all the refactor

cmd/inventory/main.go

@@ -6,14 +6,18 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"strconv"
+	"strings"
 	"sync"
 
 	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
+	"git.k6n.net/mats/platform/event"
+	orderevent "git.k6n.net/mats/platform/order"
 	"git.k6n.net/mats/slask-finder/pkg/index"
-	"git.k6n.net/mats/slask-finder/pkg/messaging"
 	"github.com/redis/go-redis/v9"
 	"github.com/redis/go-redis/v9/maintnotifications"
 
+	"git.k6n.net/mats/platform/rabbit"
 	amqp "github.com/rabbitmq/amqp091-go"
 )
 
@@ -66,6 +70,12 @@ var country = "se"
 var redisAddress = "10.10.3.18:6379"
 var redisPassword = "slaskredis"
 
+// lowWatermark is the cutoff between "low" and "high" stock for the level
+// crossings emitted on the bus (0 < qty <= lowWatermark ⇒ low). Single global
+// number for now; per-SKU / per-tenant thresholds can come later behind the
+// same inventory.LevelChanged payload.
+var lowWatermark int64 = 5
+
 func init() {
 	// Override redis config from environment variables if set
 	if addr, ok := os.LookupEnv("REDIS_ADDRESS"); ok {
@@ -77,6 +87,19 @@ func init() {
 	if ctry, ok := os.LookupEnv("COUNTRY"); ok {
 		country = ctry
 	}
+	if v, ok := os.LookupEnv("INVENTORY_LOW_WATERMARK"); ok {
+		if n, err := strconv.ParseInt(v, 10, 64); err == nil {
+			lowWatermark = n
+		}
+	}
+}
+
+// levelKey is the Redis key holding the last-emitted Level for a SKU+location.
+// It is the crossing-detection marker: the level listener only emits when the
+// freshly computed level differs from this stored value, so the bus carries
+// crossings, not every quantity tick.
+func levelKey(sku, loc string) string {
+	return "invlevel:" + sku + ":" + loc
 }
 
 func main() {
@@ -114,39 +137,121 @@ func main() {
 		rdb:                 rdb,
 		ctx:                 ctx,
 		svc:                 *s,
+		country:             country,
+		low:                 lowWatermark,
 	}
 
