Merge branch 'customer-handling' into 'dev'

Add customer management

See merge request rheinsw/rheinsw-mono-repo!17

backend/common/src/main/java/dev/rheinsw/shared/entity/BaseEntity.java

@@ -1,38 +0,0 @@
-package dev.rheinsw.shared.entity;
-
-import jakarta.persistence.Column;
-import jakarta.persistence.MappedSuperclass;
-import jakarta.persistence.PrePersist;
-import jakarta.persistence.PreUpdate;
-import lombok.Getter;
-import lombok.Setter;
-
-import java.time.LocalDateTime;
-
-/**
- * Base Entity
- *
- * @author Thatsaphorn Atchariyaphap
- * @since 26.04.25
- */
-@Getter
-@Setter
-@MappedSuperclass
-public abstract class BaseEntity {
-
-    @Column(name = "createdDateTime", nullable = false, updatable = false)
-    private LocalDateTime createdDateTime;
-
-    @Column(name = "modifiedDateTime")
-    private LocalDateTime modifiedDateTime;
-
-    @PrePersist
-    protected void onCreate() {
-        createdDateTime = LocalDateTime.now();
-    }
-
-    @PreUpdate
-    protected void onUpdate() {
-        modifiedDateTime = LocalDateTime.now();
-    }
-}

backend/common/src/test/java/dev/rheinsw/shared/entity/BaseEntityTest.java

@@ -1,58 +0,0 @@
-package dev.rheinsw.shared.entity;
-
-import org.junit.jupiter.api.Test;
-
-import java.time.LocalDateTime;
-
-import static org.junit.jupiter.api.Assertions.*;
-
-class BaseEntityTest {
-
-    // Dummy entity for testing
-    static class DummyEntity extends BaseEntity {
-    }
-
-    @Test
-    void onCreate_shouldSetCreatedDateTime() {
-        // Arrange
-        DummyEntity entity = new DummyEntity();
-
-        // Act
-        entity.onCreate();
-
-        // Assert
-        assertNotNull(entity.getCreatedDateTime(), "createdDateTime should be set");
-        assertNull(entity.getModifiedDateTime(), "modifiedDateTime should still be null after creation");
-    }
-
-    @Test
-    void onUpdate_shouldSetModifiedDateTime() {
-        // Arrange
-        DummyEntity entity = new DummyEntity();
-
-        // Act
-        entity.onUpdate();
-
-        // Assert
-        assertNotNull(entity.getModifiedDateTime(), "modifiedDateTime should be set");
-        assertNull(entity.getCreatedDateTime(), "createdDateTime should still be null if onCreate() is not called");
-    }
-
-    @Test
-    void onCreate_thenOnUpdate_shouldSetBothTimestamps() throws InterruptedException {
-        // Arrange
-        DummyEntity entity = new DummyEntity();
-
-        // Act
-        entity.onCreate();
-        LocalDateTime created = entity.getCreatedDateTime();
-        Thread.sleep(10); // slight pause to differentiate timestamps
-        entity.onUpdate();
-        LocalDateTime modified = entity.getModifiedDateTime();
-
-        // Assert
-        assertNotNull(created);
-        assertNotNull(modified);
-        assertTrue(modified.isAfter(created), "modifiedDateTime should be after createdDateTime");
-    }
-}

backend/gateway/src/main/resources/application.yml

@@ -15,4 +15,5 @@ spring:
           predicates:
             - Path=/api/**
           filters:
-            - StripPrefix=1
+            - StripPrefix=1
+            - PreserveHostHeader

backend/server/pom.xml

@@ -75,6 +75,14 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-data-jpa</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-oauth2-resource-server</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-security</artifactId>
+        </dependency>
 
         <!-- Tools -->
         <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
@@ -96,6 +104,17 @@
             <groupId>org.flywaydb</groupId>
             <artifactId>flyway-database-postgresql</artifactId>
         </dependency>
+        <!-- FIX: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Java 8 date/time type `java.time.Instant` not supported by default: add Module "com.fasterxml.jackson.datatype:jackson-datatype-jsr310" to enable handling (through reference chain: java.util.ArrayList[0]->dev.rheinsw.server.customer.model.records.CustomerNote["createdAt"]) -->
+        <dependency>
+            <groupId>com.fasterxml.jackson.datatype</groupId>
+            <artifactId>jackson-datatype-jsr310</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.vladmihalcea</groupId>
+            <artifactId>hibernate-types-60</artifactId> <!-- for Hibernate 6 -->
+            <version>2.21.1</version>
+        </dependency>
+
 
         <dependency>
             <groupId>dev.rheinsw</groupId>

backend/server/src/main/java/dev/rheinsw/server/common/controller/AbstractController.java

