try new vouchers

cmd/cart/cart-grain.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"git.tornberg.me/go-cart-actor/pkg/voucher"
 )
 
 // Legacy padded [16]byte CartId and its helper methods removed.
@@ -86,7 +87,55 @@ type Voucher struct {
 	Code  string                  `json:"code"`
 	Rules []*messages.VoucherRule `json:"rules"`
 	Id    uint32                  `json:"id"`
-	Value Price                   `json:"value"`
+	Value int64                   `json:"value"`
+}
+
+func (v *Voucher) AppliesTo(cart *CartGrain) ([]*CartItem, bool) {
+	// No rules -> applies to entire cart
+	if len(v.Rules) == 0 {
+		return cart.Items, true
+	}
+
+	// Build evaluation context once
+	ctx := voucher.EvalContext{
+		Items:        make([]voucher.Item, 0, len(cart.Items)),
+		CartTotalInc: 0,
+	}
+
+	if cart.TotalPrice != nil {
+		ctx.CartTotalInc = cart.TotalPrice.IncVat
+	}
+
+	for _, it := range cart.Items {
+		category := ""
+		if it.Meta != nil {
+			category = it.Meta.Category
+		}
+		ctx.Items = append(ctx.Items, voucher.Item{
+			Sku:       it.Sku,
+			Category:  category,
+			UnitPrice: it.Price.IncVat,
+		})
+	}
+
+	// All voucher rules must pass (logical AND)
+	for _, rule := range v.Rules {
+		expr := rule.GetCondition()
+		if expr == "" {
+			// Empty condition treated as pass (acts like a comment / placeholder)
+			continue
+		}
+		rs, err := voucher.ParseRules(expr)
+		if err != nil {
+			// Fail closed on parse error
+			return nil, false
+		}
+		if !rs.Applies(ctx) {
+			return nil, false
+		}
+	}
+
+	return cart.Items, true
 }
 
 func (c *CartGrain) GetId() uint64 {
@@ -208,9 +257,11 @@ func (c *CartGrain) UpdateTotals() {
 	for _, delivery := range c.Deliveries {
 		c.TotalPrice.Add(delivery.Price)
 	}
-	// for _, voucher := range c.Vouchers {
+	for _, voucher := range c.Vouchers {
-	// 	c.TotalPrice -= voucher.Value
+		if _, ok := voucher.AppliesTo(c); ok {
-	// 	c.TotalTax -= voucher.TaxValue
+			value := NewPriceFromIncVat(voucher.Value, 25)
-	// 	c.TotalDiscountTax += voucher.TaxValue
+
-	// }
+			c.TotalDiscount.Add(*value)
+		}
+	}
 }

cmd/cart/mutation_add_voucher.go

@@ -7,6 +7,32 @@ import (
 	"git.tornberg.me/go-cart-actor/pkg/messages"
 )
 
+func RemoveVoucher(g *CartGrain, m *messages.RemoveVoucher) error {
+	if m == nil {
+		return &actor.MutationError{
+			Message:    "RemoveVoucher: nil payload",
+			Code:       1003,
+			StatusCode: 400,
+		}
+	}
+
+	if !slices.ContainsFunc(g.Vouchers, func(v *Voucher) bool {
+		return v.Id == m.Id
+	}) {
+		return &actor.MutationError{
+			Message:    "voucher not applied",
+			Code:       1004,
+			StatusCode: 400,
+		}
+	}
+
+	g.Vouchers = slices.DeleteFunc(g.Vouchers, func(v *Voucher) bool {
+		return v.Id == m.Id
+	})
+	g.UpdateTotals()
+	return nil
+}
+
 func AddVoucher(g *CartGrain, m *messages.AddVoucher) error {
 	if m == nil {
 		return &actor.MutationError{
@@ -31,7 +57,7 @@ func AddVoucher(g *CartGrain, m *messages.AddVoucher) error {
 		Id:    g.lastVoucherId,
 		Code:  m.Code,
 		Rules: m.VoucherRules,
-		Value: *NewPriceFromIncVat(m.Value, 25.0),
+		Value: m.Value,
 	})
 	g.UpdateTotals()
 	return nil

cmd/cart/pool-server.go

@@ -12,6 +12,7 @@ import (
 
 	"git.tornberg.me/go-cart-actor/pkg/actor"
 	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+	"git.tornberg.me/go-cart-actor/pkg/voucher"
 	"github.com/gogo/protobuf/proto"
 )
 
