Rename files in a folder to the format of S01E01, S01E02, etc. so that parsers like Sonarr can correctly identify them.

tv-rename

#!/usr/bin/env node

/* TV Renamer
  Purpose: Rename files in a folder to the format of S01E01, S01E02, etc.
    So that parsers like Sonarr can correctly identify them. The Episode number
    is based on a natural sort of the files in the current directory.

  Usage: tv-renamer
    No parameters. The user is prompted for Season # and asked to confirm before
    any files are renamed.
 */

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

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

let orderedFileNames = fs.readdirSync(process.cwd())
  .filter(file => !file.startsWith('.'))
  .sort((fileA, fileB) => {
    // split file names into alphabetic / numerical chunks
    let fileATokens = fileA.split(/(\d+)/g);
    let fileBTokens = fileB.split(/(\d+)/g);
    let minNumTokens = Math.min(fileATokens.length, fileBTokens.length);

    for (let i = 0; i < minNumTokens; i++) {
      if (fileATokens[i] != fileBTokens[i]) {
        if (isNumerical(fileATokens[i]) && isNumerical(fileBTokens[i])) {
          let numA = Number(fileATokens[i]);
          let numB = Number(fileBTokens[i]);
          return numA - numB;
        } else {
          return fileATokens[i].localeCompare(fileBTokens[i]);
        }
      }
    }
    return fileA.localeCompare(fileB);
  });

readLine.question('Season Number: ', (numberString) => {
  let seasonNumber = Number(numberString);

  let processedFiles = orderedFileNames.map((originalName, index) => {
    let seasonString = `S${leftPad(seasonNumber, 2, '0')}E${leftPad(index + 1, 2, '0')}`;
    let extension = `${path.extname(originalName)}`;
    let newName = `${seasonString} ${path.basename(originalName, extension).replace(/\s*\d+\s*/g, '')}${extension}`;
    return {
      originalName,
      newName,
    };
  });

  console.log(" === RENAME PREVIEW === ");
  processedFiles.forEach(file => {
    console.log(` - Old: "${file.originalName}"`);
    console.log(` + New: "${file.newName}"`);
    console.log();
  });

  readLine.question("Looks good? (y/N): ", (response) => {
    response = response.trim();
    // if (!response || response.toLowerCase() === 'n')
    if (response.toLowerCase() === 'y') {
      processedFiles.forEach((file, index, arr) => {
        let indexString = leftPad(index+1, arr.length.toString().length, '0');
        console.log(`(${indexString}/${arr.length}) Renaming "${file.originalName}" to "${file.newName}"`);
        fs.renameSync(file.originalName, file.newName);
      });
    }

    readLine.close();
  });

});


// Utility Functions
function isNumerical(s) {
  return (/\d+/g).test(s);
}
function isAlphabetical(s) {
  return (/\D+/g).test(s);
}
function leftPad(s, len, char) {
  s = '' + s;
  return new Array((len - s.length + 1) / char.length).join().replace(/,/g, char) + s;
}