refactor: extract shared utilities (isMarkdownFile, isPlainObject, resolveSymlink) (#33)

src/shared/file-utils.ts

@@ -0,0 +1,26 @@
+import { lstatSync, readlinkSync } from "fs"
+import { resolve } from "path"
+
+export function isMarkdownFile(entry: { name: string; isFile: () => boolean }): boolean {
+  return !entry.name.startsWith(".") && entry.name.endsWith(".md") && entry.isFile()
+}
+
+export function isSymbolicLink(filePath: string): boolean {
+  try {
+    return lstatSync(filePath, { throwIfNoEntry: false })?.isSymbolicLink() ?? false
+  } catch {
+    return false
+  }
+}
+
+export function resolveSymlink(filePath: string): string {
+  try {
+    const stats = lstatSync(filePath, { throwIfNoEntry: false })
+    if (stats?.isSymbolicLink()) {
+      return resolve(filePath, "..", readlinkSync(filePath))
+    }
+    return filePath
+  } catch {
+    return filePath
+  }
+}