import { fabric } from "fabric-with-all";
import { findObjectById } from "../utils/helper";

/**
 * 图片导出管理器
 * 负责处理画布的图片导出功能，支持多种导出选项和图层过滤
 */
export class ExportManager {
  constructor(canvasManager, layerManager) {
    this.canvasManager = canvasManager;
    this.layerManager = layerManager;
    this.canvas = canvasManager.canvas;
  }

  /**
   * 导出图片
   * @param {Object} options 导出选项
   * @param {Boolean} options.isContainBg 是否包含背景图层
   * @param {Boolean} options.isContainFixed 是否包含固定图层
   * @param {String} options.layerId 导出具体图层ID
   * @param {Array} options.layerIdArray 导出多个图层ID数组
   * @param {String} options.expPicType 导出图片类型 (png/jpg/svg)
   * @param {Boolean} options.restoreOpacityInRedGreen 红绿图模式下是否恢复透明度为1
   * @returns {String} 导出的图片数据URL
   */
  exportImage(options = {}) {
    const {
      isContainBg = false,
      isContainFixed = false,
      layerId = "",
      layerIdArray = [],
      expPicType = "png",
      restoreOpacityInRedGreen = true,
    } = options;

    try {
      // 检查是否为红绿图模式
      const isRedGreenMode = this.layerManager?.isInRedGreenMode?.() || false;

      // 如果指定了具体图层ID，导出指定图层
      if (layerId) {
        return this._exportSpecificLayer(
          layerId,
          expPicType,
          isRedGreenMode,
          restoreOpacityInRedGreen
        );
      }

      // 如果指定了多个图层ID，导出多个图层
      if (layerIdArray && layerIdArray.length > 0) {
        return this._exportMultipleLayers(
          layerIdArray,
          expPicType,
          isContainBg,
          isContainFixed,
          isRedGreenMode,
          restoreOpacityInRedGreen
        );
      }

      // 默认导出所有可见图层
      return this._exportAllLayers(
        expPicType,
        isContainBg,
        isContainFixed,
        isRedGreenMode,
        restoreOpacityInRedGreen
      );
    } catch (error) {
      console.error("导出图片失败:", error);
      throw new Error(`图片导出失败: ${error.message}`);
    }
  }

  /**
   * 导出指定单个图层
   * @param {String} layerId 图层ID
   * @param {String} expPicType 导出类型
   * @param {Boolean} isRedGreenMode 是否为红绿图模式
   * @param {Boolean} restoreOpacityInRedGreen 红绿图模式下是否恢复透明度为1
   * @returns {String} 图片数据URL
   * @private
   */
  _exportSpecificLayer(
    layerId,
    expPicType,
    isRedGreenMode,
    restoreOpacityInRedGreen
  ) {
    if (!this.layerManager) {
      throw new Error("图层管理器未初始化");
    }

    const layer = this._getLayerById(layerId);
    if (!layer) {
      throw new Error(`未找到ID为 ${layerId} 的图层`);
    }

    if (!layer.visible) {
      console.warn(`图层 ${layer.name} 不可见，将导出空白图片`);
    }

    // 收集所有需要导出的对象
    const objectsToExport = this._collectObjectsFromLayer(layer);

    if (objectsToExport.length === 0) {
      console.warn(`图层 ${layer.name} 没有可导出的对象`);
      return this._generateEmptyImage(expPicType);
    }

    // 红绿图模式下使用固定尺寸和裁剪
    if (isRedGreenMode) {
      return this._exportWithRedGreenMode(
        objectsToExport,
        expPicType,
        restoreOpacityInRedGreen
      );
    }

    // 普通模式使用画布尺寸
    return this._exportWithCanvasSize(
      objectsToExport,
      expPicType,
      restoreOpacityInRedGreen
    );
  }

