Add server-authoritative RZ Coin rewards

api/QuestionsApi/Controllers/QuestionsController.cs

@@ -20,6 +20,7 @@ public class QuestionsController : ControllerBase
     private readonly QuestionBookmarkStore _bookmarks;
     private readonly ReviewQueueStore _reviewQueue;
     private readonly CreditStore _credits;
+    private readonly MasteryAwardService _masteryAwards;
 
     public QuestionsController(
         QuestionStore questions,
@@ -30,7 +31,8 @@ public class QuestionsController : ControllerBase
         ServiceMetrics metrics,
         QuestionBookmarkStore bookmarks,
         ReviewQueueStore reviewQueue,
-        CreditStore credits)
+        CreditStore credits,
+        MasteryAwardService masteryAwards)
     {
         _questions = questions;
         _attempts = attempts;
@@ -41,6 +43,7 @@ public class QuestionsController : ControllerBase
         _bookmarks = bookmarks;
         _reviewQueue = reviewQueue;
         _credits = credits;
+        _masteryAwards = masteryAwards;
     }
 
     [HttpGet("systems")]
@@ -152,6 +155,8 @@ public class QuestionsController : ControllerBase
         if (string.IsNullOrWhiteSpace(userId))
             return Unauthorized();
 
+        await _masteryAwards.PrepareAsync(userId);
+
         var record = await _attempts.RecordFirstAttemptAsync(
             question.ExternalId,
             userId,
@@ -178,8 +183,18 @@ public class QuestionsController : ControllerBase
             _metrics.AttemptDuplicate();
         }
         await _reviewQueue.AddFromFirstAttemptAsync(record.Attempt);
-        if (record.Inserted && record.Attempt.IsCorrect && req.MetTimeLimit)
-            await _credits.AwardForFirstAnswerAsync(userId, record.Attempt.Id ?? "");
+        var creditAwards = new List<CreditAward>();
+        if (record.Inserted && record.Attempt.IsCorrect)
+        {
+            var amount = CreditEconomy.FirstCorrectAmount(question.Difficulty);
+            var difficult = question.Difficulty >= 4;
+            var award = await _credits.AwardAsync(userId, new CreditAwardRequest(
+                $"answer:{record.Attempt.Id}", amount,
+                difficult ? CreditReasonCodes.DifficultCorrect : CreditReasonCodes.FirstCorrect,
+                difficult ? $"Difficulty {question.Difficulty} first correct answer" : "First correct answer",
+                "question_attempt", record.Attempt.Id ?? ""));
+            if (award.Award is not null) creditAwards.Add(award.Award);
+        }
 
         var ratingOwner = Guid.NewGuid().ToString("N");
         var shouldRate = await _attempts.TryAcquireRatingLeaseAsync(
@@ -205,6 +220,7 @@ public class QuestionsController : ControllerBase
             throw;
         }
 
+        creditAwards.AddRange(await _masteryAwards.AwardPromotionsAsync(userId));
         return Ok(new FirstQuestionAttemptResponse
         {
             QuestionExternalId = question.ExternalId,
@@ -213,7 +229,8 @@ public class QuestionsController : ControllerBase
                 await _statistics.GetPercentagesForQuestionAsync(question.ExternalId)),
             QuestionElo = rating.QuestionElo,
             Rating = rating,
-            Credits = await _credits.GetStatusAsync(userId)
+            Credits = await _credits.GetStatusAsync(userId),
+            CreditAwards = creditAwards
         });
     }