server-exam/app/service/answer.js

'use strict';
const { CrudService } = require('naf-framework-mongoose-free/lib/service');
const { BusinessError, ErrorCode } = require('naf-core').Error;
const _ = require('lodash');
const { ObjectId } = require('mongoose').Types;
const axios = require('axios');

// 结果
class AnswerService extends CrudService {
  constructor(ctx) {
    super(ctx, 'answer');
    this.model = this.ctx.model.Answer;
    this.configModel = this.ctx.model.Config;
    this.questionModel = this.ctx.model.Question;
    this.questTypeModel = this.ctx.model.QuestionType;
  }

  /**
   * 生成试卷,不是考试就不创建数据
   * @param {Object} body 参数
   * @property {Boolean} exam 是否考试
   * @property {String} exam_place_id 考场id
   * @property {String} user_id 保安员id
   */
  async getExamQuestion({ exam = false, ...info }) {
    const config = await this.configModel.findOne();
    const questionTypeList = await this.questTypeModel.find();
    // 是否真的生成数据
    let save = false;
    if (exam && _.get(config, 'can_exam')) save = true;
    // 分为;练习试卷和考试试卷2套题型分配比例,规则是为考试试卷提供额外条件
    const { proportion, exam_proportion, score: maxScore } = config;
    const questions = [];
    let plan;
    if (save) {
      // 因为有 额外的规则会影响正常进行分配的方式.所以需要处额外规则与正常规则之间问题
      // 额外规则: exam_proportion中is_exam的总和加一起不能超过5%
      const pMinScore = exam_proportion.reduce((p, n) => p + _.multiply(_.get(n, 'number_min', 0), _.get(n, 'score', 0)), 0);
      if (pMinScore > maxScore) throw new BusinessError(ErrorCode.DATA_INVALID, '考试题型设置出现错误');
      plan = this.getPlan(exam_proportion, maxScore, true);
    } else {
      const pMinScore = proportion.reduce((p, n) => p + _.multiply(_.get(n, 'number_min', 0), _.get(n, 'score', 0)), 0);
      if (pMinScore > maxScore) throw new BusinessError(ErrorCode.DATA_INVALID, '练习题型设置出现错误');
      // 循环题型,抽题,生成答案字段放到questions中
      // 先计算出方案,再取出题目
      plan = this.getPlan(proportion, maxScore);
    }
    for (const p of plan) {
      const { type, num } = p;
      for (let i = 0; i < num; i++) {
        const notIn = questions.map(i => i._id);
        const quest = await this.getQuestion(type, notIn);
        if (quest && quest.type) {
          const questionType = questionTypeList.find(f => ObjectId(f._id).equals(quest.type));
          if (questionType) {
            quest.type = _.omit(questionType, [ 'meta', '__v' ]);
            // 生成试卷,把答案的位置也给放上,免去前端生成或者没生成报错
            if (questionType.type === 'checkbox') quest.answer = [];
            else quest.answer = null;
            questions.push(quest);
          }
        }
      }
    }

    if (!save) return { questions };
    // 组织数据,生成答案
    const obj = { ...info, config: _.pick(config, [ 'can_exam', 'exam_proportion', 'rules', 'score' ]), questions };
    // 创建答案
    const result = await this.model.create(obj);
    return result;
  }
  /**
   * 计算计划:什么类型多少题
   * @param {Array} proportion 比例
   * @param {Number} maxScore 总分数
   */
  getPlan(proportion, maxScore) {
    const plan = [];
    // 剩余分数
    let lessScore = maxScore;
    // 分为2种,1种是考试专用类型,另一种是通常考试类型
    proportion = proportion.map(i => ({ ...i, num: 0 }));
    const exam_proportion = proportion.filter(f => f.is_exam);
    let mscore = this.computedPercent(5, maxScore);
    // 考试类型不能超过5%
    let limit = 0;
    do {
      for (const p of exam_proportion) {
        const { score } = p;
        if (mscore - score < 0) {
          // 减完成负数了,不能减
          limit++;
          continue;
        } else {
          p.num++;
          mscore -= score;
          lessScore -= score;
        }
      }
      // limit到100次基本说明无限循环了,跳出来,有问题咱可以外面抛异常.别这里搞事消耗
    } while (mscore > 0 && limit < 100);
    // 整理成plan,合并进去么
    const exam_plan = exam_proportion.map(i => {
      const { score, _id: type, num } = i;
      const obj = { type, score, num, overRange: true };
      return obj;
    });
    plan.push(...exam_plan);
    const usual_proportion = proportion.filter(f => !f.is_exam);
    for (const p of usual_proportion) {
      const { number_min, number_max, score, _id: type } = p;
      let { max = 0, min = 0 } = p;
      // 为0说明是没限制,需要计算下
      if (min === 0) min = this.computedNum(number_min, score, maxScore);
      if (max === 0) max = this.computedNum(number_max, score, maxScore);
      const num = _.random(min, max);
      lessScore -= _.multiply(score, num);
      plan.push({ type, num, score, min, max });
    }

