Restructured - new game changer

client/postgresql/postgres.go

@@ -0,0 +1,37 @@
+package postgresql
+
+import (
+	"context"
+	"errors"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgconn"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func Connect(connStr string) (*pgxpool.Pool, error) {
+	pool, err := pgxpool.New(context.Background(), connStr)
+	if err != nil {
+		return nil, err
+	}
+
+	return pool, nil
+}
+
+func IsDuplicatedRow(err error) error {
+	var pgErr *pgconn.PgError
+
+	if errors.As(err, &pgErr) && pgErr.Code == "23505" {
+		return errors.New("duplicated row found")
+	}
+
+	return nil
+}
+
+func NoRowsInQuerySet(err error) error {
+	if err == pgx.ErrNoRows {
+		return errors.New("no rows found")
+	}
+
+	return nil
+}

client/rabbitmq/rabbitmq.go

@@ -0,0 +1,104 @@
+package rabbitmq
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"log"
+
+	amqp "github.com/rabbitmq/amqp091-go"
+)
+
+type Message map[string]interface{}
+
+func Connect(url string) (*amqp.Connection, *amqp.Channel, error) {
+	conn, err := amqp.Dial(url)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	ch, err := conn.Channel()
+	if err != nil {
+		log.Printf("Failed to open a channel: %v\n", err)
+		return nil, nil, err
+	}
+
+	return conn, ch, nil
+}
+
+func Close(conn *amqp.Connection) error {
+	return conn.Close()
+}
+
+func Serialize(msg any) (string, error) { // FIXME move to separate service
+	var b bytes.Buffer
+	encoder := json.NewEncoder(&b)
+	err := encoder.Encode(msg)
+
+	return b.String(), err
+}
+
+func Deserialize(b []byte) (Message, error) { // FIXME move to separate service
+	var msg Message
+	buf := bytes.NewBuffer(b)
+	decoder := json.NewDecoder(buf)
+	err := decoder.Decode(&msg)
+
+	return msg, err
+}
+
+func NewExchange(chn *amqp.Channel, name string) error {
+	err := chn.ExchangeDeclare(
+		name,
+		"direct", // type
+		true,     // durable
+		false,    // auto-deleted
+		false,    // internal
+		false,    // no-wait
+		nil,      // arguments
+	)
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func Publish(chn *amqp.Channel, name, routingKey string, msg any) error {
+	jsonData, err := Serialize(msg)
+	if err != nil {
+		return err
+	}
+
+	msgBody := fmt.Sprintf(`{"event":"%T","data":%s}`, msg, jsonData)
+	chn.Publish(
+		name,       // exchange name
+		routingKey, // routing key
+		false,      // mandatory
+		false,      // immediate
+		amqp.Publishing{
+			ContentType: "application/json",
+			Body:        []byte(msgBody),
+		},
+	)
+
+	return nil
+}
+
+func BindQueueToExchange(chn *amqp.Channel, queueName, exchName, routingKey string) error {
+	err := chn.QueueBind(
+		queueName,  // queue name
+		routingKey, // routing key
+		exchName,   // exchange name
+		false,
+		nil,
+	)
+	if err != nil {
+		log.Printf("Failed to bind a queue: %s\n", queueName)
+
+		return err
+	}
+
+	return nil
+}