lib: remove source field from Post interface, use gray-matter for reading time only

lib/posts.ts

@@ -16,9 +16,7 @@ export interface PostMeta {
   readingTime: number
 }
 
-export interface Post extends PostMeta {
-  source: string // raw MDX string, NOT compiled
-}
+export interface Post extends PostMeta {}
 
 const getMdxFiles = cache(async () => {
   try {
@@ -64,9 +62,10 @@ export const getPost = async (slug: string): Promise<Post | null> => {
 
   const filePath = path.join(postsDirectory, file)
   const raw = await fs.promises.readFile(filePath, 'utf8')
-  const { data, content } = matter(raw)
+  const { data } = matter(raw)
 
-  const readingTime = Math.max(1, Math.ceil(content.split(/\s+/).length / 200))
+  const contentForReadingTime = raw.replace(/^---[\s\S]*?---\s*?/, '')
+  const readingTime = Math.max(1, Math.ceil(contentForReadingTime.split(/\s+/).filter(Boolean).length / 200))
 
   return {
     slug,
@@ -76,7 +75,6 @@ export const getPost = async (slug: string): Promise<Post | null> => {
     tags: data.tags ?? [],
     author: data.author ?? null,
     coverImage: data.coverImage ?? null,
-    source: content,
     readingTime,
   } satisfies Post
 }