  /**
   * 导出多个指定图层
   * @param {Array} layerIdArray 图层ID数组
   * @param {String} expPicType 导出类型
   * @param {Boolean} isContainBg 是否包含背景图层
   * @param {Boolean} isContainFixed 是否包含固定图层
   * @param {Boolean} isRedGreenMode 是否为红绿图模式
   * @param {Boolean} restoreOpacityInRedGreen 红绿图模式下是否恢复透明度为1
   * @returns {String} 图片数据URL
   * @private
   */
  _exportMultipleLayers(
    layerIdArray,
    expPicType,
    isContainBg,
    isContainFixed,
    isRedGreenMode,
    restoreOpacityInRedGreen
  ) {
    if (!this.layerManager) {
      throw new Error("图层管理器未初始化");
    }

    // 按图层顺序收集对象（从底到顶）
    const objectsToExport = this._collectObjectsByLayerOrder(
      layerIdArray,
      isContainBg,
      isContainFixed
    );

    if (objectsToExport.length === 0) {
      console.warn("没有可导出的对象");
      return this._generateEmptyImage(expPicType);
    }

    // 红绿图模式下使用固定尺寸和裁剪
    if (isRedGreenMode) {
      return this._exportWithRedGreenMode(
        objectsToExport,
        expPicType,
        restoreOpacityInRedGreen
      );
    }

    // 普通模式使用画布尺寸
    return this._exportWithCanvasSize(
      objectsToExport,
      expPicType,
      restoreOpacityInRedGreen
    );
  }

  /**
   * 导出所有图层
   * @param {String} expPicType 导出类型
   * @param {Boolean} isContainBg 是否包含背景图层
   * @param {Boolean} isContainFixed 是否包含固定图层
   * @param {Boolean} isRedGreenMode 是否为红绿图模式
   * @param {Boolean} restoreOpacityInRedGreen 红绿图模式下是否恢复透明度为1
   * @returns {String} 图片数据URL
   * @private
   */
  _exportAllLayers(
    expPicType,
    isContainBg,
    isContainFixed,
    isRedGreenMode,
    restoreOpacityInRedGreen
  ) {
    // 按图层顺序收集对象（从底到顶）
    const objectsToExport = this._collectObjectsByLayerOrder(
      null, // 导出所有图层
      isContainBg,
      isContainFixed
    );

    if (objectsToExport.length === 0) {
      console.warn("没有可导出的对象");
      return this._generateEmptyImage(expPicType);
    }

    // 红绿图模式下使用固定尺寸和裁剪
    if (isRedGreenMode) {
      return this._exportWithRedGreenMode(
        objectsToExport,
        expPicType,
        restoreOpacityInRedGreen
      );
    }

    // 普通模式使用画布尺寸
    return this._exportWithCanvasSize(
      objectsToExport,
      expPicType,
      restoreOpacityInRedGreen
    );
  }

  /**
   * 从图层收集对象（优化版本 - 通过ID查找画布中的真实对象）
   * @param {Object} layer 图层对象
   * @returns {Array} 画布中的真实对象数组
   * @private
   */
  _collectObjectsFromLayer(layer) {
    if (!layer) {
      return [];
    }

    const realObjects = [];

    // 收集当前图层的对象
    if (layer.fabricObjects && layer.fabricObjects.length > 0) {
      for (const layerObj of layer.fabricObjects) {
        if (!layerObj || !layerObj.id) continue;

        // 通过ID在画布中查找真实对象
        const realObj = this._findRealObjectById(layerObj.id);
        if (realObj && realObj.visible !== false) {
          realObjects.push(realObj);
        }
      }
    }

    // 递归收集子图层的对象
    if (layer.children && layer.children.length > 0) {
      for (const childLayer of layer.children) {
        const childObjects = this._collectObjectsFromLayer(childLayer);
        realObjects.push(...childObjects);
      }
    }

    return realObjects;
  }

  /**
   * 通过ID在画布中查找真实对象
   * @param {String} objectId 对象ID
   * @returns {Object|null} 画布中的真实对象
   * @private
   */
  _findRealObjectById(objectId) {
    if (!objectId || !this.canvas) {
      return null;
    }

    try {
      // 使用helper工具查找对象
      const result = findObjectById(this.canvas, objectId);
      return result?.object || null;
    } catch (error) {
      console.warn(`查找对象 ${objectId} 失败:`, error);
      return null;
    }
  }

