❔ Validate list of objects after reading excel file

public class Person
{
    public string FullName { get; set; }

    public string Email { get; set; }

    public string City { get; set; }
}

public class PersonValidator : AbstractValidator<Person>
{
    private readonly IPersonRepository _personRepository;
    private readonly List<Person> _peopleFromExcelFile;

    public PersonValidator(IPersonRepository personRepository, List<Person> peopleFromExcelFile)
    {
        _personRepository = personRepository;
        _peopleFromExcelFile = peopleFromExcelFile;

        RuleFor(x => x.FullName)
            .NotEmpty()
            .WithMessage("Full name is empty!");

        RuleFor(x => x.Email)
            .NotEmpty()
            .WithMessage("Email is empty");
            
        RuleFor(x => x.Email)
            .Must(PersonMailDoNotExistInRepository)
            .WithMessage("Email already exists in database");

        RuleFor(x => x.Email)
            .Must(EmailIsNotDuplicateInExcelFile)
            .WithMessage("Email is duplicated in excel file");
    }

    private bool PersonMailDoNotExistInRepository(string email)
    {
        return _personRepository.GetByEmail(email) == null;
    }

    private bool EmailIsNotDuplicateInExcelFile(string email)
    {
        return _peopleFromExcelFile.Count(x =>  x.Email == email) == 1;
    }
}