import { UploadFile } from "antd";
import jsSHA from "jssha";

// 默认分片大小：5MB（适合大多数网络环境）
export const DEFAULT_CHUNK_SIZE = 1024 * 1024 * 5;
// 大文件阈值：10MB
export const LARGE_FILE_THRESHOLD = 1024 * 1024 * 10;
// 最大并发上传数
export const MAX_CONCURRENT_UPLOADS = 3;
// 文本文件读取块大小：20MB（用于计算 SHA256）
const BUFFER_CHUNK_SIZE = 1024 * 1024 * 20;

/**
 * 将文件分割为多个分片
 * @param file 文件对象
 * @param chunkSize 分片大小（字节），默认 5MB
 * @returns 分片数组（Blob 列表）
 */
export function sliceFile(file: Blob, chunkSize = DEFAULT_CHUNK_SIZE): Blob[] {
  const totalSize = file.size;
  const chunks: Blob[] = [];
  
  // 小文件不需要分片
  if (totalSize <= chunkSize) {
    return [file];
  }
  
  let start = 0;
  while (start < totalSize) {
    const end = Math.min(start + chunkSize, totalSize);
    const blob = file.slice(start, end);
    chunks.push(blob);
    start = end;
  }
  
  return chunks;
}

/**
 * 计算文件的 SHA256 哈希值
 * @param file 文件 Blob
 * @param onProgress 进度回调（可选）
 * @returns SHA256 哈希字符串
 */
export function calculateSHA256(
  file: Blob, 
  onProgress?: (percent: number) => void
): Promise<string> {
  return new Promise((resolve, reject) => {
    const hash = new jsSHA("SHA-256", "ARRAYBUFFER", { encoding: "UTF8" });
    const reader = new FileReader();
    let processedSize = 0;

    function readChunk(start: number, end: number) {
      const slice = file.slice(start, end);
      reader.readAsArrayBuffer(slice);
    }

    function processChunk(offset: number) {
      const start = offset;
      const end = Math.min(start + BUFFER_CHUNK_SIZE, file.size);
      readChunk(start, end);
    }

    reader.onloadend = function (e) {
      const arraybuffer = reader.result as ArrayBuffer;
      if (!arraybuffer) {
        reject(new Error("Failed to read file"));
        return;
      }

      hash.update(arraybuffer);
      processedSize += (e.target as FileReader).result?.byteLength || 0;
      
      if (onProgress) {
        const percent = Math.min(100, Math.round((processedSize / file.size) * 100));
        onProgress(percent);
      }
      
      if (processedSize < file.size) {
        processChunk(processedSize);
      } else {
        resolve(hash.getHash("HEX", { outputLen: 256 }));
      }
    };

    reader.onerror = () => reject(new Error("File reading failed"));
    processChunk(0);
  });
}

/**
 * 批量计算多个文件的 SHA256
 * @param files 文件列表
 * @param onFileProgress 单个文件进度回调（可选）
 * @returns 哈希值数组
 */
export async function calculateSHA256Batch(
  files: Blob[],
  onFileProgress?: (index: number, percent: number) => void
): Promise<string[]> {
  const results: string[] = [];
  
  for (let i = 0; i < files.length; i++) {
    const hash = await calculateSHA256(files[i], (percent) => {
      onFileProgress?.(i, percent);
    });
    results.push(hash);
  }
  
  return results;
}

/**
 * 检查文件是否存在（未被修改或删除）
 * @param fileList 文件列表
 * @returns 返回第一个不存在的文件，或 null（如果都存在）
 */
export function checkIsFilesExist(
  fileList: Array<{ originFile?: Blob }>
): Promise<{ originFile?: Blob } | null> {
  return new Promise((resolve) => {
    if (!fileList.length) {
      resolve(null);
      return;
    }

    let checkedCount = 0;
    const totalCount = fileList.length;

    const loadEndFn = (file: { originFile?: Blob }, e: ProgressEvent<FileReader>) => {
      checkedCount++;
      const fileNotExist = !e.target?.result;
      if (fileNotExist) {
        resolve(file);
        return;
      }
      if (checkedCount >= totalCount) {
        resolve(null);
      }
    };