@@ -0,0 +1,39 @@
+package dev.rheinsw.server.common.controller;
+
+import dev.rheinsw.server.security.session.CurrentSessionProvider;
+import dev.rheinsw.server.security.session.model.CurrentSession;
+import dev.rheinsw.server.security.user.UserService;
+import dev.rheinsw.server.common.entity.User;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Autowired;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+@RequiredArgsConstructor
+public abstract class AbstractController {
+
+    protected CurrentSessionProvider currentSessionProvider;
+    protected UserService userService;
+
+    @Autowired
+    protected void setCurrentSessionProvider(CurrentSessionProvider currentSessionProvider) {
+        this.currentSessionProvider = currentSessionProvider;
+    }
+
+    protected CurrentSession getCurrentSession() {
+        return currentSessionProvider.getCurrentSession();
+    }
+
+    @Autowired
+    protected void setUserService(UserService userService) {
+        this.userService = userService;
+    }
+
+    protected User getUserFromCurrentSession() {
+        return userService.getUserBySession(getCurrentSession());
+    }
+
+
+}

backend/server/src/main/java/dev/rheinsw/server/common/controller/exception/ApiException.java

@@ -0,0 +1,15 @@
+package dev.rheinsw.server.common.controller.exception;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 06.07.25
+ */
+public class ApiException extends RuntimeException {
+    public ApiException(String message) {
+        super(message);
+    }
+
+    public ApiException(Throwable cause) {
+        super(cause);
+    }
+}

backend/server/src/main/java/dev/rheinsw/server/common/controller/exception/handler/GlobalExceptionHandler.java

@@ -0,0 +1,47 @@
+package dev.rheinsw.server.common.controller.exception.handler;
+
+import dev.rheinsw.server.common.controller.exception.ApiException;
+import dev.rheinsw.server.common.usecase.exception.UseCaseException;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.time.Instant;
+import java.util.List;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 06.07.25
+ */
+@ControllerAdvice
+public class GlobalExceptionHandler {
+
+    @ExceptionHandler(ApiException.class)
+    public ResponseEntity<ApiErrorResponse> handleBusinessException(ApiException ex) {
+        return ResponseEntity.badRequest().body(
+                new ApiErrorResponse(Instant.now(), ex.getMessage(), List.of(ex.getMessage()))
+        );
+    }
+
+    @ExceptionHandler(UseCaseException.class)
+    public ResponseEntity<ApiErrorResponse> handleUseCaseException(UseCaseException ex) {
+        return ResponseEntity.badRequest().body(
+                new ApiErrorResponse(Instant.now(), ex.getMessage(), List.of(ex.getMessage()))
+        );
+    }
+
+
+    @ExceptionHandler(Exception.class)
+    public ResponseEntity<ApiErrorResponse> handleGeneric(Exception ex) {
+        ex.printStackTrace(); // log the stack trace
+        return ResponseEntity.internalServerError().body(
+                new ApiErrorResponse(Instant.now(), "Ein unerwarteter Fehler ist aufgetreten", List.of(ex.getMessage()))
+        );
+    }
+
+    public record ApiErrorResponse(
+            Instant timestamp,
+            String message,
+            List<String> errors
+    ) {
+    }
+}

backend/server/src/main/java/dev/rheinsw/server/common/entity/BaseEntity.java

@@ -0,0 +1,48 @@
+package dev.rheinsw.server.common.entity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.EntityListeners;
+import jakarta.persistence.MappedSuperclass;
+import jakarta.persistence.Version;
+import lombok.Getter;
+import lombok.Setter;
+import org.springframework.data.annotation.CreatedBy;
+import org.springframework.data.annotation.CreatedDate;
+import org.springframework.data.annotation.LastModifiedBy;
+import org.springframework.data.annotation.LastModifiedDate;
+import org.springframework.data.jpa.domain.support.AuditingEntityListener;
+
+import java.time.Instant;
+
+/**
+ * Base Entity
+ *
+ * @author Thatsaphorn Atchariyaphap
+ * @since 26.04.25
+ */
+@MappedSuperclass
+@EntityListeners(AuditingEntityListener.class)
+@Getter
+@Setter
+public abstract class BaseEntity {
+
+    @CreatedDate
+    @Column(name = "created_at", nullable = false, updatable = false)
+    protected Instant createdAt;
+
+    @LastModifiedDate
+    @Column(name = "updated_at")
+    protected Instant updatedAt;
+
+    @CreatedBy
+    @Column(name = "created_by", updatable = false)
+    protected Long createdBy;
+
+    @LastModifiedBy
+    @Column(name = "updated_by")
+    protected Long updatedBy;
+
+    @Version
+    @Column(name = "version")
+    protected Long version;
+}