@@ -444,9 +445,20 @@ func (s *PoolServer) ProxyHandler(fn func(w http.ResponseWriter, r *http.Request
 	}
 }
 
+type AddVoucherRequest struct {
+	VoucherCode string `json:"code"`
+}
+
 func (s *PoolServer) AddVoucherHandler(w http.ResponseWriter, r *http.Request, cartId CartId) error {
-	msg := &messages.AddVoucher{}
+	data := &AddVoucherRequest{}
-	json.NewDecoder(r.Body).Decode(msg)
+	json.NewDecoder(r.Body).Decode(data)
+	v := voucher.Service{}
+	msg, err := v.GetVoucher(data.VoucherCode)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return err
+	}
 	reply, err := s.ApplyLocal(cartId, msg)
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)

pkg/voucher/parser.go

@@ -0,0 +1,347 @@
+package voucher
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+/*
+Package voucher - rule parser
+
+A lightweight parser for voucher rule expressions.
+
+Supported rule kinds (case-insensitive keywords):
+
+  sku=SKU1|SKU2|SKU3
+    - At least one of the listed SKUs must be present in the cart.
+
+  category=CatA|CatB|CatC
+    - At least one of the listed categories must be present.
+
+  min_total>=12345
+    - Cart total (Inc VAT) must be at least this value (int64).
+
+  min_item_price>=5000
+    - At least one individual item (Inc VAT single unit price) must be at least this value (int64).
+
+Rule list grammar (simplified):
+  rules := rule (sep rule)*
+  rule  := (sku|category) '=' valueList
+         | (min_total|min_item_price) comparator number
+  valueList := value ('|' value)*
+  comparator := '>='   (only comparator currently supported for numeric rules)
+  sep := ';' | ',' | newline
+
+Whitespace is ignored around tokens.
+
+Example:
+  sku=ABC123|XYZ999; category=Shoes|Bags
+  min_total>=10000
+  min_item_price>=2500, category=Accessories
+
+Parsing returns a RuleSet which can later be evaluated against a generic context.
+The evaluation context uses simple Item abstractions to avoid tight coupling with
+the cart implementation (which currently lives under cmd/cart and cannot be
+imported due to being in package main).
+
+This is intentionally conservative and extensible:
+  * Adding new rule kinds: extend RuleKind constants, add parse + evaluate logic.
+  * Supporting new operators: extend numeric rule parsing & evaluation.
+*/
+
+var (
+	// ErrEmptyExpression is returned when the input string has only whitespace.
+	ErrEmptyExpression = errors.New("voucher: empty rule expression")
+	// ErrInvalidRule indicates a syntactic or semantic issue with a single rule fragment.
+	ErrInvalidRule = errors.New("voucher: invalid rule")
+)
+
+// RuleKind enumerates supported rule kinds.
+type RuleKind string
+
+const (
+	RuleSku          RuleKind = "sku"
+	RuleCategory     RuleKind = "category"
+	RuleMinTotal     RuleKind = "min_total"
+	RuleMinItemPrice RuleKind = "min_item_price"
+)
+
+// ruleCondition represents a single, parsed rule.
+type ruleCondition struct {
+	Kind       RuleKind
+	StringVals []string // For sku / category multi-value list
+	MinValue   *int64   // For numeric threshold rules
+	// Operator reserved for future (e.g., >, >=, ==). Currently always ">=" for numeric kinds.
+	Operator string
+}
+
+// RuleSet groups multiple rule conditions (logical AND).
+// All conditions must pass for Applies() to return true.
+type RuleSet struct {
+	Conditions []ruleCondition
