CustomerService.cs

using System.Linq.Expressions;
using System.Security.Cryptography.X509Certificates;
using AppBoot.DependencyInjection;
using Contracts.Sales;
using DataAccess;
using Sales.DataModel.SalesLT;
using Sales.DataModel.Values;

namespace Sales.Services;

[Service(typeof(ICustomerService))]
class CustomerService(IRepository repository) : ICustomerService
{
    public CustomerData[] GetCustomersWithOrders()
    {
        return GetCustomersWithOrdersFilteredBy(x => true);
    }

    private CustomerData[] GetCustomersWithOrdersFilteredBy(Expression<Func<Customer, bool>> filter)
    {
        var q = repository.GetEntities<Customer>()
            .Where(c => c.SalesOrderHeaders != null && c.SalesOrderHeaders.Any())
            .Where(filter)
            .OrderBy(c => c.CompanyName)
            .Select(c => new CustomerData
            {
                Id = c.CustomerID,
                CompanyName = c.CompanyName,
                SalesPerson = c.SalesPerson
            });

        return q.ToArray();
    }

    public CustomerData[] GetCustomersWithOrdersStartingWith(string prefix)
    {
        Expression<Func<Customer, bool>> filter;
        if (string.IsNullOrEmpty(prefix))
            filter = x => true;
        else
            filter = c => c.CompanyName != null && c.CompanyName.StartsWith(prefix);

        return GetCustomersWithOrdersFilteredBy(filter);
    }

    public CustomerData[] GetCustomersWithOrdersContaining(string fragment)
    {
        Expression<Func<Customer, bool>> filter;
        if (string.IsNullOrEmpty(fragment))
            filter = x => true;
        else
            filter = c => c.CompanyName != null && c.CompanyName.Contains(fragment);

        return GetCustomersWithOrdersFilteredBy(filter);
    }

    public CustomerWithOverdueOrdersData[] GetCustomersWithOverdueOrders()
    {
        var today = DateTime.Today;
        var closedStatuses = new[] { SalesOrderHeaderStatusValues.Shipped, SalesOrderHeaderStatusValues.Cancelled };

        return repository.GetEntities<Customer>()
            .Where(c => c.SalesOrderHeaders.Any(o =>
                o.DueDate < today &&
                !closedStatuses.Contains(o.Status)))
            .Select(c => new CustomerWithOverdueOrdersData
            {
                CustomerName = c.CompanyName ?? $"{c.FirstName} {c.LastName}",
                OverdueOrdersCount = c.SalesOrderHeaders
                    .Where(o => o.DueDate < today && !closedStatuses.Contains(o.Status))
                    .Count(),
                OldestDueDate = c.SalesOrderHeaders
                    .Where(o => o.DueDate < today && !closedStatuses.Contains(o.Status))
                    .Min(o => o.DueDate)
            })
            .OrderBy(x => x.OldestDueDate)
            .ToArray();
    }
}