backend/server/src/main/java/dev/rheinsw/server/common/entity/User.java

@@ -0,0 +1,68 @@
+package dev.rheinsw.server.common.entity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+import jakarta.persistence.Version;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+import org.springframework.data.annotation.CreatedBy;
+import org.springframework.data.annotation.CreatedDate;
+import org.springframework.data.annotation.LastModifiedBy;
+import org.springframework.data.annotation.LastModifiedDate;
+
+import java.time.Instant;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+@Entity
+@Table(name = "users")
+@Getter
+@Setter
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+public class User {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY) // auto-increment
+    private Long id;
+
+    @Column(nullable = false, unique = true)
+    private String keycloakId; // the `sub` field from JWT, as a string
+
+    @Column(nullable = false, unique = true)
+    private String username;
+
+    @Column(nullable = false)
+    private String email;
+
+    @CreatedDate
+    @Column(name = "created_at", nullable = false, updatable = false)
+    protected Instant createdAt;
+
+    @LastModifiedDate
+    @Column(name = "updated_at")
+    protected Instant updatedAt;
+
+    @CreatedBy
+    @Column(name = "created_by", updatable = false)
+    protected Long createdBy;
+
+    @LastModifiedBy
+    @Column(name = "updated_by")
+    protected Long updatedBy;
+
+
+    @Version
+    @Column(name = "version")
+    protected Long version;
+}

backend/server/src/main/java/dev/rheinsw/server/common/entity/config/JpaAuditingConfig.java

@@ -0,0 +1,13 @@
+package dev.rheinsw.server.common.entity.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+@Configuration
+@EnableJpaAuditing(auditorAwareRef = "auditorProvider")
+public class JpaAuditingConfig {
+}

backend/server/src/main/java/dev/rheinsw/server/common/usecase/exception/UseCaseException.java

@@ -0,0 +1,15 @@
+package dev.rheinsw.server.common.usecase.exception;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 06.07.25
+ */
+public class UseCaseException extends RuntimeException {
+    public UseCaseException(String message) {
+        super(message);
+    }
+
+    public UseCaseException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

backend/server/src/main/java/dev/rheinsw/server/customer/controller/CustomerController.java

@@ -0,0 +1,79 @@
+package dev.rheinsw.server.customer.controller;
+
+import dev.rheinsw.server.common.controller.AbstractController;
+import dev.rheinsw.server.customer.dtos.CreateCustomerDto;
+import dev.rheinsw.server.customer.dtos.CustomerValidationRequest;
+import dev.rheinsw.server.customer.model.Customer;
+import dev.rheinsw.server.customer.repository.CustomerRepository;
+import dev.rheinsw.server.customer.usecase.LoadCustomerQuery;
+import dev.rheinsw.server.customer.usecase.RegisterCustomerUseCase;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+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;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.UUID;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+@RestController
+@RequestMapping("/customers")
+@RequiredArgsConstructor
+public class CustomerController extends AbstractController {
+
+    private final CustomerRepository repository;
+    private final RegisterCustomerUseCase registerCustomerUseCase;
+    private final LoadCustomerQuery loadCustomerQuery;
+
+    @PostMapping
+    public ResponseEntity<UUID> register(@RequestBody CreateCustomerDto request) {
+        var currentUser = getUserFromCurrentSession();
+
+        var result = registerCustomerUseCase.register(
+                currentUser,
+                request.email(),
+                request.name(),
+                request.companyName(),
+                request.phoneNumbers(),
+                request.street(),
+                request.zip(),
+                request.city(),
+                request.notes()
+        );
+
+        return ResponseEntity.ok(result);
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<Customer> loadById(@PathVariable UUID id) {
+        return ResponseEntity.ok(loadCustomerQuery.loadById(id));
+    }
+
+    @GetMapping
+    public ResponseEntity<List<Customer>> findAll() {
+        var result = loadCustomerQuery.findAll();
+        return ResponseEntity.ok(result);
+    }
+
+    @PostMapping("/validate")
+    public ResponseEntity<List<Customer>> validateCustomer(@RequestBody CustomerValidationRequest request) {
+        List<Customer> matches = repository.findPotentialDuplicates(
+                request.email(),
+                request.companyName(),
+                request.street(),
+                request.zip(),
+                request.city()
+        );
+
+        return ResponseEntity.ok(matches);
+    }
+
+}

backend/server/src/main/java/dev/rheinsw/server/customer/dtos/CreateCustomerDto.java

