feat: add file validation utilities

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/utils/file.js

@@ -0,0 +1,43 @@
+const FILE_TYPES = {
+  document: 2 * 1024 * 1024 * 1024, // 2GB
+  photo: 10 * 1024 * 1024, // 10MB
+  video: 2 * 1024 * 1024 * 1024, // 2GB
+  audio: 200 * 1024 * 1024, // 200MB
+  voice: 200 * 1024 * 1024, // 200MB
+  animation: 2 * 1024 * 1024 * 1024 // 2GB
+};
+
+export const getFileType = (mime, caption) => {
+  const mimeUpper = mime?.split('/')[0]?.toLowerCase();
+  const captionLower = caption?.toLowerCase();
+
+  if (mimeUpper === 'video') return 'video';
+  if (mimeUpper === 'audio') return 'audio';
+  if (mimeUpper === 'document') return 'document';
+  if (mimeUpper === 'image') return captionLower?.includes('gif') ? 'animation' : 'photo';
+  if (captionLower?.includes('voice')) return 'voice';
+  if (captionLower?.includes('animation')) return 'animation';
+
+  return mimeUpper || 'document';
+};
+
+export const checkFileSize = (sizeBytes, fileType) => {
+  const limit = FILE_TYPES[fileType] || FILE_TYPES.document;
+  return sizeBytes <= limit;
+};
+
+export const extractFileName = (msg, request) => {
+  if (request?.headers?.['x-file-name']) {
+    return request.headers['x-file-name'];
+  }
+  return msg.document?.fileName || msg.photo?.slice(-1)[0]?.fileName || msg.audio?.fileName ||
+         msg.voice?.fileName || msg.animation?.fileName || 'file';
+};
+
+export const extractMimeType = (msg, request) => {
+  if (request?.headers?.['x-mime-type']) {
+    return request.headers['x-mime-type'];
+  }
+  return msg.document?.mimeType || msg.photo?.slice(-1)[0]?.mimeType || msg.audio?.mimeType ||
+         msg.voice?.mimeType || msg.animation?.mimeType || 'application/octet-stream';
+};