Refactor to introduce Govor.Application and Govor.Contracts layers

Moved service implementations and interfaces from Govor.API and Govor.Core to new Govor.Application and Govor.Contracts projects. Updated namespaces and references throughout the solution. Added custom exception classes for authentication and invite services. Adjusted dependency injection and project references to use the new structure. This refactor improves separation of concerns and prepares the codebase for better maintainability and scalability.

Govor.Application/Services/InvitesService.cs

@@ -0,0 +1,51 @@
+using Govor.API.Services.Authentication.Interfaces;
+using Govor.Application.Exceptions.InvitesService;
+using Govor.Core.Models;
+using Govor.Core.Repositories.Invaites;
+using Govor.Data.Repositories.Exceptions;
+
+namespace Govor.Application.Services;
+
+public class InvitesService : IInvitesService
+{
+    private readonly IInvitesRepository _invitesRepository;
+
+    public InvitesService(IInvitesRepository invitesRepository)
+    {
+        _invitesRepository = invitesRepository;
+    }
+    
+    public async Task<string> GetRole(User user)
+    {
+        try
+        {
+            var invitation = await _invitesRepository.FindByIdAsync(user.InviteId);
+            return invitation.IsAdmin ? "Admin" : "User";
+        }
+        catch (NotFoundByKeyException<Guid>)
+        {
+            return "User"; 
+        }
+    }
+
+    public Invitation Validate(string inviteCode)
+    {
+        var invite = _invitesRepository.FindByCodeAsync(inviteCode).Result;
+
+        if (invite.EndDate < DateTime.Now ||
+            invite.MaxParticipants <= invite.Users.Count)
+        {
+            invite.IsActive = false;
+            _invitesRepository.UpdateAsync(invite);
+            throw new InviteLinkInvalidException(inviteCode);
+        }
+
+        return invite;
+    }
+
+    public string GenerateInvitationLink(Invitation invitation)
+    {
+        throw new NotImplementedException();
+    }
+}
+