using System;
using System.Data;
using System.Collections.Generic;

public class CustomerBusinessLogicLayer
{
   //need default constructor for View
    public CustomerBusinessLogicLayer()
   {
   }

    // Returns an sorted list of all customers (with all fields included)
    public List<Customer> GetCustomers()
    {
        return GetCustomers("LastName");
    }

   // Returns a sorted list of all customers (with all fields included)
    public List<Customer> GetCustomers(String sortExpression)
   {
      List<Customer> customers = new List<Customer>();
      DataSet ds = CustomerDataAccessLayer.GetCustomers();

      foreach (DataRow row in ds.Tables[0].Rows)
      {
         customers.Add(new Customer((int)row["CustomerId"], (String)row["FirstName"],
                                    (String)row["LastName"], (decimal)row["CreditLimit"],
                                    (String)row["PhoneNumber"]));
      }

      customers.Sort(new CustomerComparer(sortExpression));
      return customers;
   }

   // Returns one customer with all fields filled in
    public List<Customer> GetCustomersById(int id)
   {
      List<Customer> customers = new List<Customer>();
      DataSet ds = CustomerDataAccessLayer.GetCustomerById(id);

      foreach (DataRow row in ds.Tables[0].Rows)
      {
         customers.Add(new Customer((int)row["CustomerId"], (String)row["FirstName"], 
                                    (String)row["LastName"], (decimal)row["CreditLimit"],
                                    (String)row["PhoneNumber"]));
      }
      return customers;
   }

   // Updates an existing customer in database (note: business logic omitted to simplify example)
    public  void UpdateCustomer(String firstName, String lastName, decimal creditLimit, string phoneNumber, int customerId)
   {
      CustomerDataAccessLayer.UpdateCustomer(customerId, firstName, lastName, creditLimit, phoneNumber);
   }

    // Inserts a new customer in database (note: business logic omitted to simplify example)
    public void InsertCustomer(int customerId, String firstName, String lastName, decimal creditLimit, string phoneNumber)
    {
        CustomerDataAccessLayer.InsertCustomer(customerId, firstName, lastName, creditLimit, phoneNumber);
    }

    // Deletes an existing customer from database (note: business logic omitted to simplify example)
    public void DeleteCustomer(int customerId)
    {
        CustomerDataAccessLayer.DeleteCustomer(customerId);
    }
}