  /**
   * 导出对象
   * @param {Object} obj fabric对象
   * @param {String} expPicType 导出类型
   * @param {Boolean} isRedGreenMode 是否为红绿图模式
   * @param {Boolean} restoreOpacityInRedGreen 红绿图模式下是否恢复透明度为1
   * @returns {String} 图片数据URL
   * @private
   */
  async _exportObject(
    obj,
    expPicType,
    isRedGreenMode,
    restoreOpacityInRedGreen
  ) {
    // 红绿图模式下使用固定尺寸和裁剪
    if (isRedGreenMode) {
      return this._exportWithRedGreenMode(
        [obj],
        expPicType,
        restoreOpacityInRedGreen
      );
    }

    // 普通模式使用画布尺寸
    return this._exportWithCanvasSize(
      [obj],
      expPicType,
      restoreOpacityInRedGreen
    );
  }

  /**
   * 按图层顺序收集对象（优化版本 - 从底到顶）
   * @param {Array|null} layerIdArray 图层ID数组，null表示所有图层
   * @param {Boolean} isContainBg 是否包含背景图层
   * @param {Boolean} isContainFixed 是否包含固定图层
   * @returns {Array} 按正确顺序排列的真实对象数组
   * @private
   */
  _collectObjectsByLayerOrder(layerIdArray, isContainBg, isContainFixed) {
    const objectsToExport = [];
    const allLayers = this._getAllLayersFlattened(); // 获取扁平化的图层列表

    // 图层数组是从顶到底的顺序，需要反向遍历以获得从底到顶的渲染顺序
    for (let i = allLayers.length - 1; i >= 0; i--) {
      const layer = allLayers[i];

      // 如果指定了图层ID数组，只处理指定的图层
      if (layerIdArray && !layerIdArray.includes(layer.id)) continue;

      // 检查图层类型过滤条件
      if (!this._shouldIncludeLayer(layer, isContainBg, isContainFixed))
        continue;

      if (layer.visible) {
        const layerObjects = this._collectObjectsFromLayer(layer);
        objectsToExport.push(...layerObjects);
      }
    }

    return objectsToExport;
  }

  /**
   * 获取扁平化的图层列表（包含子图层）
   * @returns {Array} 扁平化的图层数组
   * @private
   */
  _getAllLayersFlattened() {
    const flattenedLayers = [];
    const rootLayers = this._getAllLayers();

    const flattenLayer = (layer) => {
      flattenedLayers.push(layer);

      // 递归处理子图层
      if (layer.children && layer.children.length > 0) {
        for (const childLayer of layer.children) {
          flattenLayer(childLayer);
        }
      }
    };

    // 处理所有根图层
    for (const layer of rootLayers) {
      flattenLayer(layer);
    }

    return flattenedLayers;
  }

  /**
   * 计算对象组的边界
   * @param {Array} objects 对象数组
   * @returns {Object} 边界信息 {left, top, width, height}
   * @private
   */
  _calculateGroupBounds(objects) {
    if (!objects || objects.length === 0) {
      return { left: 0, top: 0, width: 1, height: 1 };
    }

    let minX = Infinity;
    let minY = Infinity;
    let maxX = -Infinity;
    let maxY = -Infinity;

    objects.forEach((obj) => {
      if (!obj || typeof obj.getBoundingRect !== "function") {
        return;
      }

      const bounds = obj.getBoundingRect();
      minX = Math.min(minX, bounds.left);
      minY = Math.min(minY, bounds.top);
      maxX = Math.max(maxX, bounds.left + bounds.width);
      maxY = Math.max(maxY, bounds.top + bounds.height);
    });

    if (minX === Infinity || minY === Infinity) {
      return { left: 0, top: 0, width: 1, height: 1 };
    }

    // 添加小量边距避免边缘裁切
    const padding = 2;
    return {
      left: minX - padding,
      top: minY - padding,
      width: maxX - minX + padding * 2,
      height: maxY - minY + padding * 2,
    };
  }

