volume.sh

#!/usr/bin/env bash

ME=$(basename $0)
MUTEFILE=~/.channels.mute

usage() {
    cat <<END
$ME COMMAND [ARGS...]: Volume control / muting

Commands:

    -t [CHANNEL]        Toggle muting of CHANNEL
                        (Default input channel)
    -l                  Show current volumes of all channels
    -s CHANNEL [VALUE]  Set the volume of CHANNEL to VALUE
                        or show the current volume of CHANNEL
                        (Default input channel)
    -h                  This help

END
}

osa() {
    osascript <<< "$@"
    return $?
}

getvol() {
    local which="$1"
    osa $which volume of \(get volume settings\)
    return $?
}

setvol() {
    local which="$1"
    local volume="$2"
    osa set volume "$which" volume "$volume"
    return $?
}

show() {
    local which="$1"
    echo -n "$which: "
    getvol "$which"
    return $?
}

toggle() {
    local which="$1"
    local ret=
    local current="$(getvol "$which")"

    if [ "$current" -gt 0 ]; then
        echo "$which $current" > "$MUTEFILE"
        setvol "$which" 0
        ret=$?
    else
        setvol "$which" "$(getlast "$which")"
        ret=$?
    fi

    return $ret
}

getlast() {
    local which="$1"
    local last=
    local ret=0
    local CHANNEL=
    local VOLUME=
    local TEMPFILE="$(mktemp mute.XXXX)"

    while read CHANNEL VOLUME; do
        if [ "$CHANNEL" = "$which" ]; then
            last="$VOLUME"
            break
        else
            echo "$CHANNEL $VOLUME" >> "$TEMPFILE"
        fi
    done < "$MUTEFILE"

    if [ -n "$last" ]; then
        ret=1
        last=64
    fi

    mv "$TEMPFILE" "$MUTEFILE"

    echo "$last"
    return $ret
}

main() {
    local cmd="$1"
    shift
    local which="${1:-input}"
    [ -n "$1" ] && shift

    case $cmd in
        -t)
            toggle "$which"
            show "$which"
            ;;
        -s)
            [ -n "$1" ] && setvol "$which" "$1"
            show "$which"
            ;;
        -l)
            osa get volume settings
            ;;
        *)
            usage
            exit 1
            ;;
    esac
}

main "$@"