#!/usr/bin/env zsh

PANEL_FIFO="$1"
PREFIX="$2"
DELAY="$3"
MAX_LEN="$(("$4"-3))"

exec 5>"$PANEL_FIFO"

main() {
    local win_id="$(bspc query -N -n focused)"
    local win_name="$(xprop -id "$win_id" | grep "^WM_NAME" | cut -d' ' -f3- | tr -d '"')"
    local trimmed_win_name="${win_name:0:$MAX_LEN}"
    if [[ "$win_name" != "$trimmed_win_name" ]]; then
        win_name="${trimmed_win_name}..."
    fi

    REPLY="$trimmed_win_name"
}

# Run 2 loops here, one for instant updates once other window is focused
# in bspwm, other for timed updates, in case the window changes it's title
# on it's own (such as when we switch a tab in firefox)

{print init; stdbuf -oL bspc subscribe node} | while read line; do
    case ${line} in
        node_focus* ) main ;;
        init ) main ;;
        * ) continue ;;
    esac

    echo "$PREFIX $REPLY" >&5
done &

while :; do
    main
    echo "$PREFIX $REPLY" >&5
    sleep "$DELAY"
done

wait $!