[PM-28260] Optimize bulk reinvite endpoint (#6670)

* Implement optimized bulk invite resend command

- Added IBulkResendOrganizationInvitesCommand interface to define the bulk resend operation.
- Created BulkResendOrganizationInvitesCommand class to handle the logic for resending invites to multiple organization users.
- Integrated logging and validation to ensure only valid users receive invites.
- Included error handling for non-existent organizations and invalid user statuses.

* Add unit tests for BulkResendOrganizationInvitesCommand

- Implemented comprehensive test cases for the BulkResendOrganizationInvitesCommand class.
- Validated user statuses and ensured correct handling of valid and invalid users during bulk invite resends.
- Included tests for scenarios such as organization not found and empty user lists.
- Utilized Xunit and NSubstitute for effective testing and mocking of dependencies.

* Add IBulkResendOrganizationInvitesCommand to service collection

- Registered IBulkResendOrganizationInvitesCommand in the service collection for dependency injection.

* Update OrganizationUsersController to utilize IBulkResendOrganizationInvitesCommand

- Added IBulkResendOrganizationInvitesCommand to the OrganizationUsersController for handling bulk invite resends based on feature flag.
- Updated BulkReinvite method to conditionally use the new command or the legacy service based on the feature flag status.
- Enhanced unit tests to verify correct command usage depending on feature flag state, ensuring robust testing for both scenarios.

test/Core.Test/AdminConsole/OrganizationFeatures/OrganizationUsers/InviteUsers/BulkResendOrganizationInvitesCommandTests.cs

@@ -0,0 +1,113 @@
+using Bit.Core.AdminConsole.Entities;
+using Bit.Core.AdminConsole.OrganizationFeatures.OrganizationUsers.InviteUsers;
+using Bit.Core.AdminConsole.OrganizationFeatures.OrganizationUsers.InviteUsers.Models;
+using Bit.Core.Entities;
+using Bit.Core.Enums;
+using Bit.Core.Exceptions;
+using Bit.Core.Repositories;
+using Bit.Test.Common.AutoFixture;
+using Bit.Test.Common.AutoFixture.Attributes;
+using NSubstitute;
+using Xunit;
+
+namespace Bit.Core.Test.AdminConsole.OrganizationFeatures.OrganizationUsers.InviteUsers;
+
+[SutProviderCustomize]
+public class BulkResendOrganizationInvitesCommandTests
+{
+    [Theory]
+    [BitAutoData]
+    public async Task BulkResendInvitesAsync_ValidatesUsersAndSendsBatchInvite(
+        Organization organization,
+        OrganizationUser validUser1,
+        OrganizationUser validUser2,
+        OrganizationUser acceptedUser,
+        OrganizationUser wrongOrgUser,
+        SutProvider<BulkResendOrganizationInvitesCommand> sutProvider)
+    {
+        validUser1.OrganizationId = organization.Id;
+        validUser1.Status = OrganizationUserStatusType.Invited;
+        validUser2.OrganizationId = organization.Id;
+        validUser2.Status = OrganizationUserStatusType.Invited;
+        acceptedUser.OrganizationId = organization.Id;
+        acceptedUser.Status = OrganizationUserStatusType.Accepted;
+        wrongOrgUser.OrganizationId = Guid.NewGuid();
+        wrongOrgUser.Status = OrganizationUserStatusType.Invited;
+
+        var users = new List<OrganizationUser> { validUser1, validUser2, acceptedUser, wrongOrgUser };
+        var userIds = users.Select(u => u.Id).ToList();
+
+        sutProvider.GetDependency<IOrganizationUserRepository>().GetManyAsync(userIds).Returns(users);
+        sutProvider.GetDependency<IOrganizationRepository>().GetByIdAsync(organization.Id).Returns(organization);
+
+        var result = (await sutProvider.Sut.BulkResendInvitesAsync(organization.Id, null, userIds)).ToList();
+
+        Assert.Equal(4, result.Count);
+        Assert.Equal(2, result.Count(r => string.IsNullOrEmpty(r.Item2)));
+        Assert.Equal(2, result.Count(r => r.Item2 == "User invalid."));
+
+        await sutProvider.GetDependency<ISendOrganizationInvitesCommand>()
+            .Received(1)
+            .SendInvitesAsync(Arg.Is<SendInvitesRequest>(req =>
+                req.Organization == organization &&
+                req.Users.Length == 2 &&
+                req.InitOrganization == false));
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task BulkResendInvitesAsync_AllInvalidUsers_DoesNotSendInvites(
+        Organization organization,
+        List<OrganizationUser> organizationUsers,
+        SutProvider<BulkResendOrganizationInvitesCommand> sutProvider)
+    {
+        foreach (var user in organizationUsers)
+        {
+            user.OrganizationId = organization.Id;
+            user.Status = OrganizationUserStatusType.Confirmed;
+        }
+
+        var userIds = organizationUsers.Select(u => u.Id).ToList();
+        sutProvider.GetDependency<IOrganizationUserRepository>().GetManyAsync(userIds).Returns(organizationUsers);
+        sutProvider.GetDependency<IOrganizationRepository>().GetByIdAsync(organization.Id).Returns(organization);
+
+        var result = (await sutProvider.Sut.BulkResendInvitesAsync(organization.Id, null, userIds)).ToList();
+
+        Assert.Equal(organizationUsers.Count, result.Count);
+        Assert.All(result, r => Assert.Equal("User invalid.", r.Item2));
+        await sutProvider.GetDependency<ISendOrganizationInvitesCommand>().DidNotReceive()
+            .SendInvitesAsync(Arg.Any<SendInvitesRequest>());
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task BulkResendInvitesAsync_OrganizationNotFound_ThrowsNotFoundException(
+        Guid organizationId,
+        List<Guid> userIds,
+        List<OrganizationUser> organizationUsers,
+        SutProvider<BulkResendOrganizationInvitesCommand> sutProvider)
+    {
+        sutProvider.GetDependency<IOrganizationUserRepository>().GetManyAsync(userIds).Returns(organizationUsers);
+        sutProvider.GetDependency<IOrganizationRepository>().GetByIdAsync(organizationId).Returns((Organization?)null);
+
+        await Assert.ThrowsAsync<NotFoundException>(() =>
+            sutProvider.Sut.BulkResendInvitesAsync(organizationId, null, userIds));
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task BulkResendInvitesAsync_EmptyUserList_ReturnsEmpty(
+        Organization organization,
+        SutProvider<BulkResendOrganizationInvitesCommand> sutProvider)
+    {
+        var emptyUserIds = new List<Guid>();
+        sutProvider.GetDependency<IOrganizationUserRepository>().GetManyAsync(emptyUserIds).Returns(new List<OrganizationUser>());
+        sutProvider.GetDependency<IOrganizationRepository>().GetByIdAsync(organization.Id).Returns(organization);
+
+        var result = await sutProvider.Sut.BulkResendInvitesAsync(organization.Id, null, emptyUserIds);
+
+        Assert.Empty(result);
+        await sutProvider.GetDependency<ISendOrganizationInvitesCommand>().DidNotReceive()
+            .SendInvitesAsync(Arg.Any<SendInvitesRequest>());
+    }
+}