04. Generator haseł

const CHARS = {
  uppercase: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
  lowercase: 'abcdefghijklmnopqrstuvwxyz',
  digits: '0123456789',
  special: '!@#$%^&*()_+-=[]{}|;:,.<>?',
};

export function generatePassword(options) {
  const { length, useUppercase, useLowercase, useDigits, useSpecial } = options;
  let charset = '';
  const guaranteed = [];

  if (useUppercase) { charset += CHARS.uppercase; guaranteed.push(randomChar(CHARS.uppercase)); }
  if (useLowercase) { charset += CHARS.lowercase; guaranteed.push(randomChar(CHARS.lowercase)); }
  if (useDigits)    { charset += CHARS.digits;    guaranteed.push(randomChar(CHARS.digits)); }
  if (useSpecial)   { charset += CHARS.special;   guaranteed.push(randomChar(CHARS.special)); }

  if (!charset) return '';

  const remaining = Array.from(
    { length: length - guaranteed.length },
    () => randomChar(charset)
  );

  return shuffle([...guaranteed, ...remaining]).join('');
}

function randomChar(str) {
  return str[Math.floor(Math.random() * str.length)];
}

function shuffle(arr) {
  return arr.sort(() => Math.random() - 0.5);
}

export function calculateStrength(password) {
  let score = 0;
  if (password.length >= 8) score++;
  if (password.length >= 12) score++;
  if (password.length >= 16) score++;
  if (/[A-Z]/.test(password)) score++;
  if (/[a-z]/.test(password)) score++;
  if (/[0-9]/.test(password)) score++;
  if (/[^A-Za-z0-9]/.test(password)) score++;
  if (score <= 2) return 'weak';
  if (score <= 4) return 'medium';
  if (score <= 6) return 'strong';
  return 'very-strong';
}