@@ -0,0 +1,22 @@
+package dev.rheinsw.server.customer.dtos;
+
+import dev.rheinsw.server.customer.model.records.CustomerNote;
+import dev.rheinsw.server.customer.model.records.CustomerPhoneNumber;
+
+import java.util.List;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 06.07.25
+ */
+public record CreateCustomerDto(
+        String email,
+        String name,
+        String companyName,
+        List<CustomerPhoneNumber> phoneNumbers,
+        String street,
+        String zip,
+        String city,
+        List<CustomerNote> notes
+) {
+}

backend/server/src/main/java/dev/rheinsw/server/customer/dtos/CustomerValidationRequest.java

@@ -0,0 +1,14 @@
+package dev.rheinsw.server.customer.dtos;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 06.07.25
+ */
+public record CustomerValidationRequest(
+        String email,
+        String companyName,
+        String street,
+        String zip,
+        String city
+) {
+}

backend/server/src/main/java/dev/rheinsw/server/customer/model/Customer.java

@@ -0,0 +1,41 @@
+package dev.rheinsw.server.customer.model;
+
+import com.vladmihalcea.hibernate.type.json.JsonType;
+import dev.rheinsw.server.common.entity.BaseEntity;
+import dev.rheinsw.server.customer.model.records.CustomerNote;
+import dev.rheinsw.server.customer.model.records.CustomerPhoneNumber;
+import jakarta.persistence.*;
+import lombok.*;
+import org.hibernate.annotations.Type;
+
+import java.util.List;
+import java.util.UUID;
+
+@Entity
+@Table(name = "customer")
+@Getter
+@Setter
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+public class Customer extends BaseEntity {
+
+    @Id
+    private UUID id;
+
+    private String email;
+    private String name;
+    private String companyName;
+
+    @Column(name = "phone_numbers", columnDefinition = "jsonb")
+    @Type(JsonType.class)
+    private List<CustomerPhoneNumber> phoneNumbers;
+
+    private String street;
+    private String zip;
+    private String city;
+
+    @Column(name = "notes", columnDefinition = "jsonb")
+    @Type(JsonType.class)
+    private List<CustomerNote> notes;
+}

backend/server/src/main/java/dev/rheinsw/server/customer/model/records/CustomerNote.java

@@ -0,0 +1,16 @@
+package dev.rheinsw.server.customer.model.records;
+
+import java.time.Instant;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+public record CustomerNote(
+        String text,
+        Long createdBy,
+        Long updatedBy,
+        Instant createdAt,
+        Instant updatedAt
+) {
+}

backend/server/src/main/java/dev/rheinsw/server/customer/model/records/CustomerPhoneNumber.java

@@ -0,0 +1,17 @@
+package dev.rheinsw.server.customer.model.records;
+
+import java.time.Instant;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+public record CustomerPhoneNumber(
+        String number,
+        String note,
+        Long createdBy,
+        Long updatedBy,
+        Instant createdAt,
+        Instant updatedAt
+) {
+}

backend/server/src/main/java/dev/rheinsw/server/customer/repository/CustomerRepository.java

@@ -0,0 +1,37 @@
+package dev.rheinsw.server.customer.repository;
+
+import dev.rheinsw.server.customer.model.Customer;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.UUID;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+public interface CustomerRepository extends JpaRepository<Customer, UUID> {
+    Optional<Customer> findByEmail(String email);
+
+    @Query("""
+                SELECT c FROM Customer c
+                WHERE LOWER(c.email) = LOWER(:email)
+                   OR LOWER(c.companyName) = LOWER(:companyName)
+                   OR (
+                        LOWER(c.street) = LOWER(:street)
+                     AND LOWER(c.zip) = LOWER(:zip)
+                     AND LOWER(c.city) = LOWER(:city)
+                   )
+            """)
+    List<Customer> findPotentialDuplicates(
+            @Param("email") String email,
+            @Param("companyName") String companyName,
+            @Param("street") String street,
+            @Param("zip") String zip,
+            @Param("city") String city
+    );
+
+}

backend/server/src/main/java/dev/rheinsw/server/customer/usecase/CustomerUseCaseImpl.java

