/**
 * EN16931 mandatory field validator
 * Validates that invoices contain the minimum required fields per the EN16931 standard
 */
export class EN16931Validator {
  /**
   * Valid ISO 4217 currency codes (common subset)
   */
  private static readonly VALID_CURRENCIES = [
    'AED', 'AFN', 'ALL', 'AMD', 'ANG', 'AOA', 'ARS', 'AUD', 'AWG', 'AZN',
    'BAM', 'BBD', 'BDT', 'BGN', 'BHD', 'BIF', 'BMD', 'BND', 'BOB', 'BRL',
    'BSD', 'BTN', 'BWP', 'BYN', 'BZD', 'CAD', 'CDF', 'CHF', 'CLP', 'CNY',
    'COP', 'CRC', 'CUC', 'CUP', 'CVE', 'CZK', 'DJF', 'DKK', 'DOP', 'DZD',
    'EGP', 'ERN', 'ETB', 'EUR', 'FJD', 'FKP', 'GBP', 'GEL', 'GGP', 'GHS',
    'GIP', 'GMD', 'GNF', 'GTQ', 'GYD', 'HKD', 'HNL', 'HRK', 'HTG', 'HUF',
    'IDR', 'ILS', 'IMP', 'INR', 'IQD', 'IRR', 'ISK', 'JEP', 'JMD', 'JOD',
    'JPY', 'KES', 'KGS', 'KHR', 'KMF', 'KPW', 'KRW', 'KWD', 'KYD', 'KZT',
    'LAK', 'LBP', 'LKR', 'LRD', 'LSL', 'LYD', 'MAD', 'MDL', 'MGA', 'MKD',
    'MMK', 'MNT', 'MOP', 'MRU', 'MUR', 'MVR', 'MWK', 'MXN', 'MYR', 'MZN',
    'NAD', 'NGN', 'NIO', 'NOK', 'NPR', 'NZD', 'OMR', 'PAB', 'PEN', 'PGK',
    'PHP', 'PKR', 'PLN', 'PYG', 'QAR', 'RON', 'RSD', 'RUB', 'RWF', 'SAR',
    'SBD', 'SCR', 'SDG', 'SEK', 'SGD', 'SHP', 'SLL', 'SOS', 'SPL', 'SRD',
    'STN', 'SYP', 'SZL', 'THB', 'TJS', 'TMT', 'TND', 'TOP', 'TRY', 'TTD',
    'TVD', 'TWD', 'TZS', 'UAH', 'UGX', 'USD', 'UYU', 'UZS', 'VEF', 'VND',
    'VUV', 'WST', 'XAF', 'XCD', 'XDR', 'XOF', 'XPF', 'YER', 'ZAR', 'ZMW',
    'ZWD'
  ];

  /**
   * Validates that an invoice object contains all mandatory EN16931 fields
   * @param invoice The invoice object to validate
   * @throws Error if mandatory fields are missing
   */
  public static validateMandatoryFields(invoice: any): void {
    const errors: string[] = [];

    // BR-01: Invoice number is mandatory
    if (!invoice.id && !invoice.accountingDocId && !invoice.invoiceId) {
      errors.push('BR-01: Invoice number is mandatory');
    }

    // BR-02: Invoice issue date is mandatory
    if (!invoice.date && !invoice.issueDate) {
      errors.push('BR-02: Invoice issue date is mandatory');
    }

    // BR-06: Seller name is mandatory
    if (!invoice.from?.name) {
      errors.push('BR-06: Seller name is mandatory');
    }

    // BR-07: Buyer name is mandatory  
    if (!invoice.to?.name) {
      errors.push('BR-07: Buyer name is mandatory');
    }

    // BR-16: Invoice line is mandatory (at least one)
    if (!invoice.items || invoice.items.length === 0) {
      errors.push('BR-16: At least one invoice line is mandatory');
    }

    // BR-03: Invoice type code is mandatory
    if (!invoice.accountingDocType) {
      errors.push('BR-03: Invoice type code is mandatory');
    }

    // BR-05: Invoice currency code is mandatory
    if (!invoice.currency) {
      errors.push('BR-05: Invoice currency code is mandatory');
    } else {
      // Validate currency format
      if (!this.VALID_CURRENCIES.includes(invoice.currency.toUpperCase())) {
        errors.push(`Invalid currency code: ${invoice.currency}. Must be a valid ISO 4217 currency code`);
      }
    }

    // BR-08: Seller postal address is mandatory
    if (!invoice.from?.address?.city || !invoice.from?.address?.postalCode || (!invoice.from?.address?.countryCode && !invoice.from?.address?.country)) {
      errors.push('BR-08: Seller postal address (city, postal code, country) is mandatory');
    }

    // BR-10: Buyer postal address is mandatory
    if (!invoice.to?.address?.city || !invoice.to?.address?.postalCode || (!invoice.to?.address?.countryCode && !invoice.to?.address?.country)) {
      errors.push('BR-10: Buyer postal address (city, postal code, country) is mandatory');
    }

    if (errors.length > 0) {
      throw new Error(`EN16931 validation failed:\n${errors.join('\n')}`);
    }
  }

  /**
   * Validates mandatory fields for a parsed XML structure
   * @param doc The parsed XML document
   * @param format The invoice format
   * @throws Error if mandatory fields are missing in XML
   */
  public static validateXmlMandatoryFields(doc: Document, format: string): void {
    const errors: string[] = [];

    if (format === 'ubl' || format === 'xrechnung') {
      // Check for UBL mandatory fields
      const id = doc.getElementsByTagName('cbc:ID')[0]?.textContent;
      if (!id) {
        errors.push('BR-01: Invoice ID is missing in XML');
      }

      const issueDate = doc.getElementsByTagName('cbc:IssueDate')[0]?.textContent;
      if (!issueDate) {
        errors.push('BR-02: Invoice issue date is missing in XML');
      }

      const sellerName = doc.querySelector('AccountingSupplierParty PartyName Name')?.textContent ||
                         doc.querySelector('AccountingSupplierParty PartyLegalEntity RegistrationName')?.textContent;
      if (!sellerName) {
        errors.push('BR-06: Seller name is missing in XML');
      }

      const buyerName = doc.querySelector('AccountingCustomerParty PartyName Name')?.textContent ||
                        doc.querySelector('AccountingCustomerParty PartyLegalEntity RegistrationName')?.textContent;
      if (!buyerName) {
        errors.push('BR-07: Buyer name is missing in XML');
      }

      const invoiceLines = doc.getElementsByTagName('InvoiceLine');
      if (invoiceLines.length === 0) {
        errors.push('BR-16: No invoice lines found in XML');
      }
    }

    if (errors.length > 0) {
      throw new Error(`EN16931 XML validation failed:\n${errors.join('\n')}`);
    }
  }
}