import { navigation, NavigationLink, type NavigationSubItem } from "@/lib/navigation";
import { usePageContext } from "vike-react/usePageContext";
import { Link } from "@/components/common/Link";
import clsx from "clsx";

function ArrowIcon(props: React.ComponentPropsWithoutRef<"svg">) {
  return (
    <svg viewBox="0 0 16 16" aria-hidden="true" {...props}>
      <path d="m9.182 13.423-1.17-1.16 3.505-3.505H3V7.065h8.517l-3.506-3.5L9.181 2.4l5.512 5.511-5.511 5.512Z" />
    </svg>
  );
}

function PageLink({
  title,
  href,
  dir = "next",
  ...props
}: Omit<React.ComponentPropsWithoutRef<"div">, "dir" | "title"> & {
  title: string;
  href: string;
  dir?: "previous" | "next";
}) {
  const pageCategory = navigation.find((section) => {
    return section.links.some((link) => link.href === href || link.subitems.some((subitem) => subitem.href === href));
  });

  return (
    <div {...props}>
      <dt className="font-display text-sm font-medium text-slate-900 dark:text-white">
        {dir === "next" ? "Suivant" : "Précédent"}
      </dt>
      <dd className="mt-1">
        <Link
          href={href}
          className={clsx(
            "flex items-center gap-x-2 text-base font-semibold text-slate-500 hover:text-slate-600 dark:text-slate-400 dark:hover:text-slate-300",
            dir === "previous" && "flex-row-reverse",
          )}
        >
          <p className="flex flex-col gap-0">
            {pageCategory && (
              <span className="text-violet-600 dark:text-violet-400 text-sm -mb-3">{pageCategory.title}</span>
            )}
            <span>{title}</span>
          </p>
          <ArrowIcon className={clsx("h-6 w-6 flex-none fill-current", dir === "previous" && "-scale-x-100")} />
        </Link>
      </dd>
    </div>
  );
}

export function PrevNextLinks() {
  const allLinks = navigation.flatMap((section) => section.links);
  const { urlPathname } = usePageContext();

  let subItemElement: undefined | NavigationSubItem;

  const findLinkIndex = (pathname = urlPathname) => {
    for (let i = 0; i < allLinks.length; i++) {
      const link = allLinks[i];

      if (link.href === urlPathname) {
        return i;
      }

      if (link.subitems) {
        const subitemIndex = link.subitems.findIndex((subitem) => subitem.href === urlPathname);

        if (subitemIndex !== -1) {
          subItemElement = link.subitems[subitemIndex];
          return i;
        }
      }
    }
  };

  const linkIndex = findLinkIndex();
  if (linkIndex === undefined) return null;

  let previousPage: NavigationSubItem | NavigationLink | null = linkIndex > -1 ? allLinks[linkIndex - 1] : null;
  let nextPage: NavigationSubItem | NavigationLink | null = linkIndex > -1 ? allLinks[linkIndex + 1] : null;

  if (subItemElement !== undefined) {
    const subItemIndex = findLinkIndex(subItemElement.href)!;
    const currentPage = allLinks[subItemIndex];
    const subItemIndexInLink = currentPage.subitems?.findIndex((subitem) => subitem.href === urlPathname);
    if (subItemIndexInLink !== undefined && subItemIndexInLink > -1) {
      previousPage = currentPage.subitems[subItemIndexInLink - 1];
      nextPage = currentPage.subitems[subItemIndexInLink + 1];
    }
  }

  if (!nextPage && !previousPage) {
    return null;
  }

  return (
    <dl className="mt-12 flex border-t border-slate-200 pt-6 dark:border-slate-800">
      {previousPage && <PageLink dir="previous" {...previousPage} />}
      {nextPage && <PageLink className="ml-auto text-right" {...nextPage} />}
    </dl>
  );
}