+	Source     string // original, trimmed source string
+}
+
+// Item is a minimal abstraction for evaluation (decoupled from cart domain structs).
+type Item struct {
+	Sku       string
+	Category  string
+	UnitPrice int64 // Inc VAT (single unit)
+}
+
+// EvalContext bundles cart-like data necessary for evaluation.
+type EvalContext struct {
+	Items        []Item
+	CartTotalInc int64
+}
+
+// Applies returns true if all rule conditions pass for the context.
+func (rs *RuleSet) Applies(ctx EvalContext) bool {
+	for _, c := range rs.Conditions {
+		switch c.Kind {
+		case RuleSku:
+			if !anyItem(ctx.Items, func(it Item) bool {
+				return containsFold(c.StringVals, it.Sku)
+			}) {
+				return false
+			}
+		case RuleCategory:
+			if !anyItem(ctx.Items, func(it Item) bool {
+				return containsFold(c.StringVals, it.Category)
+			}) {
+				return false
+			}
+		case RuleMinTotal:
+			if c.MinValue == nil || ctx.CartTotalInc < *c.MinValue {
+				return false
+			}
+		case RuleMinItemPrice:
+			if c.MinValue == nil {
+				return false
+			}
+			if !anyItem(ctx.Items, func(it Item) bool {
+				return it.UnitPrice >= *c.MinValue
+			}) {
+				return false
+			}
+		default:
+			// Unknown kinds fail closed to avoid granting unintended discounts.
+			return false
+		}
+	}
+	return true
+}
+
+// anyItem returns true if predicate matches any item.
+func anyItem(items []Item, pred func(Item) bool) bool {
+	for _, it := range items {
+		if pred(it) {
+			return true
+		}
+	}
+	return false
+}
+
+// ParseRules parses a rule expression into a RuleSet.
+func ParseRules(input string) (*RuleSet, error) {
+	trimmed := strings.TrimSpace(input)
+	if trimmed == "" {
+		return nil, ErrEmptyExpression
+	}
+
+	fragments := splitRuleFragments(trimmed)
+	if len(fragments) == 0 {
+		return nil, ErrInvalidRule
+	}
+
+	var conditions []ruleCondition
+	for _, frag := range fragments {
+		if frag == "" {
+			continue
+		}
+		c, err := parseFragment(frag)
+		if err != nil {
+			return nil, fmt.Errorf("%w: %s (%v)", ErrInvalidRule, frag, err)
+		}
+		conditions = append(conditions, c)
+	}
+
+	if len(conditions) == 0 {
+		return nil, ErrInvalidRule
+	}
+
+	return &RuleSet{
+		Conditions: conditions,
+		Source:     trimmed,
+	}, nil
+}
+
+// splitRuleFragments splits on ; , or newline, while respecting basic structure.
+func splitRuleFragments(s string) []string {
+	// Normalize line endings
+	s = strings.ReplaceAll(s, "\r\n", "\n")
+
+	// We allow separators: newline, semicolon, comma.
+	seps := func(r rune) bool {
+		return r == ';' || r == '\n' || r == ','
+	}
+	raw := strings.FieldsFunc(s, seps)
+	out := make([]string, 0, len(raw))
+	for _, f := range raw {
+		t := strings.TrimSpace(f)
+		if t != "" {
+			out = append(out, t)
+		}
+	}
+	return out
+}
+
+// parseFragment parses an individual rule fragment.
+func parseFragment(frag string) (ruleCondition, error) {
+	lower := strings.ToLower(frag)
+
+	// Numeric rules have form: <kind> >= number
+	if strings.HasPrefix(lower, string(RuleMinTotal)) ||
+		strings.HasPrefix(lower, string(RuleMinItemPrice)) {
+
+		return parseNumericRule(frag)
+	}
+
+	// Key=Value list rules (sku / category).
+	if i := strings.Index(frag, "="); i > 0 {
+		key := strings.TrimSpace(frag[:i])
+		valPart := strings.TrimSpace(frag[i+1:])
+		if key == "" || valPart == "" {
+			return ruleCondition{}, errors.New("empty key/value")
