/**
 * Brazilian ID validation utilities (CPF/CNPJ)
 */

/**
 * Validate CPF (Cadastro de Pessoa Física) format and checksum
 * CPF format: XXX.XXX.XXX-XX (11 digits)
 */
export function validateCPF(cpf: string): { valid: boolean; formatted?: string; error?: string } {
  // Remove non-numeric characters
  const cleaned = cpf.replace(/\D/g, '');

  // Check length
  if (cleaned.length !== 11) {
    return { valid: false, error: 'CPF must have 11 digits' };
  }

  // Check for invalid patterns (all same digits)
  if (/^(\d)\1{10}$/.test(cleaned)) {
    return { valid: false, error: 'CPF cannot have all same digits' };
  }

  // Validate checksum digits
  let sum = 0;
  let remainder: number;

  // Validate first check digit
  for (let i = 1; i <= 9; i++) {
    sum += parseInt(cleaned.substring(i - 1, i)) * (11 - i);
  }
  remainder = (sum * 10) % 11;
  if (remainder === 10 || remainder === 11) remainder = 0;
  if (remainder !== parseInt(cleaned.substring(9, 10))) {
    return { valid: false, error: 'Invalid CPF checksum (first digit)' };
  }

  // Validate second check digit
  sum = 0;
  for (let i = 1; i <= 10; i++) {
    sum += parseInt(cleaned.substring(i - 1, i)) * (12 - i);
  }
  remainder = (sum * 10) % 11;
  if (remainder === 10 || remainder === 11) remainder = 0;
  if (remainder !== parseInt(cleaned.substring(10, 11))) {
    return { valid: false, error: 'Invalid CPF checksum (second digit)' };
  }

  // Format CPF
  const formatted = `${cleaned.substring(0, 3)}.${cleaned.substring(3, 6)}.${cleaned.substring(6, 9)}-${cleaned.substring(9, 11)}`;

  return { valid: true, formatted };
}

/**
 * Validate CNPJ (Cadastro Nacional da Pessoa Jurídica) format and checksum
 * CNPJ format: XX.XXX.XXX/XXXX-XX (14 digits)
 */
export function validateCNPJ(cnpj: string): { valid: boolean; formatted?: string; error?: string } {
  // Remove non-numeric characters
  const cleaned = cnpj.replace(/\D/g, '');

  // Check length
  if (cleaned.length !== 14) {
    return { valid: false, error: 'CNPJ must have 14 digits' };
  }

  // Check for invalid patterns (all same digits)
  if (/^(\d)\1{13}$/.test(cleaned)) {
    return { valid: false, error: 'CNPJ cannot have all same digits' };
  }

  // Validate checksum digits
  let length = cleaned.length - 2;
  let numbers = cleaned.substring(0, length);
  const digits = cleaned.substring(length);
  let sum = 0;
  let pos = length - 7;

  // Validate first check digit
  for (let i = length; i >= 1; i--) {
    sum += parseInt(numbers.charAt(length - i)) * pos--;
    if (pos < 2) pos = 9;
  }
  let result = sum % 11 < 2 ? 0 : 11 - (sum % 11);
  if (result !== parseInt(digits.charAt(0))) {
    return { valid: false, error: 'Invalid CNPJ checksum (first digit)' };
  }

  // Validate second check digit
  length = length + 1;
  numbers = cleaned.substring(0, length);
  sum = 0;
  pos = length - 7;
  for (let i = length; i >= 1; i--) {
    sum += parseInt(numbers.charAt(length - i)) * pos--;
    if (pos < 2) pos = 9;
  }
  result = sum % 11 < 2 ? 0 : 11 - (sum % 11);
  if (result !== parseInt(digits.charAt(1))) {
    return { valid: false, error: 'Invalid CNPJ checksum (second digit)' };
  }

  // Format CNPJ
  const formatted = `${cleaned.substring(0, 2)}.${cleaned.substring(2, 5)}.${cleaned.substring(5, 8)}/${cleaned.substring(8, 12)}-${cleaned.substring(12, 14)}`;

  return { valid: true, formatted };
}

/**
 * Validate Brazilian tax ID (CPF or CNPJ)
 */
export function validateBrazilianTaxId(taxId: string): {
  valid: boolean;
  type?: 'CPF' | 'CNPJ';
  formatted?: string;
  error?: string;
} {
  const cleaned = taxId.replace(/\D/g, '');

  if (cleaned.length === 11) {
    const cpfResult = validateCPF(taxId);
    return {
      ...cpfResult,
      type: cpfResult.valid ? 'CPF' : undefined,
    };
  } else if (cleaned.length === 14) {
    const cnpjResult = validateCNPJ(taxId);
    return {
      ...cnpjResult,
      type: cnpjResult.valid ? 'CNPJ' : undefined,
    };
  }

  return {
    valid: false,
    error: 'Tax ID must be 11 digits (CPF) or 14 digits (CNPJ)',
  };
}

/**
 * Format tax ID for display (CPF or CNPJ)
 */
export function formatTaxId(taxId: string): string {
  const cleaned = taxId.replace(/\D/g, '');
  if (cleaned.length === 11) {
    return `${cleaned.substring(0, 3)}.${cleaned.substring(3, 6)}.${cleaned.substring(6, 9)}-${cleaned.substring(9, 11)}`;
  } else if (cleaned.length === 14) {
    return `${cleaned.substring(0, 2)}.${cleaned.substring(2, 5)}.${cleaned.substring(5, 8)}/${cleaned.substring(8, 12)}-${cleaned.substring(12, 14)}`;
  }
  return taxId;
}