  /**
   * 克隆对象并添加到临时画布，调整位置偏移
   * @param {fabric.Canvas} tempCanvas 临时画布
   * @param {Object} obj 要克隆的对象
   * @param {Object} bounds 边界信息
   * @param {Boolean} isRedGreenMode 是否为红绿图模式
   * @param {Boolean} restoreOpacityInRedGreen 是否恢复透明度
   * @returns {Promise<Object>} 克隆的对象
   * @private
   */
  async _cloneAndAddObjectWithOffset(
    tempCanvas,
    obj,
    bounds,
    isRedGreenMode,
    restoreOpacityInRedGreen
  ) {
    try {
      const cloned = await this._cloneObjectForExport(
        obj,
        isRedGreenMode && restoreOpacityInRedGreen
      );

      if (cloned) {
        // 获取对象当前边界
        const objBounds = obj.getBoundingRect();

        // 计算相对于组边界的偏移
        const offsetX = objBounds.left - bounds.left;
        const offsetY = objBounds.top - bounds.top;

        // 设置新位置（相对于临时画布的原点）
        cloned.set({
          left: offsetX + objBounds.width / 2,
          top: offsetY + objBounds.height / 2,
          originX: "center",
          originY: "center",
        });

        cloned.setCoords();
        tempCanvas.add(cloned);
        return cloned;
      }
    } catch (error) {
      console.warn(`克隆对象失败: ${obj?.id || "未知"}`, error);
    }

    return null;
  }

  /**
   * 红绿图模式导出（使用固定图层底图作为画布尺寸和裁剪区域）
   * @param {Array} objectsToExport 要导出的对象数组
   * @param {String} expPicType 导出类型
   * @param {Boolean} restoreOpacityInRedGreen 是否恢复透明度为1
   * @returns {String} 图片数据URL
   * @private
   */
  async _exportWithRedGreenMode(
    objectsToExport,
    expPicType,
    restoreOpacityInRedGreen
  ) {
    // 获取固定图层对象（衣服底图）作为参考
    const fixedLayerObject =
      this._getFixedLayerObject() ?? this.canvas.clipPath;
    if (!fixedLayerObject) {
      console.warn("红绿图模式下未找到固定图层对象，使用画布尺寸");
      return this._exportWithCanvasSize(
        objectsToExport,
        expPicType,
        restoreOpacityInRedGreen
      );
    }

    // 获取固定图层对象的边界矩形（包含位置、尺寸、缩放等信息）
    const fixedBounds = fixedLayerObject?.getBoundingRect?.();

    // 使用固定图层的实际显示尺寸作为导出画布尺寸
    const canvasWidth = Math.round(fixedBounds.width);
    const canvasHeight = Math.round(fixedBounds.height);

    console.log(`红绿图模式导出，画布尺寸: ${canvasWidth}x${canvasHeight}`);
    console.log("固定图层边界:", fixedBounds);

    // 创建固定尺寸的临时画布
    const scaleFactor = 2; // 高清导出
    const tempCanvas = document.createElement("canvas");
    tempCanvas.width = canvasWidth * scaleFactor;
    tempCanvas.height = canvasHeight * scaleFactor;
    tempCanvas.style.width = canvasWidth + "px";
    tempCanvas.style.height = canvasHeight + "px";

    const tempFabricCanvas = new fabric.StaticCanvas(tempCanvas, {
      width: canvasWidth,
      height: canvasHeight,
      backgroundColor: null,
      enableRetinaScaling: true,
      imageSmoothingEnabled: true,
    });
    tempFabricCanvas.setZoom(1);

    try {
      // 获取裁剪路径对象（如果存在）
      const clipPathObject = await this._getClipPathObject(fixedBounds);

      // 克隆并添加所有对象到临时画布，需要调整位置相对于固定图层
      for (let i = 0; i < objectsToExport.length; i++) {
        const obj = objectsToExport[i];
        const cloned = await this._cloneObjectForExport(
          obj,
          restoreOpacityInRedGreen && true
        );
        if (cloned) {
          // 调整对象位置：将原画布坐标转换为以固定图层为原点的相对坐标
          cloned.set({
            left: cloned.left - fixedBounds.left,
            top: cloned.top - fixedBounds.top,
          });

          // 更新对象坐标
          cloned.setCoords();

