/**
 * @author tlwr [toby@toby.codes]
 * @copyright Crown Copyright 2017
 * @license Apache-2.0
 */

import Operation from "../Operation";
import kbpgp from "kbpgp";
import { ASP, importPrivateKey, importPublicKey } from "../lib/PGP";
import OperationError from "../errors/OperationError";
import promisifyDefault from "es6-promisify";
const promisify = promisifyDefault.promisify;

/**
 * PGP Encrypt and Sign operation
 */
class PGPEncryptAndSign extends Operation {

    /**
     * PGPEncryptAndSign constructor
     */
    constructor() {
        super();

        this.name = "PGP Encrypt and Sign";
        this.module = "PGP";
        this.description = "Input: the cleartext you want to sign.\n<br><br>\nArguments: the ASCII-armoured private key of the signer (plus the private key password if necessary)\nand the ASCII-armoured PGP public key of the recipient.\n<br><br>\nThis operation uses PGP to produce an encrypted digital signature.\n<br><br>\nPretty Good Privacy is an encryption standard (OpenPGP) used for encrypting, decrypting, and signing messages.\n<br><br>\nThis function uses the Keybase implementation of PGP.";
        this.inputType = "string";
        this.outputType = "string";
        this.args = [
            {
                "name": "Private key of signer",
                "type": "text",
                "value": ""
            },
            {
                "name": "Private key passphrase",
                "type": "string",
                "value": ""
            },
            {
                "name": "Public key of recipient",
                "type": "text",
                "value": ""
            }
        ];
    }

    /**
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     *
     * @throws {OperationError} if failure to sign message
     */
    async run(input, args) {
        const message = input,
            privateKey = args[0],
            passphrase = args[1],
            publicKey = args[2];
        let signedMessage;

        if (!privateKey) throw new OperationError("Enter the private key of the signer.");
        if (!publicKey) throw new OperationError("Enter the public key of the recipient.");
        const privKey = await importPrivateKey(privateKey, passphrase);
        const pubKey = await importPublicKey(publicKey);

        try {
            signedMessage = await promisify(kbpgp.box)({
                "msg": message,
                "encrypt_for": pubKey,
                "sign_with": privKey,
                "asp": ASP
            });
        } catch (err) {
            throw new OperationError(`Couldn't sign message: ${err}`);
        }

        return signedMessage;
    }

}

export default PGPEncryptAndSign;