index.js

const Fs = require('fs');
const _ = require('lodash');
const Json2csv = require('json2csv');
const Code = require('./subjectCode.json');
const Path = require('path');
const SchoolCode = 30794;

var argv = require('minimist')(process.argv.slice(2));

if (!argv.path) {
  console.log('node index.js --path="PathToTxt"');
} else {
  var filename = argv.path;
  const filePath = Path.join('./', filename);
  const data = Fs.readFileSync(filePath, 'utf-8');
  console.log(`Converting ${filename}:`);
  convertFile(data, filename);
}

function convertCodeToText (array) {
  return array.map(string => {
    const obj = _.find(Code, {'code': string});
    return obj
      ? obj.abbr
      : string;
  });
}

function parseTxt2JSON (lines) {
  return lines.map(line => {
    const basicInfoRegExp = new RegExp(`^(\\d)+\\s+(\\w\\d{6}\\w)\\s+(\\d{4})(\\d{2})(\\d{2})WEBSAMS\\s+DSE\\s+(\\d{4})([\\w\\s]+)${SchoolCode}+(\\d+)\\s+(.*)$`);
    const schema = {
      'id': '$2',
      'dob': '$3-$4-$5',
      'name': '$7',
      'hkeaaId': '$8',
      'grades': '$9'
    };

    const jsonString = JSON.parse(
    // construct literal object with regex parsing
    // the grades are saved as result and parsed separately
    line
      .replace(/5\*\*/g, '7') // convert 5** to 7
      .replace(/5\*/g, '6') // convert 5* to 6
      .replace(basicInfoRegExp, JSON.stringify(schema)));

    // split string into array of words
    jsonString.name = _.words(jsonString.name).join(' ');

    const APLRegExp = /([B]\d{3})\s+(\w{2})\s+([YN])/g;
    // handle subgrade of A010
    // const A010RegExp = /(A010)\s+1\s+([\dUX])\s+2\s+([\dUX])\s+3\s+([\dUX])\s+4\s+([\dUX])\s+5\s+([\dUX])/g;
    // From 2016 A010 only have 4 sub-subject
    const A010RegExp = / (A010)\s+1\s+([\dUX])\s+2\s+([\dUX])\s+3\s+([\dUX])\s+4\s+([\dUX])/g;
    // handle subgrade of A020
    const A020RegExp = /(A020)\s+1\s+([\dUX])\s+2\s+([\dUX])\s+3\s+([\dUX])\s+4\s+([\dUX])/g;
    const generalSubjectRegExp = /([ABC]\d{3})\s+([\dUX])/g;
    // https://regex101.com/r/lZ8lO0/1
    // to solve the case for ... A165    A161   5     A162    4  ...
    // remove redundant A165 before A161 or A162
    const A165RegExp = /A165\s+([ABC])/g;

    // parse grades
    const resultString = '{' + jsonString.grades.replace(APLRegExp, '"APL":"$1-$2-$3",').replace(A165RegExp, '$1')
    // convert to e.g. CHI-S:23223
    // From 2016 A010 only have 4 sub-subject
    // .replace(A010RegExp, '"$1S":"$2$3$4$5$6",')
      .replace(A010RegExp, '"$1S":"$2$3$4$5",')
    // convert to e.g. ENG-S:2322
      .replace(A020RegExp, '"$1S":"$2$3$4$5",')
    // convert to e.g. PHY:2
      .replace(generalSubjectRegExp, '"$1":"$2",')
    // remove all spaces
      .replace(/\s+/g, '')
    // remove the last comma
      .slice(0, -1) + '}';

    const resultObj = _(jsonString)
    // remove grades
      .omit('grades').merge(JSON.parse(resultString)).value();

    return resultObj;
  });
}

function convertFile (file, filename) {
  // body...
  // https://lodash.com/docs#compact
  const dataArray = _.compact(file.split('\r\n'));
  const convertedData = parseTxt2JSON(dataArray);
  const filePath = Path.join('./result', Path.basename(filename, '.txt'));
  console.log(filePath);

  const fields = ['id', 'dob', 'name', 'hkeaaId', 'A010', 'A020', 'A030', 'A031', 'A032', 'A040', 'A070', 'A080', 'A100', 'A110', 'A120', 'A130', 'A140', 'A150', 'A161', 'A162', 'A163', 'A165', 'A172', 'A200', 'A230', 'A010S', 'A020S', 'APL'];
  const fieldNames = convertCodeToText(fields);

  const config = {
    data: convertedData,
    fields: fields,
    fieldNames: fieldNames
  };

  Json2csv(config, (err, csv) => {
    if (err) throw err;
    Fs.writeFileSync(filePath + '.csv', csv, 'utf-8');
  });

  const namedKeyData = convertedData.map((student) => {
    return _.mapKeys(student, (value, key) => {
      const code = _.find(Code, {'code': key});
      return code
        ? code.abbr
        : key;
    });
  });

  Fs.writeFileSync(filePath + '.json', JSON.stringify(namedKeyData, null, 2), 'utf-8');
  console.log('Process Complete!');
}