import { siteConfig } from "@/lib/site";
import { toBerlinOffsetISOString } from "./dates";
import type { BookingSetting, Contact, Event, Offer, Post, SeoSetting } from "@/payload-types";

// Server-only builders — every function here returns `null` instead of
// guessing when the real data needed for a valid/honest result isn't
// present. Nothing here ever invents a review, price, address or phone
// number (see section 27/35 of the SEO brief).

/** JSON.stringify with `<` escaped so this can never be broken out of by any (currently non-existent) embedded "</script>" sequence. */
function toSafeJsonLdString(data: unknown): string {
  return JSON.stringify(data).replace(/</g, "\\u003c");
}

type JsonLdValue = Record<string, unknown>;

export function organizationName(settings: SeoSetting | null | undefined): string {
  return settings?.businessName?.trim() || siteConfig.name;
}

function hasFullAddress(booking: BookingSetting | null | undefined): booking is BookingSetting & { street: string; city: string; postalCode: string } {
  return Boolean(booking?.street?.trim() && booking?.city?.trim() && booking?.postalCode?.trim());
}

function postalAddress(booking: BookingSetting) {
  return {
    "@type": "PostalAddress",
    streetAddress: booking.street!.trim(),
    postalCode: booking.postalCode!.trim(),
    addressLocality: booking.city!.trim(),
    ...(booking.region?.trim() ? { addressRegion: booking.region.trim() } : {}),
    ...(booking.country?.trim() ? { addressCountry: booking.country.trim() } : {}),
  };
}

/**
 * Organization (always safe — just a name and a URL) upgraded to
 * ProfessionalService/LocalBusiness once a real, complete street address
 * has actually been entered in the CMS. Phone/opening hours/geo are added
 * only when present; nothing is fabricated to "complete" the schema.
 */
export function organizationOrLocalBusinessJsonLd(args: {
  settings: SeoSetting | null | undefined;
  booking: BookingSetting | null | undefined;
  contact: Contact | null | undefined;
  siteUrl: string;
}): JsonLdValue {
  const name = organizationName(args.settings);
  const base: JsonLdValue = {
    "@context": "https://schema.org",
    name,
    url: args.siteUrl,
  };
  if (args.settings?.businessDescription?.trim()) base.description = args.settings.businessDescription.trim();
  if (args.contact?.email) base.email = args.contact.email;

  if (!hasFullAddress(args.booking)) {
    return { ...base, "@type": "Organization" };
  }

  const result: JsonLdValue = {
    ...base,
    "@type": "ProfessionalService",
    address: postalAddress(args.booking),
  };

  if (args.contact?.phone?.trim()) result.telephone = args.contact.phone.trim();
  if (typeof args.settings?.latitude === "number" && typeof args.settings?.longitude === "number") {
    result.geo = { "@type": "GeoCoordinates", latitude: args.settings.latitude, longitude: args.settings.longitude };
  }
  if (args.settings?.openingHours?.length) {
    result.openingHoursSpecification = args.settings.openingHours.map((entry) => ({
      "@type": "OpeningHoursSpecification",
      dayOfWeek: entry.days.map((day) => `https://schema.org/${day}`),
      opens: entry.opens,
      closes: entry.closes,
    }));
  }
  if (args.settings?.socialLinks?.length) {
    result.sameAs = args.settings.socialLinks.map((link) => link.url).filter(Boolean);
  }

  return result;
}

export function websiteJsonLd(siteUrl: string): JsonLdValue {
  return {
    "@context": "https://schema.org",
    "@type": "WebSite",
    name: siteConfig.name,
    url: siteUrl,
  };
}

export function webPageJsonLd(args: { name: string; description: string; url: string }): JsonLdValue {
  return {
    "@context": "https://schema.org",
    "@type": "WebPage",
    name: args.name,
    description: args.description,
    url: args.url,
  };
}

export function breadcrumbJsonLd(items: { name: string; url?: string }[]): JsonLdValue | null {
  if (items.length === 0) return null;
  return {
    "@context": "https://schema.org",
    "@type": "BreadcrumbList",
    // The last item's "item" URL is deliberately omitted when absent —
    // that's the current page, and per Google's guidelines a BreadcrumbList
    // entry doesn't need a URL for the page the visitor is already on.
    itemListElement: items.map((item, index) => ({
      "@type": "ListItem",
      position: index + 1,
      name: item.name,
      ...(item.url ? { item: item.url } : {}),
    })),
  };
}

