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/lib/transfer-protocol.ts

@@ -0,0 +1,117 @@
+export const TRANSFER_CHUNK_SIZE = 64 * 1024;
+export const SIGNAL_POLL_INTERVAL_MS = 1000;
+
+interface TransferFileIdentity {
+  name: string;
+  lastModified: number;
+  size: number;
+}
+
+export interface TransferFileDescriptor {
+  id: string;
+  name: string;
+  size: number;
+  contentType: string;
+  relativePath: string;
+}
+
+export type TransferControlMessage =
+  {
+    type: 'manifest';
+    files: TransferFileDescriptor[];
+  }
+  | {
+      type: 'receive-request';
+      fileIds: string[];
+      archive: boolean;
+    }
+  | ({
+      type: 'file-meta';
+    } & TransferFileDescriptor)
+  | {
+      type: 'file-complete';
+      id: string;
+    }
+  | {
+      type: 'transfer-complete';
+    };
+
+export function createTransferFileId(file: TransferFileIdentity) {
+  return `${file.name}-${file.lastModified}-${file.size}`;
+}
+
+export function getTransferFileRelativePath(file: File) {
+  const rawRelativePath = ('webkitRelativePath' in file && typeof file.webkitRelativePath === 'string' && file.webkitRelativePath)
+    ? file.webkitRelativePath
+    : file.name;
+
+  const normalizedPath = rawRelativePath
+    .replaceAll('\\', '/')
+    .split('/')
+    .map((segment) => segment.trim())
+    .filter(Boolean)
+    .join('/');
+
+  return normalizedPath || file.name;
+}
+
+export function createTransferFileManifest(files: File[]): TransferFileDescriptor[] {
+  return files.map((file) => ({
+    id: createTransferFileId(file),
+    name: file.name,
+    size: file.size,
+    contentType: file.type || 'application/octet-stream',
+    relativePath: getTransferFileRelativePath(file),
+  }));
+}
+
+export function createTransferFileManifestMessage(files: TransferFileDescriptor[]) {
+  return JSON.stringify({
+    type: 'manifest',
+    files,
+  } satisfies TransferControlMessage);
+}
+
+export function createTransferReceiveRequestMessage(fileIds: string[], archive: boolean) {
+  return JSON.stringify({
+    type: 'receive-request',
+    fileIds,
+    archive,
+  } satisfies TransferControlMessage);
+}
+
+export function createTransferFileMetaMessage(payload: TransferFileDescriptor) {
+  return JSON.stringify({
+    type: 'file-meta',
+    ...payload,
+  } satisfies TransferControlMessage);
+}
+
+export function createTransferFileCompleteMessage(id: string) {
+  return JSON.stringify({
+    type: 'file-complete',
+    id,
+  } satisfies TransferControlMessage);
+}
+
+export function createTransferCompleteMessage() {
+  return JSON.stringify({
+    type: 'transfer-complete',
+  } satisfies TransferControlMessage);
+}
+
+export function parseTransferControlMessage(payload: string): TransferControlMessage | null {
+  try {
+    return JSON.parse(payload) as TransferControlMessage;
+  } catch {
+    return null;
+  }
+}
+
+export async function toTransferChunk(data: ArrayBuffer | Blob) {
+  if (data instanceof Blob) {
+    return new Uint8Array(await data.arrayBuffer());
+  }
+
+  return new Uint8Array(data);
+}