chore: initial commit

internal/svc/product/controller/kafka.go

@@ -0,0 +1,114 @@
+// 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/product/v1"
+	"github.com/hexolan/stocklet/internal/svc/product"
+)
+
+type kafkaController struct {
+	cl *kgo.Client
+
+	svc pb.ProductServiceServer
+
+	ctx       context.Context
+	ctxCancel context.CancelFunc
+}
+
+func NewKafkaController(cl *kgo.Client) product.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.Product_State_Created_Topic,
+		messaging.Product_State_Deleted_Topic,
+		messaging.Product_Attribute_Price_Topic,
+		messaging.Product_PriceQuotation_Topic,
+
+		messaging.Order_State_Created_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_Created_Topic,
+	)
+
+	return &kafkaController{cl: cl, ctx: ctx, ctxCancel: ctxCancel}
+}
+
+func (c *kafkaController) Attach(svc pb.ProductServiceServer) {
+	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_Created_Topic:
+				c.consumeOrderCreatedEventTopic(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) consumeOrderCreatedEventTopic(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.OrderCreatedEvent
+		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.ProcessOrderCreatedEvent(ctx, &event)
+	})
+}

internal/svc/product/controller/postgres.go

@@ -0,0 +1,294 @@
+// 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"
+	"golang.org/x/exp/maps"
+
+	"github.com/doug-martin/goqu/v9"
+	_ "github.com/doug-martin/goqu/v9/dialect/postgres"
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgtype"
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/hexolan/stocklet/internal/pkg/errors"
+	pb "github.com/hexolan/stocklet/internal/pkg/protogen/product/v1"
+	"github.com/hexolan/stocklet/internal/svc/product"
+)
+
+const pgProductBaseQuery string = "SELECT id, name, description, price, created_at, updated_at FROM products"
+
+type postgresController struct {
+	cl *pgxpool.Pool
+}
+
+func NewPostgresController(cl *pgxpool.Pool) product.StorageController {
+	return postgresController{cl: cl}
+}
+
+func (c postgresController) GetProduct(ctx context.Context, productId string) (*pb.Product, error) {
+	return c.getProduct(ctx, nil, productId)
+}
+
+func (c postgresController) getProduct(ctx context.Context, tx *pgx.Tx, productId string) (*pb.Product, error) {
+	// Determine if a db transaction is being used
+	var row pgx.Row
+	const query = pgProductBaseQuery + " WHERE id=$1"
+	if tx == nil {
+		row = c.cl.QueryRow(ctx, query, productId)
+	} else {
+		row = (*tx).QueryRow(ctx, query, productId)
+	}
+
+	// Scan row to protobuf obj
+	product, err := scanRowToProduct(row)
+	if err != nil {
+		return nil, err
+	}
+
+	return product, nil
+}
+
+// todo: implementing pagination mechanism
+func (c postgresController) GetProducts(ctx context.Context) ([]*pb.Product, error) {
+	rows, err := c.cl.Query(ctx, pgProductBaseQuery+" LIMIT 10")
+	if err != nil {
+		return nil, errors.WrapServiceError(errors.ErrCodeService, "query error", err)
+	}
+
+	products := []*pb.Product{}
+	for rows.Next() {
+		productObj, err := scanRowToProduct(rows)
+		if err != nil {
+			return nil, err
+		}
+
+		products = append(products, productObj)
+	}
+
+	if rows.Err() != nil {
+		return nil, errors.WrapServiceError(errors.ErrCodeService, "error whilst scanning rows", rows.Err())
+	}
+
+	return products, nil
+}
+
+// Update a product price.
+func (c postgresController) UpdateProductPrice(ctx context.Context, productId string, price float32) (*pb.Product, error) {
+	// Begin a DB transaction
+	tx, err := c.cl.Begin(ctx)
+	if err != nil {
+		return nil, errors.WrapServiceError(errors.ErrCodeExtService, "failed to begin transaction", err)
+	}
+	defer tx.Rollback(ctx)
+
+	// Update product price
+	_, err = tx.Exec(ctx, "UPDATE products SET price=$1 WHERE id=$2", price, productId)
+	if err != nil {
+		return nil, errors.WrapServiceError(errors.ErrCodeExtService, "failed to update product price", err)
+	}
+
+	// Get updated product
+	productObj, err := c.getProduct(ctx, &tx, productId)
+	if err != nil {
+		return nil, err
+	}
+
+	// Add the event to the outbox table with the transaction
+	evt, evtTopic, err := product.PrepareProductPriceUpdatedEvent(productObj)
+	if err != nil {
+		return nil, errors.WrapServiceError(errors.ErrCodeService, "failed to create event", err)
+	}
+
+	_, err = tx.Exec(ctx, "INSERT INTO event_outbox (aggregateid, aggregatetype, payload) VALUES ($1, $2, $3)", productObj.Id, evtTopic, evt)
+	if err != nil {
+		return nil, errors.WrapServiceError(errors.ErrCodeExtService, "failed to insert event", err)
+	}
+
+	// Commit the transaction
+	err = tx.Commit(ctx)
+	if err != nil {
+		return nil, errors.WrapServiceError(errors.ErrCodeExtService, "failed to commit transaction", err)
+	}
+
+	return productObj, nil
+}
+
+// Delete a product by its specified id.
+func (c postgresController) DeleteProduct(ctx context.Context, productId string) error {
+	// Begin a DB transaction
+	tx, err := c.cl.Begin(ctx)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeExtService, "failed to begin transaction", err)
