import { randomUUID } from 'crypto';
import { ModelService } from './modelService.js';
import { logger } from '../utils/logger.js';
import { compressImageData } from '../utils/image.js';
import { validateBase64Image } from '../utils/imageDownloader.js';
import {
HomeworkSubmission,
HomeworkGradingResponse,
GradeHomeworkParams,
Question,
GradingResult,
} from '../types.js';
export class GradingService {
private modelService: ModelService;
constructor() {
this.modelService = new ModelService();
}
/**
* 批改作业主方法 - 支持Base64和URL
*/
async gradeHomework(params: GradeHomeworkParams): Promise<HomeworkGradingResponse> {
try {
// 验证输入参数
this.validateInput(params);
// 获取图片数据（支持Base64和URL）
let imageData: string;
if ('imageUrl' in params && params.imageUrl) {
const { downloadImageAsBase64 } = await import('../utils/imageDownloader.js');
imageData = await downloadImageAsBase64(params.imageUrl);
} else if ('imageData' in params && params.imageData) {
imageData = params.imageData;
} else {
throw new Error('未提供有效的图片数据');
}
// 处理图片数据
const processedImageData = this.processImageData(imageData);
// 创建作业提交记录
const submission: HomeworkSubmission = {
id: randomUUID(),
studentName: params.studentName,
subject: params.subject,
imageData: processedImageData,
questions: params.questions,
submittedAt: new Date().toISOString(),
};
// 调用AI模型进行批改
const gradingResults = await this.modelService.gradeHomework(
processedImageData,
params.subject,
params.studentName,
params.questions
);
// 构建批改响应
const response = this.buildGradingResponse(submission.id, gradingResults);
return response;
} catch (error) {
throw new Error(`批改失败: ${error instanceof Error ? error.message : '未知错误'}`);
}
}
/**
* 验证输入参数
*/
private validateInput(params: GradeHomeworkParams): void {
// 检查是否有图片数据（支持Base64和URL）
const hasImageData = 'imageData' in params && params.imageData && params.imageData.trim() !== '';
const hasImageUrl = 'imageUrl' in params && params.imageUrl && params.imageUrl.trim() !== '';
if (!hasImageData && !hasImageUrl) {
throw new Error('必须提供图片数据（imageData或imageUrl）');
}
if (!params.studentName || params.studentName.trim() === '') {
throw new Error('学生姓名不能为空');
}
if (!params.subject || params.subject.trim() === '') {
throw new Error('作业科目不能为空');
}
// 验证Base64图片格式（如果是Base64方式）
if (hasImageData) {
const validation = validateBase64Image(params.imageData);
if (!validation.isValid) {
throw new Error(`图片格式不正确：${validation.error}`);
}
}
}
/**
* 处理图片数据
*/
private processImageData(imageData: string): string {
try {
// 压缩图片（限制在1MB以内）
const compressedImage = compressImageData(imageData, 1024);
return compressedImage;
} catch (error) {
return imageData;
}
}
/**
* 构建批改响应
*/
private buildGradingResponse(
submissionId: string,
gradingResults: GradingResult[]
): HomeworkGradingResponse {
// 计算总分
const totalScore = gradingResults.reduce((sum, result) => sum + result.score, 0);
const maxTotalScore = gradingResults.reduce((sum, result) => sum + result.maxScore, 0);
// 计算等级
const grade = this.calculateGrade(totalScore, maxTotalScore);
// 生成总体反馈
const overallFeedback = this.generateOverallFeedback(gradingResults, totalScore, maxTotalScore);
return {
submissionId,
totalScore,
maxTotalScore,
grade,
results: gradingResults,
overallFeedback,
gradedAt: new Date().toISOString(),
};
}
/**
* 计算等级
*/
private calculateGrade(score: number, maxScore: number): 'A' | 'B' | 'C' | 'D' | 'F' {
const percentage = maxScore > 0 ? (score / maxScore) * 100 : 0;
if (percentage >= 90) return 'A';
if (percentage >= 80) return 'B';
if (percentage >= 70) return 'C';
if (percentage >= 60) return 'D';
return 'F';
}
/**
* 生成总体反馈
*/
private generateOverallFeedback(
results: GradingResult[],
totalScore: number,
maxTotalScore: number
): string {
const correctCount = results.filter(r => r.isCorrect).length;
const totalCount = results.length;
const percentage = maxTotalScore > 0 ? (totalScore / maxTotalScore) * 100 : 0;
let feedback = '';
if (percentage >= 90) {
feedback = '优秀！作业完成得非常出色，继续保持！';
} else if (percentage >= 80) {
feedback = '良好！整体表现不错，还有提升空间。';
} else if (percentage >= 70) {
feedback = '中等！需要更加努力，注意细节。';
} else if (percentage >= 60) {
feedback = '及格！需要加强学习，多做练习。';
} else {
feedback = '需要改进！建议重新学习相关知识，寻求帮助。';
}
feedback += `\n\n详细情况：\n`;
feedback += `- 总得分：${totalScore}/${maxTotalScore} (${percentage.toFixed(1)}%)\n`;
feedback += `- 正确题数：${correctCount}/${totalCount}\n`;
feedback += `- 错误题数：${totalCount - correctCount}/${totalCount}\n`;
if (correctCount < totalCount) {
feedback += `\n建议重点复习以下知识点：\n`;
results
.filter(r => !r.isCorrect)
.slice(0, 3) // 只显示前3个错误
.forEach((result, index) => {
feedback += `${index + 1}. ${result.explanation}\n`;
});
}
return feedback;
}
/**
* 批量批改作业
*/
async batchGradeHomework(submissions: GradeHomeworkParams[]): Promise<HomeworkGradingResponse[]> {
logger.info(`开始批量批改 ${submissions.length} 份作业`);
const results: HomeworkGradingResponse[] = [];
const errors: string[] = [];
for (let i = 0; i < submissions.length; i++) {
const submission = submissions[i];
try {
const result = await this.gradeHomework(submission);
results.push(result);
logger.info(`第 ${i + 1}/${submissions.length} 份作业批改完成`);
} catch (error) {
const errorMsg = `第 ${i + 1} 份作业(${submission.studentName})批改失败: ${error instanceof Error ? error.message : '未知错误'}`;
logger.error(errorMsg);
errors.push(errorMsg);
}
}
if (errors.length > 0) {
logger.warn(`批量批改完成，其中 ${errors.length} 份作业批改失败`);
} else {
logger.info(`批量批改完成，所有 ${results.length} 份作业都成功批改`);
}
return results;
}
}