workspace/code/file-preview/g3-file/common.js

var G3FileUtils = {
  /**
   * 格式化文件大小
   * @param {number} bytes - 文件大小（字节）
   * @returns {string} 格式化后的大小
   */
  formatFileSize: function (bytes) {
    var numBytes = typeof bytes === "string" ? parseFloat(bytes) : bytes;
    if (
      numBytes === null ||
      numBytes === undefined ||
      isNaN(numBytes) ||
      numBytes <= 0
    ) {
      return "-";
    }

    var k = 1024;
    var sizes = ["B", "KB", "MB", "GB", "TB"];

    var i = Math.floor(Math.log(numBytes) / Math.log(k));
    i = Math.max(0, Math.min(i, sizes.length - 1));

    return (numBytes / Math.pow(k, i)).toFixed(2) + " " + sizes[i];
  },

  /**
   * 格式化日期
   * @param {string} dateStr - 日期字符串
   * @returns {string} 格式化后的日期
   */
  formatDate: function (dateStr) {
    if (!dateStr) return "-";

    var date = new Date(dateStr);

    if (isNaN(date.getTime())) {
      return "-";
    }

    var year = date.getFullYear();
    var month = ("0" + (date.getMonth() + 1)).slice(-2);
    var day = ("0" + date.getDate()).slice(-2);
    var hours = ("0" + date.getHours()).slice(-2);
    var minutes = ("0" + date.getMinutes()).slice(-2);
    var seconds = ("0" + date.getSeconds()).slice(-2);

    return (
      year +
      "-" +
      month +
      "-" +
      day +
      " " +
      hours +
      ":" +
      minutes +
      ":" +
      seconds
    );
  },

  /**
   * 判断是否为图片文件
   * @param {string} filename - 文件名
   * @returns {boolean} 是否为图片文件
   */
  isImageFile: function (filename) {
    if (!filename || typeof filename !== "string") return false;

    const ext = filename.slice(filename.lastIndexOf(".") + 1).toLowerCase();
    const imageExts = new Set(["jpg", "jpeg", "png", "gif", "bmp", "webp"]);

    return imageExts.has(ext);
  },

  /**
   * 获取文件图标
   * @param {string} filename - 文件名
   * @returns {string} 图标HTML
   */
  getFileIcon: function (filename) {
    var ext = filename.split(".").pop().toLowerCase();

    if (this.isImageFile(filename)) {
      return "";
    }

    // 根据不同的文件类型显示不同的图标
    const audioTypes = ["mp3", "wav", "aac", "flac", "ogg"];
    if (audioTypes.includes(ext)) {
      return G3FileIcons.file.audio;
    }

    // 视频类型
    const videoTypes = ["mp4", "avi", "mkv", "mov", "wmv"];
    if (videoTypes.includes(ext)) {
      return G3FileIcons.file.video;
    }

    if (ext === "txt") {
      return G3FileIcons.file.txt;
    }

    if (ext === "pdf") {
      return G3FileIcons.file.pdf;
    }

    // 文档类型
    const documentTypes = ["docx", "xlsx", "pptx", "office"];
    if (documentTypes.includes(ext)) {
      return G3FileIcons.file.docs;
    }

    // 压缩包类型
    const archiveTypes = ["zip", "rar", "tar", "gz"];
    if (archiveTypes.includes(ext)) {
      return G3FileIcons.file.zip;
    }

    return G3FileIcons.file.default;
  },

  /**
   * 获取唯一文件名
   * @param {string} fileName - 原始文件名
   * @param {Set} files - 已存在的文件名集合
   * @returns {string} 唯一文件名
   */
  getUniqueFileName: function (fileName, files) {
    const originalFileName = fileName;
    let uniqueFileName = fileName;
    let counter = 1;

    while (files.has(uniqueFileName)) {
      const fileNameWithoutExtension = originalFileName.replace(
        /\.[^/.]+$/,
        "",
      );
      const extension = originalFileName.slice(
        originalFileName.lastIndexOf("."),
      );
      uniqueFileName = `${fileNameWithoutExtension} (${counter})${extension}`;
      counter++;
    }

    return uniqueFileName;
  },

  /**
   * 压缩图片
   * @param {File} file - 图片文件
   * @param {Object} options - 压缩选项
   * @returns {Promise<File|Blob>} 压缩后的文件
   */
  compressImage: async function (file, options = {}) {
    const {
      minSize = 300 * 1024,
      maxSize = 1.2 * 1024 * 1024,
      maxWidth = 1920,
      maxHeight = 1920,
    } = options;

    if (!file || !file.type.startsWith("image/")) return file;

    const originSize = file.size;

    if (originSize <= maxSize) {
      return file;
    }

    const img = await new Promise((resolve, reject) => {
      const reader = new FileReader();
      reader.onload = () => {
        const image = new Image();
        image.onload = () => resolve(image);
        image.onerror = reject;
        image.src = reader.result;
      };
      reader.onerror = reject;
      reader.readAsDataURL(file);
    });

    const canvas = document.createElement("canvas");
    const ctx = canvas.getContext("2d");

    let w = img.width;
    let h = img.height;

    const scale = Math.min(1, maxWidth / w, maxHeight / h);
    w = Math.round(w * scale);
    h = Math.round(h * scale);

    canvas.width = w;
    canvas.height = h;
    ctx.drawImage(img, 0, 0, w, h);

    const getBlob = (q) =>
      new Promise((resolve) => {
        canvas.toBlob((b) => resolve(b), "image/jpeg", q);
      });

    let quality = 0.92;

    if (originSize > 4 * 1024 * 1024) {
      quality = 0.88;
    }

    const blob = await getBlob(quality);

    if (blob && blob.size < minSize) {
      const safe = await getBlob(0.97);
      return safe || file;
    }

    return blob || file;
  },

  /**
   * 生成唯一ID
   * @returns {string} 唯一ID
   */
  generateUniqueId: function () {
    return "file_" + Math.random().toString(36).slice(2) + Date.now();
  },

  /**
   * Base64 编码
   * @param {string} str - 字符串
   * @returns {string} Base64 编码结果
   */
  base64Encode: function (str) {
    return btoa(
      encodeURIComponent(str).replace(/%([0-9A-F]{2})/g, function (match, p1) {
        return String.fromCharCode("0x" + p1);
      }),
    );
  },
};