Reapply "feat(loyalty): EnakPoint & EnakCoin" (#32)

This reverts commit 4e24f9bbb0.

internal/processor/earning_calculator_test.go

@@ -0,0 +1,121 @@
+package processor
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"apskel-pos-be/internal/entities"
+	"apskel-pos-be/internal/models"
+)
+
+// 1 EnakPoint per Rp 100 and 1 EnakCoin per Rp 25.000, as in the F1 example.
+func prdEarningSettings() models.OutletLoyaltySettings {
+	return models.OutletLoyaltySettings{
+		Point: models.LoyaltyEarnSettings{Enabled: true, EarnPerAmount: 100, EarnValue: 1},
+		Coin:  models.LoyaltyEarnSettings{Enabled: true, EarnPerAmount: 25000, EarnValue: 1},
+	}
+}
+
+func TestCalculateEarning_PRDExample(t *testing.T) {
+	// Subtotal after discount Rp 87.500, paid in full in cash.
+	order := &entities.Order{Subtotal: 97500, DiscountAmount: 10000, TaxAmount: 9625, TotalAmount: 97125}
+
+	got := CalculateEarning(order, 0, prdEarningSettings())
+	assert.Equal(t, 87500.0, got.Basis)
+	assert.Equal(t, int64(875), got.Point.Amount)
+	assert.Equal(t, int64(3), got.Coin.Amount)
+
+	// Rp 20.000 of it paid with EnakPoint earns nothing.
+	got = CalculateEarning(order, 20000, prdEarningSettings())
+	assert.Equal(t, 67500.0, got.Basis)
+	assert.Equal(t, int64(675), got.Point.Amount)
+	assert.Equal(t, int64(2), got.Coin.Amount)
+}
+
+func TestCalculateEarning_TaxIsNotPartOfTheBasis(t *testing.T) {
+	withoutTax := &entities.Order{Subtotal: 50000}
+	withTax := &entities.Order{Subtotal: 50000, TaxAmount: 5500, TotalAmount: 55500}
+	assert.Equal(t, CalculateEarning(withoutTax, 0, prdEarningSettings()), CalculateEarning(withTax, 0, prdEarningSettings()))
+	assert.Equal(t, int64(500), CalculateEarning(withTax, 0, prdEarningSettings()).Point.Amount)
+}
+
+func TestCalculateEarning_BelowMinimum(t *testing.T) {
+	s := prdEarningSettings()
+	s.Point.MinOrderAmount = 50000
+
+	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 49999}, 0, s).Point.Amount)
+	assert.Equal(t, int64(500), CalculateEarning(&entities.Order{Subtotal: 50000}, 0, s).Point.Amount, "the minimum itself earns")
+	// The minimum applies to the basis, after discount and EnakPoint.
+	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 60000}, 15000, s).Point.Amount)
+	// Coin has its own minimum.
+	assert.Equal(t, int64(1), CalculateEarning(&entities.Order{Subtotal: 49999}, 0, s).Coin.Amount)
+}
+
+func TestCalculateEarning_MaxPerOrder(t *testing.T) {
+	s := prdEarningSettings()
+	max := int64(300)
+	s.Point.MaxPerOrder = &max
+
+	got := CalculateEarning(&entities.Order{Subtotal: 87500}, 0, s)
+	assert.Equal(t, int64(300), got.Point.Amount)
+	assert.True(t, got.Point.Capped)
+	assert.Equal(t, int64(300), got.Metadata(got.Point)["max_per_order"])
+
+	got = CalculateEarning(&entities.Order{Subtotal: 20000}, 0, s)
+	assert.Equal(t, int64(200), got.Point.Amount)
+	assert.False(t, got.Point.Capped)
+
+	zero := int64(0)
+	s.Point.MaxPerOrder = &zero
+	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 87500}, 0, s).Point.Amount)
+}
+
+func TestCalculateEarning_DisabledEarnsNothing(t *testing.T) {
+	s := prdEarningSettings()
+	s.Point.Enabled = false
+	got := CalculateEarning(&entities.Order{Subtotal: 87500}, 0, s)
+	assert.Equal(t, int64(0), got.Point.Amount)
+	assert.Equal(t, int64(3), got.Coin.Amount, "each currency is switched on its own")
+
+	s.Coin.Enabled = false
+	got = CalculateEarning(&entities.Order{Subtotal: 87500}, 0, s)
+	assert.Equal(t, int64(0), got.Coin.Amount)
+	assert.Equal(t, 87500.0, got.Basis, "the basis is still reported")
+
+	// The defaults of an outlet that never set anything earn nothing.
+	var defaults models.OutletLoyaltySettings
+	loadLoyaltyFields(outletLoyaltyFields(&defaults), nil, "test")
+	got = CalculateEarning(&entities.Order{Subtotal: 87500}, 0, defaults)
+	assert.Equal(t, int64(0), got.Point.Amount)
+	assert.Equal(t, int64(0), got.Coin.Amount)
+}
+
+func TestCalculateEarning_EdgeCases(t *testing.T) {
+	s := prdEarningSettings()
+
+	// floor, not round.
+	assert.Equal(t, int64(875), CalculateEarning(&entities.Order{Subtotal: 87599.99}, 0, s).Point.Amount)
+	// Values float64 cannot hold exactly do not lose a point: computed in float64 this
+	// basis divides to 4956.999…, which a naive floor turns into 4956.
+	per250 := prdEarningSettings()
+	per250.Point.EarnPerAmount = 250
+	assert.Equal(t, int64(4957), CalculateEarning(&entities.Order{Subtotal: 1240155.48, DiscountAmount: 749.11}, 156.37, per250).Point.Amount)
+	// Paying more with EnakPoint than the basis leaves nothing, never a negative amount.
+	got := CalculateEarning(&entities.Order{Subtotal: 10000}, 15000, s)
+	assert.Equal(t, 0.0, got.Basis)
+	assert.Equal(t, int64(0), got.Point.Amount)
+	// earn_value multiplies.
+	s.Point.EarnValue = 5
+	assert.Equal(t, int64(4375), CalculateEarning(&entities.Order{Subtotal: 87500}, 0, s).Point.Amount)
+	// A zero earn_value earns nothing even when enabled.
+	s.Point.EarnValue = 0
+	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 87500}, 0, s).Point.Amount)
+}
+
+func TestCalculateEarning_MetadataSnapshot(t *testing.T) {
+	got := CalculateEarning(&entities.Order{Subtotal: 87500}, 0, prdEarningSettings())
+	assert.Equal(t, entities.Metadata{
+		"basis": 87500.0, "earn_per_amount": int64(100), "earn_value": int64(1), "min_order_amount": int64(0), "capped": false,
+	}, got.Metadata(got.Point))
+}