Bump postgresql from 42.2.12 to 42.4.1

Bumps [postgresql](https://github.com/pgjdbc/pgjdbc) from 42.2.12 to 42.4.1.
- [Release notes](https://github.com/pgjdbc/pgjdbc/releases)
- [Changelog](https://github.com/pgjdbc/pgjdbc/blob/master/CHANGELOG.md)
- [Commits](https://github.com/pgjdbc/pgjdbc/compare/REL42.2.12...REL42.4.1)

---
updated-dependencies:
- dependency-name: org.postgresql:postgresql
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/master.yaml

@@ -35,4 +35,36 @@ jobs:
       - name: SonarCloud Scan
         run: mvn -B clean verify -Psonar,component-test -Dsonar.login=${{ secrets.SONAR_TOKEN }}
         env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  artifact:
+    name: Publish - GitHub Packages
+    runs-on: ubuntu-18.04
+    needs: [test, sonar]
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: Set up JDK 11
+        uses: actions/setup-java@v1
+        with:
+          java-version: 11.0.4
+      - name: Publish artifact on GitHub Packages
+        run: mvn -B clean deploy -DskipTests
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  docker:
+    name: Publish - Docker Hub
+    runs-on: ubuntu-18.04
+    needs: [test, sonar]
+    env:
+      REPO: ${{ secrets.DOCKER_REPO }}
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: Login to Docker Hub
+        run: docker login -u ${{ secrets.DOCKER_USER }} -p ${{ secrets.DOCKER_PASS }}
+      - name: Build Docker image
+        run: docker build -t $REPO:latest -t $REPO:${GITHUB_SHA::8} .
+      - name: Publish Docker image
+        run: docker push $REPO

.gitignore

@@ -31,3 +31,4 @@ build/
 
 ### VS Code ###
 .vscode/
+sendgrid.env

Dockerfile

@@ -0,0 +1,11 @@
+FROM maven:3.6.3-jdk-11-slim AS build
+RUN mkdir -p /workspace
+WORKDIR /workspace
+COPY pom.xml /workspace
+COPY src /workspace/src
+RUN mvn -B -f pom.xml clean package -DskipTests
+
+FROM openjdk:11-jdk-slim
+COPY --from=build /workspace/target/*.jar app.jar
+EXPOSE 8080
+ENTRYPOINT ["java","-jar","app.jar", "--spring.profiles.active=prod"]

README.md

@@ -0,0 +1,46 @@
+# Library 
+> written in *Hexagonal (Ports & Adapters) Architecture*
+
+![Master Branch](https://github.com/wkrzywiec/library-hexagonal/workflows/Master%20Branch/badge.svg?branch=master) [![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=wkrzywiec_library-hexagonal&metric=alert_status)](https://sonarcloud.io/dashboard?id=wkrzywiec_library-hexagonal) [![Coverage](https://sonarcloud.io/api/project_badges/measure?project=wkrzywiec_library-hexagonal&metric=coverage)](https://sonarcloud.io/dashboard?id=wkrzywiec_library-hexagonal) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
+This is a small application that provides basic REST endpoints for managing library (add new book, reserve, borrow it, etc.). 
+
+The technology behind it: 
+* Java 11
+* Postgres
+* Spring Boot 
+
+## Installing / Getting started
+
+#### Using `docker-compose`
+
+In the terminal run the following command:
+```console
+$ docker-compose up
+``` 
+
+#### Using Maven (with H2 or local Postgres database)
+
+First compile an application:
+
+```console
+$ mvn clean package
+```
+
+Then, you have two options either run it with H2 database or with local Postgres database. For first approach just run:
+
+```console
+$ mvn spring-boot:run 
+```
+
+For a second option, check in the configuration file - `src/main/resources/application.yml` for profile *local-postgres* if connection details are correct and if so, run the command:
+```console
+$ mvn spring-boot:run -P local-postgres
+```
+
+#### Inside IntelliJ (with H2 or Postgres database)
+
+First configure how you run the `LibraryHexagonalApplication.java` by adding `--spring.profiles.active=h2` (for H2 database) or `--spring.profiles.active=postgres` (for Postgres database) as a **Program argument**.
+
+Then just run the `LibraryHexagonalApplication.java` class so it will use H2 database (you don't need to have postgres database up and running).
+

docker-compose.yml

@@ -0,0 +1,31 @@
+version: '3'
+
+services:
+  postgres:
+    image: "postgres:9.6-alpine"
+    container_name: postgres
+    volumes:
+      - postgres-data:/var/lib/postgresql/data
+    ports:
+      - 5432:5432
+    environment:
+      - POSTGRES_SERVER=postgres
+      - POSTGRES_DB=library
+      - POSTGRES_USER=library
+      - POSTGRES_PASSWORD=library
+
+  library:
+    build: .
+    container_name: library-app
+    ports:
+      - 8080:8080
+    environment:
+      - POSTGRES_SERVER=postgres
+      - POSTGRES_DB=library
+      - POSTGRES_USER=library
+      - POSTGRES_PASSWORD=library
+    depends_on:
+      - postgres
+
+volumes:
+  postgres-data:

pom.xml

@@ -6,7 +6,7 @@
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
 		<version>2.2.6.RELEASE</version>
-		<relativePath/> <!-- lookup parent from repository -->
+		<relativePath/>
 	</parent>
 
 	<groupId>io.wkrzywiec.hexagonal</groupId>
@@ -17,9 +17,15 @@
 
 	<properties>
 		<java.version>11</java.version>
-		<spring-cloud.version>Hoxton.M3</spring-cloud.version>
 		<surefire.and.failsafe.report.dir>target/test-report</surefire.and.failsafe.report.dir>
-		<code.coverage.exclusions></code.coverage.exclusions>
+		<code.coverage.exclusions>
+			**/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/**,
+			**/io/wkrzywiec/hexagonal/library/domain/email/core/model/**,
+			**/io/wkrzywiec/hexagonal/library/domain/inventory/core/model/**,
+			**/io/wkrzywiec/hexagonal/library/domain/user/core/model/**,
+			**/io/wkrzywiec/hexagonal/library/**/*Entity.java,
+			**/io/wkrzywiec/hexagonal/library/LibraryHexagonalApplication.java
+		</code.coverage.exclusions>
 	</properties>
 
 	<dependencies>
@@ -27,6 +33,10 @@
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-actuator</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-web</artifactId>
@@ -47,6 +57,11 @@
 			<artifactId>gson</artifactId>
 			<version>2.8.6</version>
 		</dependency>
+		<dependency>
+			<groupId>com.fasterxml.jackson.module</groupId>
+			<artifactId>jackson-module-jaxb-annotations</artifactId>
+			<version>2.11.0</version>
+		</dependency>
 
 		<dependency>
 			<groupId>com.h2database</groupId>
@@ -54,6 +69,21 @@
 			<scope>runtime</scope>
 			<version>1.4.200</version>
 		</dependency>
+		<dependency>
+			<groupId>org.postgresql</groupId>
+			<artifactId>postgresql</artifactId>
+			<version>42.4.1</version>
+		</dependency>
+		<dependency>
+			<groupId>org.liquibase</groupId>
+			<artifactId>liquibase-core</artifactId>
+			<version>3.9.0</version>
+		</dependency>
+		<dependency>
+			<groupId>com.sendgrid</groupId>
+			<artifactId>sendgrid-java</artifactId>
+			<version>4.4.8</version>
+		</dependency>
 
 		<dependency>
 			<groupId>org.springdoc</groupId>
@@ -61,16 +91,28 @@
 			<version>1.2.32</version>
 		</dependency>
 
+		<!--	TEST dependencies	-->
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
-			<exclusions>
-				<exclusion>
-					<groupId>org.junit.vintage</groupId>
-					<artifactId>junit-vintage-engine</artifactId>
-				</exclusion>
-			</exclusions>
+		</dependency>
+		<dependency>
+			<groupId>org.spockframework</groupId>
+			<artifactId>spock-core</artifactId>
+			<version>1.3-groovy-2.5</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.spockframework</groupId>
+			<artifactId>spock-spring</artifactId>
+			<version>1.3-groovy-2.5</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>io.rest-assured</groupId>
+			<artifactId>rest-assured</artifactId>
+			<scope>test</scope>
 		</dependency>
 		<dependency>
 			<groupId>com.tngtech.archunit</groupId>
@@ -78,10 +120,7 @@
 			<version>0.13.1</version>
 			<scope>test</scope>
 		</dependency>
-		<dependency>
-			<groupId>io.rest-assured</groupId>
-			<artifactId>rest-assured</artifactId>
-		</dependency>
+
 	</dependencies>
 
 	<build>
@@ -103,6 +142,10 @@
 				</executions>
 				<configuration>
 					<reportsDirectory>${surefire.and.failsafe.report.dir}</reportsDirectory>
+					<includes>
+						<include>**/*ITCase.java</include>
+						<include>**/*ComponentTest.java</include>
+					</includes>
 				</configuration>
 			</plugin>
 			<plugin>
@@ -110,8 +153,25 @@
 				<artifactId>maven-surefire-plugin</artifactId>
 				<configuration>
 					<reportsDirectory>${surefire.and.failsafe.report.dir}</reportsDirectory>
+					<includes>
+						<include>**/*Spec.java</include>
+						<include>**/*Test.java</include>
+					</includes>
 				</configuration>
 			</plugin>
+			<plugin>
+				<groupId>org.codehaus.gmavenplus</groupId>
+				<artifactId>gmavenplus-plugin</artifactId>
+				<version>1.10.0</version>
+				<executions>
+					<execution>
+						<goals>
+							<goal>addTestSources</goal>
+							<goal>compileTests</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
 			<plugin>
 				<groupId>org.jacoco</groupId>
 				<artifactId>jacoco-maven-plugin</artifactId>
@@ -156,6 +216,33 @@
 	</build>
 
 	<profiles>
+		<profile>
+			<id>default</id>
+			<activation>
+				<activeByDefault>true</activeByDefault>
+			</activation>
+			<properties>
+				<active-profiles>default</active-profiles>
+			</properties>
+		</profile>
+		<profile>
+			<id>prod</id>
+			<activation>
+				<activeByDefault>false</activeByDefault>
+			</activation>
+			<properties>
+				<active-profiles>prod</active-profiles>
+			</properties>
+		</profile>
+		<profile>
+			<id>local-postgres</id>
+			<activation>
+				<activeByDefault>false</activeByDefault>
+			</activation>
+			<properties>
+				<active-profiles>local-postgres</active-profiles>
+			</properties>
+		</profile>
 		<profile>
 			<id>component-test</id>
 			<build>
@@ -202,6 +289,7 @@
 				<sonar.sources>.</sonar.sources>
 				<sonar.inclusions>src/main/java/**,src/main/resources/**</sonar.inclusions>
 				<sonar.exclusions>${code.coverage.exclusions}</sonar.exclusions>
+				<sonat.tests>src/test/groovy,src/test/java</sonat.tests>
 				<sonar.projectKey>wkrzywiec_library-hexagonal</sonar.projectKey>
 				<sonar.organization>wkrzywiec</sonar.organization>
 				<sonar.coverage.jacoco.xmlReportPaths>target/site/jacoco/jacoco.xml,target/site/jacoco-it/jacoco.xml</sonar.coverage.jacoco.xmlReportPaths>
@@ -229,4 +317,12 @@
 			</build>
 		</profile>
 	</profiles>
+
+	<distributionManagement>
+		<repository>
+			<id>github</id>
+			<name>Library REST application (hexagonal)</name>
+			<url>https://maven.pkg.github.com/wkrzywiec/library-hexagonal</url>
+		</repository>
+	</distributionManagement>
 </project>

src/component-test/java/io/wkrzywiec/hexagonal/library/application/AddNewBookTest.java

