Agents/MainWindow.axaml.cs

using Avalonia.Controls;
using System;
using Agents.Models;
using System.Collections.ObjectModel;
using Avalonia.Interactivity;
using System.Linq;
using System.Runtime.ExceptionServices;

namespace Agents
{
    public partial class MainWindow : Window
    {
        
        static User11Context db = new User11Context(); // ïîäêëþ÷åíèå ê ÁÄ
        ObservableCollection<Agent> AgentsitemSource = new ObservableCollection<Agent>(db.Agents.OrderBy(it=>it.Title)); // îñíîâíîé ëèñò äëÿ Àãåíòîâ
        ObservableCollection<Agent> ListAgents2; // âòîðîé ëèñò äëÿ ñîðòèðîâêè Àãåíòîâ ïî óìîë÷àíèþ

        public MainWindow()
        {
            InitializeComponent();

            ListAgents.ItemsSource = AgentsitemSource;
            ListAgents2 = AgentsitemSource;
        }

        private void SortAg(object? sender, Avalonia.Controls.SelectionChangedEventArgs e) // Âûáîð ñîðòèðîâêè Àãåíòîâ
        {
            SortAgent();
        }

        private void ListAgents_SelectionChanged(object? sender, Avalonia.Controls.SelectionChangedEventArgs e) // Ñîáûòèå âûáîðà Àãåíòà è âûâîä ñïèêà ïðîäóêòîâ
        {
            UpdateInfoListProduct();
        }
        
        private void SortListProductAgents_method(object? sender, Avalonia.Controls.SelectionChangedEventArgs e) // âûáîð ñîðòèðîâêè ñïèñêà òîâàðîâ
        {
            UpdateInfoListProduct();
        }

        

        void SortAgent() // ñîðòèðîâêà Àãåíòîâ
        {
            switch (SortListAgents.SelectedIndex)
            {
                case 1: AgentsitemSource = new ObservableCollection<Agent>(AgentsitemSource.OrderByDescending(it => it.Title).ToList()); break; // ïî óáûâàíèþ
                case 2: AgentsitemSource = new ObservableCollection<Agent>(AgentsitemSource.OrderBy(it => it.Title).ToList()); break; // ïî âîçðàñòàíèþ
                default: AgentsitemSource = ListAgents2; break; // èçíà÷àëüíûé ïîðÿäîê áåç ñîðòèðîâêè
            }

            ListAgents.ItemsSource = new ObservableCollection<Agent>(AgentsitemSource);
        }

        private void UpdateInfoListProduct() // ñïèñîê òîâàðîâ è èíôîðìàöèÿ î íèõ
        {
            Agent? agent = db.Agents.Where(it => it == ListAgents.SelectedItem).FirstOrDefault();  // íàõîäèì âûäåëåííîãî Àãåíòà
            if (agent != null)
            {
                Productsale? PS = db.Productsales.Where(it => it.Agentid == agent.Id).FirstOrDefault();
                var prods = db.Productsales
                .Where(PWS => PWS.Agentid == agent.Id)
                .Select(PWS => new ProductDTO
                {
                    Title = PWS.Product.Title,
                    Image = PWS.Product.Image,
                    Producttypeid = PWS.Product.Producttypeid,
                    Productionpersoncount = PWS.Product.Productionpersoncount,
                    Mincostforagent = PWS.Product.Mincostforagent,
                    Description = PWS.Product.Description,
                    Articlenumber = PWS.Product.Articlenumber,
                    SalesCount = db.Productsales.Where(it => it.Productid == PWS.Productid).Count(),
                    ProductDiscount = productDiscount(db.Productsales.Where(it => it.Productid == PWS.Productid).Count())
                }).ToList();

                switch (SortListProductAgents.SelectedIndex)
                {
                    case 1: prods = prods.OrderBy(p => p.Title).ToList(); break;
                    case 2: prods = prods.OrderByDescending(p => p.Title).ToList(); break;
                    default: break;
                }

                ListProducts.ItemsSource = new ObservableCollection<ProductDTO>(prods);
            }
        }
        

        static int productDiscount(int SalesCount) // ðàñ÷¸ò ñêèäîê
        {
            int Discount = 0;
            if (10_000 <= SalesCount && SalesCount < 50_000)
            {
                Discount = 5;
            }
            else if (50_000 <= SalesCount && SalesCount < 150_000)
            {
                Discount = 10;
            }
            else if (150_000 <= SalesCount && SalesCount < 500_000)
            {
                Discount = 20;
            }
            else if (SalesCount>500_000)
            {
                Discount = 25;
            }

            return Discount;
        }

        void Button_search(object sender, RoutedEventArgs e) // ïîèñêîâèê àãåíòîâ
        {
            string? Search = search.Text;
            if (search.Text != "")
            {
                AgentsitemSource = new ObservableCollection<Agent>(db.Agents.Where(it => it.Title == search.Text || 
                                                                                         it.Address == search.Text || 
                                                                                         it.Inn == search.Text || 
                                                                                         it.Kpp == search.Text || 
                                                                                         it.Directorname == search.Text || 
                                                                                         it.Phone == search.Text || 
                                                                                         it.Email == search.Text 
                                                                                         
                                                                                         ));
                if (AgentsitemSource != null)
                {
                    ListAgents.ItemsSource = AgentsitemSource;
                    ListAgents2 = AgentsitemSource;
                    SortAgent();
                }
                else
                {
                    ListAgents.ItemsSource = null;
                }
            }
            else
            {
                AgentsitemSource = new ObservableCollection<Agent>(db.Agents.OrderBy(it => it.Title));
                ListAgents2 = AgentsitemSource;
                SortAgent();
            }
        }

        private void ButtonUpdate(object sender, RoutedEventArgs e) // Îáíîâëåíèå ñïèñêà ïðîäóêòîâ äëÿ âûäåëåííîãî Àãåíòà
        {
            UpdateInfoListProduct();
        }

        private void ButtonAgentEidtor(object sender, RoutedEventArgs e) // ïåðåõîä â îêíî ðåäàêòèðîâàíèÿ Àãåíòîâ
        {
            new AgentEidtor().Show();
            Close();
        }

        private void ButtonProductEidtor(object sender, RoutedEventArgs e) // ïåðåõîä â îêíî ðåäàêòèðîâàíèÿ òîâàðîâ
        {
            new ProductEditor().Show();
            Close();
        }

        private void ButtonAddProduct(object sender, RoutedEventArgs e) // ïåðåõîä â îêíî äîáàâëåíèÿ òîâàðîâ
        {
            new AddProduct().Show();
            Close();
        }
    }
}