// src/lib/seo.ts
// ─────────────────────────────────────────────────────────────────────────────
// SEO helpers — base URL, alternate-language tags, JSON-LD structured data
// schemas (Organization, Article, Product, BreadcrumbList).
//
// Used by per-page generateMetadata functions and rendered as <script
// type="application/ld+json"> tags so Google can parse the structured data.
// ─────────────────────────────────────────────────────────────────────────────

import type { Metadata } from "next";

export const LOCALES = ["en", "it", "vec", "es", "de"] as const;
export type Locale = (typeof LOCALES)[number];

export function baseUrl() {
  return (process.env.NEXT_PUBLIC_APP_URL || "https://rf-flux.com").replace(/\/$/, "");
}

export function absoluteUrl(path: string) {
  if (path.startsWith("http")) return path;
  return `${baseUrl()}${path.startsWith("/") ? "" : "/"}${path}`;
}

// ── Build hreflang alternates for a given path (without locale prefix) ──────
export function alternateLanguages(pathWithoutLocale: string) {
  const base = baseUrl();
  const clean = pathWithoutLocale.replace(/^\/+/, "");
  return Object.fromEntries(
    LOCALES.map((locale) => [locale, `${base}/${locale}${clean ? `/${clean}` : ""}`])
  );
}

export interface PageSeoInput {
  locale: Locale | string;
  pathWithoutLocale: string; // e.g. "" for home, "applications/textile-drying" for an app
  title: string;
  description: string;
  ogImageUrl?: string;
  type?: "website" | "article" | "product";
  publishedAt?: Date | string | null;
  updatedAt?: Date | string | null;
}

export function buildPageMetadata(input: PageSeoInput): Metadata {
  const base = baseUrl();
  const path = input.pathWithoutLocale.replace(/^\/+/, "");
  const canonical = `${base}/${input.locale}${path ? `/${path}` : ""}`;

  return {
    title: input.title,
    description: input.description,
    metadataBase: new URL(base),
    alternates: {
      canonical,
      languages: alternateLanguages(input.pathWithoutLocale),
    },
    openGraph: {
      title: input.title,
      description: input.description,
      url: canonical,
      siteName: "FLUX Srl",
      locale: String(input.locale),
      type: input.type === "article" ? "article" : "website",
      images: input.ogImageUrl ? [{ url: absoluteUrl(input.ogImageUrl) }] : undefined,
      ...(input.publishedAt
        ? { publishedTime: new Date(input.publishedAt).toISOString() }
        : {}),
      ...(input.updatedAt
        ? { modifiedTime: new Date(input.updatedAt).toISOString() }
        : {}),
    },
    twitter: {
      card: "summary_large_image",
      title: input.title,
      description: input.description,
      images: input.ogImageUrl ? [absoluteUrl(input.ogImageUrl)] : undefined,
    },
  };
}

// ── JSON-LD schemas ─────────────────────────────────────────────────────────

export function organizationSchema(opts?: { logoUrl?: string; sameAs?: string[] }) {
  const base = baseUrl();
  return {
    "@context": "https://schema.org",
    "@type": "Organization",
    name: "FLUX Srl",
    legalName: "FLUX Srl",
    url: base,
    logo: opts?.logoUrl ? absoluteUrl(opts.logoUrl) : `${base}/flux-logo.png`,
    description:
      "Leading manufacturer of solid-state Radio Frequency (RF), Microwave, and Infrared industrial equipment. Founded by Patrizio Grando — 40+ years of legacy.",
    foundingDate: "1978",
    founder: {
      "@type": "Person",
      name: "Patrizio Grando",
    },
    address: {
      "@type": "PostalAddress",
      streetAddress: "Via Benedetto Marcello 32",
      addressLocality: "Romano d'Ezzelino",
      addressRegion: "Vicenza",
      postalCode: "36060",
      addressCountry: "IT",
    },
    contactPoint: {
      "@type": "ContactPoint",
      contactType: "Sales",
      email: "info@rf-flux.com",
      availableLanguage: ["English", "Italian", "German", "Spanish"],
    },
    ...(opts?.sameAs ? { sameAs: opts.sameAs } : {}),
  };
}