@@ -1,83 +0,0 @@
-package io.wkrzywiec.hexagonal.library.application;
-
-import io.restassured.RestAssured;
-import io.restassured.response.ValidatableResponse;
-import io.wkrzywiec.hexagonal.library.TestData;
-import io.wkrzywiec.hexagonal.library.domain.book.model.BookDetailsDTO;
-import io.wkrzywiec.hexagonal.library.domain.book.model.ExternalBookIdDTO;
-import io.wkrzywiec.hexagonal.library.infrastructure.repository.BookEntity;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.DisplayName;
-import org.junit.jupiter.api.Test;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.boot.web.server.LocalServerPort;
-import org.springframework.http.HttpStatus;
-import org.springframework.jdbc.core.BeanPropertyRowMapper;
-import org.springframework.jdbc.core.JdbcTemplate;
-
-import static io.restassured.RestAssured.given;
-import static org.hamcrest.Matchers.greaterThan;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
-public class AddNewBookTest {
-
-    @LocalServerPort
-    private int port;
-
-    @Autowired
-    private JdbcTemplate jdbc;
-
-    private String baseURL;
-
-    @BeforeEach
-    public void init(){
-        this.baseURL = "http://localhost:" + port;
-        RestAssured.enableLoggingOfRequestAndResponseIfValidationFails();
-    }
-
-    @Test
-    @DisplayName("Search for a new book in Google Books")
-    public void whenSearchForBook_thenGetList(){
-        //when
-        ValidatableResponse response = given()
-                .when()
-                    .param("query", "lean startup")
-                    .get( baseURL + "/google/books")
-                    .prettyPeek()
-                .then();
-
-        //then
-        response.statusCode(HttpStatus.OK.value())
-                .contentType("application/json")
-                .body("items.size()", greaterThan(0));
-    }
-
-    @Test
-    @DisplayName("Add new book to a database")
-    public void givenGoogleBooId_whenAddNewBook_thenBookIsSaved(){
-        //given
-        BookDetailsDTO homoDeusBookDetails = TestData.homoDeusBookDetailsDTO();
-        ExternalBookIdDTO googleBookId =
-                ExternalBookIdDTO.builder()
-                        .value(homoDeusBookDetails.getBookExternalId())
-                        .build();
-
-        //when
-        ValidatableResponse response =
-                given()
-                        .contentType("application/json")
-                        .body(googleBookId)
-                .when()
-                    .post( baseURL + "/books")
-                    .prettyPeek()
-                .then();
-
-        //then
-        String homoDeusSql = "select * from book where book_external_id = '" + homoDeusBookDetails.getBookExternalId() + "'";
-        BookEntity savedBook = (BookEntity) jdbc.queryForObject(homoDeusSql, new BeanPropertyRowMapper(BookEntity.class));
-        assertEquals(homoDeusBookDetails.getTitle(), savedBook.getTitle());
-        assertEquals(homoDeusBookDetails.getTitle(), savedBook.getTitle());
-    }
-}

src/component-test/java/io/wkrzywiec/hexagonal/library/domain/BaseComponentTest.java

@@ -0,0 +1,28 @@
+package io.wkrzywiec.hexagonal.library.domain;
+
+import io.restassured.RestAssured;
+import io.wkrzywiec.hexagonal.library.DatabaseHelper;
+import org.junit.jupiter.api.BeforeEach;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.web.server.LocalServerPort;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+public abstract class BaseComponentTest {
+
+    @LocalServerPort
+    private int port;
+    protected String baseURL;
+
+    @Autowired
+    protected JdbcTemplate jdbcTemplate;
+    protected DatabaseHelper databaseHelper;
+
+    @BeforeEach
+    public void init() {
+        this.baseURL = "http://localhost:" + port;
+        RestAssured.enableLoggingOfRequestAndResponseIfValidationFails();
+        databaseHelper = new DatabaseHelper(jdbcTemplate);
+    }
+}

src/component-test/java/io/wkrzywiec/hexagonal/library/domain/borrowing/BorrowBookComponentTest.java

@@ -0,0 +1,44 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing;
+
+import io.wkrzywiec.hexagonal.library.domain.BaseComponentTest;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.application.model.BookStatus;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.application.model.ChangeBookStatusRequest;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BorrowBookCommand;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.test.context.jdbc.Sql;
+
+import static io.restassured.RestAssured.given;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.springframework.test.context.jdbc.Sql.ExecutionPhase.AFTER_TEST_METHOD;
+
+public class BorrowBookComponentTest extends BaseComponentTest {
+
+    @Test
+    @DisplayName("Borrow reserved book")
+    @Sql({"/book-and-user.sql", "/reserved-book.sql"})
+    @Sql(scripts = "/clean-database.sql", executionPhase = AFTER_TEST_METHOD)
+    public void givenBookIsReserved_thenBorrowIt_thenBookIsBorrowed() {
+        //given
+        Long homoDeusBookId = databaseHelper.getHomoDeusBookId();
+        Long activeUserId = databaseHelper.getJohnDoeUserId();
+
+        ChangeBookStatusRequest borrowRequest =
+                ChangeBookStatusRequest.builder()
+                .userId(activeUserId)
+                .status(BookStatus.BORROWED)
+                .build();
+
+        //when
+        given()
+                .contentType("application/json")
+                .body(borrowRequest)
+                .when()
+                .patch( baseURL + "/books/" + homoDeusBookId + "/status")
+                .prettyPeek()
+                .then();
+
+        Long borrowId = databaseHelper.getPrimaryKeyOfBorrowedByBookId(homoDeusBookId);
+        assertTrue(borrowId > 0);
+    }
+}

src/component-test/java/io/wkrzywiec/hexagonal/library/domain/borrowing/GiveBackBookComponentTest.java

@@ -0,0 +1,45 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing;
+
+import io.wkrzywiec.hexagonal.library.domain.BaseComponentTest;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.application.model.BookStatus;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.application.model.ChangeBookStatusRequest;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.GiveBackBookCommand;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.test.context.jdbc.Sql;
+
+import static io.restassured.RestAssured.given;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.springframework.test.context.jdbc.Sql.ExecutionPhase.AFTER_TEST_METHOD;
+
+public class GiveBackBookComponentTest extends BaseComponentTest {
+
+    @Test
+    @DisplayName("Give back borrowed book")
+    @Sql({"/book-and-user.sql", "/borrowed-book.sql"})
+    @Sql(scripts = "/clean-database.sql", executionPhase = AFTER_TEST_METHOD)
+    public void givenBookIsBorrowed_thenGiveBackIt_thenItIsAvailable() {
+        //given
+        Long homoDeusBookId = databaseHelper.getHomoDeusBookId();
+        Long activeUserId = databaseHelper.getJohnDoeUserId();
+
+        ChangeBookStatusRequest giveBackRequest =
+                ChangeBookStatusRequest.builder()
+                        .userId(activeUserId)
+                        .status(BookStatus.AVAILABLE)
+                        .build();
+
+        //when
+        given()
+                .contentType("application/json")
+                .body(giveBackRequest)
+                .when()
+                .patch( baseURL + "/books/" + homoDeusBookId + "/status")
+                .prettyPeek()
+                .then();
+
+        Long bookId = databaseHelper.getPrimaryKeyOfAvailableByBookBy(homoDeusBookId);
+
+        assertEquals(homoDeusBookId, bookId);
+    }
+}

src/component-test/java/io/wkrzywiec/hexagonal/library/domain/borrowing/MakeReservationComponentTest.java

@@ -0,0 +1,49 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing;
+
+import io.wkrzywiec.hexagonal.library.domain.BaseComponentTest;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.application.model.BookStatus;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.application.model.ChangeBookStatusRequest;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BookReservationCommand;
+import io.wkrzywiec.hexagonal.library.domain.inventory.infrastructure.BookRepository;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.jdbc.Sql;
+
+import static io.restassured.RestAssured.given;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.springframework.test.context.jdbc.Sql.ExecutionPhase.AFTER_TEST_METHOD;
+
+public class MakeReservationComponentTest extends BaseComponentTest {
+
+    @Autowired
+    private BookRepository bookRepository;
+
+    @Test
+    @DisplayName("Reserve available book")
+    @Sql({"/book-and-user.sql", "/available-book.sql"})
+    @Sql(scripts = "/clean-database.sql", executionPhase = AFTER_TEST_METHOD)
+    public void givenBookIsAvailable_thenMakeReservation_thenBookIsReserved() {
+        //given
+        Long homoDeusBookId = databaseHelper.getHomoDeusBookId();
+        Long activeUserId = databaseHelper.getJohnDoeUserId();
+
+        ChangeBookStatusRequest reservationRequest =
+                ChangeBookStatusRequest.builder()
+                        .userId(activeUserId)
+                        .status(BookStatus.RESERVED)
+                        .build();
+
+        //when
+        given()
+                .contentType("application/json")
+                .body(reservationRequest)
+        .when()
+                .patch( baseURL + "/books/" + homoDeusBookId + "/status")
+                .prettyPeek()
+        .then();
+
+        Long reservationId = databaseHelper.getPrimaryKeyOfReservationByBookId(homoDeusBookId);
+        assertTrue(reservationId > 0);
+    }
+}

src/component-test/java/io/wkrzywiec/hexagonal/library/domain/inventory/AddNewBookComponentTest.java

@@ -0,0 +1,63 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory;
+
+import io.restassured.response.ValidatableResponse;
+import io.wkrzywiec.hexagonal.library.BookTestData;
+import io.wkrzywiec.hexagonal.library.domain.BaseComponentTest;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.AddNewBookCommand;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.http.HttpStatus;
+import org.springframework.test.context.jdbc.Sql;
+
+import static io.restassured.RestAssured.given;
+import static org.hamcrest.Matchers.greaterThan;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.springframework.test.context.jdbc.Sql.ExecutionPhase.AFTER_TEST_METHOD;
+
+public class AddNewBookComponentTest extends BaseComponentTest {
+
+    @Test
+    @DisplayName("Search for a new book in Google Books")
+    public void whenSearchForBook_thenGetList(){
+        //when
+        ValidatableResponse response = given()
+                .when()
+                    .param("query", "lean startup")
+                    .get( baseURL + "/google/books")
+                    .prettyPeek()
+                .then();
+
+        //then
+        response.statusCode(HttpStatus.OK.value())
+                .contentType("application/json")
+                .body("items.size()", greaterThan(0));
+    }
+
+    @Test
+    @DisplayName("Add new book to a database & make it available")
+    @Sql(scripts = "/clean-database.sql", executionPhase = AFTER_TEST_METHOD)
+    public void givenGoogleBooId_whenAddNewBook_thenBookIsSaved() {
+        //given
+        AddNewBookCommand addNewBookCommand =
+                AddNewBookCommand.builder()
+                        .googleBookId(BookTestData.homoDeusBookGoogleId())
+                        .build();
+
+        //when
+        given()
+                .contentType("application/json")
+                .body(addNewBookCommand)
+        .when()
+                .post( baseURL + "/books")
+                .prettyPeek()
+        .then();
+
+        //then
+        Long savedBookId = databaseHelper.getHomoDeusBookId();
+        assertTrue(savedBookId > 0);
+
+        Long availableBookId = databaseHelper.getPrimaryKeyOfAvailableByBookBy(savedBookId);
+
+        assertTrue(availableBookId > 0);
+    }
+}

src/component-test/java/io/wkrzywiec/hexagonal/library/domain/user/AddNewUserComponentTest.java