 	amqpUrl, ok := os.LookupEnv("RABBIT_HOST")
 	if ok {
 		log.Printf("Connecting to rabbitmq")
-		conn, err := amqp.DialConfig(amqpUrl, amqp.Config{
-			Properties: amqp.NewConnectionProperties(),
-		})
-		//a.conn = conn
+		conn, err := rabbit.Dial(amqpUrl, "cart-inventory")
 		if err != nil {
 			log.Fatalf("Failed to connect to RabbitMQ: %v", err)
 		}
-		ch, err := conn.Channel()
-		if err != nil {
-			log.Fatalf("Failed to open a channel: %v", err)
-		}
-		// items listener
-		err = messaging.ListenToTopic(ch, country, "item_added", func(d amqp.Delivery) error {
-			wg := &sync.WaitGroup{}
-			err = index.ForEachRawDataItemInJSONArray(d.Body, func(item *index.RawDataItem) error {
-				stockhandler.HandleItem(item, wg)
+		// The catalog-feed handler emits inventory.level_changed crossings
+		// directly on this connection as it writes stock.
+		stockhandler.conn = conn
+		// Reconnecting consumer: re-listen on reconnect.
+		conn.NotifyOnReconnect(func() {
+			ch, err := conn.Channel()
+			if err != nil {
+				log.Printf("inventory: channel on reconnect: %v", err)
+				return
+			}
+
+			// Producer side: declare the "inventory" topic exchange we publish
+			// inventory.level_changed crossings to. Durable + idempotent, so
+			// re-declaring on each reconnect is safe.
+			if err := ch.ExchangeDeclare("inventory", "topic", true, false, false, false, nil); err != nil {
+				log.Printf("inventory: declare inventory exchange: %v", err)
+			}
+
+			// 1) LEGACY raw `catalog.item_changed` wire — payload is a raw item
+			//    JSON array. Consumed by the historical pricewatcher +
+			//    writeradmin item-changed paths. Carries RawDataItem bodies
+			//    with full finder-style metadata (including the stock
+			//    field that the new projection wire does not).
+			//
+			//    This listener is the one that mutates Redis stock state via
+			//    StockHandler.HandleItem.
+			if err := rabbit.ListenToPattern(ch, "catalog", string(event.CatalogItemChanged), func(d amqp.Delivery) error {
+				var ev event.Event
+				if err := json.Unmarshal(d.Body, &ev); err != nil {
+					log.Printf("inventory: decode catalog event: %v", err)
+					return nil
+				}
+				if ev.Meta["country"] != "" && ev.Meta["country"] != country {
+					return nil // not for our country
+				}
+				wg := &sync.WaitGroup{}
+				if err := index.ForEachRawDataItemInJSONArray(ev.Payload, func(item *index.RawDataItem) error {
+					stockhandler.HandleItem(item, wg)
+					return nil
+				}); err != nil {
+					log.Printf("inventory: apply items: %v", err)
+				}
 				wg.Wait()
 				log.Print("Batch done...")
-				return err
-			})
-			return nil
+				return nil
+			}); err != nil {
+				log.Printf("inventory: listen on reconnect: %v", err)
+			}
+
+			// 2) (REMOVED) `catalog.projection_published` listener — moved to
+			//    the cart service. Per docs/inventory-shape.md, inventory's
+			//    bus role is emit-only (inventory.level_changed crossings back
+			//    to finder on the inventory exchange). The catalog projection
+			//    is read by the cart at checkout-time lookups via its own
+			//    in-memory CatalogCache, not by inventory. Stock state stays
+			//    sourced from the legacy raw wire (block 1 below) until
+			//    inventory itself emits level_changed on a stock mutation.
+
+			// 3) order.created → commit stock (permanent decrement), release the
+			//    cart hold, emit the level crossing. This is the async commit
+			//    path: checkout no longer decrements synchronously; it announces
+			//    a completed sale and inventory reacts. Idempotent per order.
+			if err := rabbit.ListenToPattern(ch, "order", string(event.OrderCreated), func(d amqp.Delivery) error {
+				var ev event.Event
+				if err := json.Unmarshal(d.Body, &ev); err != nil {
+					log.Printf("inventory: decode order event: %v", err)
+					return nil
+				}
+				if target := countryForEvent(&ev); target != "" && target != country {
+					return nil // not for our country/tenant
+				}
+				created, err := orderevent.Decode(ev.Payload)
+				if err != nil {
+					log.Printf("inventory: decode order.created: %v", err)
+					return nil
+				}
+				commitOrder(ctx, rdb, s, r, conn, country, lowWatermark, created)
+				return nil
+			}); err != nil {
+				log.Printf("inventory: listen order.created on reconnect: %v", err)
+			}
 		})
-		if err != nil {
-			log.Fatalf("Failed to listen to item_added topic: %v", err)
-		}
 	}
 
 	// Start HTTP server
 	log.Println("Starting HTTP server on :8080")
 	log.Fatal(http.ListenAndServe(":8080", nil))
 }
+
+// countryForEvent extracts the best-available country/tenant identifier
+// from an envelope. Lookup order: Meta["country"], Meta["tenant"], then
+// the Source prefix "catalog:<x>". An empty string means "no decoration" —
+// callers treat that as "for everyone" (same as the legacy listener).
+func countryForEvent(ev *event.Event) string {
+	if t := strings.TrimSpace(ev.Meta["country"]); t != "" {
+		return t
+	}
+	if t := strings.TrimSpace(ev.Meta["tenant"]); t != "" {
+		return t
+	}
+	if strings.HasPrefix(ev.Source, "catalog:") {
+		if t := strings.TrimSpace(strings.TrimPrefix(ev.Source, "catalog:")); t != "" {
+			return t
+		}
+	}
+	return ""
+}