nodejs turn factorio blueprint to json

string2json.mjs

/*
    https://wiki.factorio.com/Blueprint_string_format
    turn blueprint string to json
*/

import fs from "fs";
import { unzip } from "zlib";

// returns a flagged argument value, if found
function getFlaggedArg(flag) {
    for (let i = 0; i < process.argv.length; i++) {
        if (process.argv[i] == flag && process.argv.length > i + 1) {
            return process.argv[i + 1];
        }
    }
    return;
}

async function main() {
    const inFileName = getFlaggedArg("-i");

    if (!inFileName) {
        console.log('usage: -i <infile.txt>');
        return 1;
    }

    const blueprintString = fs.readFileSync(inFileName).toString();
    const blueprintVersion = blueprintString[0];
    if (blueprintVersion != 0) {
        console.error('Cannot read bluprint version ', blueprintVersion);
        return 1;
    }

    const buffer = Buffer.from(blueprintString.substring(1), 'base64');
    unzip(buffer, (err, buffer) => {
        if (err) {
            console.error('An error occurred:', err);
            process.exitCode = 1;
            return 1;
        }
        console.log(buffer.toString());
    });
}

main();