@@ -0,0 +1,40 @@
+package io.wkrzywiec.hexagonal.library.domain.user;
+
+import io.wkrzywiec.hexagonal.library.domain.BaseComponentTest;
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.AddUserCommand;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.test.context.jdbc.Sql;
+
+import static io.restassured.RestAssured.given;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.springframework.test.context.jdbc.Sql.ExecutionPhase.AFTER_TEST_METHOD;
+
+public class AddNewUserComponentTest extends BaseComponentTest {
+
+    @Test
+    @DisplayName("Create new user")
+    @Sql(scripts = "/clean-database.sql", executionPhase = AFTER_TEST_METHOD)
+    public void shouldCreateNewUser(){
+        //given
+        AddUserCommand addUserCommand = AddUserCommand.builder()
+                .firstName("John")
+                .lastName("Doe")
+                .email("john.doe@test.com")
+                .build();
+
+        //when
+        given()
+                .contentType("application/json")
+                .body(addUserCommand)
+        .when()
+                .post( baseURL + "/users")
+                .prettyPeek()
+        .then();
+
+        //then
+        Long savedUserId = databaseHelper.getJohnDoeUserId();
+        assertTrue(savedUserId > 0);
+    }
+
+}

src/component-test/resources/application.yml

@@ -4,4 +4,4 @@ spring:
     driverClassName: org.h2.Driver
     username: sa
     password: password
-    jpa.database-platform: org.hibernate.dialect.H2Dialect
+    jpa.database-platform: org.hibernate.dialect.H2Dialect

src/main/java/io/wkrzywiec/hexagonal/library/LibraryHexagonalApplication.java

@@ -1,9 +1,24 @@
 package io.wkrzywiec.hexagonal.library;
 
+import io.wkrzywiec.hexagonal.library.infrastructure.BorrowingDomainConfig;
+import io.wkrzywiec.hexagonal.library.infrastructure.EmailDomainConfig;
+import io.wkrzywiec.hexagonal.library.infrastructure.InventoryDomainConfig;
+import io.wkrzywiec.hexagonal.library.infrastructure.LibraryHexagonalConfig;
+import io.wkrzywiec.hexagonal.library.infrastructure.UserDomainConfig;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Import;
+import org.springframework.scheduling.annotation.EnableScheduling;
 
 @SpringBootApplication
+@EnableScheduling
+@Import({
+		LibraryHexagonalConfig.class,
+		InventoryDomainConfig.class,
+		BorrowingDomainConfig.class,
+		EmailDomainConfig.class,
+		UserDomainConfig.class
+})
 public class LibraryHexagonalApplication {
 
 	public static void main(String[] args) {

src/main/java/io/wkrzywiec/hexagonal/library/application/LibraryHexagonalController.java

@@ -0,0 +1,15 @@
+package io.wkrzywiec.hexagonal.library.application;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/")
+public class LibraryHexagonalController {
+
+    @GetMapping("")
+    public String getAppRoot(){
+        return "Library Hexagonal REST API";
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/book/Book.java

@@ -1,11 +0,0 @@
-package io.wkrzywiec.hexagonal.library.domain.book;
-
-import lombok.Builder;
-
-@Builder
-class Book {
-
-    long id;
-    String title;
-
-}

src/main/java/io/wkrzywiec/hexagonal/library/domain/book/BookFacade.java

@@ -1,24 +0,0 @@
-package io.wkrzywiec.hexagonal.library.domain.book;
-
-import io.wkrzywiec.hexagonal.library.domain.book.model.BookDetailsDTO;
-import io.wkrzywiec.hexagonal.library.domain.book.model.ExternalBookIdDTO;
-import io.wkrzywiec.hexagonal.library.domain.book.ports.incoming.AddNewBook;
-import io.wkrzywiec.hexagonal.library.domain.book.ports.incoming.GetBookDetails;
-import io.wkrzywiec.hexagonal.library.domain.book.ports.outgoing.BookDatabase;
-
-public class BookFacade implements AddNewBook {
-
-    private BookDatabase database;
-    private GetBookDetails getBookDetails;
-
-    public BookFacade(BookDatabase database, GetBookDetails getBookDetails) {
-        this.database = database;
-        this.getBookDetails = getBookDetails;
-    }
-
-    @Override
-    public void handle(ExternalBookIdDTO externalBookIdDTO){
-        BookDetailsDTO bookDetails = getBookDetails.handle(externalBookIdDTO.getValue());
-        database.save(bookDetails);
-    }
-}

src/main/java/io/wkrzywiec/hexagonal/library/domain/book/model/BookDetailsDTO.java

@@ -1,24 +0,0 @@
-package io.wkrzywiec.hexagonal.library.domain.book.model;
-
-import lombok.Builder;
-import lombok.EqualsAndHashCode;
-import lombok.Value;
-
-import java.util.List;
-
-@Value
-@Builder
-public class BookDetailsDTO {
-
-    private String bookExternalId;
-    private String isbn10;
-    private String isbn13;
-    private String title;
-    private List<String> authors;
-    private String publisher;
-    private String publishedDate;
-    private String description;
-    private int pages;
-    @EqualsAndHashCode.Exclude
-    private String imageLink;
-}

src/main/java/io/wkrzywiec/hexagonal/library/domain/book/model/ExternalBookIdDTO.java

@@ -1,15 +0,0 @@
-package io.wkrzywiec.hexagonal.library.domain.book.model;
-
-import lombok.AllArgsConstructor;
-import lombok.Builder;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-
-@Data
-@AllArgsConstructor
-@NoArgsConstructor
-@Builder
-public class ExternalBookIdDTO {
-
-    private String value;
-}

src/main/java/io/wkrzywiec/hexagonal/library/domain/book/ports/incoming/AddNewBook.java

@@ -1,7 +0,0 @@
-package io.wkrzywiec.hexagonal.library.domain.book.ports.incoming;
-
-import io.wkrzywiec.hexagonal.library.domain.book.model.ExternalBookIdDTO;
-
-public interface AddNewBook {
-    void handle(ExternalBookIdDTO externalBookIdDTO);
-}

src/main/java/io/wkrzywiec/hexagonal/library/domain/book/ports/incoming/GetBookDetails.java

@@ -1,7 +0,0 @@
-package io.wkrzywiec.hexagonal.library.domain.book.ports.incoming;
-
-import io.wkrzywiec.hexagonal.library.domain.book.model.BookDetailsDTO;
-
-public interface GetBookDetails {
-    BookDetailsDTO handle(String bookId);
-}

src/main/java/io/wkrzywiec/hexagonal/library/domain/book/ports/outgoing/BookDatabase.java

@@ -1,8 +0,0 @@
-package io.wkrzywiec.hexagonal.library.domain.book.ports.outgoing;
-
-import io.wkrzywiec.hexagonal.library.domain.book.model.BookDetailsDTO;
-
-public interface BookDatabase {
-
-    void save(BookDetailsDTO newBookDTO);
-}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/application/BorrowingDomainController.java

@@ -0,0 +1,50 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.application;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.application.model.ChangeBookStatusRequest;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BookReservationCommand;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BorrowBookCommand;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.GiveBackBookCommand;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.BorrowBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.GiveBackBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.ReserveBook;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PatchMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/books")
+@RequiredArgsConstructor
+public class BorrowingDomainController {
+
+    @Qualifier("GiveBackBook")
+    private final GiveBackBook giveBackBook;
+
+    @Qualifier("ReserveBook")
+    private final ReserveBook reserveBook;
+
+    @Qualifier("BorrowBook")
+    private final BorrowBook borrowBook;
+
+    @PatchMapping("/{id}/status")
+    public ResponseEntity<String> borrowBook(@PathVariable("id") Long bookId, @RequestBody ChangeBookStatusRequest request){
+        switch (request.getStatus()){
+            case AVAILABLE:
+                giveBackBook.handle(new GiveBackBookCommand(bookId, request.getUserId()));
+                return new ResponseEntity<>("Book with an id " + bookId + " was returned", HttpStatus.OK);
+            case RESERVED:
+                Long reservationId = reserveBook.handle(new BookReservationCommand(bookId, request.getUserId()));
+                return new ResponseEntity<>("Reservation has been made with an id " + reservationId, HttpStatus.OK);
+            case BORROWED:
+                borrowBook.handle(new BorrowBookCommand(bookId, request.getUserId()));
+                return new ResponseEntity<>("Book with an id " + bookId + " was borrowed", HttpStatus.OK);
+            default:
+                return new ResponseEntity<>("Book can't have status: " + request.getStatus(), HttpStatus.BAD_REQUEST);
+        }
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/application/NewBookWasAddedEventHandler.java

@@ -0,0 +1,22 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.application;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.MakeBookAvailableCommand;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.MakeBookAvailable;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.NewBookWasAddedEvent;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+
+@RequiredArgsConstructor
+@Component
+public class NewBookWasAddedEventHandler {
+
+    @Qualifier("MakeBookAvailable")
+    private final MakeBookAvailable makeBookAvailable;
+
+    @EventListener
+    public void handle(NewBookWasAddedEvent event){
+        makeBookAvailable.handle(new MakeBookAvailableCommand(event.getBookIdAsLong()));
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/application/OverdueReservationScheduler.java

@@ -0,0 +1,18 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.application;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.CancelOverdueReservations;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.scheduling.annotation.Scheduled;
+
+@RequiredArgsConstructor
+public class OverdueReservationScheduler {
+
+    @Qualifier("CancelOverdueReservations")
+    private final CancelOverdueReservations overdueReservations;
+
+    @Scheduled(fixedRate = 60 * 1000)
+    public void checkOverdueReservations(){
+        overdueReservations.cancelOverdueReservations();
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/application/model/BookStatus.java

@@ -0,0 +1,5 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.application.model;
+
+public enum BookStatus {
+    AVAILABLE, RESERVED, BORROWED
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/application/model/ChangeBookStatusRequest.java

@@ -0,0 +1,12 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.application.model;
+
+import lombok.Builder;
+import lombok.Data;
+
+@Data
+@Builder
+public class ChangeBookStatusRequest {
+
+    private BookStatus status;
+    private Long userId;
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/BorrowingFacade.java

