codemod-frontmatter-to-metadata.mjs

// Codemod: Convert YAML frontmatter in MDX files to export const metadata
// Usage: node codemod-frontmatter-to-metadata.mjs
// This script scans all MDX files in the content directory, extracts YAML frontmatter,
// and converts it into a JavaScript export named `metadata`.

// Dependencies: tinyglobby, js-yaml
// Install them via: `pnpm add -D tinyglobby js-yaml`

import fs from "fs"
import path from "path"
import yaml from "js-yaml"
import { glob } from "tinyglobby"

const CONTENT_DIR = path.join(
  path.dirname(new URL(import.meta.url).pathname),
  "../content",
)

function parseFrontmatter(content) {
  const match = content.match(/^---([\s\S]*?)---\n?/)
  if (!match) return null
  try {
    return yaml.load(match[1])
  } catch (e) {
    return null
  }
}

function removeFrontmatter(content) {
  return content.replace(/^---([\s\S]*?)---\n?/, "")
}

function metadataBlock(obj) {
  const entries = Object.entries(obj)
    .map(([key, value]) => `  ${key}: ${JSON.stringify(value)}`)
    .join(",\n")
  return `export const metadata = {\n${entries}\n}\n\n`
}

async function run() {
  const files = await glob(`${CONTENT_DIR}/**/*.mdx`)
  for (const file of files) {
    const raw = fs.readFileSync(file, "utf8")
    const meta = parseFrontmatter(raw)
    if (!meta) continue
    const rest = removeFrontmatter(raw)
    const newContent = metadataBlock(meta) + rest.trimStart()
    fs.writeFileSync(file, newContent)
    console.log("Updated:", file)
  }
}

run()