go-cart-actor/cart_state_mapper.go

package main

import (
	messages "git.tornberg.me/go-cart-actor/proto"
)

// cart_state_mapper.go
//
// Utilities to translate between internal CartGrain state and the gRPC
// (typed) protobuf representation CartState. This replaces the previous
// JSON blob framing and enables type-safe replies over gRPC, as well as
// internal reuse for HTTP handlers without an extra marshal / unmarshal
// hop (you can marshal CartState directly for JSON responses if desired).
//
// Only the one‑way mapping (CartGrain -> CartState) is strictly required
// for mutation / state replies. A reverse helper is included in case
// future features (e.g. snapshot import, replay, or migration) need it.

// ToCartState converts the in‑memory CartGrain into a protobuf CartState.
func ToCartState(c *CartGrain) *messages.CartState {
	if c == nil {
		return nil
	}

	items := make([]*messages.CartItemState, 0, len(c.Items))
	for _, it := range c.Items {
		if it == nil {
			continue
		}
		itemDiscountPerUnit := max(0, it.OrgPrice-it.Price)
		itemTotalDiscount := itemDiscountPerUnit * int64(it.Quantity)

		items = append(items, &messages.CartItemState{
			Id:            int64(it.Id),
			ItemId:        int64(it.ItemId),
			Sku:           it.Sku,
			Name:          it.Name,
			Price:         it.Price,
			Qty:           int32(it.Quantity),
			TotalPrice:    it.TotalPrice,
			TotalTax:      it.TotalTax,
			OrgPrice:      it.OrgPrice,
			TaxRate:       int32(it.TaxRate),
			TotalDiscount: itemTotalDiscount,
			Brand:         it.Brand,
			Category:      it.Category,
			Category2:     it.Category2,
			Category3:     it.Category3,
			Category4:     it.Category4,
			Category5:     it.Category5,
			Image:         it.Image,
			Type:          it.ArticleType,
			SellerId:      it.SellerId,
			SellerName:    it.SellerName,
			Disclaimer:    it.Disclaimer,
			Outlet:        deref(it.Outlet),
			StoreId:       deref(it.StoreId),
			Stock:         int32(it.Stock),
		})
	}

	deliveries := make([]*messages.DeliveryState, 0, len(c.Deliveries))
	for _, d := range c.Deliveries {
		if d == nil {
			continue
		}
		itemIds := make([]int64, 0, len(d.Items))
		for _, id := range d.Items {
			itemIds = append(itemIds, int64(id))
		}
		var pp *messages.PickupPoint
		if d.PickupPoint != nil {
			// Copy to avoid accidental shared mutation (proto points are fine but explicit).
			pp = &messages.PickupPoint{
				Id:      d.PickupPoint.Id,
				Name:    d.PickupPoint.Name,
				Address: d.PickupPoint.Address,
				City:    d.PickupPoint.City,
				Zip:     d.PickupPoint.Zip,
				Country: d.PickupPoint.Country,
			}
		}
		deliveries = append(deliveries, &messages.DeliveryState{
			Id:          int64(d.Id),
			Provider:    d.Provider,
			Price:       d.Price,
			Items:       itemIds,
			PickupPoint: pp,
		})
	}

	return &messages.CartState{
		Id:                c.Id.String(),
		Items:             items,
		TotalPrice:        c.TotalPrice,
		TotalTax:          c.TotalTax,
		TotalDiscount:     c.TotalDiscount,
		Deliveries:        deliveries,
		PaymentInProgress: c.PaymentInProgress,
		OrderReference:    c.OrderReference,
		PaymentStatus:     c.PaymentStatus,
	}
}

// FromCartState merges a protobuf CartState into an existing CartGrain.
// This is optional and primarily useful for snapshot import or testing.
func FromCartState(cs *messages.CartState, g *CartGrain) *CartGrain {
	if cs == nil {
		return g
	}
	if g == nil {
		g = &CartGrain{}
	}
	g.Id = ToCartId(cs.Id)
	g.TotalPrice = cs.TotalPrice
	g.TotalTax = cs.TotalTax
	g.TotalDiscount = cs.TotalDiscount
	g.PaymentInProgress = cs.PaymentInProgress
	g.OrderReference = cs.OrderReference
	g.PaymentStatus = cs.PaymentStatus

	// Items
	g.Items = g.Items[:0]
	for _, it := range cs.Items {
		if it == nil {
			continue
		}
		outlet := toPtr(it.Outlet)
		storeId := toPtr(it.StoreId)
		g.Items = append(g.Items, &CartItem{
			Id:          int(it.Id),
			ItemId:      int(it.ItemId),
			Sku:         it.Sku,
			Name:        it.Name,
			Price:       it.Price,
			Quantity:    int(it.Qty),
			TotalPrice:  it.TotalPrice,
			TotalTax:    it.TotalTax,
			OrgPrice:    it.OrgPrice,
			TaxRate:     int(it.TaxRate),
			Brand:       it.Brand,
			Category:    it.Category,
			Category2:   it.Category2,
			Category3:   it.Category3,
			Category4:   it.Category4,
			Category5:   it.Category5,
			Image:       it.Image,
			ArticleType: it.Type,
			SellerId:    it.SellerId,
			SellerName:  it.SellerName,
			Disclaimer:  it.Disclaimer,
			Outlet:      outlet,
			StoreId:     storeId,
			Stock:       StockStatus(it.Stock),
			// Tax, TaxRate already set via Price / Totals if needed
		})
		if it.Id > int64(g.lastItemId) {
			g.lastItemId = int(it.Id)
		}
	}

	// Deliveries
	g.Deliveries = g.Deliveries[:0]
	for _, d := range cs.Deliveries {
		if d == nil {
			continue
		}

		intIds := make([]int, 0, len(d.Items))
		for _, id := range d.Items {
			intIds = append(intIds, int(id))
		}
		var pp *messages.PickupPoint
		if d.PickupPoint != nil {
			pp = &messages.PickupPoint{
				Id:      d.PickupPoint.Id,
				Name:    d.PickupPoint.Name,
				Address: d.PickupPoint.Address,
				City:    d.PickupPoint.City,
				Zip:     d.PickupPoint.Zip,
				Country: d.PickupPoint.Country,
			}
		}
		g.Deliveries = append(g.Deliveries, &CartDelivery{
			Id:          int(d.Id),
			Provider:    d.Provider,
			Price:       d.Price,
			Items:       intIds,
			PickupPoint: pp,
		})
		if d.Id > int64(g.lastDeliveryId) {
			g.lastDeliveryId = int(d.Id)
		}
	}

	return g
}

// Helper to safely de-reference optional string pointers to value or "".
func deref(p *string) string {
	if p == nil {
		return ""
	}
	return *p
}

func toPtr(s string) *string {
	if s == "" {
		return nil
	}
	return &s
}