+	}
+	defer tx.Rollback(ctx)
+
+	// Get product
+	productObj, err := c.getProduct(ctx, &tx, productId)
+	if err != nil {
+		return err
+	}
+
+	// Delete product
+	_, err = tx.Exec(ctx, "DELETE FROM products WHERE id=$1", productId)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeExtService, "failed to delete product", err)
+	}
+
+	// Add the event to the outbox table with the transaction
+	evt, evtTopic, err := product.PrepareProductDeletedEvent(productObj)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeService, "failed to create event", err)
+	}
+
+	_, err = tx.Exec(ctx, "INSERT INTO event_outbox (aggregateid, aggregatetype, payload) VALUES ($1, $2, $3)", productObj.Id, evtTopic, evt)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeExtService, "failed to insert event", err)
+	}
+
+	// Commit the transaction
+	err = tx.Commit(ctx)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeExtService, "failed to commit transaction", err)
+	}
+
+	return nil
+}
+
+func (c postgresController) PriceOrderProducts(ctx context.Context, orderId string, customerId string, productQuantities map[string]int32) error {
+	// Begin a DB transaction
+	tx, err := c.cl.Begin(ctx)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeExtService, "failed to begin transaction", err)
+	}
+	defer tx.Rollback(ctx)
+
+	// Get prices of all specified products (in productQuantities)
+	productIds := maps.Keys(productQuantities)
+	statement, args, err := goqu.Dialect("postgres").From("products").Select("id", "price").Where(goqu.C("id").In(productIds)).Prepared(true).ToSQL()
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeService, "failed to build statement", err)
+	}
+
+	rows, err := tx.Query(ctx, statement, args...)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeExtService, "failed to fetch price quotes", err)
+	}
+
+	var productPrices map[string]float32
+	for rows.Next() {
+		var productId string
+		var productPrice float32
+		err := rows.Scan(&productId, &productPrice)
+		if err != nil {
+			return errors.WrapServiceError(errors.ErrCodeNotFound, "failed to fetch price quotes: error whilst scanning row", err)
+		}
+
+		productPrices[productId] = productPrice
+	}
+
+	if rows.Err() != nil {
+		return errors.WrapServiceError(errors.ErrCodeService, "failed to fetch price quotes: error whilst scanning rows", rows.Err())
+	}
+
+	// Calculate total price
+	// Also ensuring that all items in the itemQuantities have a fetched price
+	var totalPrice float32
+	for productId, quantity := range productQuantities {
+		productPrice, ok := productPrices[productId]
+		if !ok {
+			// Prepare and dispatch failure product pricing event
+			evt, evtTopic, err := product.PrepareProductPriceQuoteEvent_Unavaliable(orderId)
+			if err != nil {
+				return errors.WrapServiceError(errors.ErrCodeService, "failed to create event", err)
+			}
+
+			_, err = c.cl.Exec(ctx, "INSERT INTO event_outbox (aggregateid, aggregatetype, payload) VALUES ($1, $2, $3)", orderId, evtTopic, evt)
+			if err != nil {
+				return errors.WrapServiceError(errors.ErrCodeExtService, "failed to insert event", err)
+			}
+
+			return nil
+		}
+
+		// Add to total price
+		totalPrice += productPrice * float32(quantity)
+	}
+
+	// Prepare and dispatch succesful product pricing event
+	evt, evtTopic, err := product.PrepareProductPriceQuoteEvent_Avaliable(
+		orderId,
+		productQuantities,
+		productPrices,
+		totalPrice,
+	)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeService, "failed to create event", err)
+	}
+
+	_, err = tx.Exec(ctx, "INSERT INTO event_outbox (aggregateid, aggregatetype, payload) VALUES ($1, $2, $3)", orderId, evtTopic, evt)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeExtService, "failed to insert event", err)
+	}
+
+	// Commit the transaction
+	err = tx.Commit(ctx)
+	if err != nil {
+		return errors.WrapServiceError(errors.ErrCodeExtService, "failed to commit transaction", err)
+	}
+
+	return nil
+}
+
+// Scan a postgres row to a protobuf object
+func scanRowToProduct(row pgx.Row) (*pb.Product, error) {
+	var productObj pb.Product
+
+	// Temporary variables that require conversion
+	var tmpCreatedAt pgtype.Timestamp
+	var tmpUpdatedAt pgtype.Timestamp
+
+	err := row.Scan(
+		&productObj.Id,
+		&productObj.Name,
+		&productObj.Description,
+		&productObj.Price,
+		&tmpCreatedAt,
+		&tmpUpdatedAt,
+	)
+	if err != nil {
+		if err == pgx.ErrNoRows {
+			return nil, errors.WrapServiceError(errors.ErrCodeNotFound, "product not found", err)
+		} else {
+			return nil, errors.WrapServiceError(errors.ErrCodeExtService, "failed to scan object from database", err)
+		}
+	}
+
+	// convert postgres timestamps to unix format
+	if tmpCreatedAt.Valid {
+		productObj.CreatedAt = tmpCreatedAt.Time.Unix()
+	} else {
+		return nil, errors.NewServiceError(errors.ErrCodeUnknown, "failed to scan object from database (timestamp conversion)")
+	}
+
+	if tmpUpdatedAt.Valid {
+		unixUpdated := tmpUpdatedAt.Time.Unix()
+		productObj.UpdatedAt = &unixUpdated
+	}
+
+	return &productObj, nil
+}