    for (const file of fileList) {
      const fileReader = new FileReader();
      const actualFile = file.originFile;
      
      if (!actualFile) {
        checkedCount++;
        if (checkedCount >= totalCount) {
          resolve(null);
        }
        continue;
      }
      
      fileReader.readAsArrayBuffer(actualFile.slice(0, 1));
      fileReader.onloadend = (e) => loadEndFn(file, e);
      fileReader.onerror = () => {
        checkedCount++;
        resolve(file);
      };
    }
  });
}

/**
 * 判断文件是否为大文件
 * @param size 文件大小（字节）
 * @param threshold 阈值（字节），默认 10MB
 */
export function isLargeFile(size: number, threshold = LARGE_FILE_THRESHOLD): boolean {
  return size > threshold;
}

/**
 * 格式化文件大小为人类可读格式
 * @param bytes 字节数
 * @param decimals 小数位数
 */
export function formatFileSize(bytes: number, decimals = 2): string {
  if (bytes === 0) return "0 B";
  
  const k = 1024;
  const sizes = ["B", "KB", "MB", "GB", "TB", "PB"];
  const i = Math.floor(Math.log(bytes) / Math.log(k));
  
  return `${parseFloat((bytes / Math.pow(k, i)).toFixed(decimals))} ${sizes[i]}`;
}

/**
 * 并发执行异步任务
 * @param tasks 任务函数数组
 * @param maxConcurrency 最大并发数
 * @param onTaskComplete 单个任务完成回调（可选）
 */
export async function runConcurrentTasks<T>(
  tasks: (() => Promise<T>)[],
  maxConcurrency: number,
  onTaskComplete?: (index: number, result: T) => void
): Promise<T[]> {
  const results: T[] = new Array(tasks.length);
  let index = 0;

  async function runNext(): Promise<void> {
    const currentIndex = index++;
    if (currentIndex >= tasks.length) return;

    const result = await tasks[currentIndex]();
    results[currentIndex] = result;
    onTaskComplete?.(currentIndex, result);
    
    await runNext();
  }

  const workers = Array(Math.min(maxConcurrency, tasks.length))
    .fill(null)
    .map(() => runNext());

  await Promise.all(workers);
  return results;
}

/**
 * 按行分割文本文件内容
 * @param text 文本内容
 * @param skipEmptyLines 是否跳过空行，默认 true
 * @returns 行数组
 */
export function splitTextByLines(text: string, skipEmptyLines = true): string[] {
  const lines = text.split(/\r?\n/);
  if (skipEmptyLines) {
    return lines.filter((line) => line.trim() !== "");
  }
  return lines;
}

/**
 * 创建分片信息对象
 * @param file 原始文件
 * @param chunkSize 分片大小
 */
export function createFileSliceInfo(
  file: File | Blob,
  chunkSize = DEFAULT_CHUNK_SIZE
): {
  originFile: Blob;
  slices: Blob[];
  name: string;
  size: number;
  totalChunks: number;
} {
  const slices = sliceFile(file, chunkSize);
  return {
    originFile: file,
    slices,
    name: (file as File).name || "unnamed",
    size: file.size,
    totalChunks: slices.length,
  };
}

/**
 * 支持的文本文件 MIME 类型前缀
 */
export const TEXT_FILE_MIME_PREFIX = "text/";

/**
 * 支持的文本文件 MIME 类型集合
 */
export const TEXT_FILE_MIME_TYPES = new Set([
  "application/json",
  "application/xml",
  "application/csv",
  "application/ndjson",
  "application/x-ndjson",
  "application/x-yaml",
  "application/yaml",
  "application/javascript",
  "application/x-javascript",
  "application/sql",
  "application/rtf",
  "application/xhtml+xml",
  "application/svg+xml",
]);

