// app/sitemap.ts
import { getAllTags, getSortedPostsData } from '@/lib/posts';
import { MetadataRoute } from 'next';

export default function sitemap(): MetadataRoute.Sitemap {
  const baseUrl = 'https://steffenillium.de';

  // Improvement 1: Fetch all posts with a single, more efficient call
  const allPosts = getSortedPostsData();
  const postUrls: MetadataRoute.Sitemap = allPosts.map((post) => ({
    url: `${baseUrl}/${post.href}`,
    lastModified: new Date(post.date),
    changeFrequency: 'yearly',
    priority: 0.7,
  }));


  const allTags = getAllTags(2);
  const tagUrls: MetadataRoute.Sitemap = allTags.map((tag) => ({
    url: `${baseUrl}/tags/${tag.name}`,
    lastModified: new Date(),
    changeFrequency: 'monthly',
    priority: 0.5,
  }));

  // The types for changeFrequency and lastModified will now be correctly inferred
  const staticRoutes: MetadataRoute.Sitemap = [
    {
      url: baseUrl,
      lastModified: new Date(),
      priority: 1,
      changeFrequency: 'monthly',
    },
    {
      url: `${baseUrl}/experience`,
      lastModified: new Date(),
      priority: 0.8,
      changeFrequency: 'monthly',
    },
    {
      url: `${baseUrl}/research`,
      lastModified: new Date(),
      priority: 0.9,
      changeFrequency: 'yearly',
    },
    {
      url: `${baseUrl}/publications`,
      lastModified: new Date(),
      priority: 0.9,
      changeFrequency: 'yearly',
    },
    {
      url: `${baseUrl}/tags`,
      lastModified: new Date(),
      priority: 0.7,
      changeFrequency: 'monthly',
    },
  ];

  return [...staticRoutes, ...postUrls, ...tagUrls];
}