@@ -0,0 +1,91 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ActiveUser;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.AvailableBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BookReservationCommand;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BookReservedEvent;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BorrowBookCommand;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BorrowedBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.GiveBackBookCommand;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.MakeBookAvailableCommand;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.OverdueReservation;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ReservationDetails;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ReservedBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception.ActiveUserNotFoundException;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception.AvailableBookNotFoundExeption;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception.BorrowedBookNotFoundException;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception.ReservedBookNotFoundException;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.BorrowBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.CancelOverdueReservations;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.GiveBackBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.MakeBookAvailable;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.ReserveBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.outgoing.BorrowingDatabase;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.outgoing.BorrowingEventPublisher;
+
+import java.util.List;
+
+public class BorrowingFacade implements MakeBookAvailable, ReserveBook, CancelOverdueReservations, BorrowBook, GiveBackBook {
+
+    private final BorrowingDatabase database;
+    private final BorrowingEventPublisher eventPublisher;
+
+    public BorrowingFacade(BorrowingDatabase database, BorrowingEventPublisher eventPublisher) {
+        this.database = database;
+        this.eventPublisher = eventPublisher;
+    }
+
+    @Override
+    public void handle(MakeBookAvailableCommand bookAvailableCommand) {
+        database.save(new AvailableBook(bookAvailableCommand.getBookId()));
+    }
+
+    @Override
+    public Long handle(BookReservationCommand bookReservation) {
+        AvailableBook availableBook =
+                database.getAvailableBook(bookReservation.getBookId())
+                .orElseThrow(() -> new AvailableBookNotFoundExeption(bookReservation.getBookId()));
+
+        ActiveUser activeUser =
+                database.getActiveUser(bookReservation.getUserId())
+                .orElseThrow(() -> new ActiveUserNotFoundException(bookReservation.getUserId()));
+
+        ReservedBook reservedBook = activeUser.reserve(availableBook);
+        ReservationDetails reservationDetails = database.save(reservedBook);
+        eventPublisher.publish(new BookReservedEvent(reservationDetails));
+        return reservationDetails.getReservationId().getIdAsLong();
+    }
+
+    @Override
+    public void cancelOverdueReservations() {
+        List<OverdueReservation> overdueReservationList = database.findReservationsForMoreThan(3L);
+        overdueReservationList.forEach(
+                overdueBook -> database.save(new AvailableBook(overdueBook.getBookIdentificationAsLong())));
+    }
+
+    @Override
+    public void handle(BorrowBookCommand borrowBookCommand) {
+        ActiveUser activeUser =
+                database.getActiveUser(borrowBookCommand.getUserId())
+                        .orElseThrow(() -> new ActiveUserNotFoundException(borrowBookCommand.getUserId()));
+        ReservedBook reservedBook =
+                database.getReservedBook(borrowBookCommand.getBookId())
+                .orElseThrow(() -> new ReservedBookNotFoundException(borrowBookCommand.getBookId()));
+
+        BorrowedBook borrowedBook = activeUser.borrow(reservedBook);
+        database.save(borrowedBook);
+    }
+
+    @Override
+    public void handle(GiveBackBookCommand command) {
+        BorrowedBook borrowedBook =
+                database.getBorrowedBook(command.getBookId())
+                .orElseThrow(() -> new BorrowedBookNotFoundException(command.getBookId()));
+        ActiveUser activeUser =
+                database.getActiveUser(command.getUserId())
+                        .orElseThrow(() -> new ActiveUserNotFoundException(command.getUserId()));
+
+        AvailableBook availableBook = activeUser.giveBack(borrowedBook);
+        database.save(availableBook);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/ActiveUser.java

@@ -0,0 +1,65 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception.TooManyBooksAssignedToUserException;
+import lombok.EqualsAndHashCode;
+
+import java.util.List;
+
+@EqualsAndHashCode
+public class ActiveUser {
+
+    private final Long id;
+    private final List<ReservedBook> reservedBooks;
+    private final List<BorrowedBook> borrowedBooks;
+
+    public ActiveUser(Long id, List<ReservedBook> reservedBooks, List<BorrowedBook> borrowedBooks) {
+        this.id = id;
+        this.reservedBooks = reservedBooks;
+        this.borrowedBooks = borrowedBooks;
+    }
+
+    public ReservedBook reserve(AvailableBook availableBook){
+        if (hasUserNotReachedLimitOfBooks()){
+            ReservedBook reservedBook = new ReservedBook(availableBook.getIdAsLong(), id);
+            reservedBooks.add(reservedBook);
+            return reservedBook;
+        } else {
+            throw new TooManyBooksAssignedToUserException(id);
+        }
+    }
+
+    public BorrowedBook borrow(ReservedBook reservedBook) {
+        if (hasUserNotReachedLimitOfBooks()){
+            BorrowedBook borrowedBook = new BorrowedBook(reservedBook.getIdAsLong(), id);
+            borrowedBooks.add(borrowedBook);
+            return borrowedBook;
+        } else {
+            throw new TooManyBooksAssignedToUserException(id);
+        }
+    }
+
+    public AvailableBook giveBack(BorrowedBook borrowedBook) {
+        boolean isBookRemovedFromUserAccount = borrowedBooks.removeIf(book -> book.equals(borrowedBook));
+        if (isBookRemovedFromUserAccount){
+            return new AvailableBook(borrowedBook.getIdAsLong());
+        } else {
+            throw new IllegalArgumentException("User with an id: " + id + " didn't borrow book with an id: " + borrowedBook.getIdAsLong());
+        }
+    }
+
+    public Long getIdAsLong(){
+        return id;
+    }
+
+    public List<ReservedBook> getReservedBookList(){
+        return reservedBooks;
+    }
+
+    public List<BorrowedBook> getBorrowedBookList() {
+        return borrowedBooks;
+    }
+
+    private boolean hasUserNotReachedLimitOfBooks(){
+        return reservedBooks.size() + borrowedBooks.size() < 3;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/AvailableBook.java

@@ -0,0 +1,18 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.EqualsAndHashCode;
+
+@EqualsAndHashCode
+public class AvailableBook implements Book {
+
+    private final Long id;
+
+    public AvailableBook(Long id) {
+        this.id = id;
+    }
+
+    @Override
+    public Long getIdAsLong() {
+        return id;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/Book.java

@@ -0,0 +1,5 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+interface Book {
+    Long getIdAsLong();
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/BookReservationCommand.java

@@ -0,0 +1,13 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+
+@AllArgsConstructor
+@Getter
+@Builder
+public class BookReservationCommand {
+    private Long bookId;
+    private Long userId;
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/BookReservedEvent.java

@@ -0,0 +1,35 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import java.time.Instant;
+
+public class BookReservedEvent {
+
+    private final ReservationId reservationId;
+    private final Long userId;
+    private final ReservedBook reservedBook;
+    private final Instant timestamp;
+
+    public BookReservedEvent(ReservationDetails reservationDetails) {
+        this.reservationId = reservationDetails.getReservationId();
+        this.userId = reservationDetails.getReservedBook().getAssignedUserIdAsLong();
+        this.reservedBook = reservationDetails.getReservedBook();
+        timestamp = Instant.now();
+    }
+
+    public Long getReservationIdAsLong() {
+        return reservationId.getIdAsLong();
+    }
+
+    public Long getUserIdAsLong() {
+        return userId;
+    }
+
+    public Long getBookIdAsLong() {
+        return reservedBook.getIdAsLong();
+    }
+
+    public String getEventTimeStampAsString() {
+        return timestamp.toString();
+    }
+
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/BorrowBookCommand.java

@@ -0,0 +1,13 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+
+@AllArgsConstructor
+@Getter
+@Builder
+public class BorrowBookCommand {
+    private Long bookId;
+    private Long userId;
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/BorrowedBook.java

@@ -0,0 +1,39 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.EqualsAndHashCode;
+
+import java.time.Instant;
+
+@EqualsAndHashCode
+public class BorrowedBook implements Book {
+
+    private Long bookId;
+    private Long userId;
+    @EqualsAndHashCode.Exclude
+    private Instant borrowedDate;
+
+    public BorrowedBook(Long bookId, Long userId) {
+        this.bookId = bookId;
+        this.userId = userId;
+        this.borrowedDate = Instant.now();
+    }
+
+    public BorrowedBook(Long bookId, Long userId, Instant borrowedDate) {
+        this.bookId = bookId;
+        this.userId = userId;
+        this.borrowedDate = borrowedDate;
+    }
+
+    @Override
+    public Long getIdAsLong() {
+        return bookId;
+    }
+
+    public Long getAssignedUserIdAsLong(){
+        return userId;
+    }
+
+    public Instant getBorrowedDateAsInstant(){
+        return borrowedDate;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/DueDate.java

@@ -0,0 +1,14 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.AllArgsConstructor;
+
+import java.time.Instant;
+
+@AllArgsConstructor
+public class DueDate {
+    private final Instant timeStamp;
+
+    public Instant asInstant(){
+        return timeStamp;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/GiveBackBookCommand.java

@@ -0,0 +1,13 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+
+@AllArgsConstructor
+@Getter
+@Builder
+public class GiveBackBookCommand {
+    private Long bookId;
+    private Long userId;
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/MakeBookAvailableCommand.java

@@ -0,0 +1,12 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+
+@AllArgsConstructor
+@Getter
+@Builder
+public class MakeBookAvailableCommand {
+    private Long bookId;
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/OverdueReservation.java

@@ -0,0 +1,13 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.AllArgsConstructor;
+
+@AllArgsConstructor
+public class OverdueReservation {
+    private Long reservationId;
+    private Long bookIdentification;
+
+    public Long getBookIdentificationAsLong() {
+        return bookIdentification;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/ReservationDetails.java

@@ -0,0 +1,17 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+
+@Getter
+@EqualsAndHashCode
+public class ReservationDetails {
+
+    private final ReservationId reservationId;
+    private final ReservedBook reservedBook;
+
+    public ReservationDetails(ReservationId reservationId, ReservedBook reservedBook) {
+        this.reservationId = reservationId;
+        this.reservedBook = reservedBook;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/ReservationId.java

@@ -0,0 +1,16 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.EqualsAndHashCode;
+
+@EqualsAndHashCode
+public class ReservationId {
+    private final Long id;
+
+    public ReservationId(Long id) {
+        this.id = id;
+    }
+
+    public Long getIdAsLong(){
+        return id;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/ReservedBook.java

@@ -0,0 +1,38 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model;
+
+import lombok.EqualsAndHashCode;
+
+import java.time.Instant;
+
+@EqualsAndHashCode
+public class ReservedBook implements Book {
+
+    private final Long bookId;
+    private final Long userId;
+    private final Instant reservedDate;
+
+    public ReservedBook(Long bookId, Long userId) {
+        this.bookId = bookId;
+        this.userId = userId;
+        this.reservedDate = Instant.now();
+    }
+
+    public ReservedBook(Long bookId, Long userId, Instant reservedDate) {
+        this.bookId = bookId;
+        this.userId = userId;
+        this.reservedDate = reservedDate;
+    }
+
+    @Override
+    public Long getIdAsLong() {
+        return bookId;
+    }
+
+    public Long getAssignedUserIdAsLong(){
+        return userId;
+    }
+
+    public Instant getReservedDateAsInstant(){
+        return reservedDate;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/exception/ActiveUserNotFoundException.java

