chore: initial commit

internal/svc/warehouse/controller/kafka.go

@@ -0,0 +1,161 @@
+// Copyright (C) 2024 Declan Teevan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package controller
+
+import (
+	"context"
+
+	"github.com/rs/zerolog/log"
+	"github.com/twmb/franz-go/pkg/kgo"
+	"google.golang.org/protobuf/proto"
+
+	"github.com/hexolan/stocklet/internal/pkg/messaging"
+	eventpb "github.com/hexolan/stocklet/internal/pkg/protogen/events/v1"
+	pb "github.com/hexolan/stocklet/internal/pkg/protogen/warehouse/v1"
+	"github.com/hexolan/stocklet/internal/svc/warehouse"
+)
+
+type kafkaController struct {
+	cl *kgo.Client
+
+	svc pb.WarehouseServiceServer
+
+	ctx       context.Context
+	ctxCancel context.CancelFunc
+}
+
+func NewKafkaController(cl *kgo.Client) warehouse.ConsumerController {
+	// Create a cancellable context for the consumer
+	ctx, ctxCancel := context.WithCancel(context.Background())
+
+	// Ensure the required Kafka topics exist
+	err := messaging.EnsureKafkaTopics(
+		cl,
+
+		messaging.Warehouse_Stock_Created_Topic,
+		messaging.Warehouse_Stock_Added_Topic,
+		messaging.Warehouse_Stock_Removed_Topic,
+		messaging.Warehouse_Reservation_Failed_Topic,
+		messaging.Warehouse_Reservation_Reserved_Topic,
+		messaging.Warehouse_Reservation_Returned_Topic,
+		messaging.Warehouse_Reservation_Consumed_Topic,
+
+		messaging.Order_State_Pending_Topic,
+		messaging.Shipping_Shipment_Allocation_Topic,
+		messaging.Payment_Processing_Topic,
+	)
+	if err != nil {
+		log.Warn().Err(err).Msg("kafka: raised attempting to ensure svc topics")
+	}
+
+	// Add the consumption topics
+	cl.AddConsumeTopics(
+		messaging.Order_State_Pending_Topic,
+		messaging.Shipping_Shipment_Allocation_Topic,
+		messaging.Payment_Processing_Topic,
+	)
+
+	return &kafkaController{cl: cl, ctx: ctx, ctxCancel: ctxCancel}
+}
+
+func (c *kafkaController) Attach(svc pb.WarehouseServiceServer) {
+	c.svc = svc
+}
+
+func (c *kafkaController) Start() {
+	if c.svc == nil {
+		log.Panic().Msg("consumer: no service interface attached")
+	}
+
+	for {
+		fetches := c.cl.PollFetches(c.ctx)
+		if errs := fetches.Errors(); len(errs) > 0 {
+			log.Panic().Any("kafka-errs", errs).Msg("consumer: unrecoverable kafka errors")
+		}
+
+		fetches.EachTopic(func(ft kgo.FetchTopic) {
+			switch ft.Topic {
+			case messaging.Order_State_Pending_Topic:
+				c.consumeOrderPendingEventTopic(ft)
+			case messaging.Shipping_Shipment_Allocation_Topic:
+				c.consumeShipmentAllocationEventTopic(ft)
+			case messaging.Payment_Processing_Topic:
+				c.consumePaymentProcessedEventTopic(ft)
+			default:
+				log.Warn().Str("topic", ft.Topic).Msg("consumer: recieved records from unexpected topic")
+			}
+		})
+	}
+}
+
+func (c *kafkaController) Stop() {
+	// Cancel the consumer context
+	c.ctxCancel()
+}
+
+func (c *kafkaController) consumeOrderPendingEventTopic(ft kgo.FetchTopic) {
+	log.Info().Str("topic", ft.Topic).Msg("consumer: recieved records from topic")
+
+	// Process each message from the topic
+	ft.EachRecord(func(record *kgo.Record) {
+		// Unmarshal the event
+		var event eventpb.OrderPendingEvent
+		err := proto.Unmarshal(record.Value, &event)
+		if err != nil {
+			log.Panic().Err(err).Msg("consumer: failed to unmarshal event")
+		}
+
+		// Process the event
+		ctx := context.Background()
+		c.svc.ProcessOrderPendingEvent(ctx, &event)
+	})
+}
+
+func (c *kafkaController) consumeShipmentAllocationEventTopic(ft kgo.FetchTopic) {
+	log.Info().Str("topic", ft.Topic).Msg("consumer: recieved records from topic")
+
+	// Process each message from the topic
+	ft.EachRecord(func(record *kgo.Record) {
+		// Unmarshal the event
+		var event eventpb.ShipmentAllocationEvent
+		err := proto.Unmarshal(record.Value, &event)
+		if err != nil {
+			log.Panic().Err(err).Msg("consumer: failed to unmarshal event")
+		}
+
+		// Process the event
+		ctx := context.Background()
+		c.svc.ProcessShipmentAllocationEvent(ctx, &event)
+	})
+}
+
+func (c *kafkaController) consumePaymentProcessedEventTopic(ft kgo.FetchTopic) {
+	log.Info().Str("topic", ft.Topic).Msg("consumer: recieved records from topic")
+
+	// Process each message from the topic
+	ft.EachRecord(func(record *kgo.Record) {
+		// Unmarshal the event
+		var event eventpb.PaymentProcessedEvent
+		err := proto.Unmarshal(record.Value, &event)
+		if err != nil {
+			log.Panic().Err(err).Msg("consumer: failed to unmarshal event")
+		}
+
+		// Process the event
+		ctx := context.Background()
+		c.svc.ProcessPaymentProcessedEvent(ctx, &event)
+	})
+}