public class RulesCustomerRepository : ICustomerRepository
{
    private readonly ICustomerRepository _customerRepository;

    public RulesCustomerRepository(ICustomerRepository customerRepository)
    {
        if (customerRepository == null)
            throw new ArgumentNullException(nameof(customerRepository));

        _customerRepository = customerRepository;
    }

    public void Create(Customer customer)
    {
        if (customer == null)
            throw new ArgumentNullException(nameof(customer));

        if (Find(c => c.Name.Value.Equals(customer.Name.Value)).Any())
            throw new Exception("A customer with this name already exists");

        if (!customer.EmailAddress.IsEmpty() && Find(c => c.EmailAddress.Value.Equals(customer.EmailAddress.Value)).Any())
            throw new Exception("A customer with this Email Address already exists");

        _customerRepository.Create(customer);
    }

    public Customer Find(int id)
    {
        if (id <= 0)
            throw new ArgumentOutOfRangeException(nameof(id));

        return _customerRepository.Find(id);
    }

    public IEnumerable<Customer> Find(Func<Customer, bool> predicate)
    {
        if (predicate == null)
            throw new ArgumentNullException(nameof(predicate));

        return _customerRepository.Find(predicate);
    }

    public void Update(Customer customer)
    {
        if (customer == null)
            throw new ArgumentNullException(nameof(customer));

        if (Find(c => c.Name.Value.Equals(customer.Name.Value) && c.Id.Value != customer.Id.Value).Any())
            throw new Exception("A customer with this name already exists");

        if (!customer.EmailAddress.IsEmpty() && Find(c => c.EmailAddress.Value.Equals(customer.EmailAddress.Value) && c.Id.Value != customer.Id.Value).Any())
            throw new Exception("A customer with this Email Address already exist");

        _customerRepository.Update(customer);
    }

    public void Delete(Id id)
    {
        if (id <= 0)
            throw new ArgumentOutOfRangeException(nameof(id));

        _customerRepository.Delete(id);
    }
}