// app/layout.tsx
import type { Metadata } from 'next';

export const metadata: Metadata = {
  metadataBase: new URL(process.env.NEXT_PUBLIC_SITE_URL!),
  title: {
    template: '%s | Studio Name',
    default: 'Studio Name - Pilates & Yoga',
  },
  description: 'Professional Pilates and Yoga coaching for strength and calm.',
  robots: {
    index: true,
    follow: true,
    googleBot: {
      index: true,
      follow: true,
      'max-video-preview': -1,
      'max-image-preview': 'large',
      'max-snippet': -1,
    },
  },
};

// app/[locale]/services/page.tsx
import type { Metadata } from 'next';
import { getTranslations } from 'next-intl/server';
import { locales } from '@/i18n.config';

type Props = {
  params: Promise<{ locale: string }>;
};

export async function generateMetadata({ params }: Props): Promise<Metadata> {
  const { locale } = await params;
  const t = await getTranslations({ locale, namespace: 'meta.services' });
  const siteUrl = process.env.NEXT_PUBLIC_SITE_URL;

  return {
    title: t('title'),
    description: t('description'),
    alternates: {
      canonical: `${siteUrl}/${locale}/services`,
      languages: Object.fromEntries(
        locales.map((loc) => [loc, `${siteUrl}/${loc}/services`])
      ),
    },
    openGraph: {
      title: t('title'),
      description: t('description'),
      url: `${siteUrl}/${locale}/services`,
      siteName: 'Studio Name',
      locale: locale.replace('-', '_'),
      type: 'website',
      images: [
        {
          url: `${siteUrl}/og/services.jpg`,
          width: 1200,
          height: 630,
          alt: t('title'),
        },
      ],
    },
    twitter: {
      card: 'summary_large_image',
      title: t('title'),
      description: t('description'),
      images: [`${siteUrl}/og/services.jpg`],
    },
  };
}

// lib/metadata.ts
import type { Metadata } from 'next';
import { locales, type Locale } from '@/i18n.config';

interface GenerateMetadataOptions {
  locale: Locale;
  path: string;
  title: string;
  description: string;
  image?: string;
  noIndex?: boolean;
}

export function generatePageMetadata({
  locale,
  path,
  title,
  description,
  image = '/og/default.jpg',
  noIndex = false,
}: GenerateMetadataOptions): Metadata {
  const siteUrl = process.env.NEXT_PUBLIC_SITE_URL!;
  const fullUrl = `${siteUrl}/${locale}${path}`;
  const imageUrl = image.startsWith('http') ? image : `${siteUrl}${image}`;

  return {
    title,
    description,
    robots: noIndex ? { index: false, follow: false } : undefined,
    alternates: {
      canonical: fullUrl,
      languages: Object.fromEntries(
        locales.map((loc) => [loc, `${siteUrl}/${loc}${path}`])
      ),
    },
    openGraph: {
      title,
      description,
      url: fullUrl,
      siteName: 'Studio Name',
      locale: locale.replace('-', '_'),
      type: 'website',
      images: [{ url: imageUrl, width: 1200, height: 630, alt: title }],
    },
    twitter: {
      card: 'summary_large_image',
      title,
      description,
      images: [imageUrl],
    },
  };
}

// app/[locale]/about/page.tsx
import { generatePageMetadata } from '@/lib/metadata';
import { getTranslations } from 'next-intl/server';

export async function generateMetadata({ params }: Props): Promise<Metadata> {
  const { locale } = await params;
  const t = await getTranslations({ locale, namespace: 'meta.about' });

  return generatePageMetadata({
    locale: locale as Locale,
    path: '/about',
    title: t('title'),
    description: t('description'),
    image: '/og/about.jpg',
  });
}

// app/[locale]/programmes/[slug]/page.tsx
import { getProgrammeBySlug } from '@/lib/data';

export async function generateMetadata({ params }: Props): Promise<Metadata> {
  const { locale, slug } = await params;
  const programme = await getProgrammeBySlug(locale as Locale, slug);
  
  if (!programme) {
    return { title: 'Not Found' };
  }

  return generatePageMetadata({
    locale: locale as Locale,
    path: `/programmes/${slug}`,
    title: programme.title,
    description: programme.outcomes.slice(0, 2).join('. '),
  });
}

<link rel="canonical" href="https://example.com/en/services" />
<link rel="alternate" hreflang="pt-PT" href="https://example.com/pt-PT/services" />
<link rel="alternate" hreflang="en" href="https://example.com/en/services" />
<link rel="alternate" hreflang="tr" href="https://example.com/tr/services" />
<link rel="alternate" hreflang="es" href="https://example.com/es/services" />
<link rel="alternate" hreflang="fr" href="https://example.com/fr/services" />
<link rel="alternate" hreflang="de" href="https://example.com/de/services" />
<link rel="alternate" hreflang="x-default" href="https://example.com/pt-PT/services" />

// messages/en.json
{
  "meta": {
    "home": {
      "title": "Pilates & Yoga Coaching",
      "description": "Transform your body with personalized training"
    },
    "services": {
      "title": "Our Services",
      "description": "1:1 sessions, group classes, and online coaching"
    },
    "about": {
      "title": "About Us",
      "description": "Meet your instructor and learn our approach"
    }
  }
}