import { useEffect, useId, useRef, type ReactNode } from 'react';
import { useI18n } from '../i18n';

interface ModalProps {
  title: string;
  onClose(): void;
  children: ReactNode;
  footer?: ReactNode;
  wide?: boolean;
}

/**
 * A dialog that behaves like one: Escape closes it, focus starts inside and
 * cannot Tab out, and it returns focus to whatever opened it.
 */
export function Modal({ title, onClose, children, footer, wide }: ModalProps): ReactNode {
  const ref = useRef<HTMLDivElement>(null);
  const titleId = useId();
  const returnFocusTo = useRef<Element | null>(null);

  useEffect(() => {
    returnFocusTo.current = document.activeElement;
    const first = ref.current?.querySelector<HTMLElement>(
      'input:not([type=hidden]), select, textarea, button',
    );
    first?.focus();

    return () => {
      if (returnFocusTo.current instanceof HTMLElement) returnFocusTo.current.focus();
    };
  }, []);

  useEffect(() => {
    function onKeyDown(event: KeyboardEvent) {
      if (event.key === 'Escape') {
        event.stopPropagation();
        onClose();
        return;
      }
      if (event.key !== 'Tab') return;

      const focusable = ref.current?.querySelectorAll<HTMLElement>(
        'a[href], button:not([disabled]), input:not([disabled]), select:not([disabled]), textarea:not([disabled]), [tabindex]:not([tabindex="-1"])',
      );
      if (!focusable?.length) return;
      const first = focusable[0]!;
      const last = focusable[focusable.length - 1]!;

      if (event.shiftKey && document.activeElement === first) {
        event.preventDefault();
        last.focus();
      } else if (!event.shiftKey && document.activeElement === last) {
        event.preventDefault();
        first.focus();
      }
    }

    document.addEventListener('keydown', onKeyDown, true);
    return () => document.removeEventListener('keydown', onKeyDown, true);
  }, [onClose]);

  return (
    <div
      className="scrim"
      onMouseDown={(e) => {
        if (e.target === e.currentTarget) onClose();
      }}
    >
      <div
        className={wide ? 'modal wide' : 'modal'}
        role="dialog"
        aria-modal="true"
        aria-labelledby={titleId}
        ref={ref}
      >
        <h2 id={titleId}>{title}</h2>
        {children}
        {footer && <div className="mf">{footer}</div>}
      </div>
    </div>
  );
}

interface ConfirmProps {
  title: string;
  message: ReactNode;
  confirmLabel?: string;
  destructive?: boolean;
  busy?: boolean;
  onConfirm(): void;
  onCancel(): void;
}

export function ConfirmDialog({
  title,
  message,
  confirmLabel,
  destructive,
  busy,
  onConfirm,
  onCancel,
}: ConfirmProps): ReactNode {
  const { t } = useI18n();
  return (
    <Modal
      title={title}
      onClose={onCancel}
      footer={
        <>
          <button className="btn" onClick={onCancel} disabled={busy}>
            {t('common.cancel')}
          </button>
          <button
            className={destructive ? 'btn destructive' : 'btn primary'}
            onClick={onConfirm}
            disabled={busy}
          >
            {busy ? t('common.working') : (confirmLabel ?? t('common.confirm'))}
          </button>
        </>
      }
    >
      <div className="mb">{message}</div>
    </Modal>
  );
}