@@ -0,0 +1,10 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception;
+
+public class ActiveUserNotFoundException extends RuntimeException {
+    public ActiveUserNotFoundException(Long bookId){
+        super("There is no active user with an ID: " + bookId,
+                null,
+                false,
+                false);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/exception/AvailableBookNotFoundExeption.java

@@ -0,0 +1,10 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception;
+
+public class AvailableBookNotFoundExeption extends RuntimeException {
+    public AvailableBookNotFoundExeption(Long bookId){
+        super("There is no available book with an ID: " + bookId,
+                null,
+                false,
+                false);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/exception/BorrowedBookNotFoundException.java

@@ -0,0 +1,10 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception;
+
+public class BorrowedBookNotFoundException extends RuntimeException {
+    public BorrowedBookNotFoundException(Long bookId) {
+        super("There is no borrowed book with an ID: " + bookId,
+                null,
+                false,
+                false);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/exception/ReservedBookNotFoundException.java

@@ -0,0 +1,10 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception;
+
+public class ReservedBookNotFoundException extends RuntimeException {
+    public ReservedBookNotFoundException(Long bookId) {
+        super("There is no reserved book with an ID: " + bookId,
+                null,
+                false,
+                false);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/model/exception/TooManyBooksAssignedToUserException.java

@@ -0,0 +1,10 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.exception;
+
+public class TooManyBooksAssignedToUserException extends RuntimeException {
+    public TooManyBooksAssignedToUserException(Long userId){
+        super("You can't assign another book to user account: " + userId + ". Reason: Too many books already assigned.",
+                null,
+                false,
+                false);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/ports/incoming/BorrowBook.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BorrowBookCommand;
+
+public interface BorrowBook {
+    void handle(BorrowBookCommand borrowBookCommand);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/ports/incoming/CancelOverdueReservations.java

@@ -0,0 +1,5 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming;
+
+public interface CancelOverdueReservations {
+    void cancelOverdueReservations();
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/ports/incoming/GiveBackBook.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.GiveBackBookCommand;
+
+public interface GiveBackBook {
+    void handle(GiveBackBookCommand command);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/ports/incoming/MakeBookAvailable.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.MakeBookAvailableCommand;
+
+public interface MakeBookAvailable {
+    void handle(MakeBookAvailableCommand bookAvailableCommand);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/ports/incoming/ReserveBook.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BookReservationCommand;
+
+public interface ReserveBook {
+    Long handle(BookReservationCommand bookReservation);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/ports/outgoing/BorrowingDatabase.java

@@ -0,0 +1,23 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.outgoing;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ActiveUser;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.AvailableBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BorrowedBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.DueDate;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.OverdueReservation;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ReservationDetails;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ReservedBook;
+
+import java.util.List;
+import java.util.Optional;
+
+public interface BorrowingDatabase {
+    void save(AvailableBook availableBook);
+    ReservationDetails save(ReservedBook reservedBook);
+    void save(BorrowedBook borrowedBook);
+    Optional<AvailableBook> getAvailableBook(Long bookId);
+    Optional<ActiveUser> getActiveUser(Long userId);
+    List<OverdueReservation> findReservationsForMoreThan(Long days);
+    Optional<ReservedBook> getReservedBook(Long bookId);
+    Optional<BorrowedBook> getBorrowedBook(Long bookId);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/core/ports/outgoing/BorrowingEventPublisher.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.outgoing;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BookReservedEvent;
+
+public interface BorrowingEventPublisher {
+    public void publish(BookReservedEvent event);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/infrastructure/BorrowingDatabaseAdapter.java

@@ -0,0 +1,172 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BorrowedBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure.entity.OverdueReservationEntity;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ActiveUser;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.AvailableBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.DueDate;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.OverdueReservation;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ReservationDetails;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ReservationId;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ReservedBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.outgoing.BorrowingDatabase;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure.mapper.BorrowedBookRowMapper;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure.mapper.ReservedBookRowMapper;
+import lombok.RequiredArgsConstructor;
+import org.springframework.dao.DataAccessException;
+import org.springframework.jdbc.core.BeanPropertyRowMapper;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+import java.sql.Timestamp;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+@RequiredArgsConstructor
+public class BorrowingDatabaseAdapter implements BorrowingDatabase {
+
+    private final JdbcTemplate jdbcTemplate;
+
+    @Override
+    public void save(AvailableBook availableBook) {
+        jdbcTemplate.update(
+                "INSERT INTO available (book_id) VALUES (?)",
+                availableBook.getIdAsLong());
+
+        jdbcTemplate.update(
+                "DELETE FROM reserved WHERE book_id = ?",
+                availableBook.getIdAsLong());
+
+        jdbcTemplate.update(
+                "DELETE FROM borrowed WHERE book_id = ?",
+                availableBook.getIdAsLong());
+    }
+
+    @Override
+    public Optional<AvailableBook> getAvailableBook(Long bookId) {
+        try {
+            return Optional.ofNullable(
+                    jdbcTemplate.queryForObject(
+                    "SELECT book_id FROM available WHERE book_id = ?",
+                    AvailableBook.class,
+                            bookId));
+        } catch (DataAccessException exception) {
+            return Optional.empty();
+        }
+    }
+
+    @Override
+    public Optional<ActiveUser> getActiveUser(Long userId) {
+        try {
+            jdbcTemplate.queryForObject(
+                            "SELECT id FROM public.library_user as u WHERE u.id = ?",
+                            Long.class,
+                            userId);
+        } catch (DataAccessException exception) {
+            return Optional.empty();
+        }
+
+        List<ReservedBook> reservedBooksByUser = getReservedBooksByUser(userId);
+        List<BorrowedBook> borrowedBooksByUser = getBorrowedBooksByUser(userId);
+        return Optional.of(new ActiveUser(userId, reservedBooksByUser, borrowedBooksByUser));
+    }
+
+    @Override
+    public ReservationDetails save(ReservedBook reservedBook) {
+       jdbcTemplate.update(
+               "INSERT INTO reserved (book_id, user_id, reserved_date) VALUES (?, ?, ?)",
+               reservedBook.getIdAsLong(),
+               reservedBook.getAssignedUserIdAsLong(),
+               Timestamp.from(reservedBook.getReservedDateAsInstant()));
+
+        jdbcTemplate.update(
+                "DELETE FROM available WHERE book_id = ?",
+                reservedBook.getIdAsLong());
+
+       ReservationId reservationId = jdbcTemplate.queryForObject(
+               "SELECT id FROM reserved WHERE book_id = ?",
+               ReservationId.class,
+               reservedBook.getIdAsLong());
+       return new ReservationDetails(reservationId, reservedBook);
+    }
+
+    @Override
+    public void save(BorrowedBook borrowedBook) {
+        jdbcTemplate.update(
+                "INSERT INTO borrowed (book_id, user_id, borrowed_date) VALUES (?, ?, ?)",
+                borrowedBook.getIdAsLong(),
+                borrowedBook.getAssignedUserIdAsLong(),
+                Timestamp.from(borrowedBook.getBorrowedDateAsInstant()));
+
+        jdbcTemplate.update(
+                "DELETE FROM reserved WHERE book_id = ?",
+                borrowedBook.getIdAsLong());
+
+        jdbcTemplate.update(
+                "DELETE FROM available WHERE book_id = ?",
+                borrowedBook.getIdAsLong());
+
+    }
+
+    @Override
+    public List<OverdueReservation> findReservationsForMoreThan(Long days) {
+        List<OverdueReservationEntity> entities = jdbcTemplate.query(
+                "SELECT id AS reservationId, book_id AS bookIdentification FROM reserved WHERE DATEADD(day, ?, reserved_date) > NOW()",
+                new BeanPropertyRowMapper<OverdueReservationEntity>(OverdueReservationEntity.class),
+               days);
+        return entities.stream()
+                .map(entity -> new OverdueReservation(entity.getReservationId(), entity.getBookIdentification()))
+                .collect(Collectors.toList());
+    }
+
+    @Override
+    public Optional<ReservedBook> getReservedBook(Long bookId) {
+        try {
+            return Optional.ofNullable(
+                    jdbcTemplate.queryForObject(
+                            "SELECT book_id, user_id, reserved_date FROM reserved WHERE book_id = ?",
+                            new ReservedBookRowMapper(),
+                            bookId));
+        } catch (DataAccessException exception) {
+            return Optional.empty();
+        }
+    }
+
+    @Override
+    public Optional<BorrowedBook> getBorrowedBook(Long bookId) {
+        try {
+            return Optional.ofNullable(
+                    jdbcTemplate.queryForObject(
+                            "SELECT book_id, user_id, borrowed_date FROM borrowed WHERE book_id = ?",
+                            new BorrowedBookRowMapper(),
+                            bookId));
+        } catch (DataAccessException exception) {
+            return Optional.empty();
+        }
+    }
+
+    private List<ReservedBook> getReservedBooksByUser(Long userId) {
+        try {
+            return jdbcTemplate.query(
+                    "SELECT book_id, user_id, reserved_date FROM reserved WHERE user_id = ?",
+                    new ReservedBookRowMapper(),
+                    userId
+            );
+        } catch (DataAccessException exception){
+            return new ArrayList<>();
+        }
+    }
+
+    private List<BorrowedBook> getBorrowedBooksByUser(Long userId) {
+        try {
+            return jdbcTemplate.query(
+                    "SELECT book_id, user_id, borrowed_date FROM borrowed WHERE user_id = ?",
+                    new BorrowedBookRowMapper(),
+                    userId
+            );
+        } catch (DataAccessException exception){
+            return new ArrayList<>();
+        }
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/infrastructure/SpringBorrowingEventPublisherAdapter.java

@@ -0,0 +1,19 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BookReservedEvent;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.outgoing.BorrowingEventPublisher;
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.stereotype.Component;
+
+@Component
+@RequiredArgsConstructor
+public class SpringBorrowingEventPublisherAdapter implements BorrowingEventPublisher {
+
+    private final ApplicationEventPublisher eventPublisher;
+
+    @Override
+    public void publish(BookReservedEvent event) {
+        eventPublisher.publishEvent(event);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/infrastructure/entity/OverdueReservationEntity.java

@@ -0,0 +1,9 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure.entity;
+
+import lombok.Data;
+
+@Data
+public class OverdueReservationEntity {
+    private Long reservationId;
+    private Long bookIdentification;
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/infrastructure/mapper/BorrowedBookRowMapper.java

@@ -0,0 +1,20 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure.mapper;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BorrowedBook;
+import org.springframework.jdbc.core.RowMapper;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+
+public class BorrowedBookRowMapper implements RowMapper<BorrowedBook> {
+
+    @Override
+    public BorrowedBook mapRow(ResultSet rs, int rowNum) throws SQLException {
+        return new BorrowedBook(
+                rs.getLong("book_id"),
+                rs.getLong("user_id"),
+                rs.getTimestamp("borrowed_date").toInstant()
+        );
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/borrowing/infrastructure/mapper/ReservedBookRowMapper.java

