all the refactor

pkg/promotions/mcp/tools.go

@@ -1,61 +1,32 @@
 package mcp
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"time"
 
 	"git.k6n.net/mats/go-cart-actor/pkg/cart"
 	"git.k6n.net/mats/go-cart-actor/pkg/promotions"
+	pmcp "git.k6n.net/mats/platform/mcp"
+	"git.k6n.net/mats/platform/tax"
 )
 
 // tool is one MCP tool: a name, a description, a JSON-Schema for its arguments,
 // and the handler that runs it.
-type tool struct {
-	Name        string                                  `json:"name"`
-	Description string                                  `json:"description"`
-	InputSchema json.RawMessage                         `json:"inputSchema"`
-	invoke      func(args json.RawMessage) (any, error) `json:"-"`
-}
-
-func (s *Server) callTool(req *rpcRequest) *rpcResponse {
-	var p struct {
-		Name      string          `json:"name"`
-		Arguments json.RawMessage `json:"arguments"`
-	}
-	if err := json.Unmarshal(req.Params, &p); err != nil {
-		return errorResponse(req.ID, codeInvalidParams, "invalid params")
-	}
-	var t *tool
-	for i := range s.tools {
-		if s.tools[i].Name == p.Name {
-			t = &s.tools[i]
-			break
-		}
-	}
-	if t == nil {
-		return errorResponse(req.ID, codeInvalidParams, "unknown tool: "+p.Name)
-	}
-	out, err := t.invoke(p.Arguments)
-	if err != nil {
-		return result(req.ID, toolError(err))
-	}
-	return result(req.ID, toolText(out))
-}
-
-func (s *Server) buildTools() []tool {
-	return []tool{
+func (s *Server) buildTools() []pmcp.Tool {
+	return []pmcp.Tool{
 		{
 			Name:        "list_promotions",
 			Description: "List all promotion rules the cart engine evaluates, optionally filtered by status (active|inactive|scheduled|expired).",
-			InputSchema: object(props{
-				"status": str("optional status filter: active|inactive|scheduled|expired"),
+			InputSchema: pmcp.Object(pmcp.Props{
+				"status": pmcp.String("optional status filter: active|inactive|scheduled|expired"),
 			}, nil),
-			invoke: func(args json.RawMessage) (any, error) {
+			Invoke: func(_ context.Context, args json.RawMessage) (any, error) {
 				var a struct {
 					Status string `json:"status"`
 				}
-				if err := decode(args, &a); err != nil {
+				if err := pmcp.Decode(args, &a); err != nil {
 					return nil, err
 				}
 				rules := s.store.List()
@@ -74,12 +45,12 @@ func (s *Server) buildTools() []tool {
 		{
 			Name:        "get_promotion",
 			Description: "Fetch a single promotion rule by id.",
-			InputSchema: object(props{"id": str("the promotion id")}, []string{"id"}),
-			invoke: func(args json.RawMessage) (any, error) {
+			InputSchema: pmcp.Object(pmcp.Props{"id": pmcp.String("the promotion id")}, []string{"id"}),
+			Invoke: func(_ context.Context, args json.RawMessage) (any, error) {
 				var a struct {
 					ID string `json:"id"`
 				}
-				if err := decode(args, &a); err != nil {
+				if err := pmcp.Decode(args, &a); err != nil {
 					return nil, err
 				}
 				r, ok := s.store.Get(a.ID)
@@ -95,14 +66,14 @@ func (s *Server) buildTools() []tool {
 				"`promotion` is a full promotion-rule object (id, name, status, priority, conditions, actions). " +
 				"For a tiered volume discount (Volymrabatt) use a cart_total condition plus a tiered_discount action " +
 				"whose config.tiers each have minTotal/maxTotal (öre incl. VAT) and percent.",
-			InputSchema: object(props{
-				"promotion": obj("the full promotion rule object"),
+			InputSchema: pmcp.Object(pmcp.Props{
+				"promotion": pmcp.ObjectValue("the full promotion rule object"),
 			}, []string{"promotion"}),
-			invoke: func(args json.RawMessage) (any, error) {
+			Invoke: func(_ context.Context, args json.RawMessage) (any, error) {
 				var a struct {
 					Promotion json.RawMessage `json:"promotion"`
 				}
-				if err := decode(args, &a); err != nil {
+				if err := pmcp.Decode(args, &a); err != nil {
 					return nil, err
 				}
 				var rule promotions.PromotionRule
@@ -125,16 +96,16 @@ func (s *Server) buildTools() []tool {
 		{
 			Name:        "set_promotion_status",
 			Description: "Set a promotion's status (active|inactive|scheduled|expired) to toggle it on or off.",
-			InputSchema: object(props{
-				"id":     str("the promotion id"),
-				"status": str("new status: active|inactive|scheduled|expired"),
+			InputSchema: pmcp.Object(pmcp.Props{
+				"id":     pmcp.String("the promotion id"),
+				"status": pmcp.String("new status: active|inactive|scheduled|expired"),
 			}, []string{"id", "status"}),
-			invoke: func(args json.RawMessage) (any, error) {
+			Invoke: func(_ context.Context, args json.RawMessage) (any, error) {
 				var a struct {
 					ID     string `json:"id"`
 					Status string `json:"status"`
 				}
-				if err := decode(args, &a); err != nil {
+				if err := pmcp.Decode(args, &a); err != nil {
 					return nil, err
 				}
 				if !validStatus(a.Status) {
@@ -153,12 +124,12 @@ func (s *Server) buildTools() []tool {
 		{
 			Name:        "delete_promotion",
 			Description: "Delete a promotion rule by id.",
-			InputSchema: object(props{"id": str("the promotion id")}, []string{"id"}),
-			invoke: func(args json.RawMessage) (any, error) {
+			InputSchema: pmcp.Object(pmcp.Props{"id": pmcp.String("the promotion id")}, []string{"id"}),
+			Invoke: func(_ context.Context, args json.RawMessage) (any, error) {
 				var a struct {
 					ID string `json:"id"`
 				}
-				if err := decode(args, &a); err != nil {
+				if err := pmcp.Decode(args, &a); err != nil {
 					return nil, err
 				}
 				found, err := s.store.Delete(a.ID)
@@ -176,18 +147,18 @@ func (s *Server) buildTools() []tool {
 			Description: "Evaluate the current active promotions against a hypothetical cart total and report the " +
 				"matched discount. cartTotalIncVat is in öre incl. VAT (e.g. 5 000 000 = 50 000 kr). Useful for " +
 				"verifying Volymrabatt tiers without touching a real cart.",
-			InputSchema: object(props{
-				"cartTotalIncVat": integer("cart total incl. VAT, in öre"),
-				"itemQuantity":    integer("optional total item quantity"),
-				"customerSegment": str("optional customer segment"),
+			InputSchema: pmcp.Object(pmcp.Props{
+				"cartTotalIncVat": pmcp.Integer("cart total incl. VAT, in öre"),
+				"itemQuantity":    pmcp.Integer("optional total item quantity"),
+				"customerSegment": pmcp.String("optional customer segment"),
 			}, []string{"cartTotalIncVat"}),
-			invoke: func(args json.RawMessage) (any, error) {
+			Invoke: func(_ context.Context, args json.RawMessage) (any, error) {
 				var a struct {
 					CartTotalIncVat int64  `json:"cartTotalIncVat"`
 					ItemQuantity    int    `json:"itemQuantity"`
 					CustomerSegment string `json:"customerSegment"`
 				}
-				if err := decode(args, &a); err != nil {
+				if err := pmcp.Decode(args, &a); err != nil {
 					return nil, err
 				}
 				g := syntheticCart(a.CartTotalIncVat, a.ItemQuantity, s.defaultVatRate())
@@ -210,19 +181,19 @@ func (s *Server) buildTools() []tool {
 	}
 }
 
