Brute force turtle files splitter

index.js

/*
* Brute force turtle files splitter
* npm install argparse fs-extra
* node index.js --input /Users/pasquale/Desktop/aat/all/redomi_part1.ttl --output ./out
*/

const fs = require('fs-extra');
const { ArgumentParser } = require('argparse');


// setup arguments
const parser = new ArgumentParser({
  version: '0.0.1',
  addHelp: true,
  description: 'Turtle splitter',
});
parser.addArgument(
  ['-i', '--input'],
  {
    required: true,
    help: 'Input turtle (.ttl) file.',
  },
);
parser.addArgument(
  ['-o', '--output'],
  {
    defaultValue: './out',
    help: 'Output folder',
  },
);
parser.addArgument(
  ['-l', '--maxlines'],
  {
    type: Number,
    defaultValue: 10000,
    help: 'Max number of lines per output file.',
  },
);
const args = parser.parseArgs();

const txt = fs.readFileSync(args.input, 'utf8');
fs.ensureDirSync(args.output);

const lines = txt.split('\n').reverse();

let line = lines.pop();
const pfx = [];
while (line.startsWith('@prefix')) {
  pfx.push(line);
  line = lines.pop();
}
const prefixes = `${pfx.join('\n')}\n\n`;

let i = 0; let
  j = 0;
let curtxt = prefixes;

while (lines.length) {
  line = lines.pop();
  i++;
  curtxt += `${line}\n`;
  if (i >= args.maxlines && !line.trim()) {
    // save file
    fs.writeFileSync(`${args.output}/${j++}.ttl`, curtxt, 'utf-8');
    i = 0;
    curtxt = prefixes;
  }
}
fs.writeFileSync(`${args.output}/${j++}.ttl`, curtxt, 'utf-8');