+		}
+		kind := RuleKind(strings.ToLower(key))
+		switch kind {
+		case RuleSku, RuleCategory:
+			values := splitAndClean(valPart, "|")
+			if len(values) == 0 {
+				return ruleCondition{}, errors.New("empty value list")
+			}
+			return ruleCondition{
+				Kind:       kind,
+				StringVals: values,
+			}, nil
+		default:
+			return ruleCondition{}, fmt.Errorf("unsupported key '%s'", key)
+		}
+	}
+
+	return ruleCondition{}, fmt.Errorf("unrecognized fragment '%s'", frag)
+}
+
+func parseNumericRule(frag string) (ruleCondition, error) {
+	// Support only '>=' for now.
+	var kind RuleKind
+	var rest string
+
+	fragTrim := strings.TrimSpace(frag)
+
+	switch {
+	case strings.HasPrefix(strings.ToLower(fragTrim), string(RuleMinTotal)):
+		kind = RuleMinTotal
+		rest = strings.TrimSpace(fragTrim[len(RuleMinTotal):])
+	case strings.HasPrefix(strings.ToLower(fragTrim), string(RuleMinItemPrice)):
+		kind = RuleMinItemPrice
+		rest = strings.TrimSpace(fragTrim[len(RuleMinItemPrice):])
+	default:
+		return ruleCondition{}, fmt.Errorf("unknown numeric rule '%s'", frag)
+	}
+
+	// Expect operator and number (>= <number>)
+	rest = stripLeadingSpace(rest)
+	if !strings.HasPrefix(rest, ">=") {
+		return ruleCondition{}, fmt.Errorf("expected '>=' in '%s'", frag)
+	}
+	numStr := strings.TrimSpace(rest[2:])
+	if numStr == "" {
+		return ruleCondition{}, fmt.Errorf("missing numeric value in '%s'", frag)
+	}
+
+	value, err := strconv.ParseInt(numStr, 10, 64)
+	if err != nil {
+		return ruleCondition{}, fmt.Errorf("invalid number '%s': %v", numStr, err)
+	}
+	if value < 0 {
+		return ruleCondition{}, fmt.Errorf("negative threshold %d", value)
+	}
+
+	return ruleCondition{
+		Kind:     kind,
+		MinValue: &value,
+		Operator: ">=",
+	}, nil
+}
+
+func stripLeadingSpace(s string) string {
+	for len(s) > 0 && unicode.IsSpace(rune(s[0])) {
+		s = s[1:]
+	}
+	return s
+}
+
+func splitAndClean(s string, sep string) []string {
+	raw := strings.Split(s, sep)
+	out := make([]string, 0, len(raw))
+	for _, r := range raw {
+		t := strings.TrimSpace(r)
+		if t != "" {
+			out = append(out, t)
+		}
+	}
+	return out
+}
+
+func containsFold(list []string, candidate string) bool {
+	for _, v := range list {
+		if strings.EqualFold(v, candidate) {
+			return true
+		}
+	}
+	return false
+}
+
+// Describe returns a human-friendly summary of the parsed rule set.
+func (rs *RuleSet) Describe() string {
+	if rs == nil {
+		return "<nil>"
+	}
+	var parts []string
+	for _, c := range rs.Conditions {
+		switch c.Kind {
+		case RuleSku, RuleCategory:
+			parts = append(parts, fmt.Sprintf("%s in (%s)", c.Kind, strings.Join(c.StringVals, "|")))
+		case RuleMinTotal, RuleMinItemPrice:
+			if c.MinValue != nil {
+				parts = append(parts, fmt.Sprintf("%s %s %d", c.Kind, c.OperatorOr(">="), *c.MinValue))
+			}
+		default:
+			parts = append(parts, fmt.Sprintf("unknown(%s)", c.Kind))
+		}
+	}
+	return strings.Join(parts, " AND ")
+}
+
+func (c ruleCondition) OperatorOr(def string) string {
+	if c.Operator == "" {
+		return def
+	}
+	return c.Operator
+}
+
+// --- Convenience helpers for incremental adoption ---
+
+// MustParseRules panics on parse error (useful in tests or static initialization).
+func MustParseRules(expr string) *RuleSet {
+	rs, err := ParseRules(expr)
+	if err != nil {
+		panic(err)
+	}
+	return rs
+}

