Use int64 to calculate totals.

So we can get the right value if a discount calculation overflows its value. Signed-off-by: David Calavera <david.calavera@gmail.com>
netlify · Nov 22, 2017 · 09db216 · 09db216
1 parent 6f9eb5c
commit 09db216
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Showing 5 changed files with 87 additions and 23 deletions.
diff --git a/calculator/calculator.go b/calculator/calculator.go
@@ -15,7 +15,7 @@ type Price struct {
 	Subtotal uint64
 	Discount uint64
 	Taxes    uint64
-	Total    uint64
+	Total    int64
 }
 
 // ItemPrice is the price of a single line item.
@@ -25,7 +25,7 @@ type ItemPrice struct {
 	Subtotal uint64
 	Discount uint64
 	Taxes    uint64
-	Total    uint64
+	Total    int64
 }
 
 // Settings represent the site-wide settings for price calculation.
@@ -173,7 +173,10 @@ func CalculatePrice(settings *Settings, jwtClaims map[string]interface{}, params
 	}
 
 	for _, item := range params.Items {
-		lineLogger := priceLogger.WithField("product_type", item.ProductType()).WithField("product_sku", item.ProductSku())
+		lineLogger := priceLogger.WithFields(logrus.Fields{
+			"product_type": item.ProductType(),
+			"product_sku":  item.ProductSku(),
+		})
 
 		itemPrice := ItemPrice{Quantity: item.GetQuantity()}
 		itemPrice.Subtotal = item.PriceInLowestUnit()
@@ -228,7 +231,7 @@ func CalculatePrice(settings *Settings, jwtClaims map[string]interface{}, params
 			}
 		}
 
-		itemPrice.Total = itemPrice.Subtotal - itemPrice.Discount + itemPrice.Taxes
+		itemPrice.Total = int64(itemPrice.Subtotal+itemPrice.Taxes) - int64(itemPrice.Discount)
 		if itemPrice.Total < 0 {
 			itemPrice.Total = 0
 		}
@@ -246,10 +249,13 @@ func CalculatePrice(settings *Settings, jwtClaims map[string]interface{}, params
 		price.Subtotal += (itemPrice.Subtotal * itemPrice.Quantity)
 		price.Discount += (itemPrice.Discount * itemPrice.Quantity)
 		price.Taxes += (itemPrice.Taxes * itemPrice.Quantity)
-		price.Total += (itemPrice.Total * itemPrice.Quantity)
+		price.Total += (itemPrice.Total * int64(itemPrice.Quantity))
 	}
 
-	price.Total = price.Subtotal - price.Discount + price.Taxes
+	price.Total = int64(price.Subtotal+price.Taxes) - int64(price.Discount)
+	if price.Total < 0 {
+		price.Total = 0
+	}
 	priceLogger.WithFields(
 		logrus.Fields{
 			"total_price":    price.Total,

diff --git a/calculator/calculator_test.go b/calculator/calculator_test.go
@@ -79,7 +79,7 @@ func (c *TestCoupon) FixedDiscount(currency string) uint64 {
 func TestNoItems(t *testing.T) {
 	params := PriceParameters{"USA", "USD", nil, nil}
 	price := CalculatePrice(nil, nil, params, testLogger)
-	assert.Equal(t, uint64(0), price.Total)
+	assert.Equal(t, int64(0), price.Total)
 }
 
 func TestNoTaxes(t *testing.T) {
@@ -89,7 +89,7 @@ func TestNoTaxes(t *testing.T) {
 	assert.Equal(t, uint64(100), price.Subtotal)
 	assert.Equal(t, uint64(0), price.Taxes)
 	assert.Equal(t, uint64(0), price.Discount)
-	assert.Equal(t, uint64(100), price.Total)
+	assert.Equal(t, int64(100), price.Total)
 }
 
 func TestFixedVAT(t *testing.T) {
@@ -99,7 +99,7 @@ func TestFixedVAT(t *testing.T) {
 	assert.Equal(t, uint64(100), price.Subtotal)
 	assert.Equal(t, uint64(9), price.Taxes)
 	assert.Equal(t, uint64(0), price.Discount)
-	assert.Equal(t, uint64(109), price.Total)
+	assert.Equal(t, int64(109), price.Total)
 }
 
