fix(planting-service): 修复合同签名无法放到指定位置的问题

- 修改 generateSignedContractPdf 在同一个 PDFDocument 实例上完成填充和签名
- 移除 fillFormFields 中的 form.flatten()，保留签名字段供后续使用
- 最后统一扁平化所有表单字段，确保签名放到正确位置
- 控制器改用 generateSignedContractPdf 替代分两步调用

🤖 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

@@ -248,21 +248,19 @@ export class ContractSigningController {
         signatureCloudUrl = `data:image/png;base64,${dto.signatureBase64.slice(0, 100)}...`;
       }
 
-      // 5. 生成带签名的 PDF
+      // 5. 生成带签名的 PDF（在同一个实例上完成填充和签名）
       const signingDate = new Date().toISOString().split('T')[0];
-      let pdfBuffer = await this.pdfGeneratorService.generateContractPdf({
+      const pdfBuffer = await this.pdfGeneratorService.generateSignedContractPdf(
-        contractNo: task.contractNo,
+        {
-        userRealName: task.userRealName || '未认证',
+          contractNo: task.contractNo,
-        userIdCard: task.userIdCardNumber || '',
+          userRealName: task.userRealName || '未认证',
-        userPhone: task.userPhoneNumber || '',
+          userIdCard: task.userIdCardNumber || '',
-        treeCount: task.treeCount,
+          userPhone: task.userPhoneNumber || '',
-        signingDate,
+          treeCount: task.treeCount,
-      });
+          signingDate,
-
+        },
-      // 6. 嵌入签名到 PDF
+        { signatureImagePng: signatureBuffer },
-      pdfBuffer = await this.pdfGeneratorService.embedSignature(pdfBuffer, {
+      );
-        signatureImagePng: signatureBuffer,
-      });
       this.logger.log(`Signed PDF generated: ${pdfBuffer.length} bytes`);
 
       // 7. 上传签署后的 PDF 到 MinIO
@@ -338,21 +336,19 @@ export class ContractSigningController {
         signatureCloudUrl = `data:image/png;base64,${dto.signatureBase64.slice(0, 100)}...`;
       }
 
-      // 5. 生成带签名的 PDF
+      // 5. 生成带签名的 PDF（在同一个实例上完成填充和签名）
       const signingDate = new Date().toISOString().split('T')[0];
-      let pdfBuffer = await this.pdfGeneratorService.generateContractPdf({
+      const pdfBuffer = await this.pdfGeneratorService.generateSignedContractPdf(
-        contractNo: task.contractNo,
+        {
-        userRealName: task.userRealName || '未认证',
+          contractNo: task.contractNo,
-        userIdCard: task.userIdCardNumber || '',
+          userRealName: task.userRealName || '未认证',
-        userPhone: task.userPhoneNumber || '',
+          userIdCard: task.userIdCardNumber || '',
-        treeCount: task.treeCount,
+          userPhone: task.userPhoneNumber || '',
-        signingDate,
+          treeCount: task.treeCount,
-      });
+          signingDate,
-
+        },
-      // 6. 嵌入签名到 PDF
+        { signatureImagePng: signatureBuffer },
-      pdfBuffer = await this.pdfGeneratorService.embedSignature(pdfBuffer, {
+      );
-        signatureImagePng: signatureBuffer,
-      });
       this.logger.log(`Signed PDF generated: ${pdfBuffer.length} bytes`);
 
       // 7. 上传签署后的 PDF 到 MinIO

backend/services/planting-service/src/infrastructure/pdf/pdf-generator.service.ts

@@ -104,6 +104,9 @@ export class PdfGeneratorService {
       if (this.hasFormFields(pdfDoc)) {
         this.logger.log('Using form fields mode');
         await this.fillFormFields(pdfDoc, data, customFont);
+        // 预览PDF时扁平化所有字段（包括签名字段）
+        const form = pdfDoc.getForm();
+        form.flatten();
       } else {
         this.logger.log('Using coordinate mode (no form fields found)');
         this.fillByCoordinates(pdfDoc, data, customFont);
@@ -157,8 +160,8 @@ export class PdfGeneratorService {
       }
     }
 
-    // 扁平化表单（将字段转换为静态文本，不可再编辑）
+    // 注意：不在这里调用 form.flatten()
-    form.flatten();
+    // 签名字段需要保留，待签名嵌入后再统一扁平化
   }
 
   /**
@@ -339,6 +342,7 @@ export class PdfGeneratorService {
 
   /**
    * 生成带签名的完整合同 PDF
+   * 在同一个 PDFDocument 实例上完成填充和签名，最后统一扁平化
    * @param data 合同数据
    * @param signature 签名数据（可选，如果没有签名则只生成填充数据的 PDF）
    * @returns PDF Buffer
@@ -347,15 +351,63 @@ export class PdfGeneratorService {
     data: ContractPdfData,
     signature?: SignatureData,
   ): Promise<Buffer> {
-    // 先生成填充数据的 PDF
+    this.logger.log(`Generating signed PDF for contract: ${data.contractNo}`);
-    let pdfBuffer = await this.generateContractPdf(data);
 
-    // 如果有签名，嵌入签名
+    try {
-    if (signature) {
+      // 1. 加载 PDF 模板
-      pdfBuffer = await this.embedSignature(pdfBuffer, signature);
+      const templateBytes = fs.readFileSync(this.templatePath);
+      const pdfDoc = await PDFDocument.load(templateBytes);
+
+      // 2. 注册 fontkit 以支持自定义字体
+      pdfDoc.registerFontkit(fontkit);
+
+      // 3. 加载中文字体
+      const fontBytes = fs.readFileSync(this.fontPath);
+      const customFont = await pdfDoc.embedFont(fontBytes);
+
+      // 4. 填充表单字段（不扁平化）
+      if (this.hasFormFields(pdfDoc)) {
+        this.logger.log('Using form fields mode');
+        await this.fillFormFields(pdfDoc, data, customFont);
+      } else {
+        this.logger.log('Using coordinate mode (no form fields found)');
+        this.fillByCoordinates(pdfDoc, data, customFont);
+      }
+
+      // 5. 如果有签名，嵌入签名图片到 signature 按钮字段
+      if (signature) {
+        const signatureImage = await pdfDoc.embedPng(signature.signatureImagePng);
+
+        try {
+          const form = pdfDoc.getForm();
+          const signatureButton = form.getButton(FORM_FIELDS.SIGNATURE);
+          signatureButton.setImage(signatureImage);
+          this.logger.log('Signature embedded using form field');
+        } catch {
+          // 如果没有签名按钮字段，回退到坐标方式
+          this.logger.log('Signature button field not found, using coordinates');
+          this.embedSignatureByCoordinates(pdfDoc, signatureImage);
+        }
+      }
+
+      // 6. 最后统一扁平化所有表单字段
+      if (this.hasFormFields(pdfDoc)) {
+        const form = pdfDoc.getForm();
+        form.flatten();
+        this.logger.log('Form fields flattened');
+      }
+
+      // 7. 保存 PDF
+      const pdfBytes = await pdfDoc.save();
+      this.logger.log(`Signed PDF generated successfully for contract: ${data.contractNo}`);
+      return Buffer.from(pdfBytes);
+    } catch (error) {
+      this.logger.error(
+        `Failed to generate signed PDF for contract ${data.contractNo}:`,
+        error,
+      );
+      throw new Error(`Signed PDF generation failed: ${error.message}`);
     }
-
-    return pdfBuffer;
   }
 
 }