          // 设置裁剪路径到对象
          if (clipPathObject) {
            cloned.clipPath = clipPathObject;
          }

          tempFabricCanvas.add(cloned);
        }
      }

      // 渲染画布
      tempFabricCanvas.renderAll();

      // 生成图片
      return this._generateHighQualityDataURL(tempCanvas, expPicType);
    } finally {
      this._cleanupTempCanvas(tempFabricCanvas);
    }
  }

  /**
   * 普通模式导出（使用画布尺寸）
   * @param {Array} objectsToExport 要导出的对象数组
   * @param {String} expPicType 导出类型
   * @param {Boolean} restoreOpacityInRedGreen 是否恢复透明度为1
   * @returns {String} 图片数据URL
   * @private
   */
  async _exportWithCanvasSize(
    objectsToExport,
    expPicType,
    restoreOpacityInRedGreen
  ) {
    // 使用当前画布尺寸
    const canvasWidth = this.canvas.width;
    const canvasHeight = this.canvas.height;

    console.log(`普通模式导出，画布尺寸: ${canvasWidth}x${canvasHeight}`);

    // 创建与画布相同尺寸的临时画布
    const scaleFactor = 2; // 高清导出
    const tempCanvas = document.createElement("canvas");
    tempCanvas.width = canvasWidth * scaleFactor;
    tempCanvas.height = canvasHeight * scaleFactor;
    tempCanvas.style.width = canvasWidth + "px";
    tempCanvas.style.height = canvasHeight + "px";

    const tempFabricCanvas = new fabric.StaticCanvas(tempCanvas, {
      width: canvasWidth,
      height: canvasHeight,
      backgroundColor: null,
    });

    tempFabricCanvas.enableRetinaScaling = true;
    tempFabricCanvas.imageSmoothingEnabled = true;
    tempFabricCanvas.setZoom(scaleFactor);

    try {
      // 克隆并添加所有对象到临时画布
      for (const obj of objectsToExport) {
        const cloned = await this._cloneObjectForExport(
          obj,
          restoreOpacityInRedGreen && false // 普通模式不强制恢复透明度
        );
        if (cloned) {
          tempFabricCanvas.add(cloned);
        }
      }

      // 渲染画布
      tempFabricCanvas.renderAll();

      // 生成图片
      return this._generateHighQualityDataURL(tempCanvas, expPicType);
    } finally {
      this._cleanupTempCanvas(tempFabricCanvas);
    }
  }

  /**
   * 获取固定图层对象
   * @returns {Object|null} 固定图层对象
   * @private
   */
  _getFixedLayerObject() {
    const allLayers = this._getAllLayers();
    const fixedLayer = allLayers.find((layer) => layer.isFixed);

    if (!fixedLayer || !fixedLayer.fabricObject) {
      return null;
    }

    // 如果有ID，通过ID查找画布中的实际对象
    if (fixedLayer.fabricObject.id) {
      const result = findObjectById(this.canvas, fixedLayer.fabricObject.id);
      return result.object || fixedLayer.fabricObject;
    }

    return fixedLayer.fabricObject;
  }

  /**
   * 异步克隆fabric对象（参照createRasterizedImage的方法）
   * @param {fabric.Object} obj 要克隆的对象
   * @param {Array} propertiesToInclude 要包含的属性
   * @returns {Promise<fabric.Object>} 克隆的对象
   * @private
   */
  _cloneObjectAsync(
    obj,
    propertiesToInclude = ["id", "layerId", "layerName", "name"]
  ) {
    return new Promise((resolve, reject) => {
      if (!obj) {
        resolve(null);
        return;
      }

      try {
        obj.clone((cloned) => {
          if (cloned) {
            resolve(cloned);
          } else {
            reject(new Error("对象克隆失败"));
          }
        }, propertiesToInclude);
      } catch (error) {
        console.warn("克隆对象失败:", error);
        resolve(null);
      }
    });
  }