@@ -0,0 +1,78 @@
+package dev.rheinsw.server.customer.usecase;
+
+import dev.rheinsw.server.common.controller.exception.ApiException;
+import dev.rheinsw.server.common.usecase.exception.UseCaseException;
+import dev.rheinsw.server.customer.model.Customer;
+import dev.rheinsw.server.customer.model.records.CustomerNote;
+import dev.rheinsw.server.customer.model.records.CustomerPhoneNumber;
+import dev.rheinsw.server.customer.repository.CustomerRepository;
+import dev.rheinsw.server.common.entity.User;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Service;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.UUID;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+@Service
+@RequiredArgsConstructor
+public class CustomerUseCaseImpl implements RegisterCustomerUseCase, LoadCustomerQuery {
+
+    private final CustomerRepository repository;
+
+    @Override
+    public UUID register(
+            User creator,
+            String email,
+            String name,
+            String companyName,
+            List<CustomerPhoneNumber> phoneNumbers,
+            String street,
+            String zip,
+            String city,
+            List<CustomerNote> notes) {
+
+        if (repository.findByEmail(email).isPresent()) {
+            throw new UseCaseException("Ein Kunde mit dieser E-Mail-Adresse existiert bereits.");
+        }
+
+        final var now = Instant.now();
+        var enrichedPhoneNumbers = phoneNumbers.stream()
+                .map(p -> new CustomerPhoneNumber(p.number(), p.note(), creator.getId(), creator.getId(), now, now))
+                .toList();
+        var enrichedNotes = notes.stream()
+                .map(n -> new CustomerNote(n.text(), creator.getId(), creator.getId(), now, now))
+                .toList();
+
+        Customer customer = Customer.builder()
+                .id(UUID.randomUUID())
+                .email(email)
+                .name(name)
+                .companyName(companyName)
+                .phoneNumbers(enrichedPhoneNumbers)
+                .street(street)
+                .zip(zip)
+                .city(city)
+                .notes(enrichedNotes)
+                .build();
+
+        var result = repository.save(customer);
+        return result.getId();
+    }
+
+    @Override
+    public Customer loadById(UUID id) {
+        return repository.findById(id)
+                .orElseThrow(() -> new IllegalArgumentException("Customer not found: " + id));
+    }
+
+    @Override
+    public List<Customer> findAll() {
+        return repository.findAll();
+    }
+}

backend/server/src/main/java/dev/rheinsw/server/customer/usecase/LoadCustomerQuery.java

@@ -0,0 +1,15 @@
+package dev.rheinsw.server.customer.usecase;
+
+import dev.rheinsw.server.customer.model.Customer;
+
+import java.util.List;
+import java.util.UUID;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+public interface LoadCustomerQuery {
+    Customer loadById(UUID id);
+    List<Customer> findAll();
+}

backend/server/src/main/java/dev/rheinsw/server/customer/usecase/RegisterCustomerUseCase.java

@@ -0,0 +1,26 @@
+package dev.rheinsw.server.customer.usecase;
+
+import dev.rheinsw.server.customer.model.records.CustomerNote;
+import dev.rheinsw.server.customer.model.records.CustomerPhoneNumber;
+import dev.rheinsw.server.common.entity.User;
+
+import java.util.List;
+import java.util.UUID;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+public interface RegisterCustomerUseCase {
+    UUID register(
+            User creator,
+            String email,
+            String name,
+            String companyName,
+            List<CustomerPhoneNumber> phoneNumbers,
+            String street,
+            String zip,
+            String city,
+            List<CustomerNote> notes
+    );
+}

backend/server/src/main/java/dev/rheinsw/server/demo/model/Demo.java

@@ -0,0 +1,47 @@
+package dev.rheinsw.server.demo.model;
+
+import dev.rheinsw.server.customer.model.Customer;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.UUID;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+
+@Entity
+@Table(name = "demo")
+@Getter
+@Setter
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+public class Demo {
+    @Id
+    private UUID id;
+
+    @ManyToOne
+    @JoinColumn(name = "customer_id")
+    private Customer customer;
+
+    private String name;
+    private String demoUrl;
+    private String containerName;
+
+    private LocalDate createdDate;
+    private LocalTime createdTime;
+    private LocalDate updatedDate;
+    private LocalTime updatedTime;
+}

backend/server/src/main/java/dev/rheinsw/server/demo/model/DemoAccess.java

@@ -0,0 +1,51 @@
+package dev.rheinsw.server.demo.model;
+
+import dev.rheinsw.server.customer.model.Customer;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.UUID;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+@Entity
+@Table(name = "demo_access")
+@Getter
+@Setter
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+public class DemoAccess {
+    @Id
+    private UUID id;
+
+    @ManyToOne
+    @JoinColumn(name = "customer_id")
+    private Customer customer;
+
+    @ManyToOne
+    @JoinColumn(name = "demo_id")
+    private Demo demo;
+
+    private String codeHash;
+    private LocalDate codeExpiresDate;
+    private LocalTime codeExpiresTime;
+    private boolean used;
+
+    private LocalDate createdDate;
+    private LocalTime createdTime;
+    private LocalDate updatedDate;
+    private LocalTime updatedTime;
+}

backend/server/src/main/java/dev/rheinsw/server/demo/model/DemoAccessHistory.java