/**
 * 支持的文本文件扩展名集合
 */
export const TEXT_FILE_EXTENSIONS = new Set([
  ".txt",
  ".md",
  ".markdown",
  ".csv",
  ".tsv",
  ".json",
  ".jsonl",
  ".ndjson",
  ".log",
  ".xml",
  ".yaml",
  ".yml",
  ".sql",
  ".js",
  ".ts",
  ".jsx",
  ".tsx",
  ".html",
  ".htm",
  ".css",
  ".scss",
  ".less",
  ".py",
  ".java",
  ".c",
  ".cpp",
  ".h",
  ".hpp",
  ".go",
  ".rs",
  ".rb",
  ".php",
  ".sh",
  ".bash",
  ".zsh",
  ".ps1",
  ".bat",
  ".cmd",
  ".svg",
  ".rtf",
]);

/**
 * 判断文件是否为文本文件（支持 UploadFile 类型）
 * @param file UploadFile 对象
 */
export function isTextUploadFile(file: UploadFile): boolean {
  const mimeType = (file.type || "").toLowerCase();
  if (mimeType) {
    if (mimeType.startsWith(TEXT_FILE_MIME_PREFIX)) return true;
    if (TEXT_FILE_MIME_TYPES.has(mimeType)) return true;
  }

  const fileName = file.name || "";
  const dotIndex = fileName.lastIndexOf(".");
  if (dotIndex < 0) return false;
  const ext = fileName.slice(dotIndex).toLowerCase();
  return TEXT_FILE_EXTENSIONS.has(ext);
}

/**
 * 判断文件名是否为文本文件
 * @param fileName 文件名
 */
export function isTextFileByName(fileName: string): boolean {
  const lowerName = fileName.toLowerCase();
  
  // 先检查 MIME 类型（如果有）
  // 这里简化处理，主要通过扩展名判断
  
  const dotIndex = lowerName.lastIndexOf(".");
  if (dotIndex < 0) return false;
  const ext = lowerName.slice(dotIndex);
  return TEXT_FILE_EXTENSIONS.has(ext);
}

/**
 * 获取文件扩展名
 * @param fileName 文件名
 */
export function getFileExtension(fileName: string): string {
  const dotIndex = fileName.lastIndexOf(".");
  if (dotIndex < 0) return "";
  return fileName.slice(dotIndex).toLowerCase();
}

/**
 * 安全地读取文件为文本
 * @param file 文件对象
 * @param encoding 编码，默认 UTF-8
 */
export function readFileAsText(
  file: File | Blob,
  encoding = "UTF-8"
): Promise<string> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = (e) => resolve(e.target?.result as string);
    reader.onerror = () => reject(new Error("Failed to read file"));
    reader.readAsText(file, encoding);
  });
}

/**
 * 流式分割文件并逐行上传
 * 使用 Blob.slice 逐块读取，避免一次性加载大文件到内存
 * @param file 文件对象
 * @param datasetId 数据集ID
 * @param uploadFn 上传函数，接收 FormData 和配置，返回 Promise
 * @param onProgress 进度回调 (currentBytes, totalBytes, uploadedLines)
 * @param chunkSize 每次读取的块大小，默认 1MB
 * @param options 其他选项
 * @returns 上传结果统计
 */
export interface StreamUploadOptions {
  reqId: number;
  fileNamePrefix?: string;
  hasArchive?: boolean;
  prefix?: string;
  signal?: AbortSignal;
  maxConcurrency?: number;
}

export interface StreamUploadResult {
  uploadedCount: number;
  totalBytes: number;
  skippedEmptyCount: number;
}

export async function streamSplitAndUpload(
  file: File,
  uploadFn: (formData: FormData, config?: { onUploadProgress?: (e: { loaded: number; total: number }) => void }) => Promise<unknown>,
  onProgress?: (currentBytes: number, totalBytes: number, uploadedLines: number) => void,
  chunkSize: number = 1024 * 1024, // 1MB
  options: StreamUploadOptions
): Promise<StreamUploadResult> {
  const { reqId, fileNamePrefix, prefix, signal, maxConcurrency = 3 } = options;
  
  const fileSize = file.size;
  let offset = 0;
  let buffer = "";
  let uploadedCount = 0;
  let skippedEmptyCount = 0;
  let currentBytes = 0;
  
