import { injectDialogRootContext } from 'reka-ui';
import { watch } from 'vue';

/** Reka restores registered triggers; also support dialogs opened programmatically. */
export function useDialogFocus() {
    const context = injectDialogRootContext();
    let previousFocus: HTMLElement | null = null;

    watch(
        context.open,
        (open) => {
            if (open && typeof document !== 'undefined') {
                previousFocus =
                    document.activeElement instanceof HTMLElement
                        ? document.activeElement
                        : null;
            }
        },
        { flush: 'sync', immediate: true },
    );

    function restoreFocus(event: Event): void {
        if (
            !event.defaultPrevented &&
            !context.triggerElement.value &&
            previousFocus?.isConnected
        ) {
            event.preventDefault();
            previousFocus.focus({ preventScroll: true });
        }
    }

    return { restoreFocus };
}