@@ -0,0 +1,43 @@
+package dev.rheinsw.server.demo.model;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.UUID;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 02.07.25
+ */
+@Entity
+@Table(name = "demo_access_history")
+@Getter
+@Setter
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+public class DemoAccessHistory {
+    @Id
+    private UUID id;
+
+    @ManyToOne
+    @JoinColumn(name = "demo_access_id")
+    private DemoAccess demoAccess;
+
+    private String ipAddress;
+
+    private LocalDate accessedDate;
+    private LocalTime accessedTime;
+    private LocalDate updatedDate;
+    private LocalTime updatedTime;
+}

backend/server/src/main/java/dev/rheinsw/server/security/SecurityConfig.java

@@ -0,0 +1,50 @@
+package dev.rheinsw.server.security;
+
+import dev.rheinsw.server.security.session.UserSessionFilter;
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.method.configuration.EnableMethodSecurity;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.oauth2.server.resource.authentication.JwtAuthenticationConverter;
+import org.springframework.security.oauth2.server.resource.authentication.JwtGrantedAuthoritiesConverter;
+import org.springframework.security.web.SecurityFilterChain;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+@Configuration
+@EnableMethodSecurity
+@RequiredArgsConstructor
+public class SecurityConfig {
+
+    private final UserSessionFilter userSessionEnrichmentFilter;
+
+    @Bean
+    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
+        http
+                .authorizeHttpRequests(auth -> auth
+                        .requestMatchers("/public/**").permitAll()
+                        .anyRequest().authenticated()
+                )
+                .oauth2ResourceServer(oauth2 -> oauth2
+                        .jwt(jwt -> jwt
+                                .jwtAuthenticationConverter(jwtAuthenticationConverter())
+                        )
+                ).addFilterAfter(userSessionEnrichmentFilter, org.springframework.security.oauth2.server.resource.web.BearerTokenAuthenticationFilter.class);
+        ;
+        return http.build();
+    }
+
+    @Bean
+    public JwtAuthenticationConverter jwtAuthenticationConverter() {
+        JwtGrantedAuthoritiesConverter grantedAuthoritiesConverter = new JwtGrantedAuthoritiesConverter();
+        grantedAuthoritiesConverter.setAuthoritiesClaimName("realm_access.roles");
+        grantedAuthoritiesConverter.setAuthorityPrefix("ROLE_");
+
+        JwtAuthenticationConverter converter = new JwtAuthenticationConverter();
+        converter.setJwtGrantedAuthoritiesConverter(grantedAuthoritiesConverter);
+        return converter;
+    }
+}

backend/server/src/main/java/dev/rheinsw/server/security/audit/AuditorConfig.java

@@ -0,0 +1,35 @@
+package dev.rheinsw.server.security.audit;
+
+import dev.rheinsw.server.security.session.CurrentSessionProvider;
+import dev.rheinsw.server.security.user.UserService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.domain.AuditorAware;
+
+import java.util.Optional;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+@Configuration
+@RequiredArgsConstructor
+public class AuditorConfig {
+
+    private final CurrentSessionProvider sessionProvider;
+    private final UserService userService;
+
+    @Bean
+    public AuditorAware<Long> auditorProvider() {
+        return () -> {
+            try {
+                var session = sessionProvider.getCurrentSession();
+                var user = userService.getUserBySession(session);
+                return Optional.of(user.getId());
+            } catch (Exception e) {
+                return Optional.empty(); // anonymous access (public endpoints)
+            }
+        };
+    }
+}

backend/server/src/main/java/dev/rheinsw/server/security/session/CurrentSessionProvider.java

@@ -0,0 +1,28 @@
+package dev.rheinsw.server.security.session;
+
+import dev.rheinsw.server.security.session.model.CurrentSession;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.security.oauth2.jwt.Jwt;
+import org.springframework.stereotype.Component;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+@Component
+public class CurrentSessionProvider {
+
+    public CurrentSession getCurrentSession() {
+        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
+        if (!(auth.getPrincipal() instanceof Jwt jwt)) {
+            throw new IllegalStateException("JWT is missing or invalid");
+        }
+
+        return new CurrentSession(
+                jwt.getClaimAsString("sub"),
+                jwt.getClaimAsString("preferred_username"),
+                jwt.getClaimAsString("email")
+        );
+    }
+}

backend/server/src/main/java/dev/rheinsw/server/security/session/UserSessionFilter.java

