In memory data access, a methodology to simplify agile development

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using InMemoryDal.Entities;
using InMemoryDal.Interfaces;
using InMemoryDal.Helpers;

namespace InMemoryDal.Logic
{
    /// <summary>
    /// Customer BL
    /// </summary>
    /// <remarks>
    /// GB 28/10/2008
    /// </remarks>
    public class CustomerLogic
    {
        string _connectionString;
        private static NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger();

        public CustomerLogic(string connectionString)
        {
            _connectionString = connectionString;
        }

        public CustomerLogic()
        {
            //  gets connectin string from configuration
        }

        public Customer CreateCustomer(Guid id, String firstname, String lastname, String address)
        {
            Customer customer = new Customer();
            customer.Id = id;
            if (firstname == string.Empty)
            {
                throw new ArgumentException("Firstname empty.");
            }
            if (lastname == string.Empty)
            {
                throw new ArgumentException("Lastname empty.");
            }
            customer.Firstname = firstname;
            customer.Lastname = lastname;
            customer.Address = address;
            return customer;
        }

        public Customer NewCustomer(String firstname, String lastname, String address)
        {
            Customer customer = CreateCustomer(Guid.NewGuid(), firstname, lastname, address);
            //customer.Versione = new byte[] { };
            return customer;
        }

        public Customer AddCustomer(String firstname, String lastname, String address)
        {
            Customer entity = NewCustomer(firstname, lastname, address);

            Save(entity);
            logger.Trace(entity.ToString());
            entity = GetById(entity.Id);
            return entity;
        }

        public Customer UpdateCustomer(Guid id, String firstname, String lastname, String address, byte[] versione)
        {
            Customer entitySulDb = GetById(id);

                Customer entity = CreateCustomer(id, firstname, lastname, address);

                Save(entity);
                logger.Trace(entity.ToString());
                return GetById(id);
        }

        public void DeleteCustomer(Guid id)
        {
            OrderLogic orderLogic = new OrderLogic();
            List<Order> orders = orderLogic.GetByCustomerId(id);
            if (orders.Count != 0)
            {
                throw new ArgumentException("Can't delete customer, it has orders.");
            }
            Customer ent = GetById(id);
            Delete(ent);
            logger.Trace(ent.ToString());
        }

        public Customer GetById(Guid id)
        {
            List<Customer> lis;
            using (IOrdersSession sess = GBDipendencyInjection.GetSession())
            {
                lis = sess.DbCustomers.Search(id, string.Empty, string.Empty, string.Empty, CreateCustomer);
            }
            if (lis.Count == 1)
                return lis[0];
            else if (lis.Count == 0)
                return null;
            else
                throw new ArgumentException("DB read error");
        }

        public List<Customer> GetAll()
        {
            List<Customer> lis;
            using (IOrdersSession sess = GBDipendencyInjection.GetSession())
            {
                lis = sess.DbCustomers.Search(Guid.Empty, string.Empty, string.Empty, string.Empty, CreateCustomer);
            }
            return lis;
        }

        private void Save(Customer customer)
        {
            using (IOrdersSession sess = GBDipendencyInjection.GetSession())
            {
                IDbTransaction trans = sess.BeginTransaction();
                sess.Save(customer);
                trans.Commit();
            }
        }

        private void Delete(Customer customer)
        {
            using (IOrdersSession sess = GBDipendencyInjection.GetSession())
            {
                IDbTransaction trans = sess.BeginTransaction();
                sess.Delete(customer);
                trans.Commit();
            }
        }
    }
}