实现快传，完善快传和网盘的功能，实现文件的互传等一系列功能

front/src/pages/transfer-state.ts

@@ -0,0 +1,52 @@
+import type { TransferFileDescriptor } from '../lib/transfer-protocol';
+
+export type TransferTab = 'send' | 'receive';
+
+export function createMockTransferCode() {
+  return Math.floor(100000 + Math.random() * 900000).toString();
+}
+
+export function sanitizeReceiveCode(value: string) {
+  return value.replace(/\D/g, '').slice(0, 6);
+}
+
+export function formatTransferSize(bytes: number) {
+  if (bytes <= 0) {
+    return '0 B';
+  }
+
+  const units = ['B', 'KB', 'MB', 'GB', 'TB'];
+  let value = bytes;
+  let unitIndex = 0;
+
+  while (value >= 1024 && unitIndex < units.length - 1) {
+    value /= 1024;
+    unitIndex += 1;
+  }
+
+  const displayValue = value >= 10 || unitIndex === 0 ? value.toFixed(0) : value.toFixed(1);
+  return `${displayValue.replace(/\.0$/, '')} ${units[unitIndex]}`;
+}
+
+export function buildQrImageUrl(shareUrl: string) {
+  return `https://api.qrserver.com/v1/create-qr-code/?size=180x180&data=${encodeURIComponent(shareUrl)}`;
+}
+
+export function canSendTransferFiles(isAuthenticated: boolean) {
+  return isAuthenticated;
+}
+
+export function resolveInitialTransferTab(
+  isAuthenticated: boolean,
+  sessionId: string | null,
+): TransferTab {
+  if (!canSendTransferFiles(isAuthenticated) || sessionId) {
+    return 'receive';
+  }
+
+  return 'send';
+}
+
+export function canArchiveTransferSelection(files: Pick<TransferFileDescriptor, 'relativePath'>[]) {
+  return files.length > 1 || files.some((file) => file.relativePath.includes('/'));
+}