export function serviceJsonLd(args: {
  offer: Offer;
  description: string;
  imageUrl?: string;
  siteUrl: string;
  providerName: string;
  areaServed?: string;
}): JsonLdValue {
  const result: JsonLdValue = {
    "@context": "https://schema.org",
    "@type": "Service",
    name: args.offer.title,
    description: args.description,
    url: `${args.siteUrl}/angebote/${args.offer.slug}`,
    provider: { "@type": "Organization", name: args.providerName, url: args.siteUrl },
  };
  if (args.imageUrl) result.image = args.imageUrl;
  if (args.areaServed) result.areaServed = args.areaServed;
  // Deliberately no "offers"/price — the CMS "price" field is free text
  // (e.g. "auf Anfrage") and can't be turned into a valid structured price
  // without risking incorrect data.
  return result;
}

export function eventJsonLd(args: {
  event: Event;
  description: string;
  imageUrl?: string;
  joinUrl?: string;
  siteUrl: string;
  providerName: string;
  booking: BookingSetting | null | undefined;
}): JsonLdValue | null {
  const { event } = args;
  // Private single-session bookings must never surface as a public Event
  // (see section 18) — defense in depth alongside the page-level checks
  // that already keep them out of public listings entirely.
  if (event.isPrivateBooking) return null;
  if (!event.date) return null;

  const start = new Date(event.startTime || event.date);
  const isOnline = Boolean(event.isOnline);

  const result: JsonLdValue = {
    "@context": "https://schema.org",
    "@type": "Event",
    name: event.title,
    description: args.description,
    startDate: toBerlinOffsetISOString(start),
    eventStatus: "https://schema.org/EventScheduled",
    eventAttendanceMode: isOnline ? "https://schema.org/OnlineEventAttendanceMode" : "https://schema.org/OfflineEventAttendanceMode",
    url: `${args.siteUrl}/termine/${event.slug}`,
    organizer: { "@type": "Organization", name: args.providerName, url: args.siteUrl },
  };

  if (event.endTime) result.endDate = toBerlinOffsetISOString(new Date(event.endTime));
  if (args.imageUrl) result.image = args.imageUrl;

  if (isOnline) {
    result.location = { "@type": "VirtualLocation", url: args.joinUrl ?? result.url };
  } else if (hasFullAddress(args.booking)) {
    result.location = {
      "@type": "Place",
      name: event.location || args.booking.locationName || args.providerName,
      address: postalAddress(args.booking),
    };
  } else if (event.location) {
    // No structured address on file, but the event itself names a place —
    // still valid schema.org (address is optional on Place).
    result.location = { "@type": "Place", name: event.location };
  }

  return result;
}

export function articleJsonLd(args: {
  post: Post;
  description: string;
  imageUrl?: string;
  siteUrl: string;
  providerName: string;
}): JsonLdValue {
  const url = `${args.siteUrl}/aktuelles/${args.post.slug}`;
  return {
    "@context": "https://schema.org",
    "@type": "BlogPosting",
    headline: args.post.title,
    description: args.description,
    url,
    mainEntityOfPage: url,
    datePublished: new Date(args.post.publishDate ?? args.post.createdAt).toISOString(),
    dateModified: new Date(args.post.updatedAt).toISOString(),
    author: { "@type": "Person", name: args.post.author?.trim() || args.providerName },
    publisher: { "@type": "Organization", name: args.providerName, url: args.siteUrl },
    ...(args.imageUrl ? { image: args.imageUrl } : {}),
  };
}

/** Renders one or more JSON-LD objects as server-side <script> tags. Filters out any null entries so callers can pass conditional builders directly. */
export function JsonLd({ data }: { data: JsonLdValue | JsonLdValue[] | null | (JsonLdValue | null)[] }) {
  const items = (Array.isArray(data) ? data : [data]).filter((item): item is JsonLdValue => Boolean(item));
  if (items.length === 0) return null;
  return (
    <>
      {items.map((item, index) => (
        <script key={index} type="application/ld+json" dangerouslySetInnerHTML={{ __html: toSafeJsonLdString(item) }} />
      ))}
    </>
  );
}