  /**
   * 克隆对象用于导出（优化版本）
   * @param {Object} obj fabric对象
   * @param {Boolean} forceRestoreOpacity 是否强制恢复透明度为1
   * @param {Boolean} removeClipPath 是否移除裁剪路径
   * @returns {Promise<Object>} 克隆的对象
   * @private
   */
  async _cloneObjectForExport(
    obj,
    forceRestoreOpacity = false,
    removeClipPath = true
  ) {
    if (!obj) return null;

    try {
      // 使用异步克隆方法
      const cloned = await this._cloneObjectAsync(obj);

      if (cloned) {
        // 保持原始位置和属性
        cloned.set({
          selectable: false,
          evented: false,
          visible: true,
        });

        // 如果需要恢复透明度
        if (forceRestoreOpacity) {
          cloned.set({ opacity: 1 });
        }

        // 移除裁剪路径以避免绝对路径问题
        if (removeClipPath && cloned.clipPath) {
          console.log(`移除对象 ${cloned.id || "未知"} 的裁剪路径`);
          cloned.clipPath = null;
        }

        return cloned;
      }
    } catch (error) {
      console.warn("克隆对象失败:", error);
    }

    return null;
  }

  /**
   * 导出对象组
   * @param {Array} objectsToExport 要导出的对象数组
   * @param {String} expPicType 导出类型
   * @param {Boolean} isRedGreenMode 是否为红绿图模式
   * @param {Boolean} restoreOpacityInRedGreen 红绿图模式下是否恢复透明度为1
   * @returns {Promise<String>} 图片数据URL
   * @private
   */
  async _exportObjectsAsGroup(
    objectsToExport,
    expPicType,
    isRedGreenMode = false,
    restoreOpacityInRedGreen = true
  ) {
    if (!objectsToExport || objectsToExport.length === 0) {
      throw new Error("没有可导出的对象");
    }

    // 计算所有对象的边界
    const bounds = this._calculateGroupBounds(objectsToExport);
    console.log("导出边界:", bounds);

    // 创建高质量临时画布
    const scaleFactor = 2; // 高清导出
    const tempCanvas = document.createElement("canvas");
    tempCanvas.width = bounds.width * scaleFactor;
    tempCanvas.height = bounds.height * scaleFactor;
    tempCanvas.style.width = bounds.width + "px";
    tempCanvas.style.height = bounds.height + "px";

    const tempFabricCanvas = new fabric.StaticCanvas(tempCanvas, {
      width: bounds.width,
      height: bounds.height,
      backgroundColor: null, // 透明背景
    });

    // 启用高清缩放和图像平滑
    tempFabricCanvas.enableRetinaScaling = true;
    tempFabricCanvas.imageSmoothingEnabled = true;
    tempFabricCanvas.setZoom(scaleFactor);

    try {
      // 克隆所有对象并添加到临时画布
      const clonedObjects = [];
      for (const obj of objectsToExport) {
        const cloned = await this._cloneAndAddObjectWithOffset(
          tempFabricCanvas,
          obj,
          bounds,
          isRedGreenMode,
          restoreOpacityInRedGreen
        );
        if (cloned) {
          clonedObjects.push(cloned);
        }
      }

      console.log(`成功克隆 ${clonedObjects.length} 个对象进行导出`);

      // 渲染画布
      tempFabricCanvas.renderAll();

      // 生成高质量数据URL
      return this._generateHighQualityDataURL(tempCanvas, expPicType);
    } finally {
      this._cleanupTempCanvas(tempFabricCanvas);
    }
  }

  /**
   * 获取裁剪路径对象（优化版本）
   * @param {Object} fixedBounds 固定图层边界
   * @returns {Promise<Object|null>} 裁剪路径对象
   * @private
   */
  async _getClipPathObject(fixedBounds) {
    try {
      // const allLayers = this._getAllLayers();

      // // 查找第一个有裁剪遮罩的图层
      // let clipObject = null;

      // for (const layer of allLayers) {
      //   if (layer.clippingMask?.id) {
      //     const result = findObjectById(this.canvas, layer.clippingMask.id);
      //     if (result?.object) {
      //       clipObject = result.object;
      //       break;
      //     }
      //   }
      // }
      const clipObject = this.canvas?.clipPath;
      if (!clipObject) {
        console.warn("未找到可用的裁剪对象");
        return null;
      }

