einvoice/ts/formats/ubl/xrechnung/xrechnung.encoder.ts

import { UBLEncoder } from '../generic/ubl.encoder.js';
import type { TInvoice, TCreditNote, TDebitNote } from '../../../interfaces/common.js';
import { DOMParser, XMLSerializer } from '../../../plugins.js';

/**
 * Encoder for XRechnung (UBL) format
 * Extends the generic UBL encoder with XRechnung-specific customizations
 */
export class XRechnungEncoder extends UBLEncoder {
  /**
   * Encodes a credit note into XRechnung XML
   * @param creditNote Credit note to encode
   * @returns XRechnung XML string
   */
  protected async encodeCreditNote(creditNote: TCreditNote): Promise<string> {
    // First get the base UBL XML
    const baseXml = await super.encodeCreditNote(creditNote);
    
    // Parse and modify for XRechnung
    const doc = new DOMParser().parseFromString(baseXml, 'application/xml');
    this.applyXRechnungCustomizations(doc, creditNote as unknown as TInvoice);
    
    // Serialize back to string
    return new XMLSerializer().serializeToString(doc);
  }
  
  /**
   * Encodes a debit note (invoice) into XRechnung XML
   * @param debitNote Debit note to encode
   * @returns XRechnung XML string
   */
  protected async encodeDebitNote(debitNote: TDebitNote): Promise<string> {
    // First get the base UBL XML
    const baseXml = await super.encodeDebitNote(debitNote);
    
    // Parse and modify for XRechnung
    const doc = new DOMParser().parseFromString(baseXml, 'application/xml');
    this.applyXRechnungCustomizations(doc, debitNote as unknown as TInvoice);
    
    // Serialize back to string
    return new XMLSerializer().serializeToString(doc);
  }
  
  /**
   * Applies XRechnung-specific customizations to the document
   * @param doc XML document
   * @param invoice Invoice data
   */
  private applyXRechnungCustomizations(doc: Document, invoice: TInvoice): void {
    const root = doc.documentElement;
    
    // Update Customization ID to XRechnung 2.0
    const customizationId = root.getElementsByTagName('cbc:CustomizationID')[0];
    if (customizationId) {
      customizationId.textContent = 'urn:cen.eu:en16931:2017#compliant#urn:xoev-de:kosit:standard:xrechnung_2.0';
    }
    
    // Add or update Buyer Reference (required for XRechnung)
    let buyerRef = root.getElementsByTagName('cbc:BuyerReference')[0];
    if (!buyerRef) {
      // Find where to insert it (after DocumentCurrencyCode)
      const currencyCode = root.getElementsByTagName('cbc:DocumentCurrencyCode')[0];
      if (currencyCode) {
        buyerRef = doc.createElement('cbc:BuyerReference');
        buyerRef.textContent = invoice.buyerReference || invoice.id;
        currencyCode.parentNode!.insertBefore(buyerRef, currencyCode.nextSibling);
      }
    } else if (!buyerRef.textContent || buyerRef.textContent.trim() === '') {
      buyerRef.textContent = invoice.buyerReference || invoice.id;
    }
    
    // Update payment terms to German
    const paymentTermsNotes = root.getElementsByTagName('cac:PaymentTerms');
    if (paymentTermsNotes.length > 0) {
      const noteElement = paymentTermsNotes[0].getElementsByTagName('cbc:Note')[0];
      if (noteElement && noteElement.textContent) {
        noteElement.textContent = `Zahlung innerhalb von ${invoice.dueInDays || 30} Tagen`;
      }
    }
    
    // Add electronic address for parties if available
    this.addElectronicAddressToParty(doc, 'cac:AccountingSupplierParty', invoice.from);
    this.addElectronicAddressToParty(doc, 'cac:AccountingCustomerParty', invoice.to);
    
    // Ensure payment reference is set
    const paymentMeans = root.getElementsByTagName('cac:PaymentMeans')[0];
    if (paymentMeans) {
      let paymentId = paymentMeans.getElementsByTagName('cbc:PaymentID')[0];
      if (!paymentId) {
        paymentId = doc.createElement('cbc:PaymentID');
        paymentId.textContent = invoice.id;
        paymentMeans.appendChild(paymentId);
      }
    }
    
    // Add country code handling for German addresses
    this.fixGermanCountryCodes(doc);
  }
  
  /**
   * Adds electronic address to party if not already present
   * @param doc XML document
   * @param partyType Party type selector
   * @param party Party data
   */
  private addElectronicAddressToParty(doc: Document, partyType: string, party: any): void {
    const partyContainer = doc.getElementsByTagName(partyType)[0];
    if (!partyContainer) return;
    
    const partyElement = partyContainer.getElementsByTagName('cac:Party')[0];
    if (!partyElement) return;
    
    // Check if electronic address already exists
    const existingEndpoint = partyElement.getElementsByTagName('cbc:EndpointID')[0];
    if (!existingEndpoint && party.electronicAddress) {
      // Add electronic address at the beginning of party element
      const endpointNode = doc.createElement('cbc:EndpointID');
      endpointNode.setAttribute('schemeID', party.electronicAddress.scheme || '0204');
      endpointNode.textContent = party.electronicAddress.value;
      
      // Insert as first child of party element
      if (partyElement.firstChild) {
        partyElement.insertBefore(endpointNode, partyElement.firstChild);
      } else {
        partyElement.appendChild(endpointNode);
      }
    }
  }
  
  /**
   * Fixes German country codes in the document
   * @param doc XML document
   */
  private fixGermanCountryCodes(doc: Document): void {
    const countryNodes = doc.getElementsByTagName('cbc:IdentificationCode');
    for (let i = 0; i < countryNodes.length; i++) {
      const node = countryNodes[i];
      if (node.textContent) {
        const text = node.textContent.toLowerCase();
        if (text === 'germany' || text === 'deutschland' || text === 'de') {
          node.textContent = 'DE';
        } else if (text.length > 2) {
          // Try to use first 2 characters as country code
          node.textContent = text.substring(0, 2).toUpperCase();
        }
      }
    }
  }
}