Quo vs Mul to apply dripping (#564)

## Purpose of Changes and their Description

Fixes hyper aggressive topic dripping
Adds a test, fixes another test that was not setting the
`BlocksPerEpoch` on the params, getting a div by zero.

## Link(s) to Ticket(s) or Issue(s) resolved by this PR
PROTO-2150, RES-302


## Are these changes tested and documented?

- [X] If tested, please describe how. If not, why tests are not needed.
-- tested locally for now, in line with design
- [X] If documented, please describe where. If not, describe why docs
are not needed. -- in line with design now
- [X] Added to `Unreleased` section of `CHANGELOG.md`? -- no need since
it is a fix on new feature that already is in the Changelog.

x/emissions/keeper/keeper.go

@@ -2048,6 +2048,10 @@ func (k *Keeper) DripTopicFeeRevenue(ctx sdk.Context, topicId TopicId, block Blo
 		return err
 	}
 	blocksPerEpoch := alloraMath.NewDecFromInt64(topic.EpochLength)
+	if blocksPerEpoch.IsZero() {
+		ctx.Logger().Warn(fmt.Sprintf("Blocks per epoch is zero for topic %d. Skipping fee revenue drip.", topicId))
+		return nil
+	}
 	blocksPerWeek, err := calculateBlocksPerWeek(ctx, *k)
 	if err != nil {
 		return err
@@ -2056,8 +2060,13 @@ func (k *Keeper) DripTopicFeeRevenue(ctx sdk.Context, topicId TopicId, block Blo
 	if err != nil {
 		return err
 	}
+	if epochsPerWeek.IsZero() {
+		// Log a warning
+		ctx.Logger().Warn(fmt.Sprintf("Epochs per week is zero for topic %d. Skipping fee revenue drip.", topicId))
+		return nil
+	}
 	// this delta is the drip per epoch
-	dripPerEpoch, err := topicFeeRevenueDec.Mul(epochsPerWeek)
+	dripPerEpoch, err := topicFeeRevenueDec.Quo(epochsPerWeek)
 	if err != nil {
 		return err
 	}
@@ -2084,10 +2093,11 @@ func (k *Keeper) DripTopicFeeRevenue(ctx sdk.Context, topicId TopicId, block Blo
 		if err = k.SetLastDripBlock(ctx, topicId, topic.EpochLastEnded); err != nil {
 			return err
 		}
-		logMsg := fmt.Sprintf(
-			"Dripping topic fee revenue: block %d, topicId %d, oldRevenue %v, newRevenue %v",
-			ctx.BlockHeight(), topicId, topicFeeRevenue, newTopicFeeRevenue)
-		ctx.Logger().Debug(logMsg)
+		ctx.Logger().Debug("Dripping topic fee revenue",
+			"block", ctx.BlockHeight(),
+			"topicId", topicId,
+			"oldRevenue", topicFeeRevenue,
+			"newRevenue", newTopicFeeRevenue)
 		return k.topicFeeRevenue.Set(ctx, topicId, newTopicFeeRevenue)
 	}
 	return nil

x/emissions/keeper/keeper_test.go

@@ -3764,3 +3764,47 @@ func (s *KeeperTestSuite) TestAppendReputerLoss() {
 	s.Require().Equal(uint64(len(newAllReputerLosses.ReputerValueBundles)), params.MaxTopReputersToReward)
 	s.Require().Equal(newAllReputerLosses.ReputerValueBundles[1].ValueBundle.Reputer, reputer3)
 }
+
+func (s *KeeperTestSuite) TestDripTopicFeeRevenue() {
+	// Initialize the test environment
+	ctx := s.ctx
+	k := s.emissionsKeeper
+	require := s.Require()
+
+	// Define test data
+	topicId := uint64(1)
+	epochLength := int64(5)
+	block := int64(100)
+	// Calculated expected drip with these values: 26
+	expectedDrip := cosmosMath.NewInt(26)
+	initialRevenue := cosmosMath.NewInt(1000000) // 0.001 in Int representation (assuming 6 decimal places)
+
+	// Create and activate a topic
+	topic := types.Topic{Id: topicId, EpochLength: epochLength}
+	err := k.SetTopic(ctx, topicId, topic)
+	require.NoError(err, "Setting a new topic should not fail")
+
+	err = k.ActivateTopic(ctx, topicId)
+	require.NoError(err, "Activating the topic should not fail")
+
+	// Set up initial topic fee revenue
+	err = k.AddTopicFeeRevenue(ctx, topicId, initialRevenue)
+	require.NoError(err, "Setting initial topic fee revenue should not fail")
+
+	// Call the function under test
+	err = k.DripTopicFeeRevenue(ctx, topicId, block)
+	require.NoError(err, "DripTopicFeeRevenue should not return an error")
+
+	// Retrieve the updated topic fee revenue
+	updatedTopicFeeRevenue, err := k.GetTopicFeeRevenue(ctx, topicId)
+	require.NoError(err, "Getting topic fee revenue should not fail")
+
+	// Assert the expected results
+	require.True(updatedTopicFeeRevenue.LT(initialRevenue),
+		"The topic fee revenue should have decreased after dripping")
+
+	// Calculate expected revenue (this may need adjustment based on your actual implementation)
+	expectedRevenue := initialRevenue.Sub(expectedDrip)
+	require.Equal(expectedRevenue.String(), updatedTopicFeeRevenue.String(),
+		"The topic fee revenue should match the expected value after dripping")
+}

x/emissions/module/rewards/topic_rewards_test.go

@@ -11,6 +11,7 @@ func (s *RewardsTestSuite) TestGetAndUpdateActiveTopicWeights() {
 	ctx := s.ctx
 	maxActiveTopicsNum := uint64(2)
 	params := types.Params{
+		BlocksPerMonth:                  864000,
 		MaxActiveTopicsPerBlock:         maxActiveTopicsNum,
 		MaxPageLimit:                    uint64(100),
 		TopicRewardAlpha:                alloraMath.MustNewDecFromString("0.5"),