Added reader and diagnostics

src/lib/content/load.ts

@@ -0,0 +1,45 @@
+import { ARTICLES, PAGES, TAGS } from '../constants/collections'
+import { createDiagnostics } from '../diagnostics'
+import type { Diagnostics } from '../diagnostics/types'
+import { createContentReader } from './reader'
+import type { ArticleEntry, Content, PageEntry, TagEntry } from './types'
+
+interface CollectionReader<T> {
+  list(): Promise<string[]>
+  read(id: string): Promise<T | null>
+}
+
+function reason(error: unknown): string {
+  const [first, ...rest] = (error instanceof Error ? error.message : String(error)).split('\n')
+  return first.endsWith(':') && rest.length ? rest.join('; ') : first
+}
+
+async function readAll<T>(
+  reader: CollectionReader<T>,
+  collection: string,
+  problems: Diagnostics,
+): Promise<Map<string, T>> {
+  const entries = new Map<string, T>()
+  await Promise.all(
+    (await reader.list()).map(async (id) => {
+      try {
+        const entry = await reader.read(id)
+        if (entry) entries.set(id, entry)
+      } catch (error) {
+        problems.error(collection, id, reason(error))
+      }
+    }),
+  )
+  return entries
+}
+
+export async function loadContent(): Promise<Content> {
+  const { collections } = createContentReader()
+  const problems = createDiagnostics()
+  const [articles, pages, tags] = await Promise.all([
+    readAll<ArticleEntry>(collections.articles, ARTICLES, problems),
+    readAll<PageEntry>(collections.pages, PAGES, problems),
+    readAll<TagEntry>(collections.tags, TAGS, problems),
+  ])
+  return { articles, pages, tags, diagnostics: problems.list }
+}