  // 获取文件名基础部分
  const baseName = fileNamePrefix || file.name.replace(/\.[^/.]+$/, "");
  
  // 用于并发控制的队列
  const uploadQueue: Promise<void>[] = [];
  let uploadIndex = 0;

  /**
   * 上传单行内容
   */
  async function uploadLine(line: string, index: number): Promise<void> {
    if (!line.trim()) {
      skippedEmptyCount++;
      return;
    }

    const newFileName = `${baseName}_${String(index + 1).padStart(6, "0")}`;
    const blob = new Blob([line], { type: "text/plain" });
    const lineFile = new File([blob], newFileName, { type: "text/plain" });
    
    // 计算分片（小文件通常只需要一个分片）
    const slices = sliceFile(lineFile, DEFAULT_CHUNK_SIZE);
    const checkSum = await calculateSHA256(slices[0]);
    
    const formData = new FormData();
    formData.append("file", slices[0]);
    formData.append("reqId", reqId.toString());
    formData.append("fileNo", (index + 1).toString());
    formData.append("chunkNo", "1");
    formData.append("fileName", newFileName);
    formData.append("fileSize", lineFile.size.toString());
    formData.append("totalChunkNum", "1");
    formData.append("checkSumHex", checkSum);
    if (prefix !== undefined) {
      formData.append("prefix", prefix);
    }

    await uploadFn(formData, {
      onUploadProgress: () => {
        // 单行文件很小，进度主要用于追踪上传状态
      },
    });
  }

  /**
   * 处理并发上传
   */
  async function processUploadQueue(): Promise<void> {
    let currentIndex = 0;

    async function runNext(): Promise<void> {
      if (currentIndex >= uploadQueue.length) return;
      const task = uploadQueue[currentIndex++];
      await task;
      await runNext();
    }

    const workers = Array(Math.min(maxConcurrency, uploadQueue.length))
      .fill(null)
      .map(() => runNext());

    await Promise.all(workers);
  }

  // 逐块读取文件
  while (offset < fileSize) {
    // 检查是否已取消
    if (signal?.aborted) {
      throw new Error("Upload cancelled");
    }

    const end = Math.min(offset + chunkSize, fileSize);
    const chunk = file.slice(offset, end);
    const text = await readFileAsText(chunk);
    
    // 将新读取的内容追加到 buffer
    const combined = buffer + text;
    
    // 按换行符分割（支持 \n 和 \r\n）
    const lines = combined.split(/\r?\n/);
    
    // 保留最后一行（可能不完整）
    buffer = lines.pop() || "";
    
    // 将完整行加入上传队列
    for (const line of lines) {
      if (signal?.aborted) {
        throw new Error("Upload cancelled");
      }
      
      const currentLineIndex = uploadIndex++;
      uploadQueue.push(
        uploadLine(line, currentLineIndex).then(() => {
          uploadedCount++;
          onProgress?.(currentBytes, fileSize, uploadedCount);
        })
      );
    }
    
    currentBytes = end;
    offset = end;
    
    // 每处理完一个 chunk，更新进度
    onProgress?.(currentBytes, fileSize, uploadedCount);
  }

  // 处理最后剩余的 buffer（如果文件不以换行符结尾）
  if (buffer.trim()) {
    const currentLineIndex = uploadIndex++;
    uploadQueue.push(
      uploadLine(buffer, currentLineIndex).then(() => {
        uploadedCount++;
        onProgress?.(fileSize, fileSize, uploadedCount);
      })
    );
  }

  // 并发执行所有上传任务
  await processUploadQueue();

  return {
    uploadedCount,
    totalBytes: fileSize,
    skippedEmptyCount,
  };
}

/**
 * 判断文件是否需要流式分割上传
 * @param file 文件对象
 * @param threshold 阈值，默认 5MB
 */
export function shouldStreamUpload(file: File, threshold: number = 5 * 1024 * 1024): boolean {
  return file.size > threshold;
}