@@ -0,0 +1,19 @@
+package io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure.mapper;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.ReservedBook;
+import org.springframework.jdbc.core.RowMapper;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+public class ReservedBookRowMapper implements RowMapper<ReservedBook> {
+
+    @Override
+    public ReservedBook mapRow(ResultSet rs, int rowNum) throws SQLException {
+        return new ReservedBook(
+                rs.getLong("book_id"),
+                rs.getLong("user_id"),
+                rs.getTimestamp("reserved_date").toInstant()
+        );
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/application/BookReservedEventHandler.java

@@ -0,0 +1,24 @@
+package io.wkrzywiec.hexagonal.library.domain.email.application;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.model.BookReservedEvent;
+import io.wkrzywiec.hexagonal.library.domain.email.core.model.SendReservationConfirmationCommand;
+import io.wkrzywiec.hexagonal.library.domain.email.core.ports.incoming.SendReservationConfirmation;
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+
+@Component
+@RequiredArgsConstructor
+public class BookReservedEventHandler {
+
+    private final SendReservationConfirmation sendReservationConfirmation;
+
+    @EventListener
+    public void handle(BookReservedEvent event) {
+        sendReservationConfirmation.handle(
+                new SendReservationConfirmationCommand(
+                        event.getReservationIdAsLong(),
+                        event.getUserIdAsLong(),
+                        event.getBookIdAsLong()));
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/core/EmailCreator.java

@@ -0,0 +1,18 @@
+package io.wkrzywiec.hexagonal.library.domain.email.core;
+
+import io.wkrzywiec.hexagonal.library.domain.email.core.model.EmailAddress;
+import io.wkrzywiec.hexagonal.library.domain.email.core.model.ReservationConfirmEmail;
+
+class EmailCreator {
+
+    static ReservationConfirmEmail reservationEmail(Long reservationId, String bookTitle, String emailTo){
+
+        EmailAddress from = new EmailAddress("tom@library.com");
+        EmailAddress to = new EmailAddress(emailTo);
+
+        String subject = String.format("Library - book reservation confirmation (id - %d)", reservationId);
+        String content = String.format("Dear reader,%n you have reserved a %s book which will be waiting for you in our library for next 2 days. Your reservation id is %d. %n Have a nice day, %n Library",
+                bookTitle, reservationId);
+        return new ReservationConfirmEmail(from, to, subject, content);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/core/EmailFacade.java

@@ -0,0 +1,32 @@
+package io.wkrzywiec.hexagonal.library.domain.email.core;
+
+import io.wkrzywiec.hexagonal.library.domain.email.core.model.ReservationConfirmEmail;
+import io.wkrzywiec.hexagonal.library.domain.email.core.model.SendReservationConfirmationCommand;
+import io.wkrzywiec.hexagonal.library.domain.email.core.ports.incoming.SendReservationConfirmation;
+import io.wkrzywiec.hexagonal.library.domain.email.core.ports.outgoing.EmailSender;
+import io.wkrzywiec.hexagonal.library.domain.email.core.ports.outgoing.EmailDatabase;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class EmailFacade implements SendReservationConfirmation {
+
+    private final EmailSender emailSender;
+    private final EmailDatabase database;
+
+    @Override
+    public void handle(SendReservationConfirmationCommand sendReservationConfirmation) {
+        String bookTitle = database
+                .getTitleByBookId(sendReservationConfirmation.getBookId())
+                .orElseThrow(() -> new IllegalArgumentException("Can't get book title from database. Reason: there is no book with an id: " + sendReservationConfirmation.getBookId()));
+        String userEmailAddress = database
+                .getUserEmailAddress(sendReservationConfirmation.getUserId())
+                .orElseThrow(() -> new IllegalArgumentException("Can't get email address from database. Reason: there is no user with an id: " + sendReservationConfirmation.getUserId()));
+
+        ReservationConfirmEmail reservationConfirmEmail = EmailCreator.reservationEmail(
+                sendReservationConfirmation.getReservationId(),
+                bookTitle,
+                userEmailAddress
+        );
+        emailSender.sendReservationConfirmationEmail(reservationConfirmEmail);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/core/model/EmailAddress.java

@@ -0,0 +1,24 @@
+package io.wkrzywiec.hexagonal.library.domain.email.core.model;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class EmailAddress {
+
+    private final String value;
+
+    public EmailAddress(String value) {
+        Pattern pattern = Pattern.compile("^(.+)@(.+)$");
+        Matcher matcher = pattern.matcher(value);
+        if(matcher.matches()){
+            this.value = value;
+        } else {
+            throw new IllegalArgumentException("Provided value is not an email address");
+        }
+
+    }
+
+    public String getAsString() {
+        return value;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/core/model/ReservationConfirmEmail.java

@@ -0,0 +1,28 @@
+package io.wkrzywiec.hexagonal.library.domain.email.core.model;
+
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class ReservationConfirmEmail {
+
+    private final EmailAddress from;
+    private final EmailAddress to;
+    private final String subject;
+    private final String content;
+
+    public String getFromEmailAddressAsString(){
+        return this.from.getAsString();
+    }
+
+    public String getToEmailAddressAsString(){
+        return this.to.getAsString();
+    }
+
+    public String getSubjectAsString(){
+        return this.subject;
+    }
+
+    public String getContentAsString(){
+        return this.content;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/core/model/SendReservationConfirmationCommand.java

@@ -0,0 +1,17 @@
+package io.wkrzywiec.hexagonal.library.domain.email.core.model;
+
+import lombok.Getter;
+
+@Getter
+public class SendReservationConfirmationCommand {
+
+    private final Long reservationId;
+    private final Long userId;
+    private final Long bookId;
+
+    public SendReservationConfirmationCommand(Long reservationId, Long userId, Long bookId) {
+        this.reservationId = reservationId;
+        this.userId = userId;
+        this.bookId = bookId;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/core/ports/incoming/SendReservationConfirmation.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.email.core.ports.incoming;
+
+import io.wkrzywiec.hexagonal.library.domain.email.core.model.SendReservationConfirmationCommand;
+
+public interface SendReservationConfirmation {
+    void handle(SendReservationConfirmationCommand reservationConfirmationCommand);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/core/ports/outgoing/EmailDatabase.java

@@ -0,0 +1,8 @@
+package io.wkrzywiec.hexagonal.library.domain.email.core.ports.outgoing;
+
+import java.util.Optional;
+
+public interface EmailDatabase {
+    Optional<String> getTitleByBookId(Long bookId);
+    Optional<String> getUserEmailAddress(Long userId);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/core/ports/outgoing/EmailSender.java

@@ -0,0 +1,8 @@
+package io.wkrzywiec.hexagonal.library.domain.email.core.ports.outgoing;
+
+
+import io.wkrzywiec.hexagonal.library.domain.email.core.model.ReservationConfirmEmail;
+
+public interface EmailSender {
+    void sendReservationConfirmationEmail(ReservationConfirmEmail reservationConfirmEmail);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/infrastructure/EmailDatabaseAdapter.java

@@ -0,0 +1,38 @@
+package io.wkrzywiec.hexagonal.library.domain.email.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.email.core.ports.outgoing.EmailDatabase;
+import lombok.RequiredArgsConstructor;
+import org.springframework.dao.DataAccessException;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+import java.util.Optional;
+
+@RequiredArgsConstructor
+public class EmailDatabaseAdapter implements EmailDatabase {
+
+    private final JdbcTemplate jdbcTemplate;
+
+    @Override
+    public Optional<String> getTitleByBookId(Long bookId) {
+        try {
+            return Optional.ofNullable(jdbcTemplate.queryForObject(
+                    "SELECT title FROM book WHERE id = ?",
+                    String.class,
+                    bookId));
+        } catch (DataAccessException ex){
+            return Optional.empty();
+        }
+    }
+
+    @Override
+    public Optional<String> getUserEmailAddress(Long userId) {
+        try {
+            return Optional.ofNullable(jdbcTemplate.queryForObject(
+                    "SELECT email FROM library_user WHERE id = ?",
+                    String.class,
+                    userId));
+        } catch (DataAccessException ex){
+            return Optional.empty();
+        }
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/email/infrastructure/SendGridEmailSender.java

@@ -0,0 +1,38 @@
+package io.wkrzywiec.hexagonal.library.domain.email.infrastructure;
+
+import com.sendgrid.Method;
+import com.sendgrid.Request;
+import com.sendgrid.SendGrid;
+import com.sendgrid.helpers.mail.Mail;
+import com.sendgrid.helpers.mail.objects.Content;
+import com.sendgrid.helpers.mail.objects.Email;
+import io.wkrzywiec.hexagonal.library.domain.email.core.model.ReservationConfirmEmail;
+import io.wkrzywiec.hexagonal.library.domain.email.core.ports.outgoing.EmailSender;
+
+import java.io.IOException;
+
+public class SendGridEmailSender implements EmailSender {
+
+    @Override
+    public void sendReservationConfirmationEmail(ReservationConfirmEmail reservationConfirmEmail) {
+        Email from = new Email(reservationConfirmEmail.getFromEmailAddressAsString());
+        Email to = new Email(reservationConfirmEmail.getToEmailAddressAsString());
+        Content content = new Content("text/plain", reservationConfirmEmail.getContentAsString());
+        Mail mail = new Mail(
+                from,
+                reservationConfirmEmail.getSubjectAsString(),
+                to,
+                content);
+
+        SendGrid sg = new SendGrid(System.getenv("SENDGRID_API_KEY"));
+        Request request = new Request();
+        try {
+            request.setMethod(Method.POST);
+            request.setEndpoint("mail/send");
+            request.setBody(mail.build());
+            sg.api(request);
+        } catch (IOException ex) {
+            System.out.print(ex);
+        }
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/application/BookCommandController.java

@@ -1,7 +1,7 @@
-package io.wkrzywiec.hexagonal.library.application;
+package io.wkrzywiec.hexagonal.library.domain.inventory.application;
 
-import io.wkrzywiec.hexagonal.library.domain.book.model.ExternalBookIdDTO;
-import io.wkrzywiec.hexagonal.library.domain.book.ports.incoming.AddNewBook;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.AddNewBookCommand;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.incoming.AddNewBook;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
@@ -18,8 +18,8 @@ public class BookCommandController {
     private final AddNewBook addNewBook;
 
     @PostMapping("")
-    public ResponseEntity<String> addNewBook(@RequestBody ExternalBookIdDTO externalBookIdDTO){
-        addNewBook.handle(externalBookIdDTO);
+    public ResponseEntity<String> addNewBook(@RequestBody AddNewBookCommand addNewBookCommand){
+        addNewBook.handle(addNewBookCommand);
         return new ResponseEntity<>("New book was added to library", HttpStatus.CREATED);
     }
 }

