app/sitemap.tsを作成する。

• changeFrequencyは更新頻度
• priorityは相対的な重要度

export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
  const baseUrl = process.env.NEXT_PUBLIC_BASE_URL ?? 'http://localhost:3000';

  const defaultPages: MetadataRoute.Sitemap = [
    {
      url: `${baseUrl}/`,
      lastModified: new Date(),
      changeFrequency: 'daily',
      priority: 1,
    },
    {
      url: `${baseUrl}/about`,
      lastModified: new Date(),
      changeFrequency: 'monthly',
      priority: 0.8,
    },
    {
      url: `${baseUrl}/news`,
      lastModified: new Date(),
      changeFrequency: 'weekly',
      priority: 0.9,
    },
    {
      url: `${baseUrl}/policy`,
      lastModified: new Date(),
      changeFrequency: 'yearly',
      priority: 0.5,
    },
    {
      url: `${baseUrl}/terms`,
      lastModified: new Date(),
      changeFrequency: 'yearly',
      priority: 0.5,
    },
  ];

  try {
    const [memos, notes] = await Promise.all([getAllMemos(), getAllNotes()]);

    const memoPages = memos.map((memo) => ({
      url: `${baseUrl}/memo/${memo.id}`,
      lastModified: new Date(memo.updatedAt),
      changeFrequency: 'monthly' as const,
      priority: 0.7,
    }));

    const notePages = notes.map((note) => ({
      url: `${baseUrl}/note/${note.id}`,
      lastModified: new Date(note.updatedAt),
      changeFrequency: 'monthly' as const,
      priority: 0.7,
    }));

    return [...defaultPages, ...memoPages, ...notePages];
  } catch (error) {
    console.error('Error generating sitemap:', error);

    // エラー時は静的ページだけでも返す
    return defaultPages;
  }
}