pkg/voucher/parser_test.go

@@ -0,0 +1,179 @@
+package voucher
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestParseRules_SimpleSku(t *testing.T) {
+	rs, err := ParseRules("sku=ABC123|XYZ999|def456")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(rs.Conditions) != 1 {
+		t.Fatalf("expected 1 condition got %d", len(rs.Conditions))
+	}
+	c := rs.Conditions[0]
+	if c.Kind != RuleSku {
+		t.Fatalf("expected kind sku got %s", c.Kind)
+	}
+	if len(c.StringVals) != 3 {
+		t.Fatalf("expected 3 sku values got %d", len(c.StringVals))
+	}
+	want := []string{"ABC123", "XYZ999", "def456"}
+	for i, v := range want {
+		if c.StringVals[i] != v {
+			t.Fatalf("expected sku[%d]=%s got %s", i, v, c.StringVals[i])
+		}
+	}
+}
+
+func TestParseRules_CategoryAndSkuMixedSeparators(t *testing.T) {
+	rs, err := ParseRules("  category=Shoes|Bags ; sku= A | B , min_total>=1000\nmin_item_price>=500")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(rs.Conditions) != 4 {
+		t.Fatalf("expected 4 conditions got %d", len(rs.Conditions))
+	}
+
+	kinds := []RuleKind{RuleCategory, RuleSku, RuleMinTotal, RuleMinItemPrice}
+	for i, k := range kinds {
+		if rs.Conditions[i].Kind != k {
+			t.Fatalf("expected condition[%d] kind %s got %s", i, k, rs.Conditions[i].Kind)
+		}
+	}
+
+	// Validate numeric thresholds
+	if rs.Conditions[2].MinValue == nil || *rs.Conditions[2].MinValue != 1000 {
+		t.Fatalf("expected min_total>=1000 got %+v", rs.Conditions[2])
+	}
+	if rs.Conditions[3].MinValue == nil || *rs.Conditions[3].MinValue != 500 {
+		t.Fatalf("expected min_item_price>=500 got %+v", rs.Conditions[3])
+	}
+}
+
+func TestParseRules_Empty(t *testing.T) {
+	_, err := ParseRules("   \n  ")
+	if !errors.Is(err, ErrEmptyExpression) {
+		t.Fatalf("expected ErrEmptyExpression got %v", err)
+	}
+}
+
+func TestParseRules_Invalid(t *testing.T) {
+	_, err := ParseRules("unknown=foo")
+	if err == nil {
+		t.Fatal("expected error for unknown key")
+	}
+	_, err = ParseRules("min_total>100") // wrong operator
+	if err == nil {
+		t.Fatal("expected error for wrong operator")
+	}
+	_, err = ParseRules("min_total>=") // missing value
+	if err == nil {
+		t.Fatal("expected error for missing numeric value")
+	}
+}
+
+func TestRuleSet_Applies(t *testing.T) {
+	rs := MustParseRules("sku=ABC123|XYZ999; category=Shoes|min_total>=10000; min_item_price>=3000")
+
+	ctx := EvalContext{
+		Items: []Item{
+			{Sku: "ABC123", Category: "Shoes", UnitPrice: 2500},
+			{Sku: "FFF000", Category: "Accessories", UnitPrice: 3200},
+		},
+		CartTotalInc: 12000,
+	}
+
+	if !rs.Applies(ctx) {
+		t.Fatalf("expected rules to apply")
+	}
+
+	// Fail due to missing sku/category
+	ctx2 := EvalContext{
+		Items: []Item{
+			{Sku: "NOPE", Category: "Different", UnitPrice: 4000},
+		},
+		CartTotalInc: 20000,
+	}
+	if rs.Applies(ctx2) {
