для хранения в оперативной памяти изменено для работы с клиентом

SushiBarListImplements/DataListSingleton.cs

@@ -8,11 +8,13 @@ namespace SushiBarListImplement
         public List<Component> Components { get; set; }
         public List<Order> Orders { get; set; }
         public List<Sushi> Sushis { get; set; }
+        public List<Client> Clients { get; set; }
         private DataListSingleton()
         {
             Components = new List<Component>();
             Orders = new List<Order>();
             Sushis = new List<Sushi>();
+            Clients = new List<Client>();
         }
         public static DataListSingleton GetInstance()
         {

SushiBarListImplements/Implements/ClientStorage.cs

@@ -0,0 +1,106 @@
+using SushiBarContracts.BindingModel;
+using SushiBarContracts.SearchModel;
+using SushiBarContracts.ViewModels;
+using SushiBarListImplement;
+using SushiBarListImplements.Models;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SushiBarListImplements.Implements
+{
+    public class ClientStorage
+    {
+        private readonly DataListSingleton _source;
+        public ClientStorage()
+        {
+            _source = DataListSingleton.GetInstance();
+        }
+        public List<ClientViewModel> GetFullList()
+        {
+            var result = new List<ClientViewModel>();
+            foreach (var client in _source.Clients)
+            {
+                result.Add(client.GetViewModel);
+            }
+            return result;
+        }
+        public List<ClientViewModel> GetFilteredList(ClientSearchModel model)
+        {
+            var result = new List<ClientViewModel>();
+            if (string.IsNullOrEmpty(model.Email))
+            {
+                return result;
+            }
+            foreach (var client in _source.Clients)
+            {
+                if (client.Email.Contains(model.Email))
+                {
+                    result.Add(client.GetViewModel);
+                }
+            }
+            return result;
+        }
+        public ClientViewModel? GetElement(ClientSearchModel model)
+        {
+            if (string.IsNullOrEmpty(model.Email) && !model.Id.HasValue)
+            {
+                return null;
+            }
+            foreach (var client in _source.Clients)
+            {
+                if (!string.IsNullOrEmpty(model.Email) && client.Email == model.Email ||
+                model.Id.HasValue && client.Email == model.Email)
+                {
+                    return client.GetViewModel;
+                }
+            }
+            return null;
+        }
+        public ClientViewModel? Insert(ClientBindingModel model)
+        {
+            model.Id = 1;
+            foreach (var client in _source.Clients)
+            {
+                if (model.Id <= client.Id)
+                {
+                    model.Id = client.Id + 1;
+                }
+            }
+            var newClient = Client.Create(model);
+            if (newClient == null)
+            {
+                return null;
+            }
+            _source.Clients.Add(newClient);
+            return newClient.GetViewModel;
+        }
+        public ClientViewModel? Update(ClientBindingModel model)
+        {
+            foreach (var client in _source.Clients)
+            {
+                if (client.Id == model.Id)
+                {
+                    client.Update(model);
+                    return client.GetViewModel;
+                }
+            }
+            return null;
+        }
+        public ClientViewModel? Delete(ClientBindingModel model)
+        {
+            for (int i = 0; i < _source.Clients.Count; ++i)
+            {
+                if (_source.Clients[i].Id == model.Id)
+                {
+                    var element = _source.Clients[i];
+                    _source.Clients.RemoveAt(i);
+                    return element.GetViewModel;
+                }
+            }
+            return null;
+        }
+    }
+}

SushiBarListImplements/Models/Client.cs

@@ -0,0 +1,45 @@
+using SushiBarContracts.BindingModel;
+using SushiBarContracts.ViewModels;
+using SushiBarDataModels;
+
+namespace SushiBarListImplements.Models
+{
+    public class Client : IClientModel
+    {
+        public int Id { get; private set; }
+        public string ClientFIO { get; private set; } = string.Empty;
+        public string Email { get; set; } = string.Empty;
+        public string Password { get; set; } = string.Empty;
+        public static Client? Create(ClientBindingModel? model)
+        {
+            if (model == null)
+            {
+                return null;
+            }
+            return new Client()
+            {
+                Id = model.Id,
+                ClientFIO = model.ClientFIO,
+                Email = model.Email,
+                Password = model.Password,
+            };
+        }
+        public void Update(ClientBindingModel? model)
+        {
+            if (model == null)
+            {
+                return;
+            }
+            ClientFIO = model.ClientFIO;
+            Email = model.Email;
+            Password = model.Password;
+        }
+        public ClientViewModel GetViewModel => new()
+        {
+            Id = Id,
+            ClientFIO = ClientFIO,
+            Email = Email,
+            Password = Password
+        };
+    }
+}

SushiBarListImplements/Models/Order.cs

@@ -10,6 +10,7 @@ namespace SushiBarListImplements.Models
     {
         public int Id { get; private set; }
         public int SushiId { get; private set; }
+        public int ClientId { get; private set; }
         public int Count { get; private set; }
         public double Sum { get; private set; }
         public OrderStatus Status { get; private set; }
@@ -30,7 +31,8 @@ namespace SushiBarListImplements.Models
                 Sum = model.Sum,
                 Status = model.Status,
                 DateCreate = model.DateCreate,
-                DateImplement = model.DateImplement
+                DateImplement = model.DateImplement,
+                ClientId = model.ClientId,
             };
         }
 
@@ -46,6 +48,7 @@ namespace SushiBarListImplements.Models
             Status = model.Status;
             DateCreate = model.DateCreate;
             DateImplement = model.DateImplement;
+            ClientId = model.ClientId;
         }
 
         public OrderViewModel GetViewModel => new()
@@ -56,7 +59,8 @@ namespace SushiBarListImplements.Models
             Sum = Sum,
             Status = Status,
             DateCreate = DateCreate,
-            DateImplement = DateImplement
+            DateImplement = DateImplement,
+            ClientId = ClientId,
         };
     }
 }