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/InventoryFacade.java

@@ -0,0 +1,30 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core;
+
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.AddNewBookCommand;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Book;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.NewBookWasAddedEvent;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.incoming.AddNewBook;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing.InventoryEventPublisher;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing.GetBookDetails;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing.InventoryDatabase;
+
+
+public class InventoryFacade implements AddNewBook{
+
+    private InventoryDatabase database;
+    private GetBookDetails getBookDetails;
+    private InventoryEventPublisher eventPublisher;
+
+    public InventoryFacade(InventoryDatabase database, GetBookDetails getBookDetails, InventoryEventPublisher eventPublisher) {
+        this.database = database;
+        this.getBookDetails = getBookDetails;
+        this.eventPublisher = eventPublisher;
+    }
+
+    @Override
+    public void handle(AddNewBookCommand addNewBookCommand){
+        Book book = getBookDetails.handle(addNewBookCommand.getGoogleBookId());
+        Book savedBook = database.save(book);
+        eventPublisher.publishNewBookWasAddedEvent(new NewBookWasAddedEvent(savedBook.getIdAsLong()));
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/model/AddNewBookCommand.java

@@ -0,0 +1,14 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@AllArgsConstructor
+@NoArgsConstructor
+@Builder
+public class AddNewBookCommand {
+    private String googleBookId;
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/model/Author.java

@@ -1,6 +1,7 @@
-package io.wkrzywiec.hexagonal.library.infrastructure.repository;
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.model;
 
-import lombok.Builder;
+import lombok.EqualsAndHashCode;
+import lombok.ToString;
 
 import javax.persistence.Column;
 import javax.persistence.Entity;
@@ -9,10 +10,11 @@ import javax.persistence.GenerationType;
 import javax.persistence.Id;
 import javax.persistence.Table;
 
-@Builder
 @Entity
 @Table(name="author")
-public class AuthorEntiy {
+@EqualsAndHashCode
+@ToString
+public class Author {
 
     @Id
     @GeneratedValue(strategy= GenerationType.IDENTITY)
@@ -21,4 +23,11 @@ public class AuthorEntiy {
 
     @Column(name="name", unique=true)
     private String name;
+
+    public Author(String name) {
+        this.name = name;
+    }
+
+    private Author() {
+    }
 }

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/model/Book.java

@@ -1,13 +1,10 @@
-package io.wkrzywiec.hexagonal.library.infrastructure.repository;
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.model;
 
-import lombok.AllArgsConstructor;
-import lombok.Builder;
-import lombok.Getter;
-import lombok.NoArgsConstructor;
-import lombok.Setter;
+import lombok.EqualsAndHashCode;
 
 import javax.persistence.CascadeType;
 import javax.persistence.Column;
+import javax.persistence.Embedded;
 import javax.persistence.Entity;
 import javax.persistence.FetchType;
 import javax.persistence.GeneratedValue;
@@ -17,31 +14,20 @@ import javax.persistence.JoinColumn;
 import javax.persistence.JoinTable;
 import javax.persistence.ManyToMany;
 import javax.persistence.Table;
-
 import java.util.Set;
 
 
-@Builder
 @Entity
-@AllArgsConstructor
-@NoArgsConstructor
-@Setter
-@Getter
 @Table(name="book")
-public class BookEntity {
+@EqualsAndHashCode
+public class Book {
 
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
-    @Column(name="book_external_id")
-    private String bookExternalId;
-
-    @Column(name="isbn_10")
-    private String isbn10;
-
-    @Column(name="isbn_13")
-    private String isbn13;
+    @Embedded
+    private BookIdentification identification;
 
     @Column(name="title")
     private String title;
@@ -52,7 +38,7 @@ public class BookEntity {
             name="book_author",
             joinColumns=@JoinColumn(name="book_id"),
             inverseJoinColumns=@JoinColumn(name="author_id"))
-    private Set<AuthorEntiy> authors;
+    private Set<Author> authors;
 
     @Column(name="publisher")
     private String publisher;
@@ -63,9 +49,28 @@ public class BookEntity {
     @Column(name="description", columnDefinition="TEXT")
     private String description;
 
-    @Column(name="pages")
+    @Column(name="page_count")
     private int pages;
 
     @Column(name="imageLink", columnDefinition="TEXT")
+    @EqualsAndHashCode.Exclude
     private String imageLink;
+
+    public Book(BookIdentification identification, String title, Set<Author> authors, String publisher, String publishedDate, String description, int pages, String imageLink) {
+        this.identification = identification;
+        this.title = title;
+        this.authors = authors;
+        this.publisher = publisher;
+        this.publishedDate = publishedDate;
+        this.description = description;
+        this.pages = pages;
+        this.imageLink = imageLink;
+    }
+
+    public Long getIdAsLong(){
+        return id;
+    }
+
+    private Book() {
+    }
 }

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/model/BookIdentification.java

@@ -0,0 +1,30 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.model;
+
+import lombok.EqualsAndHashCode;
+
+import javax.persistence.Column;
+import javax.persistence.Embeddable;
+import javax.persistence.Embedded;
+
+@Embeddable
+@EqualsAndHashCode
+public class BookIdentification {
+
+    @Column(name="book_external_id")
+    private String bookExternalId;
+
+    @Embedded
+    private Isbn10 isbn10;
+
+    @Embedded
+    private Isbn13 isbn13;
+
+    public BookIdentification(String bookExternalId, Isbn10 isbn10, Isbn13 isbn13) {
+        this.bookExternalId = bookExternalId;
+        this.isbn10 = isbn10;
+        this.isbn13 = isbn13;
+    }
+
+    private BookIdentification() {
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/model/Isbn10.java

@@ -0,0 +1,28 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.model;
+
+import lombok.EqualsAndHashCode;
+
+import javax.persistence.Column;
+import javax.persistence.Embeddable;
+
+@EqualsAndHashCode
+@Embeddable
+public class Isbn10 {
+    @Column(name="isbn_10")
+    private String value;
+
+    public Isbn10(String value) {
+        if (value.matches("\\d{10}")){
+            this.value = value;
+        } else {
+            throw new IllegalArgumentException("ISBN-10 should have 10 digits only.");
+        }
+    }
+
+    private Isbn10() {
+    }
+
+    public String getAsString(){
+        return value;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/model/Isbn13.java

@@ -0,0 +1,29 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.model;
+
+import lombok.EqualsAndHashCode;
+
+import javax.persistence.Column;
+import javax.persistence.Embeddable;
+
+@EqualsAndHashCode
+@Embeddable
+public class Isbn13 {
+
+    @Column(name="isbn_13")
+    private String value;
+
+    public Isbn13(String value) {
+        if (value.matches("\\d{13}")){
+            this.value = value;
+        } else {
+            throw new IllegalArgumentException("ISBN-13 should have 10 digits only.");
+        }
+    }
+
+    private Isbn13() {
+    }
+
+    public String getAsString(){
+        return value;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/model/NewBookWasAddedEvent.java

@@ -0,0 +1,22 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.model;
+
+import java.time.Instant;
+
+public class NewBookWasAddedEvent {
+
+    private final Long bookId;
+    private final Instant timestamp;
+
+    public NewBookWasAddedEvent(Long bookId) {
+        this.bookId = bookId;
+        timestamp = Instant.now();
+    }
+
+    public Long getBookIdAsLong() {
+        return bookId;
+    }
+
+    public String getEventTimeStampAsString() {
+        return timestamp.toString();
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/ports/incoming/AddNewBook.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.incoming;
+
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.AddNewBookCommand;
+
+public interface AddNewBook {
+    void handle(AddNewBookCommand addNewBookCommand);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/ports/outgoing/GetBookDetails.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing;
+
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Book;
+
+public interface GetBookDetails {
+    Book handle(String bookId);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/ports/outgoing/InventoryDatabase.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing;
+
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Book;
+
+public interface InventoryDatabase {
+    Book save(Book book);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/core/ports/outgoing/InventoryEventPublisher.java

@@ -0,0 +1,7 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing;
+
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.NewBookWasAddedEvent;
+
+public interface InventoryEventPublisher {
+    void publishNewBookWasAddedEvent(NewBookWasAddedEvent event);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/infrastructure/BookRepository.java

@@ -0,0 +1,9 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Book;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface BookRepository extends CrudRepository<Book, Long> {
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/infrastructure/GoogleBooksAdapter.java

@@ -1,19 +1,21 @@
-package io.wkrzywiec.hexagonal.library.infrastructure.adapter;
+package io.wkrzywiec.hexagonal.library.domain.inventory.infrastructure;
 
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
-import io.wkrzywiec.hexagonal.library.domain.book.model.BookDetailsDTO;
-import io.wkrzywiec.hexagonal.library.domain.book.ports.incoming.GetBookDetails;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Author;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Book;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.BookIdentification;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Isbn10;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Isbn13;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing.GetBookDetails;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
-import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.client.RestTemplate;
 
-import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -27,10 +29,9 @@ public class GoogleBooksAdapter implements GetBookDetails {
     private final RestTemplate restTemplate;
 
     @Override
-    public BookDetailsDTO handle(String googleBookId) {
+    public Book handle(String googleBookId) {
 
         HttpHeaders requestHeader = new HttpHeaders();
-//        requestHeader.add("Accept", MediaType.ALL_VALUE);
         HttpEntity<Object> requestEntity = new HttpEntity<>(requestHeader);
 
         ResponseEntity<String> responseEntity =
@@ -46,18 +47,19 @@ public class GoogleBooksAdapter implements GetBookDetails {
 
         JsonObject volumeInfo = response.getAsJsonObject("volumeInfo");
 
-        return BookDetailsDTO.builder()
-                .bookExternalId(googleBookId)
-                .isbn10(extractIsbn(volumeInfo, "ISBN_10"))
-                .isbn13(extractIsbn(volumeInfo, "ISBN_13"))
-                .title(volumeInfo.get("title").getAsString())
-                .authors(extractAuthors(volumeInfo))
-                .publisher(volumeInfo.get("publisher").getAsString())
-                .publishedDate(volumeInfo.get("publishedDate").getAsString())
-                .description(volumeInfo.get("description").getAsString())
-                .pages(volumeInfo.get("pageCount").getAsInt())
-                .imageLink(extractImage(volumeInfo))
-                .build();
+        Isbn10 isbn10 = new Isbn10(extractIsbn(volumeInfo, "ISBN_10"));
+        Isbn13 isbn13 = new Isbn13(extractIsbn(volumeInfo, "ISBN_13"));
+
+        return new Book(
+                new BookIdentification(googleBookId, isbn10, isbn13),
+                volumeInfo.get("title").getAsString(),
+                extractAuthors(volumeInfo),
+                volumeInfo.get("publisher").getAsString(),
+                volumeInfo.get("publishedDate").getAsString(),
+                volumeInfo.get("description").getAsString(),
+                volumeInfo.get("pageCount").getAsInt(),
+                extractImage(volumeInfo)
+        );
     }
 
     private String extractIsbn(JsonObject volumeInfo, String isbnType) {
@@ -74,7 +76,7 @@ public class GoogleBooksAdapter implements GetBookDetails {
                 .orElseThrow(() -> new RuntimeException("Inside volumeInfo there is no " + isbnType));
     }
 
