einvoice/ts/formats/ubl/xrechnung.validator.ts

import { EN16931UBLValidator } from './en16931.ubl.validator.js';

/**
 * XRechnung-specific validator that extends EN16931 validation
 * Implements additional German CIUS (Core Invoice Usage Specification) rules
 */
export class XRechnungValidator extends EN16931UBLValidator {
  /**
   * Validates XRechnung-specific structure requirements
   */
  protected validateStructure(): boolean {
    // First validate EN16931 structure
    let valid = super.validateStructure();

    // XRechnung-specific: Check for proper customization ID
    const customizationID = this.getText('//cbc:CustomizationID');
    if (!customizationID || !customizationID.includes('xrechnung')) {
      this.addError(
        'XRECH-STRUCT-1',
        'XRechnung customization ID is missing or invalid',
        '//cbc:CustomizationID'
      );
      valid = false;
    }

    return valid;
  }

  /**
   * Validates XRechnung-specific business rules
   */
  protected validateBusinessRules(): boolean {
    // First validate EN16931 business rules
    let valid = super.validateBusinessRules();

    // BR-DE-1: Payment terms (BT-20) or Payment due date (BT-9) shall be provided.
    if (!this.exists('//cbc:PaymentDueDate') && !this.exists('//cac:PaymentTerms/cbc:Note')) {
      this.addError(
        'BR-DE-1',
        'Payment terms or Payment due date shall be provided',
        '//cac:PaymentTerms'
      );
      valid = false;
    }

    // BR-DE-2: The element "Buyer reference" (BT-10) shall be provided.
    if (!this.exists('//cbc:BuyerReference')) {
      this.addError(
        'BR-DE-2',
        'Buyer reference is required in XRechnung',
        '//cbc:BuyerReference'
      );
      valid = false;
    }

    // BR-DE-5: In Germany, the element "Seller VAT identifier" (BT-31) shall be provided.
    const sellerCountry = this.getText('//cac:AccountingSupplierParty//cac:PostalAddress//cac:Country/cbc:IdentificationCode');
    if (sellerCountry === 'DE' && !this.exists('//cac:AccountingSupplierParty//cac:PartyTaxScheme[cac:TaxScheme/cbc:ID="VAT"]/cbc:CompanyID')) {
      this.addError(
        'BR-DE-5',
        'Seller VAT identifier is required for German sellers',
        '//cac:AccountingSupplierParty//cac:PartyTaxScheme'
      );
      valid = false;
    }

    // BR-DE-6: In Germany, the element "Buyer VAT identifier" (BT-48) shall be provided.
    const buyerCountry = this.getText('//cac:AccountingCustomerParty//cac:PostalAddress//cac:Country/cbc:IdentificationCode');
    if (buyerCountry === 'DE' && !this.exists('//cac:AccountingCustomerParty//cac:PartyTaxScheme[cac:TaxScheme/cbc:ID="VAT"]/cbc:CompanyID')) {
      this.addError(
        'BR-DE-6',
        'Buyer VAT identifier is required for German buyers',
        '//cac:AccountingCustomerParty//cac:PartyTaxScheme'
      );
      valid = false;
    }

    // BR-DE-7: The element "Seller city" (BT-37) shall be provided.
    if (!this.exists('//cac:AccountingSupplierParty//cac:PostalAddress/cbc:CityName')) {
      this.addError(
        'BR-DE-7',
        'Seller city is required',
        '//cac:AccountingSupplierParty//cac:PostalAddress'
      );
      valid = false;
    }

    // BR-DE-8: The element "Seller post code" (BT-38) shall be provided.
    if (!this.exists('//cac:AccountingSupplierParty//cac:PostalAddress/cbc:PostalZone')) {
      this.addError(
        'BR-DE-8',
        'Seller post code is required',
        '//cac:AccountingSupplierParty//cac:PostalAddress'
      );
      valid = false;
    }

    // BR-DE-9: The element "Buyer city" (BT-52) shall be provided.
    if (!this.exists('//cac:AccountingCustomerParty//cac:PostalAddress/cbc:CityName')) {
      this.addError(
        'BR-DE-9',
        'Buyer city is required',
        '//cac:AccountingCustomerParty//cac:PostalAddress'
      );
      valid = false;
    }

    // BR-DE-10: The element "Buyer post code" (BT-53) shall be provided.
    if (!this.exists('//cac:AccountingCustomerParty//cac:PostalAddress/cbc:PostalZone')) {
      this.addError(
        'BR-DE-10',
        'Buyer post code is required',
        '//cac:AccountingCustomerParty//cac:PostalAddress'
      );
      valid = false;
    }

    // BR-DE-11: The element "Seller contact telephone number" (BT-42) shall be provided.
    if (!this.exists('//cac:AccountingSupplierParty//cac:Contact/cbc:Telephone')) {
      this.addError(
        'BR-DE-11',
        'Seller contact telephone number is required',
        '//cac:AccountingSupplierParty//cac:Contact'
      );
      valid = false;
    }

    // BR-DE-12: The element "Seller contact email address" (BT-43) shall be provided.
    if (!this.exists('//cac:AccountingSupplierParty//cac:Contact/cbc:ElectronicMail')) {
      this.addError(
        'BR-DE-12',
        'Seller contact email address is required',
        '//cac:AccountingSupplierParty//cac:Contact'
      );
      valid = false;
    }

    // BR-DE-13: The element "Buyer electronic address" (BT-49) shall be provided.
    if (!this.exists('//cac:AccountingCustomerParty//cac:Party/cbc:EndpointID')) {
      this.addError(
        'BR-DE-13',
        'Buyer electronic address (EndpointID) is required',
        '//cac:AccountingCustomerParty//cac:Party'
      );
      valid = false;
    }

    // BR-DE-14: The element "Payment means type code" (BT-81) shall be provided.
    if (!this.exists('//cac:PaymentMeans/cbc:PaymentMeansCode')) {
      this.addError(
        'BR-DE-14',
        'Payment means type code is required',
        '//cac:PaymentMeans'
      );
      valid = false;
    }

    // BR-DE-15: The element "Invoice line identifier" (BT-126) shall be provided.
    const invoiceLines = this.select('//cac:InvoiceLine | //cac:CreditNoteLine', this.doc) as Node[];
    for (let i = 0; i < invoiceLines.length; i++) {
      const line = invoiceLines[i];
      if (!this.exists('./cbc:ID', line)) {
        this.addError(
          'BR-DE-15',
          `Invoice line ${i + 1} is missing identifier`,
          `//cac:InvoiceLine[${i + 1}]`
        );
        valid = false;
      }
    }

    // German VAT ID format validation
    const supplierVatId = this.getText('//cac:AccountingSupplierParty//cbc:CompanyID[../cac:TaxScheme/cbc:ID="VAT"]');
    if (supplierVatId && supplierVatId.startsWith('DE') && !/^DE[0-9]{9}$/.test(supplierVatId)) {
      this.addError(
        'BR-DE-VAT',
        'German VAT ID format is invalid (must be DE followed by 9 digits)',
        '//cac:AccountingSupplierParty//cbc:CompanyID'
      );
      valid = false;
    }

    return valid;
  }
}