/* ============================================================================
   KNOWLEDGE HUB - one item
   ----------------------------------------------------------------------------
   /{locale}/knowledge-hub/{slug}

   Registered in app/routes.ts as "knowledgeHubDetail", a SIBLING of the
   listing route under the ":lang" layout, and typed against its generated
   `./+types/` module.

   A missing slug is a 404. A CMS outage is not: `fetchBySlug` only converts
   Strapi's own 404 into null and rethrows everything else.
   ========================================================================= */

import { useLoaderData } from "react-router";

import { Button } from "~/components/ui/Button";
import {
  formatDate,
  formatFileSize,
  sectionPath,
  toIsoDate,
  useTranslation,
  type Locale,
} from "~/i18n";
import { buildArticleJsonLd, buildBreadcrumbJsonLd, buildMeta } from "~/lib/seo";
import { requireEntity } from "~/lib/strapi";

import type { Route } from "./+types/knowledge-hub.$slug";
import {
  collectLocalizedSlugs,
  detailAlternateDescriptors,
  LOCALIZATION_POPULATE,
  SELF_ALTERNATES_HANDLE,
} from "./_shared/alternates";
import {
  CMS,
  fetchBySlug,
  toFile,
  toImage,
  type CmsFile,
  type KnowledgeEntry,
} from "./_shared/cms";
import { readRootSeo, requireLocale, withParam } from "./_shared/listing";
import {
  BackLink,
  MetaLine,
  MetaList,
  PageHeader,
  PageShell,
  TopicChips,
  type MetaItem,
} from "./_shared/listing-ui";
import { RichText } from "./_shared/RichText";
import {
  DETAIL_COPY,
  KNOWLEDGE_COPY,
  KNOWLEDGE_DETAIL_COPY,
  KNOWLEDGE_TYPE_BLURBS,
  KNOWLEDGE_TYPE_LABELS,
} from "./_shared/page-copy";

function typeLabel(value: string, locale: Locale): string {
  return KNOWLEDGE_TYPE_LABELS[locale][value] ?? value;
}

/**
 * Strapi 5 gives the Arabic translation its own slug, so this route emits its
 * own canonical + hreflang - see ./_shared/alternates.ts.
 */
export const handle = SELF_ALTERNATES_HANDLE;

/* ---------------------------------------------------------------------------
   LOADER
   ------------------------------------------------------------------------ */

export async function loader({ params }: Route.LoaderArgs) {
  const locale = requireLocale(params.lang);
  const slug = params.slug ?? "";

  const entry = requireEntity(
    await fetchBySlug<KnowledgeEntry>(CMS.knowledgeItems, slug, {
      locale,
      populate: {
        thumbnail: {
          fields: ["url", "alternativeText", "width", "height", "formats"],
        },
        // Multiple media, and the only download this type has: there is no
        // `externalUrl` field on a knowledge item.
        attachments: { fields: ["url", "name", "ext", "mime", "size"] },
        topics: { fields: ["name", "slug"] },
        localizations: LOCALIZATION_POPULATE,
      },
    }),
  );

  const attachments = (entry.attachments ?? [])
    .map((media) => toFile(media))
    .filter((file): file is CmsFile => file !== undefined)
    .map((file) => ({
      ...file,
      label: `${file.kind} · ${formatFileSize(file.sizeBytes, locale)}`,
    }));
  const date = entry.publicationDate ?? entry.publishedAt ?? undefined;

  return {
    slug: entry.slug,
    alternates: collectLocalizedSlugs(locale, entry.slug, entry.localizations),
    title: entry.title,
    summary: entry.summary ?? undefined,
    body: entry.body ?? undefined,
    typeLabel: entry.itemType ? typeLabel(entry.itemType, locale) : undefined,
    typeBlurb: entry.itemType
      ? KNOWLEDGE_TYPE_BLURBS[locale][entry.itemType]
      : undefined,
    date,
    dateIso: toIsoDate(date),
    dateLabel: date ? formatDate(date, locale) : undefined,
    modifiedIso: toIsoDate(entry.updatedAt),
    topics: (entry.topics ?? [])
      .filter((topic) => Boolean(topic?.slug && topic?.name))
      .map((topic) => ({ label: topic.name, slug: topic.slug })),
    cover: toImage(entry.thumbnail, "large"),
    attachments,
  };
}

