portfolio/src/lib/generateSitemap.js

import glob from 'fast-glob'
import path from 'path'
import {getAllArticles} from '@/lib/getAllArticles'
import {writeFile} from 'fs/promises'

const BASE_URL = process.env.NEXT_PUBLIC_SITE_URL

async function createSitemap(pages) {
    const sitemap = `<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  ${pages.map((url) => {
        return `
<url>
    <loc>${url}</loc>
    <lastmod>${new Date().toISOString()}</lastmod>
    <changefreq>monthly</changefreq>
    <priority>1.0</priority>
</url>`
    }).join("")}
</urlset>`

    await writeFile('./public/sitemap.xml', sitemap, 'utf8')
}

async function createRobots() {
    const robots = `# *
User-agent: *
Allow: /

# Host
Host: ${BASE_URL}

# Sitemaps
Sitemap: ${BASE_URL}/sitemap.xml`

    await writeFile('./public/robots.txt', robots, 'utf8')
}

export async function generateSitemap() {
    const excluded = [
        '_app.tsx',
        '_document.tsx',
        'index.tsx'
    ]

    const pages = (await glob(['*.tsx', '*.jsx'], {
        cwd: path.join(process.cwd(), 'src/pages/'),
    })).filter((page) => {
        return !excluded
            .includes(page)
    }).map((page) => {
        return `${BASE_URL}/${page}`
            .replace(/\.(tsx|jsx)$/, '')
    })

    pages.unshift(`${BASE_URL}/`)
    pages.push(`${BASE_URL}/writing`)

    const articles = await getAllArticles()
    const slugs = articles.map(({slug}) => `${BASE_URL}/writing/${slug}`)
    const allPages = [...pages, ...slugs]

    await Promise.all([
        await createSitemap(allPages),
        await createRobots()
    ])
}