fix(planting-service): 签名后查看合同返回已签名的PDF

- 修改 /tasks/:orderNo/pdf 接口，检查任务状态
- 如果已签名且有 signedPdfUrl，从 MinIO 下载已签名的 PDF
- 添加 downloadSignedPdf 方法到 MinioStorageService
- 在 ContractSigningTaskDto 中添加 signedPdfUrl 字段

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/planting-service/src/api/controllers/contract-signing.controller.ts

@@ -428,18 +428,23 @@ export class ContractSigningController {
         throw new Error('签署任务不存在');
       }
 
-      // 格式化签署日期
-      const signingDate = new Date().toISOString().split('T')[0];
+      let pdfBuffer: Buffer;
 
-      // 生成 PDF（使用 pdf-lib 直接操作 PDF 模板）
-      const pdfBuffer = await this.pdfGeneratorService.generateContractPdf({
-        contractNo: task.contractNo,
-        userRealName: task.userRealName || '未认证',
-        userIdCard: task.userIdCardNumber || '',
-        userPhone: task.userPhoneNumber || '',
-        treeCount: task.treeCount,
-        signingDate,
-      });
+      // 如果已签名且有签名PDF URL，从MinIO下载已签名的PDF
+      if (task.status === 'SIGNED' && task.signedPdfUrl) {
+        this.logger.log(`Downloading signed PDF from MinIO for order ${orderNo}`);
+        try {
+          pdfBuffer = await this.minioStorageService.downloadSignedPdf(task.signedPdfUrl);
+          this.logger.log(`Signed PDF downloaded: ${pdfBuffer.length} bytes`);
+        } catch (downloadError) {
+          this.logger.warn(`Failed to download signed PDF, regenerating: ${downloadError.message}`);
+          // 下载失败时回退到重新生成
+          pdfBuffer = await this.regeneratePreviewPdf(task);
+        }
+      } else {
+        // 未签名，生成预览PDF
+        pdfBuffer = await this.regeneratePreviewPdf(task);
+      }
 
       // 设置响应头
       res.set({
@@ -450,8 +455,29 @@ export class ContractSigningController {
 
       return new StreamableFile(pdfBuffer);
     } catch (error) {
-      this.logger.error(`Failed to generate PDF for order ${orderNo}:`, error);
+      this.logger.error(`Failed to get PDF for order ${orderNo}:`, error);
       throw error;
     }
   }
+
+  /**
+   * 生成预览PDF（不含签名）
+   */
+  private async regeneratePreviewPdf(task: {
+    contractNo: string;
+    userRealName?: string;
+    userIdCardNumber?: string;
+    userPhoneNumber?: string;
+    treeCount: number;
+  }): Promise<Buffer> {
+    const signingDate = new Date().toISOString().split('T')[0];
+    return this.pdfGeneratorService.generateContractPdf({
+      contractNo: task.contractNo,
+      userRealName: task.userRealName || '未认证',
+      userIdCard: task.userIdCardNumber || '',
+      userPhone: task.userPhoneNumber || '',
+      treeCount: task.treeCount,
+      signingDate,
+    });
+  }
 }

backend/services/planting-service/src/application/services/contract-signing.service.ts

@@ -56,6 +56,7 @@ export interface ContractSigningTaskDto {
   scrolledToBottomAt?: Date;
   acknowledgedAt?: Date;
   signedAt?: Date;
+  signedPdfUrl?: string;
 }
 
 /**
@@ -466,6 +467,7 @@ export class ContractSigningService {
       scrolledToBottomAt: task.scrolledToBottomAt,
       acknowledgedAt: task.acknowledgedAt,
       signedAt: task.signedAt,
+      signedPdfUrl: task.signedPdfUrl,
     };
   }
 }

backend/services/planting-service/src/infrastructure/storage/minio-storage.service.ts

@@ -137,6 +137,45 @@ export class MinioStorageService implements OnModuleInit {
     }
   }
 
+  /**
+   * 下载已签署的合同 PDF
+   * @param signedPdfUrl PDF 文件的公开 URL
+   * @returns PDF 文件 Buffer
+   */
+  async downloadSignedPdf(signedPdfUrl: string): Promise<Buffer> {
+    try {
+      // 从 URL 中提取对象名称
+      const objectName = this.extractObjectName(signedPdfUrl);
+
+      const dataStream = await this.minioClient.getObject(this.bucketName, objectName);
+
+      // 将流转换为 Buffer
+      const chunks: Buffer[] = [];
+      for await (const chunk of dataStream) {
+        chunks.push(Buffer.from(chunk));
+      }
+
+      const buffer = Buffer.concat(chunks);
+      this.logger.log(`Downloaded signed PDF: ${objectName}, size: ${buffer.length} bytes`);
+      return buffer;
+    } catch (error) {
+      this.logger.error(`Failed to download signed PDF from ${signedPdfUrl}: ${error.message}`);
+      throw new Error(`已签署合同下载失败: ${error.message}`);
+    }
+  }
+
+  /**
+   * 从 URL 中提取对象名称
+   */
+  private extractObjectName(objectUrl: string): string {
+    // URL 格式: https://minio.xxx.com/contracts/contracts/orderNo/signed-contract-xxx.pdf
+    // 需要提取: contracts/orderNo/signed-contract-xxx.pdf
+    const url = new URL(objectUrl);
+    const pathParts = url.pathname.split('/').filter(Boolean);
+    // 第一个是桶名，后面的是对象路径
+    return pathParts.slice(1).join('/');
+  }
+
   /**
    * 删除文件
    * @param objectUrl 文件的公开 URL