feat: preview vault images in app

src/utils/filePreview.ts

@@ -0,0 +1,38 @@
+import type { VaultEntry } from '../types'
+
+const IMAGE_PREVIEW_EXTENSIONS = new Set([
+  'apng',
+  'avif',
+  'bmp',
+  'gif',
+  'ico',
+  'jpeg',
+  'jpg',
+  'png',
+  'svg',
+  'tif',
+  'tiff',
+  'webp',
+])
+
+function extensionFromFilename(filename: string): string | null {
+  const lastSegment = filename.split(/[\\/]/u).pop() ?? filename
+  const dotIndex = lastSegment.lastIndexOf('.')
+  if (dotIndex <= 0 || dotIndex === lastSegment.length - 1) return null
+  return lastSegment.slice(dotIndex + 1).toLowerCase()
+}
+
+export function previewExtension(entry: Pick<VaultEntry, 'filename' | 'path'>): string | null {
+  return extensionFromFilename(entry.filename) ?? extensionFromFilename(entry.path)
+}
+
+export function isImagePreviewEntry(entry: Pick<VaultEntry, 'fileKind' | 'filename' | 'path'>): boolean {
+  if (entry.fileKind !== 'binary') return false
+  const extension = previewExtension(entry)
+  return extension ? IMAGE_PREVIEW_EXTENSIONS.has(extension) : false
+}
+
+export function previewFileTypeLabel(entry: Pick<VaultEntry, 'filename' | 'path'>): string {
+  const extension = previewExtension(entry)
+  return extension ? `${extension.toUpperCase()} file` : 'File'
+}