all the refactor

pkg/cart/price.go

@@ -1,159 +1,26 @@
 package cart
 
 import (
-	"encoding/json"
-	"strconv"
+	"git.k6n.net/mats/platform/money"
+	"git.k6n.net/mats/platform/tax"
 )
 
-func GetTaxAmount(total int64, tax int) int64 {
-	taxD := 10000 / float64(tax)
-	return int64(float64(total) / float64((1 + taxD)))
+// Price represents a monetary amount with optional VAT breakdown by rate.
+// The canonical definition is now in platform/tax; this is a type alias
+// for backward compatibility.
+type Price = tax.Price
+
+// NewPrice returns a new zero Price.
+func NewPrice() *Price { return tax.NewPrice() }
+
+// NewPriceFromIncVat creates a Price from an inc-VAT total and a tax rate in
+// basis points (2500 = 25%, 1250 = 12.5%). Re-exported from platform/tax.
+func NewPriceFromIncVat(incVat int64, rateBp int) *Price {
+	return tax.NewPriceFromIncVat(money.Cents(incVat), rateBp)
 }
 
-type Price struct {
-	IncVat   int64             `json:"incVat"`
-	VatRates map[float32]int64 `json:"vat,omitempty"`
-}
+// MultiplyPrice multiplies a Price by quantity and returns a new Price.
+func MultiplyPrice(p Price, qty int64) *Price { return tax.MultiplyPrice(p, qty) }
 
-func NewPrice() *Price {
-	return &Price{
-		IncVat:   0,
-		VatRates: make(map[float32]int64),
-	}
-}
-
-func NewPriceFromIncVat(incVat int64, taxRate float32) *Price {
-	tax := GetTaxAmount(incVat, int(taxRate*100))
-	return &Price{
-		IncVat: incVat,
-		VatRates: map[float32]int64{
-			taxRate: tax,
-		},
-	}
-}
-
-func (p *Price) ValueExVat() int64 {
-	exVat := p.IncVat
-	for _, amount := range p.VatRates {
-		exVat -= amount
-	}
-	return exVat
-}
-
-func (p *Price) TotalVat() int64 {
-	total := int64(0)
-	for _, amount := range p.VatRates {
-		total += amount
-	}
-	return total
-}
-
-func MultiplyPrice(p Price, qty int64) *Price {
-	ret := &Price{
-		IncVat:   p.IncVat * qty,
-		VatRates: make(map[float32]int64),
-	}
-	for rate, amount := range p.VatRates {
-		ret.VatRates[rate] = amount * qty
-	}
-	return ret
-}
-
-func (p *Price) Multiply(qty int64) {
-	p.IncVat *= qty
-	for rate, amount := range p.VatRates {
-		p.VatRates[rate] = amount * qty
-	}
-}
-
-func (p Price) MarshalJSON() ([]byte, error) {
-	// Build a stable wire format without calling Price.MarshalJSON recursively
-	exVat := p.ValueExVat()
-	var vat map[string]int64
-	if len(p.VatRates) > 0 {
-		vat = make(map[string]int64, len(p.VatRates))
-		for rate, amount := range p.VatRates {
-			// Rely on default formatting that trims trailing zeros for whole numbers
-			// Using %g could output scientific notation for large numbers; float32 rates here are small.
-			key := trimFloat(rate)
-			vat[key] = amount
-		}
-	}
-	type wire struct {
-		ExVat  int64            `json:"exVat"`
-		IncVat int64            `json:"incVat"`
-		Vat    map[string]int64 `json:"vat,omitempty"`
-	}
-	return json.Marshal(wire{ExVat: exVat, IncVat: p.IncVat, Vat: vat})
-}
-
-func (p *Price) UnmarshalJSON(data []byte) error {
-	type wire struct {
-		ExVat  int64            `json:"exVat"`
-		IncVat int64            `json:"incVat"`
-		Vat    map[string]int64 `json:"vat,omitempty"`
-	}
-	var w wire
-	if err := json.Unmarshal(data, &w); err != nil {
-		return err
-	}
-
-	p.IncVat = w.IncVat
-	if len(w.Vat) > 0 {
-		p.VatRates = make(map[float32]int64, len(w.Vat))
-		for rateStr, amount := range w.Vat {
-			rate, err := strconv.ParseFloat(rateStr, 32)
-			if err != nil {
-				return err
-			}
-			p.VatRates[float32(rate)] = amount
-		}
-	} else {
-		p.VatRates = make(map[float32]int64)
-	}
-
-	return nil
-}
-
-// trimFloat converts a float32 tax rate like 25 or 12.5 into a compact string without
-// unnecessary decimals ("25", "12.5").
-func trimFloat(f float32) string {
-	// Convert via FormatFloat then trim trailing zeros and dot.
-	s := strconv.FormatFloat(float64(f), 'f', -1, 32)
-	return s
-}
-
-func (p *Price) Add(price Price) {
-	p.IncVat += price.IncVat
-	for rate, amount := range price.VatRates {
-		p.VatRates[rate] += amount
-	}
-}
-
-func (p *Price) Subtract(price Price) {
-	p.IncVat -= price.IncVat
-	for rate, amount := range price.VatRates {
-		p.VatRates[rate] -= amount
-	}
-}
-
-func SumPrices(prices ...Price) *Price {
-	if len(prices) == 0 {
-		return NewPrice()
-	}
-
-	aggregated := NewPrice()
-
-	for _, price := range prices {
-		aggregated.IncVat += price.IncVat
-		for rate, amount := range price.VatRates {
-			aggregated.VatRates[rate] += amount
-		}
-	}
-
-	if len(aggregated.VatRates) == 0 {
-		aggregated.VatRates = nil
-	}
-
-	return aggregated
-}
+// SumPrices aggregates multiple Prices into one.
+func SumPrices(prices ...Price) *Price { return tax.SumPrices(prices...) }