const libsodium          = require('libsodium-wrappers');
const concat_typed_array = require("concat-typed-array");
const nonce_length       = libsodium.crypto_aead_xchacha20poly1305_ietf_NPUBBYTES;


module.exports = class Sodium {
    ready() {
        return libsodium.ready;
    }

    setKey(key){
         if(key === null) {
             throw "Sodium: Private key not set."
         }

        this.key = libsodium.from_hex(key);
    }

    encrypt(plaintext){
        var nonce      = libsodium.randombytes_buf(nonce_length),
            ciphertext = libsodium.crypto_aead_xchacha20poly1305_ietf_encrypt(plaintext, null, nonce, nonce, this.key);

        console.log("nonce", nonce);
        console.log("ciphertext", ciphertext);

        return concat_typed_array(Uint8Array, nonce, ciphertext);
    }

    decrypt(encryption){
        var nonce      = encryption.slice(0, nonce_length),
            ciphertext = encryption.slice(nonce_length);

        console.log("nonce", nonce);
        console.log("ciphertext", ciphertext);

        return libsodium.crypto_aead_xchacha20poly1305_ietf_decrypt(nonce, ciphertext, null, nonce, this.key, "text");
    }
}



// other file:

const Sodium = require('./sodium');

const sodium = new Sodium();

sodium.ready().then(() => {
    sodium.setKey(...);
    sodium.encrypt(...);

    //...
});