@@ -0,0 +1,40 @@
+package dev.rheinsw.server.security.session;
+
+import dev.rheinsw.server.security.session.model.CurrentSession;
+import dev.rheinsw.server.security.user.UserService;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import java.io.IOException;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+@Component
+@RequiredArgsConstructor
+public class UserSessionFilter extends OncePerRequestFilter {
+
+    private final UserService userService;
+    private final CurrentSessionProvider currentSessionProvider;
+
+    @Override
+    protected void doFilterInternal(@NonNull HttpServletRequest request,
+                                    @NonNull HttpServletResponse response,
+                                    @NonNull FilterChain filterChain) throws ServletException, IOException {
+        try {
+            CurrentSession session = currentSessionProvider.getCurrentSession();
+            userService.getUserBySession(session);
+        } catch (Exception e) {
+            // You might want to log this but not block the request
+        }
+
+        filterChain.doFilter(request, response);
+    }
+}

backend/server/src/main/java/dev/rheinsw/server/security/session/model/CurrentSession.java

@@ -0,0 +1,10 @@
+package dev.rheinsw.server.security.session.model;
+
+/**
+ * Current authenticated keycloak session
+ *
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+public record CurrentSession(String keycloakId, String username, String email) {
+}

backend/server/src/main/java/dev/rheinsw/server/security/user/UserService.java

@@ -0,0 +1,38 @@
+package dev.rheinsw.server.security.user;
+
+import dev.rheinsw.server.common.entity.User;
+import dev.rheinsw.server.security.session.model.CurrentSession;
+import dev.rheinsw.server.security.user.repository.UserRepository;
+import jakarta.transaction.Transactional;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+import java.time.Instant;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+@Service
+@RequiredArgsConstructor
+public class UserService {
+
+    private final UserRepository userRepository;
+
+    @Transactional
+    public User getUserBySession(CurrentSession session) {
+        return userRepository.findByKeycloakId(session.keycloakId())
+                .orElseGet(() -> createUser(session));
+    }
+
+    private User createUser(CurrentSession session) {
+        User newUser = User.builder()
+                .keycloakId(session.keycloakId())
+                .username(session.username())
+                .email(session.email())
+                .createdAt(Instant.now())
+                .build();
+        return userRepository.save(newUser);
+    }
+
+}

backend/server/src/main/java/dev/rheinsw/server/security/user/repository/UserRepository.java

@@ -0,0 +1,14 @@
+package dev.rheinsw.server.security.user.repository;
+
+import dev.rheinsw.server.common.entity.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+/**
+ * @author Thatsaphorn Atchariyaphap
+ * @since 04.07.25
+ */
+public interface UserRepository extends JpaRepository<User, Long> {
+    Optional<User> findByKeycloakId(String keycloakId);
+}

backend/server/src/main/resources/application.yml

@@ -4,6 +4,13 @@ server:
 spring:
   application:
     name: server
+
+  security:
+    oauth2:
+      resourceserver:
+        jwt:
+          issuer-uri: https://sso.rhein-software.dev/realms/rhein-sw
+
   datasource:
     url: jdbc:postgresql://${DB_HOST}:${DB_PORT}/${DB_NAME}
     username: ${DB_USERNAME}

backend/server/src/main/resources/db/migration/V2__init_schema.sql

@@ -1,31 +1,98 @@
-create table api_key
+-- Enable UUID extension
+CREATE
+EXTENSION IF NOT EXISTS "uuid-ossp";
+
+-- 0. USERS
+CREATE TABLE users
 (
-    id            bigint generated by default as identity
+    id          BIGSERIAL PRIMARY KEY,
-        constraint pk_api_key
+    keycloak_id VARCHAR(255) NOT NULL UNIQUE,
-            primary key,
+    username    VARCHAR(255) NOT NULL UNIQUE,
-    key           varchar(255) not null
+    email       VARCHAR(255) NOT NULL,
-        constraint uc_api_key_key
+    created_at  TIMESTAMPTZ  NOT NULL DEFAULT CURRENT_TIMESTAMP,
-            unique,
+    updated_at  TIMESTAMPTZ,
-    type          varchar(255) not null,
+    created_by  BIGINT REFERENCES users (id),
-    enabled       boolean      not null,
+    updated_by  BIGINT REFERENCES users (id),
-    frontend_only boolean      not null,
+    version     BIGINT
-    description   text,
-    created_date  date default CURRENT_DATE,
-    created_time  time default CURRENT_TIME,
-    modified_date date,
-    modified_time time
 );
 
