episode-rename.js

const fs = require('fs');

const season = 7;

const path = `\\\\192.168.1.75\\plex\\tv\\Star Trek- Deep Space Nine\\Season ${season}`

let count = 1;
fs.readdirSync(path).forEach((file) => {

    console.log(`original: ${file}`)

    let episode = count > 9 ? `${count}` : `0${count}`


    let reg = /e\d{1,3}?\d{1,3}-\d{1,3}/
    const tryAgain = file.match(reg)
    console.log(`checking if it's a double episode...`)

    if (tryAgain) {
        episode = count > 9 ? `${count}-${count + 1}` : `0${count}-${count + 1 > 9 ? `${count + 1}` : `0${count + 1}`}`
        count++
        console.log(`double episode found... setting to ${episode}`)
    } else {
        reg = /e\d{1,3}/

        const hasMatch = file.match(reg).length > 0

        if (!hasMatch) {
            throw new Error('something is wrong, could not match eXXX or eXXX-XXX')
        }
        console.log(`normal episode found... proceeding`)
    }


    const after = file.replace(reg, `s0${season}e${episode}`)

    fs.rename(`${path}\\${file}`, `${path}\\${after}`, (err) => {
        if (err) console.log('ERROR: ' + err);
    });

    console.log(`converted: ${after}`)
    count++;
});