/*** 文件分片上傳管理器* 提供文件分片、哈希計算、并發上傳和斷點續傳功能*/
class FileChunkUploader {/*** 構造函數* @param {File} file - 要上傳的文件對象* @param {Object} options - 配置選項* @param {number} [options.chunkSize=5MB] - 每個分片的大小（字節）* @param {number} [options.maxConcurrency=3] - 最大并發上傳數*/constructor(file, options = {}) {this.sourceFile = file;this.config = {chunkSize: options.chunkSize || 5 << 20, // 默認5MBmaxConcurrency: options.threads || 3, // 并發數hashWorkerPath: options.hashWorkerPath || 'hash-worker.js'};this.uploadState = {totalChunks: Math.ceil(file.size / this.config.chunkSize),uploadedChunkIndices: new Set(),fileHash: null,uploadSessionId: this._generateUniqueId()};}/*** 啟動上傳流程* @returns {Promise<Object>} 上傳結果*/async startUpload() {try {// 1. 計算文件哈希this.uploadState.fileHash = await this._calculateFileHash();// 2. 檢查是否可秒傳if (await this._checkForInstantUpload()) {return { success: true, skipped: true, reason: '文件已存在' };}// 3. 獲取已上傳分片進度await this._fetchUploadProgress();// 4. 執行分片上傳return await this._uploadAllChunks();} catch (error) {console.error('上傳失敗:', error);throw new UploadError('UPLOAD_FAILED', { cause: error });}}/*** 使用Web Worker計算文件哈希* @private* @returns {Promise<string>} 文件哈希值*/async _calculateFileHash() {return new Promise((resolve) => {const worker = new Worker(this.config.hashWorkerPath);worker.postMessage({ file: this.sourceFile,operation: 'hash'});worker.onmessage = (event) => {if (event.data.progress) {this._updateProgress(event.data.progress);} else if (event.data.hash) {resolve(event.data.hash);worker.terminate();}};});}/*** 檢查服務器是否已存在該文件* @private* @returns {Promise<boolean>}*/async _checkForInstantUpload() {const response = await fetch(`/api/files/check?hash=${this.uploadState.fileHash}`);const { exists } = await response.json();return exists;}/*** 獲取已上傳分片信息* @private*/async _fetchUploadProgress() {try {const response = await fetch(`/api/uploads/progress?sessionId=${this.uploadState.uploadSessionId}`);const { uploadedChunks } = await response.json();uploadedChunks.forEach(index => {this.uploadState.uploadedChunkIndices.add(index);});} catch (error) {console.warn('獲取上傳進度失敗，將重新上傳所有分片', error);}}/*** 上傳所有未完成的分片* @private*/async _uploadAllChunks() {const pendingChunks = this._getPendingChunks();await this._uploadWithConcurrencyControl(pendingChunks);return this._finalizeUpload();}/*** 獲取待上傳的分片索引* @private* @returns {number[]}*/_getPendingChunks() {return Array.from({ length: this.uploadState.totalChunks },(_, index) => index).filter(index => !this.uploadState.uploadedChunkIndices.has(index));}/*** 帶并發控制的分片上傳* @private* @param {number[]} chunkIndices - 待上傳分片索引*/async _uploadWithConcurrencyControl(chunkIndices) {const activeUploads = new Set();for (const chunkIndex of chunkIndices) {const uploadPromise = this._uploadSingleChunk(chunkIndex).finally(() => activeUploads.delete(uploadPromise));activeUploads.add(uploadPromise);if (activeUploads.size >= this.config.maxConcurrency) {await Promise.race(activeUploads);}}await Promise.all(activeUploads);}/*** 上傳單個分片* @private* @param {number} chunkIndex - 分片索引* @param {number} [maxRetries=3] - 最大重試次數*/async _uploadSingleChunk(chunkIndex, maxRetries = 3) {let attempt = 0;while (attempt < maxRetries) {try {const chunkData = this._getChunkData(chunkIndex);await