+		t.Fatalf("expected rules NOT to apply (sku/category mismatch)")
+	}
+
+	// Fail due to min_total
+	ctx3 := EvalContext{
+		Items: []Item{
+			{Sku: "ABC123", Category: "Shoes", UnitPrice: 2500},
+			{Sku: "FFF000", Category: "Accessories", UnitPrice: 3200},
+		},
+		CartTotalInc: 9000,
+	}
+	if rs.Applies(ctx3) {
+		t.Fatalf("expected rules NOT to apply (min_total not reached)")
+	}
+
+	// Fail due to min_item_price (no item >=3000)
+	ctx4 := EvalContext{
+		Items: []Item{
+			{Sku: "ABC123", Category: "Shoes", UnitPrice: 2500},
+			{Sku: "FFF000", Category: "Accessories", UnitPrice: 2800},
+		},
+		CartTotalInc: 15000,
+	}
+	if rs.Applies(ctx4) {
+		t.Fatalf("expected rules NOT to apply (min_item_price not satisfied)")
+	}
+}
+
+func TestRuleSet_Applies_CaseInsensitive(t *testing.T) {
+	rs := MustParseRules("SKU=abc123|xyz999; CATEGORY=Shoes")
+	ctx := EvalContext{
+		Items: []Item{
+			{Sku: "AbC123", Category: "shoes", UnitPrice: 1000},
+		},
+		CartTotalInc: 1000,
+	}
+	if !rs.Applies(ctx) {
+		t.Fatalf("expected rules to apply (case-insensitive match)")
+	}
+}
+
+func TestDescribe(t *testing.T) {
+	rs := MustParseRules("sku=A|B|min_total>=500")
+	desc := rs.Describe()
+	// Loose assertions to avoid over-specification
+	if desc == "" {
+		t.Fatalf("expected non-empty description")
+	}
+	if !(contains(desc, "sku") && contains(desc, "min_total")) {
+		t.Fatalf("description missing expected parts: %s", desc)
+	}
+}
+
+func contains(haystack, needle string) bool {
+	return len(haystack) >= len(needle) && indexOf(haystack, needle) >= 0
+}
+
+// Simple substring search (avoid importing strings to show intent explicitly here)
+func indexOf(s, sub string) int {
+outer:
+	for i := 0; i+len(sub) <= len(s); i++ {
+		for j := 0; j < len(sub); j++ {
+			if s[i+j] != sub[j] {
+				continue outer
+			}
+		}
+		return i
+	}
+	return -1
+}
+
+func TestMustParseRules_Panics(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Fatalf("expected panic for invalid expression")
+		}
+	}()
+	MustParseRules("~~ totally invalid ~~")
+}

pkg/voucher/service.go

@@ -2,7 +2,8 @@ package voucher
 
 import (
 	"errors"
-	"math"
+
+	"git.tornberg.me/go-cart-actor/pkg/messages"
 )
 
 type Rule struct {
@@ -25,16 +26,14 @@ type Service struct {
 
 var ErrInvalidCode = errors.New("invalid vouchercode")
 
-func (s *Service) GetVoucher(code string) (*Voucher, error) {
+func (s *Service) GetVoucher(code string) (*messages.AddVoucher, error) {
-	value := int64(math.Round(100 * math.Pow(10, 2)))
 	if code == "" {
 		return nil, ErrInvalidCode
 	}
-	return &Voucher{
+	value := int64(250_00)
+	return &messages.AddVoucher{
 		Code:         code,
 		Value:        value,
-		TaxValue: int64(float64(value) * 0.2),
+		VoucherRules: make([]*messages.VoucherRule, 0),
-		TaxRate:  2500,
-		rules:    nil,
 	}, nil
 }