 func TestFixedVATWhenPricesIncludeTaxes(t *testing.T) {
@@ -109,7 +109,7 @@ func TestFixedVATWhenPricesIncludeTaxes(t *testing.T) {
 	assert.Equal(t, uint64(92), price.Subtotal)
 	assert.Equal(t, uint64(8), price.Taxes)
 	assert.Equal(t, uint64(0), price.Discount)
-	assert.Equal(t, uint64(100), price.Total)
+	assert.Equal(t, int64(100), price.Total)
 }
 
 func TestCountryBasedVAT(t *testing.T) {
@@ -127,7 +127,7 @@ func TestCountryBasedVAT(t *testing.T) {
 	assert.Equal(t, uint64(100), price.Subtotal)
 	assert.Equal(t, uint64(21), price.Taxes)
 	assert.Equal(t, uint64(0), price.Discount)
-	assert.Equal(t, uint64(121), price.Total)
+	assert.Equal(t, int64(121), price.Total)
 }
 
 func TestCouponWithNoTaxes(t *testing.T) {
@@ -138,7 +138,7 @@ func TestCouponWithNoTaxes(t *testing.T) {
 	assert.Equal(t, uint64(100), price.Subtotal)
 	assert.Equal(t, uint64(0), price.Taxes)
 	assert.Equal(t, uint64(10), price.Discount)
-	assert.Equal(t, uint64(90), price.Total)
+	assert.Equal(t, int64(90), price.Total)
 }
 
 func TestCouponWithVAT(t *testing.T) {
@@ -149,7 +149,7 @@ func TestCouponWithVAT(t *testing.T) {
 	assert.Equal(t, uint64(100), price.Subtotal)
 	assert.Equal(t, uint64(9), price.Taxes)
 	assert.Equal(t, uint64(10), price.Discount)
-	assert.Equal(t, uint64(99), price.Total)
+	assert.Equal(t, int64(99), price.Total)
 }
 
 func TestCouponWithVATWhenPRiceIncludeTaxes(t *testing.T) {
@@ -161,7 +161,7 @@ func TestCouponWithVATWhenPRiceIncludeTaxes(t *testing.T) {
 	assert.Equal(t, uint64(92), price.Subtotal)
 	assert.Equal(t, uint64(8), price.Taxes)
 	assert.Equal(t, uint64(10), price.Discount)
-	assert.Equal(t, uint64(90), price.Total)
+	assert.Equal(t, int64(90), price.Total)
 }
 
 func TestCouponWithVATWhenPRiceIncludeTaxesWithQuantity(t *testing.T) {
@@ -173,7 +173,7 @@ func TestCouponWithVATWhenPRiceIncludeTaxesWithQuantity(t *testing.T) {
 	assert.Equal(t, uint64(184), price.Subtotal)
 	assert.Equal(t, uint64(16), price.Taxes)
 	assert.Equal(t, uint64(20), price.Discount)
-	assert.Equal(t, uint64(180), price.Total)
+	assert.Equal(t, int64(180), price.Total)
 }
 
 func TestPricingItems(t *testing.T) {
@@ -203,7 +203,7 @@ func TestPricingItems(t *testing.T) {
 	assert.Equal(t, uint64(100), price.Subtotal)
 	assert.Equal(t, uint64(10), price.Taxes)
 	assert.Equal(t, uint64(0), price.Discount)
-	assert.Equal(t, uint64(110), price.Total)
+	assert.Equal(t, int64(110), price.Total)
 }
 
 func TestMemberDiscounts(t *testing.T) {
@@ -217,7 +217,7 @@ func TestMemberDiscounts(t *testing.T) {
 	assert.Equal(t, uint64(92), price.Subtotal)
 	assert.Equal(t, uint64(8), price.Taxes)
 	assert.Equal(t, uint64(0), price.Discount)
-	assert.Equal(t, uint64(100), price.Total)
+	assert.Equal(t, int64(100), price.Total)
 
