Fix invited athletes in edited challenges

The list of invited athletes was not updated when editing a challenge.
This is now added, but I had to remove the challenge creator from the
search result when inviting athletes as it would break some tracking
rules in EF Core. This is not a problem though and perhaps it's better
this way. The creator will always see the challenge (and is able to join
it) anyways, so inviting yourself never made much sense.

Tevling/Components/ChallengeForm.razor.cs

@@ -72,7 +72,11 @@ protected override void OnParametersSet()
 
     private async Task<IEnumerable<Athlete>> SearchAthletes(string searchText)
     {
-        AthleteFilter filter = new() { SearchText = searchText, NotIn = Challenge.InvitedAthletes?.Select(a => a.Id) };
+        AthleteFilter filter = new()
+        {
+            SearchText = searchText,
+            NotIn = Challenge.InvitedAthletes?.Select(a => a.Id).Append(Athlete.Id)
+        };
         Athlete[] result = await AthleteService.GetAthletesAsync(filter, new Paging(MaximumSuggestions));
 
         return result;

Tevling/Services/ChallengeService.cs

@@ -113,12 +113,27 @@ public async Task<Challenge> UpdateChallengeAsync(int challengeId, ChallengeForm
         Challenge challenge = await dataContext.Challenges
             .Include(c => c.Athletes)
             .Include(c => c.CreatedBy)
+            .Include(c => c.InvitedAthletes)
+            .AsSplitQuery()
             .AsTracking()
             .FirstOrDefaultAsync(c => c.Id == challengeId, ct)
                 ?? throw new Exception($"Unknown challenge ID {challengeId}");
 
         _logger.LogInformation("Updating challenge ID {ChallengeId}", challengeId);
 
+        if (editChallenge.InvitedAthletes != null)
+        {
+            bool stillInvited(Athlete a) => editChallenge.InvitedAthletes.Any(i => i.Id == a.Id);
+
+            IEnumerable<Athlete> newInvites = editChallenge.InvitedAthletes
+                .Where(i => !challenge.InvitedAthletes!.Any(ii => ii.Id == i.Id));
+
+            challenge.InvitedAthletes = challenge.InvitedAthletes!
+                .Where(stillInvited)
+                .Concat(newInvites)
+                .ToList();
+        }
+
         challenge.Title = editChallenge.Title;
         challenge.Description = editChallenge.Description;
         challenge.Start = editChallenge.Start;