-// syntheticCart builds a one-line cart whose gross total is incVat ore so the
-// promotion engine can be evaluated against an arbitrary total. defaultVatRate
-// is the VAT rate as a float32 percentage (e.g. 25 = 25 %).
-func syntheticCart(incVat int64, qty int, defaultVatRate float32) *cart.CartGrain {
+// syntheticCart builds a one-line cart whose gross total is incVat öre so the
+// promotion engine can be evaluated against an arbitrary total. rateBp is the VAT
+// rate in basis points (2500 = 25%).
+func syntheticCart(incVat int64, qty int, rateBp int) *cart.CartGrain {
 	if qty <= 0 {
 		qty = 1
 	}
-	if defaultVatRate == 0 {
-		defaultVatRate = 25
+	if rateBp == 0 {
+		rateBp = 2500
 	}
 	g := cart.NewCartGrain(0, time.Now())
 	g.Items = []*cart.CartItem{
-		{Id: 1, Sku: "PREVIEW", Quantity: uint16(qty), Price: *cart.NewPriceFromIncVat(incVat, defaultVatRate)},
+		{Id: 1, Sku: "PREVIEW", Quantity: uint16(qty), Price: *cart.NewPriceFromIncVat(incVat, rateBp)},
 	}
 	// Quantity > 1 would multiply the row total; keep the gross equal to incVat by
 	// pricing a single unit at the full total.
@@ -240,55 +211,13 @@ func validStatus(s string) bool {
 	return false
 }
 
-// ---- result + schema helpers (mirrors the graph-cms MCP edge) -------------
-
-func toolText(v any) map[string]any {
-	b, err := json.Marshal(v)
-	if err != nil {
-		return toolError(err)
-	}
-	return map[string]any{
-		"content": []map[string]any{{"type": "text", "text": string(b)}},
-	}
-}
-
-func toolError(err error) map[string]any {
-	return map[string]any{
-		"isError": true,
-		"content": []map[string]any{{"type": "text", "text": err.Error()}},
-	}
-}
-
-// decode unmarshals tool arguments, tolerating empty/absent arguments.
-func decode(args json.RawMessage, v any) error {
-	if len(args) == 0 || string(args) == "null" {
-		return nil
-	}
-	if err := json.Unmarshal(args, v); err != nil {
-		return fmt.Errorf("invalid arguments: %w", err)
-	}
-	return nil
-}
-
-type props map[string]json.RawMessage
-
-func object(p props, required []string) json.RawMessage {
-	m := map[string]any{
-		"type":       "object",
-		"properties": p,
-	}
-	if len(required) > 0 {
-		m["required"] = required
-	}
-	b, _ := json.Marshal(m)
-	return b
-}
-
-func str(desc string) json.RawMessage  { return scalar("string", desc) }
-func obj(desc string) json.RawMessage  { return scalar("object", desc) }
-func integer(d string) json.RawMessage { return scalar("integer", d) }
-
-func scalar(typ, desc string) json.RawMessage {
-	b, _ := json.Marshal(map[string]any{"type": typ, "description": desc})
-	return b
+// defaultVatRate is the VAT rate used to build the synthetic preview cart when
+// the caller supplies none. Sourced from platform/tax (Nordic standard,
+// defaultCountry SE = 25%) rather than a magic constant.
+//
+// NOTE: reconstructed during the platform/mcp migration (the original method was
+// lost editing this untracked file). Behaviour matches the prior 25% default; if
+// the original read a per-store/configured rate, wire that provider in here.
+func (s *Server) defaultVatRate() int {
+	return tax.NewNordic("").DefaultTaxRate("")
 }