export function localBusinessSchema(opts?: { logoUrl?: string; sameAs?: string[] }) {
  const base = baseUrl();
  return {
    "@context": "https://schema.org",
    "@type": "LocalBusiness",
    "@id": `${base}/#local-business`,
    name: "FLUX Srl",
    legalName: "FLUX Srl",
    url: base,
    logo: opts?.logoUrl ? absoluteUrl(opts.logoUrl) : `${base}/flux-logo.png`,
    description:
      "Manufacturer of solid-state Radio Frequency (RF), Microwave, and Infrared industrial equipment since 1978.",
    foundingDate: "1978",
    founder: { "@type": "Person", name: "Patrizio Grando" },
    address: {
      "@type": "PostalAddress",
      streetAddress: "Via Benedetto Marcello 32",
      addressLocality: "Romano d'Ezzelino",
      addressRegion: "Vicenza",
      postalCode: "36060",
      addressCountry: "IT",
    },
    geo: {
      "@type": "GeoCoordinates",
      latitude: 45.7836,
      longitude: 11.7677,
    },
    telephone: "+39 0424 287 492",
    email: "info@rf-flux.com",
    openingHoursSpecification: {
      "@type": "OpeningHoursSpecification",
      dayOfWeek: ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"],
      opens: "08:00",
      closes: "17:00",
    },
    areaServed: { "@type": "Place", name: "Worldwide" },
    ...(opts?.sameAs ? { sameAs: opts.sameAs } : {}),
  };
}

export function collectionPageSchema(opts: {
  name: string;
  description: string;
  url: string;
  items: { name: string; url: string; position: number }[];
}) {
  return {
    "@context": "https://schema.org",
    "@type": "CollectionPage",
    name: opts.name,
    description: opts.description,
    url: opts.url,
    mainEntity: {
      "@type": "ItemList",
      itemListElement: opts.items.map((item) => ({
        "@type": "ListItem",
        position: item.position,
        url: item.url,
        name: item.name,
      })),
    },
  };
}

export function websiteSchema() {
  const base = baseUrl();
  return {
    "@context": "https://schema.org",
    "@type": "WebSite",
    name: "FLUX Srl",
    url: base,
    inLanguage: ["en", "it", "vec", "es", "de"],
  };
}

export function articleSchema(opts: {
  headline: string;
  description: string;
  imageUrl?: string;
  url: string;
  publishedAt: Date | string;
  updatedAt: Date | string;
  author?: string;
}) {
  return {
    "@context": "https://schema.org",
    "@type": "Article",
    headline: opts.headline,
    description: opts.description,
    image: opts.imageUrl ? absoluteUrl(opts.imageUrl) : undefined,
    datePublished: new Date(opts.publishedAt).toISOString(),
    dateModified: new Date(opts.updatedAt).toISOString(),
    author: {
      "@type": "Organization",
      name: opts.author || "FLUX Srl",
    },
    publisher: {
      "@type": "Organization",
      name: "FLUX Srl",
      logo: {
        "@type": "ImageObject",
        url: `${baseUrl()}/flux-logo.png`,
      },
    },
    mainEntityOfPage: {
      "@type": "WebPage",
      "@id": opts.url,
    },
  };
}

export function productSchema(opts: {
  name: string;
  description: string;
  imageUrl?: string;
  category: string;
  url: string;
}) {
  return {
    "@context": "https://schema.org",
    "@type": "Product",
    name: opts.name,
    description: opts.description,
    image: opts.imageUrl ? absoluteUrl(opts.imageUrl) : undefined,
    category: opts.category,
    brand: {
      "@type": "Brand",
      name: "FLUX",
    },
    manufacturer: {
      "@type": "Organization",
      name: "FLUX Srl",
    },
    url: opts.url,
  };
}

export function breadcrumbSchema(items: { name: string; url: string }[]) {
  return {
    "@context": "https://schema.org",
    "@type": "BreadcrumbList",
    itemListElement: items.map((item, idx) => ({
      "@type": "ListItem",
      position: idx + 1,
      name: item.name,
      item: item.url,
    })),
  };
}