set -eu

# Time-out in seconds for single volume press
TO=0.150
# Time-out in seconds for holding down volume button
TO_HOLD=0.100
# Duration of vibration in ms
DUR_S=100
# How long to keep your phone awake when using volume buttons in ms
WL_MAX=1500

# Track the toggle state
STATE=0  # 0 = Start Activity, 1 = Stop Activity

on_both_pressed() {
    if [ "$STATE" -eq 0 ]; then
        # Launch RecordingStartActivity
        cmd intent -t activity -p com.fadcam/.RecordingStartActivity 
        STATE=1
    else
        # Launch RecordingStopActivity
        cmd intent -t activity -p com.fadcam/.RecordingStopActivity
        STATE=0
    fi
    cmd vibrate $DUR_S
}


on_up() {
    read -t $TO key && {
        [ "$key" = "$PRESS_DOWN" ] && {
            on_both_pressed
            return
        }
        cmd volume current up
        return
    }
    while true; do
        read -t $TO_HOLD key || {
            cmd volume current up
            continue
        }
        return 
    done
}


on_down() {
    read -t $TO key && {
        [ "$key" = "$PRESS_UP" ] && {
            on_both_pressed
            return
        }
        cmd volume current down
        return
    }
    while true; do
        read -t $TO_HOLD key || {
            cmd volume current down
            continue
        }
        return 
    done
}


loop() {
    while read key; do
        cmd wakelock acquire $WL_MAX
        case "$key" in
            "$PRESS_UP" )
                on_up
            ;;
            "$PRESS_DOWN" )
                on_down
            ;;
        esac
        cmd wakelock release
    done
}


encode_list() {
    ENCODED=""; for arg in "$@"; do
        ENCODED="${ENCODED}${#arg}:${arg}"
    done
    ENCODED="${#ENCODED}:$ENCODED"
}
cmd() {
    encode_list "$@"; 
    echo "$ENCODED"
}

loop