feat: add posts content layer with gray-matter + compileMDX

lib/posts.ts

@@ -0,0 +1,77 @@
+import fs from 'fs/promises'
+import path from 'path'
+import matter from 'gray-matter'
+import { compileMDX } from 'next-mdx-remote/rsc'
+import { cache } from 'react'
+import { useMDXComponents } from '@/mdx-components'
+
+const postsDirectory = path.join(process.cwd(), 'content/posts')
+
+export interface PostMeta {
+  slug: string
+  title: string
+  date: string
+  excerpt: string
+}
+
+export interface Post extends PostMeta {
+  source: string
+}
+
+const getMdxFiles = cache(async () => {
+  try {
+    const files = await fs.readdir(postsDirectory)
+    return files.filter((f) => f.endsWith('.mdx') || f.endsWith('.md'))
+  } catch {
+    return []
+  }
+})
+
+export const getPosts = cache(async (): Promise<PostMeta[]> => {
+  const files = await getMdxFiles()
+  return Promise.all(
+    files.map(async (file) => {
+      const filePath = path.join(postsDirectory, file)
+      const raw = await fs.readFile(filePath, 'utf8')
+      const { data } = matter(raw)
+      return {
+        slug: file.replace(/\.(mdx|md)$/, ''),
+        title: data.title ?? file,
+        date: data.date ?? 'Unknown',
+        excerpt: data.excerpt ?? '',
+      } as PostMeta
+    })
+  ).then((posts) =>
+    posts.sort((a, b) => new Date(b.date).getTime() - new Date(a.date).getTime())
+  )
+})
+
+export const getPost = async (slug: string): Promise<Post | null> => {
+  const files = await getMdxFiles()
+  const file = files.find((f) => f.replace(/\.(mdx|md)$/, '') === slug)
+  if (!file) return null
+
+  const filePath = path.join(postsDirectory, file)
+  const raw = await fs.readFile(filePath, 'utf8')
+  const { data, content } = matter(raw)
+  const components = useMDXComponents({})
+
+  const { content: compiledContent } = await compileMDX({
+    source: content,
+    components,
+    options: { parseFrontmatter: true },
+  })
+
+  return {
+    slug,
+    title: data.title ?? file,
+    date: data.date ?? 'Unknown',
+    excerpt: data.excerpt ?? '',
+    source: compiledContent,
+  } as unknown as Post
+}
+
+export const getReadingTime = (content: string): number => {
+  const words = content.replace(/<[^>]*>/g, '').trim().split(/\s+/).filter(Boolean).length
+  return Math.max(1, Math.ceil(words / 200))
+}