fix: progressive billing billed tier 0 multiple times

openmeterio · Jan 20, 2025 · 167a934 · 167a934
1 parent a2ade61
commit 167a934
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Showing 5 changed files with 334 additions and 95 deletions.
diff --git a/openmeter/billing/service/lineservice/usagebasedline.go b/openmeter/billing/service/lineservice/usagebasedline.go
@@ -452,7 +452,7 @@ func (l usageBasedLine) calculateGraduatedTieredPriceDetailedLines(usage *featur
 
 			tierIndex := in.TierIndex + 1
 
-			if in.Tier.UnitPrice != nil {
+			if in.Tier.UnitPrice != nil && in.Quantity.IsPositive() {
 				newLine := newDetailedLineInput{
 					Name:                   fmt.Sprintf("%s: usage price for tier %d", l.line.Name, tierIndex),
 					Quantity:               in.Quantity,
@@ -474,8 +474,11 @@ func (l usageBasedLine) calculateGraduatedTieredPriceDetailedLines(usage *featur
 				out = append(out, newLine)
 			}
 
+			// If have already billed this flat price for the previous split line, so we can skip it
+			shouldFirstFlatLineBeBilled := in.TierIndex > 0 || l.IsFirstInPeriod()
+
 			// Flat price is always billed for the whole tier when we are crossing the tier boundary
-			if in.Tier.FlatPrice != nil && in.AtTierBoundary {
+			if in.Tier.FlatPrice != nil && in.AtTierBoundary && shouldFirstFlatLineBeBilled {
 				newLine := newDetailedLineInput{
 					Name:                   fmt.Sprintf("%s: flat price for tier %d", l.line.Name, tierIndex),
 					Quantity:               alpacadecimal.NewFromFloat(1),
@@ -650,7 +653,7 @@ func tieredPriceCalculator(in tieredPriceCalculatorInput) error {
 
 	previousTierQty := alpacadecimal.Zero
 	for idx, tier := range in.TieredPrice.WithSortedTiers().Tiers {
-		if previousTierQty.GreaterThan(in.ToQty) {
+		if previousTierQty.GreaterThanOrEqual(in.ToQty) {
 			// We already have enough data to bill for this tiered price
 			break
 		}
@@ -675,6 +678,17 @@ func tieredPriceCalculator(in tieredPriceCalculatorInput) error {
 		previousTierQty = tierUpperBound
 	}
 
+	if in.ToQty.Equal(alpacadecimal.Zero) {
+		// We need to add the first range, in case there's a flat price component
+		qtyRanges = append(qtyRanges, tierRange{
+			Tier:           in.TieredPrice.Tiers[0],
+			TierIndex:      0,
+			AtTierBoundary: true,
+			FromQty:        alpacadecimal.Zero,
+			ToQty:          alpacadecimal.Zero,
+		})
+	}
+
 	if in.IntrospectRangesFn != nil {
 		in.IntrospectRangesFn(qtyRanges)
 	}

diff --git a/openmeter/billing/service/lineservice/usagebasedline_test.go b/openmeter/billing/service/lineservice/usagebasedline_test.go
@@ -839,15 +839,7 @@ func TestTieredGraduatedCalculation(t *testing.T) {
 			usage: featureUsageResponse{
 				LinePeriodQty: alpacadecimal.NewFromFloat(0),
 			},
-			expect: newDetailedLinesInput{
-				{
-					Name:                   "feature: flat price for tier 1",
-					PerUnitAmount:          alpacadecimal.NewFromFloat(100),
-					Quantity:               alpacadecimal.NewFromFloat(1),
-					ChildUniqueReferenceID: "graduated-tiered-1-flat-price",
-					PaymentTerm:            productcatalog.InArrearsPaymentTerm,
-				},
-			},
+			expect: newDetailedLinesInput{},
 		})
 	})
 
@@ -940,14 +932,9 @@ func TestTieredGraduatedCalculation(t *testing.T) {
 			},
 			expect: newDetailedLinesInput{
 				{
-					Name:                   "feature: flat price for tier 1",
-					PerUnitAmount:          alpacadecimal.NewFromFloat(100),
-					Quantity:               alpacadecimal.NewFromFloat(1),
-					ChildUniqueReferenceID: "graduated-tiered-1-flat-price",
-					PaymentTerm:            productcatalog.InArrearsPaymentTerm,
-				},
-				{
-					Name:                   "feature: minimum spend",
+					Name: "feature: minimum spend",
+					// We have a flat fee of 100 for tier 1, and given that it was invoiced as part of the previous split we need to remove
+					// that from the charge.
 					PerUnitAmount:          alpacadecimal.NewFromFloat(900),
 					Quantity:               alpacadecimal.NewFromFloat(1),
 					ChildUniqueReferenceID: GraduatedMinSpendChildUniqueReferenceID,