import type { PageServerLoad } from "./$types";
import { error } from "@sveltejs/kit";
import { getCalendarItemBySlug } from "$lib/cms";
import { marked } from "$lib/markdown-safe";
import { env } from "$env/dynamic/public";

/**
 * Eigenständige Detail-Seite pro Termin: alle Infos + Aktionen ungekürzt,
 * eigene OG-Tags (Link-Previews FB/WhatsApp/Twitter) und ein Link zum
 * Kalender (KEIN Redirect mehr — die Seite ist das Ziel des QR-/Direktlinks).
 *
 * terminZeit ist mit Offset gespeichert (z. B. 10:00+02:00). Labels müssen in
 * Europe/Berlin gerendert werden, sonst zeigt der SSR-Prozess (Server-TZ=UTC)
 * 2h zu früh.
 */
const TZ = "Europe/Berlin";

export const load: PageServerLoad = async ({ params, setHeaders }) => {
  const slug = params.slug;
  const rawItem = await getCalendarItemBySlug(slug, { locale: "de" });
  if (!rawItem) throw error(404, "Termin nicht gefunden");
  const item = rawItem as typeof rawItem & {
    location?: unknown;
    description?: string;
    terminEnde?: string;
    tags?: string[];
    image?: unknown;
    attachment?: { src?: string; label?: string };
    link?: unknown;
  };

  const siteBaseUrl = (env.PUBLIC_SITE_URL || "").replace(/\/$/, "");
  const title = (item.title ?? "Termin").trim();
  const terminZeit = item.terminZeit;
  const terminEnde = item.terminEnde ?? null;
  const hasTime = !!terminZeit && !/T00:00:00/.test(terminZeit);

  const weekdayLabel = terminZeit
    ? new Date(terminZeit).toLocaleDateString("de-DE", { weekday: "long", timeZone: TZ })
    : "";
  const dateLabel = terminZeit
    ? new Date(terminZeit).toLocaleDateString("de-DE", {
        day: "2-digit",
        month: "long",
        year: "numeric",
        timeZone: TZ,
      })
    : "";
  const timeLabel = hasTime
    ? new Date(terminZeit).toLocaleTimeString("de-DE", {
        hour: "2-digit",
        minute: "2-digit",
        timeZone: TZ,
      }) + " Uhr"
    : "";
  const endDateLabel =
    terminEnde && !/T00:00:00/.test(terminEnde)
      ? new Date(terminEnde).toLocaleDateString("de-DE", {
          day: "2-digit",
          month: "long",
          year: "numeric",
          timeZone: TZ,
        })
      : "";

  const locObj =
    typeof item.location === "object" && item.location !== null
      ? (item.location as { text?: string; lat?: number; lng?: number })
      : null;
  const locationText = locObj
    ? (locObj.text ?? "").trim() || null
    : typeof item.location === "string"
      ? item.location.trim() || null
      : null;
  const hasCoords =
    !!locObj && typeof locObj.lat === "number" && typeof locObj.lng === "number";

  // Externer Link / Post-Link
  let externalLink: string | null = null;
  const link = item.link as { url?: string; _slug?: string } | string | undefined;
  if (typeof link === "string" && link) externalLink = link;
  else if (link && typeof link === "object") {
    if (link.url) externalLink = link.url;
    else if (link._slug) externalLink = `/post/${encodeURIComponent(link._slug)}`;
  }

  const descriptionHtml = item.description
    ? (marked.parse(item.description) as string)
    : "";
  const descriptionPlain = descriptionHtml
    .replace(/<[^>]+>/g, " ")
    .replace(/\s+/g, " ")
    .trim();

  const tags = Array.isArray(item.tags) ? item.tags.filter((t) => typeof t === "string") : [];

  const seoDescription = [
    dateLabel + (timeLabel ? `, ${timeLabel}` : ""),
    locationText,
    descriptionPlain ? descriptionPlain.slice(0, 200) : null,
  ]
    .filter(Boolean)
    .join(" · ");

  const socialImage = `${siteBaseUrl}/api/social/calendar/${encodeURIComponent(slug)}?format=og`;
  const calendarUrl = `/kalender/#event-${slug}`;
  const canonical = `${siteBaseUrl}/kalender/termin/${encodeURIComponent(slug)}/`;

  // schema.org Event — Rich-Result/SEO für Termine (Datum, Ort, Veranstalter).
  const jsonLd = terminZeit
    ? [
        {
          "@context": "https://schema.org",
          "@type": "Event",
          name: title,
          startDate: terminZeit,
          ...(terminEnde ? { endDate: terminEnde } : {}),
          eventAttendanceMode: "https://schema.org/OfflineEventAttendanceMode",
          eventStatus: "https://schema.org/EventScheduled",
          ...(siteBaseUrl ? { url: canonical } : {}),
          inLanguage: "de-DE",
          ...(descriptionPlain ? { description: descriptionPlain.slice(0, 500) } : {}),
          image: socialImage,
          organizer: {
            "@type": "Organization",
            name: "Windwiderstand Thüringen",
            ...(siteBaseUrl ? { url: siteBaseUrl } : {}),
          },
          ...(locationText
            ? {
                location: {
                  "@type": "Place",
                  name: locationText,
                  ...(hasCoords
                    ? {
                        geo: {
                          "@type": "GeoCoordinates",
                          latitude: locObj!.lat,
                          longitude: locObj!.lng,
                        },
                      }
                    : {}),
                },
              }
            : {}),
        },
      ]
    : [];

  const breadcrumbItems = [
    { label: "Start", href: "/" },
    { label: "Kalender", href: "/kalender/" },
    { label: title },
  ];

  setHeaders({
    "cache-control": "public, s-maxage=300, stale-while-revalidate=3600",
  });

  return {
    seoTitle: `${title} – Windwiderstand Thüringen`,
    seoDescription,
    socialImage,
    ogType: "article" as const,
    jsonLd,
    breadcrumbItems,
    calendarUrl,
    item: {
      slug,
      title,
      terminZeit: terminZeit ?? null,
      terminEnde,
      hasTime,
      weekdayLabel,
      dateLabel,
      timeLabel,
      endDateLabel,
      locationText,
      descriptionHtml,
      tags,
      image: item.image ?? null,
      attachment:
        item.attachment && item.attachment.src
          ? { src: item.attachment.src, label: item.attachment.label ?? "Anhang" }
          : null,
      externalLink,
    },
  };
};