tsv_file_parser.js

const fs = require('fs');
const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});


const tsvFileName = process.argv[2];
const tsvFile = fs.readFileSync(tsvFileName, 'utf8');

const lines = tsvFile.split('\n');
const headings = lines[0].split('\t');

function addWord(word, obj) {

  // Update min
  if (obj.min === null) {
    obj.min = word;
  } else if (word < obj.min) {
    obj.min = word;
  }

  // Update max
  if (obj.max === null) {
    obj.max = word;
  } else if (word > obj.max) {
    obj.max = word;
  }

  // Update the full column!
  obj.values.push(word);
}

// Initialize list of columns
const columns = [];
headings.forEach(h => {
  columns.push({
    'min': null,
    'max': null,
    'values': [],
    'heading': h
  });
});

const rows = lines.slice(1);
rows.forEach((line, i) => {
  const words = line.split('\t');
  words.forEach((word, index) => {
    var obj = columns[index];
    addWord(word, obj);
  });
});

function offerHelp(prefix, suffix) {
  prefix && console.log(prefix);
  console.log('\nColumns:', headings);
  console.log('\nCommands:\n  max <column>\n  min <column>\n  search <column> <search_term>\n  help\n');
  suffix && console.log(suffix);
}

function search(column, search_term) {
  return column.values.includes(search_term) ? 'Value was found' : 'Value not found :(';
}

offerHelp('What would you like to know?');

rl.on('line', input => {

  try {

    if (input.trim() === 'help') {
      offerHelp();

    } else {
      const command = input.split(' ')[0].trim();
      const columnName = input.split(' ')[1].trim();
      const column = headings.indexOf(columnName);
      let result;

      if (command === 'search') {
        result = search(column, input.split(' ')[2].trim());
      } else {
        result = columns[column][command];
      }
      console.log(result);
    }

  } catch (e) {
    console.log('That was not a valid option, please try again.');
  }

  rl.setPrompt('\nWhat would you like to know? (Type "help" for options)\n');
  rl.prompt();
});