Track real first attempt question stats

api/QuestionsApi/Services/QuestionAttemptStore.cs

@@ -0,0 +1,79 @@
+using MongoDB.Driver;
+using QuestionsApi.Models;
+
+namespace QuestionsApi.Services;
+
+public class QuestionAttemptStore
+{
+    private readonly IMongoCollection<QuestionAttempt> _col;
+
+    public QuestionAttemptStore(IConfiguration cfg)
+    {
+        var cs = cfg["MongoDB:ConnectionString"] ?? "mongodb://127.0.0.1:27017";
+        var dbName = cfg["MongoDB:DatabaseName"] ?? "GameDb";
+        var client = new MongoClient(cs);
+        var db = client.GetDatabase(dbName);
+        _col = db.GetCollection<QuestionAttempt>("QuestionAttempts");
+
+        var firstAttemptIndex = Builders<QuestionAttempt>.IndexKeys
+            .Ascending(a => a.QuestionExternalId)
+            .Ascending(a => a.UserId);
+        _col.Indexes.CreateOne(new CreateIndexModel<QuestionAttempt>(
+            firstAttemptIndex,
+            new CreateIndexOptions { Unique = true }));
+
+        var questionIndex = Builders<QuestionAttempt>.IndexKeys.Ascending(a => a.QuestionExternalId);
+        _col.Indexes.CreateOne(new CreateIndexModel<QuestionAttempt>(questionIndex));
+    }
+
+    public async Task RecordFirstAttemptAsync(string questionExternalId, string userId, string choiceId, bool isCorrect)
+    {
+        var attempt = new QuestionAttempt
+        {
+            QuestionExternalId = questionExternalId,
+            UserId = userId,
+            ChoiceId = choiceId,
+            IsCorrect = isCorrect,
+            CreatedUtc = DateTime.UtcNow
+        };
+
+        try
+        {
+            await _col.InsertOneAsync(attempt);
+        }
+        catch (MongoWriteException ex) when (ex.WriteError.Category == ServerErrorCategory.DuplicateKey)
+        {
+        }
+    }
+
+    public async Task<Dictionary<string, int>> GetPercentagesForQuestionAsync(string questionExternalId)
+    {
+        var results = await GetPercentagesByQuestionAsync([questionExternalId]);
+        return results.GetValueOrDefault(questionExternalId, []);
+    }
+
+    public async Task<Dictionary<string, Dictionary<string, int>>> GetPercentagesByQuestionAsync(IEnumerable<string> questionExternalIds)
+    {
+        var ids = questionExternalIds.Where(id => !string.IsNullOrWhiteSpace(id)).Distinct().ToList();
+        if (ids.Count == 0)
+            return [];
+
+        var attempts = await _col.Find(a => ids.Contains(a.QuestionExternalId)).ToListAsync();
+        var output = new Dictionary<string, Dictionary<string, int>>();
+
+        foreach (var group in attempts.GroupBy(a => a.QuestionExternalId))
+        {
+            var total = group.Count();
+            if (total == 0)
+                continue;
+
+            output[group.Key] = group
+                .GroupBy(a => a.ChoiceId)
+                .ToDictionary(
+                    choiceGroup => choiceGroup.Key,
+                    choiceGroup => (int)Math.Round(choiceGroup.Count() * 100.0 / total));
+        }
+
+        return output;
+    }
+}

api/QuestionsApi/Services/QuestionStore.cs

@@ -50,6 +50,9 @@ public class QuestionStore
     public async Task<Question?> GetByIdAsync(string id) =>
         await _col.Find(q => q.Id == id).FirstOrDefaultAsync();
 
+    public async Task<Question?> GetByExternalIdAsync(string externalId) =>
+        await _col.Find(q => q.ExternalId == externalId).FirstOrDefaultAsync();
+
     public async Task<Question?> CreateAsync(UpsertQuestionRequest req)
     {
         var question = FromRequest(req);