    // 小于0相当于重来一遍
    if (lessScore < 0) return this.getPlan(proportion, maxScore);
    // 等于0,直接返回就行
    else if (lessScore === 0) return plan;
    // 大于0,还有分数,需要继续分配,拿着plan挨个轮,轮到没分为止
    let breakWhile = false;
    // 能不能用该计划
    let cantUse = true;
    do {
      if (lessScore > 0) {
        // 这里,不一定是所有的题型都超出范围.还有可能是 差1分 但是1分的题已经到上限了,只剩下2分的题了
        // 所以只看所有类型超没超出范围没有意义,而是需要看没超出范围的题目,能不能把剩下的 分 填上
        const inRange = plan.filter(f => !f.overRange);
        let next = false;
        for (const ir of inRange) {
          const { score } = ir;
          if (lessScore - score >= 0) {
            // 至少这个类型能填上,可以往下继续
            next = true;
            break;
          }
        }
        if (!next) {
          breakWhile = true;
          cantUse = false;
        } else {
          for (const p of plan) {
            if (lessScore === 0) {
              breakWhile = true;
              break;
            }
            const { score, overRange, min, max } = p;
            // 是否超出范围,超出下一个
            if (overRange) continue;

            // 先计算分数够不够减的
            if (lessScore - score < 0) continue;
            // 再计算 该类型加完 1道题后,会不会超出范围
            if (!_.inRange(p.num + 1, min, max + 1)) {
              p.overRange = true;
              continue;
            }
            lessScore -= score;
            p.num += 1;
          }
        }
      } else breakWhile = true;
    } while (!breakWhile);
    if (cantUse) return plan;
    return this.getPlan(proportion, maxScore);
  }

  /**
   * 计算该类型的题数
   * @param {Number} num 该类型占比
   * @param {Number} score 该类型题分数
   * @param {Number} maxScore 试卷满分
   * @return {Number} 返回多少道题
   */
  computedNum(num, score, maxScore) {
    return _.ceil(_.divide(_.multiply(_.divide(_.multiply(score, num), maxScore), 100), score));
  }
  /**
   * 算该百分比的分数
   * @param {Number} num 占比
   * @param {Number} maxScore 满分
   */
  computedPercent(num, maxScore) {
    return _.ceil(_.multiply(_.divide(num, maxScore), 100));
  }

  /**
   * 根据题型查找,考试调用次数最少的题
   * @param {ObjectId} type 题型
   * @param {Array} notIn 已经被取出来的题.不要再拿了
   */
  async getQuestion(type, notIn) {
    // TODO 正式环境需要将这个删了,不能出重复的题
    notIn = [];
    const data = await this.questionModel.findOne({ type, _id: { $nin: notIn } }).sort({ times: 1 });
    if (data) {
      data.times = data.times + 1;
      await data.save();
    }

    return _.pick(data, '_id', 'title', 'type', 'selects');
  }

  async update(filter, update, { projection } = {}) {
    const { _id, id } = filter;
    if (_id || id) filter = { _id: ObjectId(_id || id) };
    const entity = await this.model.findOne(filter).exec();
    if (!entity) throw new BusinessError(ErrorCode.DATA_NOT_EXIST);
    entity.set(update);
    await entity.save();
    // 需要处理原数据
    const r = await this.updateScore(entity);
    if (!r) throw new BusinessError(ErrorCode.DATABASE_FAULT, '未能同步数据,交卷失败');
    const res = await this.model.findOne(filter, projection).exec();

    return res;
  }
  /**
   * 修改原数据的考试成绩
   * @param {Object} data 数据
   */
  async updateScore(data) {
    const id = _.get(data, 'exam_info.id');
    const exam_achieve = _.get(data, 'score');
    const body = { data: { exam_achieve, status: '3' }, query: { id } };
    const middleConfig = this.app.config.middleServer;
    const { ip, port } = middleConfig;
    const res = await axios({
      method: 'post',
      url: `http://${ip}:${port}/db/update?table=examination_examinee`,
      data: body,
      responseType: 'json',
    });
    if (res && _.get(res, 'data.code') === 0) return true;
  }
}

module.exports = AnswerService;