      // 克隆对象作为裁剪路径
      const clonedClipPath = await this._cloneObjectForExport(
        clipObject,
        false,
        false
      );

      if (!clonedClipPath) {
        console.warn("无法克隆裁剪对象");
        return null;
      }

      // 调整裁剪路径的位置相对于固定图层
      clonedClipPath.set({
        left: clonedClipPath.left - fixedBounds.left,
        top: clonedClipPath.top - fixedBounds.top,
        absolutePositioned: true, // 使用绝对定位
      });

      // 更新坐标
      clonedClipPath.setCoords();

      console.log("成功创建裁剪路径:", {
        objectType: clonedClipPath.type,
        position: { left: clonedClipPath.left, top: clonedClipPath.top },
        size: { width: clonedClipPath.width, height: clonedClipPath.height },
      });

      return clonedClipPath;
    } catch (error) {
      console.error("获取裁剪路径失败:", error);
      return null;
    }
  }

  /**
   * 生成高质量数据URL
   * @param {HTMLCanvasElement} canvas 画布元素
   * @param {String} expPicType 导出类型
   * @returns {String} 数据URL
   * @private
   */
  _generateHighQualityDataURL(canvas, expPicType) {
    const format = expPicType.toLowerCase();

    switch (format) {
      case "jpg":
      case "jpeg":
        // 对于JPEG，使用较高质量，但JPEG不支持透明背景
        return canvas.toDataURL("image/jpeg", 0.95);
      case "svg":
        // SVG导出需要特殊处理，这里先返回高质量PNG
        console.warn("SVG导出暂未实现，返回高质量PNG格式");
        return canvas.toDataURL("image/png", 1.0);
      case "png":
      default:
        // PNG使用最高质量，支持透明背景
        return canvas.toDataURL("image/png", 1.0);
    }
  }

  /**
   * 生成空白图片
   * @param {String} expPicType 导出类型
   * @returns {String} 空白图片数据URL
   * @private
   */
  _generateEmptyImage(expPicType) {
    const emptyCanvas = document.createElement("canvas");
    emptyCanvas.width = 1;
    emptyCanvas.height = 1;

    // 确保透明背景
    const ctx = emptyCanvas.getContext("2d");
    ctx.clearRect(0, 0, 1, 1);

    return this._generateHighQualityDataURL(emptyCanvas, expPicType);
  }

  /**
   * 清理临时画布资源
   * @param {fabric.StaticCanvas} tempFabricCanvas 临时Fabric画布
   * @private
   */
  _cleanupTempCanvas(tempFabricCanvas) {
    if (tempFabricCanvas) {
      try {
        tempFabricCanvas.dispose();
      } catch (error) {
        console.warn("清理临时画布失败:", error);
      }
    }
  }

  /**
   * 获取所有图层
   * @returns {Array} 图层数组
   * @private
   */
  _getAllLayers() {
    if (this.layerManager && this.layerManager.layers) {
      return this.layerManager.layers.value || [];
    }
    return [];
  }

  /**
   * 根据ID获取图层
   * @param {String} layerId 图层ID
   * @returns {Object|null} 图层对象
   * @private
   */
  _getLayerById(layerId) {
    if (this.layerManager && this.layerManager.getLayerById) {
      return this.layerManager.getLayerById(layerId);
    }

    // 备用方法：直接从图层数组中查找
    const allLayers = this._getAllLayers();
    return allLayers.find((layer) => layer.id === layerId) || null;
  }

  /**
   * 检查图层是否应该包含在导出中
   * @param {Object} layer 图层对象
   * @param {Boolean} isContainBg 是否包含背景图层
   * @param {Boolean} isContainFixed 是否包含固定图层
   * @returns {Boolean} 是否应该包含
   * @private
   */
  _shouldIncludeLayer(layer, isContainBg, isContainFixed) {
    if (!layer) return false;

    // 检查背景图层
    if (layer.isBackground) {
      return isContainBg;
    }

    // 检查固定图层
    if (layer.isFixed) {
      return isContainFixed;
    }

    // 普通图层总是包含
    return true;
  }
}