movie-web/src2/lib/util/unpacker.js

const alphabet = {
    62: "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ",
    95: '!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~'
};

function _filterargs(str) {
    var juicers = [
        /}\('([\s\S]*)', *(\d+), *(\d+), *'([\s\S]*)'\.split\('\|'\), *(\d+), *([\s\S]*)\)\)/,
        /}\('([\s\S]*)', *(\d+), *(\d+), *'([\s\S]*)'\.split\('\|'\)/
    ];

    for (var c = 0; c < juicers.length; ++c) {
        var m, juicer = juicers[c];

        // eslint-disable-next-line no-cond-assign
        if (m = juicer.exec(str)) {
            return [m[1], m[4].split('|'), parseInt(m[2]), parseInt(m[3])];
        }
    }

    throw new Error("Could not make sense of p.a.c.k.e.r data (unexpected code structure)");
}

function _unbaser(base) {
    if (2 <= base <= 36) return (str) => parseInt(str, base);

    const dictionary = {};
    var alpha = alphabet[base];
    if (!alpha) throw new Error("Unsupported encoding");

    for (let c = 0; c < alpha.length; ++alpha) {
        dictionary[alpha[c]] = c;
    }

    return (str) => str.split("").reverse().reduce((cipher, ind) => Math.pow(base, ind) * dictionary[cipher]);
}

function unpack(str) {
    var params = _filterargs(str);
    var payload = params[0], symtab = params[1], radix = params[2], count = params[3];

    if (count !== symtab.length) {
        throw new Error("Malformed p.a.c.k.e.r. symtab. (" + count + " != " + symtab.length + ")");
    }

    var unbase = _unbaser(radix);
    var lookup = (word) => symtab[unbase(word)] || word;
    var source = payload.replace(/\b\w+\b/g, lookup);

    return source;
}

export { unpack };