-    private List<String> extractAuthors(JsonObject volumeInfo) {
+    private Set<Author> extractAuthors(JsonObject volumeInfo) {
         return StreamSupport.stream(
                 ofNullable(volumeInfo)
                         .map(volume -> volume.getAsJsonArray("authors"))
@@ -82,7 +84,8 @@ public class GoogleBooksAdapter implements GetBookDetails {
                         .spliterator(),
                 false)
                 .map(JsonElement::getAsString)
-                .collect(Collectors.toList());
+                .map(Author::new)
+                .collect(Collectors.toSet());
     }
 
     private String extractImage(JsonObject volumeInfo) {

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/infrastructure/InventoryDatabaseAdapter.java

@@ -0,0 +1,16 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.Book;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing.InventoryDatabase;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class InventoryDatabaseAdapter implements InventoryDatabase {
+
+    private final BookRepository repository;
+
+    @Override
+    public Book save(Book book) {
+        return repository.save(book);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/inventory/infrastructure/SpringInventoryEventPublisherAdapter.java

@@ -0,0 +1,17 @@
+package io.wkrzywiec.hexagonal.library.domain.inventory.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.model.NewBookWasAddedEvent;
+import io.wkrzywiec.hexagonal.library.domain.inventory.core.ports.outgoing.InventoryEventPublisher;
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.ApplicationEventPublisher;
+
+@RequiredArgsConstructor
+public class SpringInventoryEventPublisherAdapter implements InventoryEventPublisher {
+
+    private final ApplicationEventPublisher applicationEventPublisher;
+
+    @Override
+    public void publishNewBookWasAddedEvent(NewBookWasAddedEvent event) {
+        applicationEventPublisher.publishEvent(event);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/application/UserCommandController.java

@@ -0,0 +1,25 @@
+package io.wkrzywiec.hexagonal.library.domain.user.application;
+
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.AddUserCommand;
+import io.wkrzywiec.hexagonal.library.domain.user.core.ports.incoming.AddNewUser;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/users")
+@RequiredArgsConstructor
+public class UserCommandController {
+
+    private final AddNewUser addNewUser;
+
+    @PostMapping("")
+    public ResponseEntity<String> addNewUser(@RequestBody AddUserCommand addUserCommand){
+        addNewUser.handle(addUserCommand);
+        return new ResponseEntity<>("New user was added to library", HttpStatus.CREATED);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/core/UserFacade.java

@@ -0,0 +1,25 @@
+package io.wkrzywiec.hexagonal.library.domain.user.core;
+
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.AddUserCommand;
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.EmailAddress;
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.User;
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.UserIdentifier;
+import io.wkrzywiec.hexagonal.library.domain.user.core.ports.incoming.AddNewUser;
+import io.wkrzywiec.hexagonal.library.domain.user.core.ports.outgoing.UserDatabase;
+import lombok.AllArgsConstructor;
+
+@AllArgsConstructor
+public class UserFacade implements AddNewUser {
+
+    private final UserDatabase database;
+
+    @Override
+    public UserIdentifier handle(AddUserCommand addUserCommand) {
+        User user = new User(
+                new EmailAddress(addUserCommand.getEmail()),
+                addUserCommand.getFirstName(),
+                addUserCommand.getLastName()
+        );
+        return database.save(user);
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/core/model/AddUserCommand.java

@@ -0,0 +1,17 @@
+package io.wkrzywiec.hexagonal.library.domain.user.core.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@AllArgsConstructor
+@NoArgsConstructor
+@Builder
+public class AddUserCommand {
+
+    private String email;
+    private String firstName;
+    private String lastName;
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/core/model/EmailAddress.java

@@ -0,0 +1,28 @@
+package io.wkrzywiec.hexagonal.library.domain.user.core.model;
+
+import lombok.EqualsAndHashCode;
+
+import javax.persistence.Column;
+import javax.persistence.Embeddable;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+@Embeddable
+@EqualsAndHashCode
+public class EmailAddress {
+
+    @Column(name="email")
+    private String value;
+
+    public EmailAddress(String value) {
+        Pattern pattern = Pattern.compile("^(.+)@(.+)$");
+        Matcher matcher = pattern.matcher(value);
+        if(matcher.matches()){
+            this.value = value;
+        } else {
+            throw new IllegalArgumentException("Provided value is not an email address");
+        }
+    }
+
+    private EmailAddress(){}
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/core/model/User.java

@@ -0,0 +1,43 @@
+package io.wkrzywiec.hexagonal.library.domain.user.core.model;
+
+import lombok.EqualsAndHashCode;
+
+import javax.persistence.Column;
+import javax.persistence.Embedded;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+@Entity
+@Table(name="library_user")
+@EqualsAndHashCode
+public class User {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @EqualsAndHashCode.Exclude
+    private Long id;
+
+    @Embedded
+    private EmailAddress emailAddress;
+
+    @Column(name="first_name")
+    private String firstName;
+
+    @Column(name="last_name")
+    private String lastName;
+
+    public User(EmailAddress emailAddress, String firstName, String lastName) {
+        this.emailAddress = emailAddress;
+        this.firstName = firstName;
+        this.lastName = lastName;
+    }
+
+    public Long getIdentifierAsLong(){
+        return id;
+    }
+
+    private User(){}
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/core/model/UserIdentifier.java

@@ -0,0 +1,15 @@
+package io.wkrzywiec.hexagonal.library.domain.user.core.model;
+
+
+public class UserIdentifier {
+
+    private final Long id;
+
+    public UserIdentifier(Long id) {
+        this.id = id;
+    }
+
+    public Long getAsLong(){
+        return id;
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/core/ports/incoming/AddNewUser.java

@@ -0,0 +1,8 @@
+package io.wkrzywiec.hexagonal.library.domain.user.core.ports.incoming;
+
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.AddUserCommand;
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.UserIdentifier;
+
+public interface AddNewUser {
+    UserIdentifier handle(AddUserCommand addUserCommand);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/core/ports/outgoing/UserDatabase.java

@@ -0,0 +1,8 @@
+package io.wkrzywiec.hexagonal.library.domain.user.core.ports.outgoing;
+
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.User;
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.UserIdentifier;
+
+public interface UserDatabase {
+    UserIdentifier save(User user);
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/infrastructure/UserDatabaseAdapter.java

@@ -0,0 +1,18 @@
+package io.wkrzywiec.hexagonal.library.domain.user.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.User;
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.UserIdentifier;
+import io.wkrzywiec.hexagonal.library.domain.user.core.ports.outgoing.UserDatabase;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class UserDatabaseAdapter implements UserDatabase {
+
+    private final UserRepository userRepository;
+
+    @Override
+    public UserIdentifier save(User user) {
+        User savedUser = userRepository.save(user);
+        return new UserIdentifier(savedUser.getIdentifierAsLong());
+    }
+}

src/main/java/io/wkrzywiec/hexagonal/library/domain/user/infrastructure/UserRepository.java

@@ -0,0 +1,9 @@
+package io.wkrzywiec.hexagonal.library.domain.user.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.user.core.model.User;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface UserRepository extends CrudRepository<User, Long> {
+}

src/main/java/io/wkrzywiec/hexagonal/library/infrastructure/BookDomainConfig.java

@@ -1,36 +0,0 @@
-package io.wkrzywiec.hexagonal.library.infrastructure;
-
-import io.wkrzywiec.hexagonal.library.domain.book.BookFacade;
-import io.wkrzywiec.hexagonal.library.domain.book.ports.incoming.AddNewBook;
-import io.wkrzywiec.hexagonal.library.domain.book.ports.incoming.GetBookDetails;
-import io.wkrzywiec.hexagonal.library.domain.book.ports.outgoing.BookDatabase;
-import io.wkrzywiec.hexagonal.library.infrastructure.adapter.BookDatabaseAdapter;
-import io.wkrzywiec.hexagonal.library.infrastructure.adapter.GoogleBooksAdapter;
-import io.wkrzywiec.hexagonal.library.infrastructure.repository.PostgresBookRepository;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.web.client.RestTemplate;
-
-@Configuration
-public class BookDomainConfig {
-
-    @Bean
-    RestTemplate restTemplate(){
-        return new RestTemplate();
-    }
-
-    @Bean
-    BookDatabase bookRepository(PostgresBookRepository repository){
-        return new BookDatabaseAdapter(repository);
-    }
-
-    @Bean
-    GetBookDetails getBookDetails(RestTemplate restTemplate){
-        return new GoogleBooksAdapter(restTemplate);
-    }
-
-    @Bean
-    AddNewBook addNewBook(BookDatabase database, GetBookDetails getBookDetails){
-        return new BookFacade(database, getBookDetails);
-    }
-}

src/main/java/io/wkrzywiec/hexagonal/library/infrastructure/BorrowingDomainConfig.java

@@ -0,0 +1,59 @@
+package io.wkrzywiec.hexagonal.library.infrastructure;
+
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.BorrowingFacade;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.BorrowBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.CancelOverdueReservations;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.GiveBackBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.MakeBookAvailable;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.incoming.ReserveBook;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.outgoing.BorrowingDatabase;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.core.ports.outgoing.BorrowingEventPublisher;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure.BorrowingDatabaseAdapter;
+import io.wkrzywiec.hexagonal.library.domain.borrowing.infrastructure.SpringBorrowingEventPublisherAdapter;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.context.annotation.Bean;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+public class BorrowingDomainConfig {
+
+    @Bean
+    public BorrowingDatabase borrowingDatabase(JdbcTemplate jdbcTemplate) {
+        return new BorrowingDatabaseAdapter(jdbcTemplate);
+    }
+
+    @Bean
+    public BorrowingEventPublisher borrowingEventPublisher(ApplicationEventPublisher applicationEventPublisher){
+        return new SpringBorrowingEventPublisherAdapter(applicationEventPublisher);
+    }
+
+    @Bean
+    @Qualifier("MakeBookAvailable")
+    public MakeBookAvailable makeBookAvailable(BorrowingDatabase database, BorrowingEventPublisher borrowingEventPublisher) {
+        return new BorrowingFacade(database, borrowingEventPublisher);
+    }
+
+    @Bean
+    @Qualifier("ReserveBook")
+    public ReserveBook reserveBook(BorrowingDatabase database, BorrowingEventPublisher borrowingEventPublisher){
+        return new BorrowingFacade(database, borrowingEventPublisher);
+    }
+
+    @Bean
+    @Qualifier("BorrowBook")
+    public BorrowBook borrowBook(BorrowingDatabase database, BorrowingEventPublisher borrowingEventPublisher){
+        return new BorrowingFacade(database, borrowingEventPublisher);
+    }
+
+    @Bean
+    @Qualifier("GiveBackBook")
+    public GiveBackBook giveBackBook(BorrowingDatabase database, BorrowingEventPublisher borrowingEventPublisher){
+        return new BorrowingFacade(database, borrowingEventPublisher);
+    }
+
+    @Bean
+    @Qualifier("CancelOverdueReservations")
+    public CancelOverdueReservations cancelOverdueReservations(BorrowingDatabase database, BorrowingEventPublisher borrowingEventPublisher){
+        return new BorrowingFacade(database, borrowingEventPublisher);
+    }
+}