grep -qv '{\s*"success"\s*:\s*true\s*}'; then
    echo "Error: unexpected responce from WLED API." >&2
    exit 1
fi