/* ---------------------------------------------------------------------------
   META
   ------------------------------------------------------------------------ */

export function meta({ matches, loaderData }: Route.MetaArgs) {
  const root = readRootSeo(matches);
  const entry = loaderData as Awaited<ReturnType<typeof loader>> | undefined;
  const section = KNOWLEDGE_COPY[root.locale];

  if (!entry) {
    return buildMeta({
      locale: root.locale,
      pathname: root.pathname,
      siteUrl: root.siteUrl,
      title: section.heading,
      description: section.metaDescription,
    });
  }

  const descriptors = buildMeta({
    locale: root.locale,
    pathname: root.pathname,
    siteUrl: root.siteUrl,
    title: entry.title,
    description: entry.summary ?? entry.typeBlurb ?? section.metaDescription,
    type: "article",
    ...(entry.cover ? { image: { url: entry.cover.src, alt: entry.cover.alt } } : {}),
    ...(entry.dateIso
      ? {
          article: {
            publishedTime: entry.dateIso,
            ...(entry.modifiedIso ? { modifiedTime: entry.modifiedIso } : {}),
            ...(entry.typeLabel ? { section: entry.typeLabel } : {}),
            tags: entry.topics.map((topic) => topic.label),
          },
        }
      : {}),
    jsonLd: [
      buildBreadcrumbJsonLd(root.siteUrl, [
        { name: "SHARP-ER", pathname: sectionPath("home", root.locale) },
        { name: section.heading, pathname: sectionPath("knowledgeHub", root.locale) },
        { name: entry.title, pathname: root.pathname },
      ]),
      ...(entry.dateIso
        ? [
            buildArticleJsonLd({
              siteUrl: root.siteUrl,
              locale: root.locale,
              headline: entry.title,
              pathname: root.pathname,
              datePublished: entry.dateIso,
              ...(entry.modifiedIso ? { dateModified: entry.modifiedIso } : {}),
              ...(entry.summary ? { description: entry.summary } : {}),
              ...(entry.cover ? { image: entry.cover.src } : {}),
              ...(entry.typeLabel ? { section: entry.typeLabel } : {}),
              keywords: entry.topics.map((topic) => topic.label),
            }),
          ]
        : []),
    ],
  });

  return [
    ...descriptors,
    ...detailAlternateDescriptors({
      siteUrl: root.siteUrl,
      section: "knowledgeHub",
      locale: root.locale,
      slugs: entry.alternates,
    }),
  ];
}

/* ---------------------------------------------------------------------------
   PAGE
   ------------------------------------------------------------------------ */

export default function KnowledgeItemDetail() {
  const entry = useLoaderData<typeof loader>();
  const { t, locale } = useTranslation();

  const listingPath = sectionPath("knowledgeHub", locale);
  const detail = KNOWLEDGE_DETAIL_COPY[locale];
  const shared = DETAIL_COPY[locale];

  const metaItems: MetaItem[] = [
    ...(entry.dateLabel
      ? [
          {
            label: shared.published,
            value: <time dateTime={entry.dateIso ?? entry.date}>{entry.dateLabel}</time>,
          },
        ]
      : []),
    ...(entry.typeLabel
      ? [{ label: t("filters.category"), value: entry.typeLabel }]
      : []),
  ];

  return (
    <PageShell>
      <BackLink to={listingPath} label={detail.backToListing} />

      <article className="flex flex-col gap-2xl">
        <PageHeader
          eyebrow={entry.typeLabel}
          heading={entry.title}
          intro={entry.summary}
        >
          <MetaLine items={[entry.dateLabel ?? ""]} />
        </PageHeader>

        {entry.cover ? (
          <img
            src={entry.cover.src}
            alt={entry.cover.alt}
            width={entry.cover.width}
            height={entry.cover.height}
            decoding="async"
            className="w-full rounded-card border border-border-subtle object-cover"
          />
        ) : null}

        <div className="grid gap-2xl lg:grid-cols-[minmax(0,1fr)_18rem] lg:items-start">
          <div className="flex max-w-[var(--layout-prose-max)] flex-col gap-lg">
            <RichText value={entry.body} />

            {entry.attachments.length > 0 ? (
              <ul className="flex list-none flex-col gap-md">
                {entry.attachments.map((file) => (
                  <li
                    key={file.url}
                    className="flex flex-wrap items-center gap-md"
                  >
                    <Button
                      as="a"
                      href={file.url}
                      variant="primary"
                      download={file.name}
                    >
                      {t("actions.download")}
                    </Button>
                    <span className="body-sm text-text-tertiary">
                      {file.name} · {file.label}
                    </span>
                  </li>
                ))}
              </ul>
            ) : null}
          </div>

          <aside className="flex flex-col gap-lg">
            <MetaList heading={detail.aboutThis} items={metaItems} />
            <TopicChips
              heading={shared.topics}
              topics={entry.topics.map((topic) => ({
                label: topic.label,
                href: `${listingPath}${withParam(new URLSearchParams(), "topic", topic.slug)}`,
              }))}
            />
          </aside>
        </div>
      </article>
    </PageShell>
  );
}