this._sendChunkToServer(chunkIndex, chunkData);this.uploadState.uploadedChunkIndices.add(chunkIndex);this._saveProgressLocally();return;} catch (error) {attempt++;if (attempt >= maxRetries) {throw new UploadError('CHUNK_UPLOAD_FAILED', {chunkIndex,attempts: maxRetries,error});}}}}/*** 獲取分片數據* @private* @param {number} chunkIndex * @returns {Blob}*/_getChunkData(chunkIndex) {const start = chunkIndex * this.config.chunkSize;const end = Math.min(start + this.config.chunkSize, this.sourceFile.size);return this.sourceFile.slice(start, end);}/*** 發送分片到服務器* @private*/async _sendChunkToServer(chunkIndex, chunkData) {const formData = new FormData();formData.append('file', chunkData);formData.append('chunkIndex', chunkIndex);formData.append('totalChunks', this.uploadState.totalChunks);formData.append('fileHash', this.uploadState.fileHash);formData.append('sessionId', this.uploadState.uploadSessionId);const response = await fetch('/api/uploads/chunk', {method: 'POST',body: formData});if (!response.ok) {throw new Error(`服務器返回錯誤: ${response.status}`);}}/*** 完成上傳并合并分片* @private*/async _finalizeUpload() {const response = await fetch('/api/uploads/complete', {method: 'POST',headers: {'Content-Type': 'application/json'},body: JSON.stringify({fileHash: this.uploadState.fileHash,sessionId: this.uploadState.uploadSessionId,totalChunks: this.uploadState.totalChunks})});if (!response.ok) {throw new Error('合并分片失敗');}return { success: true };}/*** 生成唯一ID* @private*/_generateUniqueId() {return Math.random().toString(36).substring(2) + Date.now().toString(36);}/*** 本地保存上傳進度* @private*/_saveProgressLocally() {const progressData = {sessionId: this.uploadState.uploadSessionId,uploadedChunks: Array.from(this.uploadState.uploadedChunkIndices),timestamp: Date.now()};localStorage.setItem(`uploadProgress_${this.uploadState.fileHash}`,JSON.stringify(progressData));}
}/*** 上傳錯誤類*/
class UploadError extends Error {constructor(code, details = {}) {super();this.name = 'UploadError';this.code = code;this.details = details;this.message = this._getErrorMessage();}_getErrorMessage() {const messages = {'UPLOAD_FAILED': '文件上傳失敗','CHUNK_UPLOAD_FAILED': `分片上傳失敗 (嘗試次數: ${this.details.attempts})`,'NETWORK_ERROR': '網絡連接出現問題'};return messages[this.code] || '發生未知錯誤';}
}

// hash-worker.js
// 導入 SparkMD5 庫用于計算文件哈希
self.importScripts('spark-md5.min.js');// 監聽主線程消息
self.onmessage = async (event) => {const file = event.data.file;const chunkSize = 2 * 1024 * 1024; // 2MB 的切片大小const totalChunks = Math.ceil(file.size / chunkSize);const hasher = new self.SparkMD5.ArrayBuffer();// 分片計算文件哈希for (let currentChunk = 0; currentChunk < totalChunks; currentChunk++) {const chunkData = await getFileChunk(file, currentChunk * chunkSize, chunkSize);hasher.append(chunkData);// 向主線程發送進度更新self.postMessage({ progress: (currentChunk + 1) / totalChunks });}// 計算完成發送最終哈希值self.postMessage({ hash: hasher.end() });
};/*** 讀取文件指定分片* @param {File} file - 目標文件* @param {number} start - 起始字節位置* @param {number} length - 分片長度* @returns {Promise<ArrayBuffer>}*/
function getFileChunk(file, start, length) {return new Promise((resolve) => {const reader = new FileReader();reader.onload = (loadEvent) => resolve(loadEvent.target.result);reader.readAsArrayBuffer(file.slice(start, start + length));});
}