Change structure of code to a frontend and backend one

cmd/backend/issues.go

@@ -0,0 +1,65 @@
+package backend
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"log"
+)
+
+func (db *DB) AddIssue() (int64, error) {
+	query := "INSERT INTO issues (published) VALUES (?)"
+	result, err := db.Exec(query, false)
+	if err != nil {
+		return 0, fmt.Errorf("error inserting issue into DB: %v", err)
+	}
+
+	id, err := result.LastInsertId()
+	if err != nil {
+		return 0, fmt.Errorf("error getting ID of added issue: %v", err)
+	}
+
+	return id, nil
+}
+
+func (db *DB) PublishLatestIssue() error {
+	txOptions := &sql.TxOptions{Isolation: sql.LevelSerializable}
+	updateQuery := "UPDATE issues SET published = true WHERE published = false"
+	insertQuery := "INSERT INTO issues (published) VALUES (?)"
+
+	for i := 0; i < TxMaxRetries; i++ {
+		err := func() error {
+			tx, err := db.BeginTx(context.Background(), txOptions)
+			if err != nil {
+				return fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			if _, err := tx.Exec(updateQuery); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error publishing issue: %v", err)
+			}
+
+			if _, err := tx.Exec(insertQuery, false); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error inserting new issue into DB: %v", err)
+			}
+
+			if err = tx.Commit(); err != nil {
+				return fmt.Errorf("error committing transaction when publishing issue: %v", err)
+			}
+			return nil
+		}()
+		if err == nil {
+			return nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+
+	return fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}