 	claims := map[string]interface{}{}
 	require.NoError(t, json.Unmarshal([]byte(`{"app_metadata": {"plan": "member"}}`), &claims))
@@ -228,7 +228,7 @@ func TestMemberDiscounts(t *testing.T) {
 	assert.Equal(t, uint64(92), price.Subtotal)
 	assert.Equal(t, uint64(8), price.Taxes)
 	assert.Equal(t, uint64(10), price.Discount)
-	assert.Equal(t, uint64(90), price.Total)
+	assert.Equal(t, int64(90), price.Total)
 }
 
 func TestFixedMemberDiscounts(t *testing.T) {
@@ -246,7 +246,7 @@ func TestFixedMemberDiscounts(t *testing.T) {
 	assert.Equal(t, uint64(92), price.Subtotal)
 	assert.Equal(t, uint64(8), price.Taxes)
 	assert.Equal(t, uint64(0), price.Discount)
-	assert.Equal(t, uint64(100), price.Total)
+	assert.Equal(t, int64(100), price.Total)
 
 	claims := map[string]interface{}{}
 	require.NoError(t, json.Unmarshal([]byte(`{"app_metadata": {"plan": "member"}}`), &claims))
@@ -257,7 +257,7 @@ func TestFixedMemberDiscounts(t *testing.T) {
 	assert.Equal(t, uint64(92), price.Subtotal)
 	assert.Equal(t, uint64(8), price.Taxes)
 	assert.Equal(t, uint64(10), price.Discount)
-	assert.Equal(t, uint64(90), price.Total)
+	assert.Equal(t, int64(90), price.Total)
 }
 
 func TestMixedDiscounts(t *testing.T) {
@@ -269,7 +269,7 @@ func TestMixedDiscounts(t *testing.T) {
 	assert.NoError(t, err)
 
 	item := &TestItem{
-		sku:      "inclusive-design-patterns",
+		sku:      "design-systems-ebook",
 		itemType: "Book",
 		quantity: 1,
 		price:    3490,
@@ -287,5 +287,5 @@ func TestMixedDiscounts(t *testing.T) {
 		},
 	}
 	price = CalculatePrice(&settings, claims, params, testLogger)
-	assert.Equal(t, 1990, int(price.Total))
+	assert.Equal(t, int64(0), price.Total)
 }
diff --git a/claims/claims_test.go b/claims/claims_test.go
@@ -0,0 +1,31 @@
+package claims
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestClaims(t *testing.T) {
+	b, err := ioutil.ReadFile("test/jwt_payload_fixture.json")
+	assert.NoError(t, err)
+
+	var claims map[string]interface{}
+	err = json.Unmarshal(b, &claims)
+
+	required := map[string]string{
+		"app_metadata.subscription.plan": "smashing",
+	}
+
+	matches := HasClaims(claims, required)
+	assert.True(t, matches)
+
+	required = map[string]string{
+		"app_metadata.subscription.plan": "member",
+	}
+
+	matches = HasClaims(claims, required)
+	assert.False(t, matches)
+}
diff --git a/claims/test/jwt_payload_fixture.json b/claims/test/jwt_payload_fixture.json
@@ -0,0 +1,24 @@
+{
+  "exp": 1511383997,
+  "sub": "68904e78-96c0-4de1-aa37-fa71b1790756",
+  "email": "matt@netlify.com",
+  "app_metadata": {
+    "customer": {
+      "id": "c_id"
+    },
+    "provider": "email",
+    "roles": [
+      "cms",
+      "admin"
+    ],
+    "subscription": {
+      "id": "sub_id",
+      "plan": "smashing"
+    }
+  },
+  "user_metadata": {
+    "firstname": "Matt",
+    "full_name": "Matt Biilmann",
+    "lastname": "Biilmann"
+  }
+}
diff --git a/models/order.go b/models/order.go
@@ -159,7 +159,10 @@ func (o *Order) CalculateTotal(settings *calculator.Settings, claims map[string]
 	o.SubTotal = price.Subtotal
 	o.Taxes = price.Taxes
 	o.Discount = price.Discount
-	o.Total = price.Total
+
+	if price.Total > 0 {
+		o.Total = uint64(price.Total)
+	}
 }
 
 func (o *Order) BeforeDelete(tx *gorm.DB) error {