/// <reference types="node" />
/// <reference types="pdfkit" />
import { Secret } from 'jsonwebtoken';
import { InvoiceSignedPayload } from './InvoiceSignedPayload';
import { InvoiceInterface } from './InvoiceInterface';
export declare class Invoice {
    invoice: InvoiceInterface;
    private privateKey;
    readonly subtotalWithoutTax: number;
    readonly amountDue: number;
    /**
     * @param {InvoiceInterface} invoice Invoice information
     * @param {Secret} privateKey prime256v1 private key
     */
    constructor(invoice: InvoiceInterface, privateKey: string);
    /**
     * Sign payload containing invoice information with private key
     * @param {InvoiceSignedPayload} signedPayload The payload to be signed
     * @param {Secret} privateKey The secret key to use
     * @return {string} The signed JWT token
     */
    static signJwt(signedPayload: InvoiceSignedPayload, privateKey: Secret): string;
    /**
     * Prove the authenticity of a token by verifying its signature
     * @param {string} token The token to be verified
     * @param {Secret} key The issuer's public key
     * @return {InvoiceSignedPayload} The verified payload
     */
    static verifyJwt(token: string, key: Secret): InvoiceSignedPayload;
    /**
     * Generate a signed token containing the instance information
     * @return {string} The signed JWT token
     */
    createJwt(): string;
    /**
     * Generate a signed token and convert it to a QR Code PNG image
     * @return {Promise<Buffer>}
     */
    createQRCodeBuffer(): Promise<Buffer>;
    /**
     * Generate the final PDF file containing the cryptographic stamp of authenticity
     * @return {Promise<PDFKit.PDFDocument>}
     */
    generatePDF(): Promise<PDFKit.PDFDocument>;
}