/**
 * Password Validator
 * T0197: Validates password strength with minimum 8 characters, uppercase, lowercase, number, and special character
 */

export interface PasswordValidationResult {
  isValid: boolean;
  errors: string[];
  strength: {
    length: boolean;
    upper: boolean;
    lower: boolean;
    number: boolean;
    special: boolean;
  };
}

/**
 * Validates password strength according to security rules
 * @param password - The password to validate
 * @returns Validation result with isValid flag, errors array, and strength checks
 */
export function validatePasswordStrength(
  password: string
): PasswordValidationResult {
  const errors: string[] = [];
  const strength = {
    length: false,
    upper: false,
    lower: false,
    number: false,
    special: false,
  };

  // Length check (minimum 8 characters)
  if (password.length < 8) {
    errors.push('password must be at least 8 characters');
  } else {
    strength.length = true;
  }

  // Maximum length check
  if (password.length > 128) {
    errors.push('password must be less than 128 characters');
  }

  // Upper case check
  if (!/[A-Z]/.test(password)) {
    errors.push('password must contain at least one uppercase letter');
  } else {
    strength.upper = true;
  }

  // Lower case check
  if (!/[a-z]/.test(password)) {
    errors.push('password must contain at least one lowercase letter');
  } else {
    strength.lower = true;
  }

  // Number check
  if (!/[0-9]/.test(password)) {
    errors.push('password must contain at least one number');
  } else {
    strength.number = true;
  }

  // Special character check
  if (!/[!@#$%^&*(),.?":{}|<>]/.test(password)) {
    errors.push('password must contain at least one special character');
  } else {
    strength.special = true;
  }

  return {
    isValid: errors.length === 0,
    errors,
    strength,
  };
}

/**
 * Calculates password strength score (0-5)
 * @param password - The password to score
 * @returns Score from 0 to 5
 */
export function calculatePasswordStrength(password: string): number {
  const result = validatePasswordStrength(password);
  let score = 0;

  if (result.strength.length) score++;
  if (result.strength.upper) score++;
  if (result.strength.lower) score++;
  if (result.strength.number) score++;
  if (result.strength.special) score++;

  return score;
}