led

#!/bin/sh -e

# The intended usecase is to supplement a notification system. Say for example you
# received an email from person A. You may get some on screen notification, but
# for most of us that will disappear after a while. So if you weren't looking at
# the screen that moment, you may have missed it. Instead you can run `led push
# blue email-A on` and a blue (if available) led will turn on. When you finally get
# to checking your email `led pop email-A` to unset the led. If in between you also
# received an email from B and ran `led push blue email-B on` then the led would
# remain on until pop was run for this id. If you didn't care about the specific
# user, you could just run `led push blue email on` and only 1 pop would be needed

LED_SYS_DIR=${LED_SYS_DIR:-/sys/class/leds}
LED_PATH=$(echo "$LED_SYS_DIR"/*"$2"*)

if [ -z "$1" ] || [ "$1" = "list" ]; then
    if  [ -n "$2" ]; then
        printf "on off "
        cat "$LED_PATH/trigger"
    else
        ls "$LED_SYS_DIR"
    fi
    exit 0
elif [ "$1" = "get" ]; then
    sed "s/.*\[\(.*\)\].*/\1 $(cat "$LED_PATH/brightness")/" < "$LED_PATH/trigger"
    exit 0
elif [ "$1" = "check" ]; then
    read -r value _ < "$LED_PATH/trigger"
    [ "$value" = "[none]" ]
    read -r brightness _ <"$LED_PATH/brightness"
    [ "$brightness" -eq 0 ]
    exit
fi

LED_DATA_DIR=${LED_DATA_DIR:-${XDG_DATA_HOME:-$HOME/.local/share}/led}

mkdir -p "$LED_DATA_DIR"
[ "0$LED_LOCK" -eq 1 ] || LED_LOCK=1 exec flock "$LED_DATA_DIR/.lock" "$0" "$@"

SUBCOMMAND=$1
LABEL="${3:-default}"
LED_ACTION="${4:-on}"
LED_PRIORITY="${5:-1}"
LED_INFO_DIR="$LED_DATA_DIR/$(basename "$LED_PATH")"
LED_INFO_FILE="$LED_INFO_DIR/$LABEL"

setLED() {
    case "$1" in
        on)
            echo 1 > "$LED_PATH/brightness"
            ;;
        off)
            echo 0 > "$LED_PATH/brightness"
            ;;
        *)
            echo "$1" > "$LED_PATH/trigger"
            ;;
    esac
}

if [ "$SUBCOMMAND" = "push" ]; then
    mkdir -p "$LED_INFO_DIR"
    priority="$LED_PRIORITY$(date -u +%C%y%m%d%H%M%S)"
    echo "$priority $LED_ACTION" > "$LED_INFO_FILE"
    for f in "$LED_INFO_DIR"/*; do
        read -r p _ < "$f"
        [ "$priority" -lt "${p:-1}" ] && exit 0
    done
    setLED "$LED_ACTION"
elif [ "$SUBCOMMAND" = "pop" ]; then
    [ -d "$LED_INFO_DIR" ] || exit 0
    rm -f "$LED_INFO_FILE" || true
    sort -r "$LED_INFO_DIR"/* 2>/dev/null | {
        while read -r _ action; do
           setLED "$action" && exit 0
       done
       exit 1
    } || {
        rm -r "$LED_INFO_DIR"
        setLED off
    }
elif [ "$SUBCOMMAND" = "clear" ]; then
    rm -f "$LED_INFO_FILE"
    setLED off
else
    echo "$0 push led_name [label [action [priority]]]"
    echo "$0 pop led_name [label]"
    echo "$0 clear led_name"
    echo "$0 list led_name"
    echo "$0"
    [ "$SUBCOMMAND" != -h ] && [ "$SUBCOMMAND" != --help ] && exit 2
    exit 0
fi