Refactor data layer, add business layer

BusinessLayer/BusinessLayer.csproj

@@ -4,4 +4,8 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="../DataAccessLayer/DataAccessLayer.csproj" />
+  </ItemGroup>
 </Project>

BusinessLayer/Services/IService.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+
+namespace BusinessLayer.Services
+{
+    public interface IService<T>
+        where T : class
+    {
+        IEnumerable<T> GetAll(int? limit, int? offset);
+        T? GetById(Guid id);
+        void Add(T entity);
+        void Update(T entity);
+        void Delete(Guid id);
+    }
+}

BusinessLayer/Services/IUserService.cs

@@ -0,0 +1,10 @@
+using DataAccessLayer.Entities;
+
+namespace BusinessLayer.Services
+{
+    public interface IUserService : IService<UserAccount>
+    {
+        UserAccount? GetByUsername(string username);
+        UserAccount? GetByEmail(string email);
+    }
+}

BusinessLayer/Services/UserService.cs

@@ -0,0 +1,50 @@
+using DataAccessLayer;
+using DataAccessLayer.Entities;
+
+namespace BusinessLayer.Services
+{
+    public class UserService : IUserService
+    {
+        private readonly IUserAccountRepository _userAccountRepository;
+
+        public UserService(IUserAccountRepository userAccountRepository)
+        {
+            _userAccountRepository = userAccountRepository;
+        }
+
+        public IEnumerable<UserAccount> GetAll(int? limit, int? offset)
+        {
+            return _userAccountRepository.GetAll(limit, offset);
+        }
+
+        public UserAccount? GetById(Guid id)
+        {
+            return _userAccountRepository.GetById(id);
+        }
+
+        public UserAccount? GetByUsername(string username)
+        {
+            return _userAccountRepository.GetByUsername(username);
+        }
+
+        public UserAccount? GetByEmail(string email)
+        {
+            return _userAccountRepository.GetByEmail(email);
+        }
+
+        public void Add(UserAccount userAccount)
+        {
+            _userAccountRepository.Add(userAccount);
+        }
+
+        public void Update(UserAccount userAccount)
+        {
+            _userAccountRepository.Update(userAccount);
+        }
+
+        public void Delete(Guid id)
+        {
+            _userAccountRepository.Delete(id);
+        }
+    }
+}