+-- 1. CONTACT REQUESTS
 CREATE TABLE contact_requests
 (
-    id             BIGSERIAL PRIMARY KEY,
+    id            BIGSERIAL PRIMARY KEY,
-    name           VARCHAR(100),
+    name          VARCHAR(100),
-    email          VARCHAR(100),
+    email         VARCHAR(100),
-    message        VARCHAR(1000),
+    message       VARCHAR(1000),
-    company        VARCHAR(100),
+    company       VARCHAR(100),
-    phone          VARCHAR(20),
+    phone         VARCHAR(20),
-    website        VARCHAR(100),
+    website       VARCHAR(100),
-    captcha_token  VARCHAR(1024),
+    captcha_token VARCHAR(1024),
-    submitted_date DATE,
+    submitted_at  TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
-    submitted_time TIME
+);
-);
+
+-- 2. CUSTOMER
+CREATE TABLE customer
+(
+    id            UUID PRIMARY KEY     DEFAULT uuid_generate_v4(),
+    email         TEXT        NOT NULL UNIQUE,
+    name          TEXT,
+    company_name  TEXT,
+    phone_numbers JSONB,
+    street        TEXT,
+    zip           TEXT,
+    city          TEXT,
+    notes         JSONB,
+    created_at    TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at    TIMESTAMPTZ,
+    created_by    BIGINT REFERENCES users (id),
+    updated_by    BIGINT REFERENCES users (id),
+    version       BIGINT
+);
+CREATE INDEX idx_customer_email ON customer (email);
+
+-- 3. DEMO
+CREATE TABLE demo
+(
+    id             UUID PRIMARY KEY     DEFAULT uuid_generate_v4(),
+    customer_id    UUID        NOT NULL REFERENCES customer (id) ON DELETE CASCADE,
+    name           TEXT        NOT NULL,
+    demo_url       TEXT        NOT NULL,
+    container_name TEXT        NOT NULL,
+    created_at     TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at     TIMESTAMPTZ,
+    created_by     BIGINT REFERENCES users (id),
+    updated_by     BIGINT REFERENCES users (id),
+    version        BIGINT
+);
+CREATE INDEX idx_demo_customer_id ON demo (customer_id);
+
+-- 4. DEMO ACCESS
+CREATE TABLE demo_access
+(
+    id              UUID PRIMARY KEY     DEFAULT uuid_generate_v4(),
+    customer_id     UUID        NOT NULL REFERENCES customer (id) ON DELETE CASCADE,
+    demo_id         UUID        NOT NULL REFERENCES demo (id) ON DELETE CASCADE,
+    code_hash       TEXT        NOT NULL,
+    code_expires_at TIMESTAMPTZ NOT NULL,
+    used            BOOLEAN              DEFAULT FALSE,
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at      TIMESTAMPTZ,
+    created_by      BIGINT REFERENCES users (id),
+    updated_by      BIGINT REFERENCES users (id),
+    version         BIGINT
+);
+CREATE INDEX idx_demo_access_demo_id ON demo_access (demo_id);
+
+-- 5. DEMO ACCESS HISTORY
+CREATE TABLE demo_access_history
+(
+    id             UUID PRIMARY KEY     DEFAULT uuid_generate_v4(),
+    demo_access_id UUID        NOT NULL REFERENCES demo_access (id) ON DELETE CASCADE,
+    ip_address     TEXT        NOT NULL,
+    accessed_at    TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    created_at     TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at     TIMESTAMPTZ,
+    created_by     BIGINT REFERENCES users (id),
+    updated_by     BIGINT REFERENCES users (id),
+    version        BIGINT
+);

internal_frontend/app/api/customers/customerRoutes.ts

@@ -0,0 +1,4 @@
+export const customerRoutes = {
+    create: "/customers",
+    validate: "/customers/validate",
+};

internal_frontend/app/api/customers/route.ts

@@ -0,0 +1,14 @@
+import {NextRequest, NextResponse} from "next/server";
+import {serverCall} from "@/lib/api/serverCall";
+
+export async function GET() {
+    const data = await serverCall("/customers", "GET");
+    const customers = await data.json();
+    return NextResponse.json(customers);
+}
+
+export async function POST(req: NextRequest) {
+    const body = await req.json()
+    const result = await serverCall("/customers", "POST", body);
+    return NextResponse.json(result.json());
+}

internal_frontend/app/customers/page.tsx

@@ -0,0 +1,196 @@
+"use client";
+
+import {useState, useEffect, useMemo} from "react";
+import {useRouter} from "next/navigation";
+import {Button} from "@/components/ui/button";
+import {Input} from "@/components/ui/input";
+import {Card, CardContent} from "@/components/ui/card";
+import {
+    Pagination,
+    PaginationContent,
+    PaginationItem,
+    PaginationNext,
+    PaginationPrevious
+} from "@/components/ui/pagination";
+import {
+    Table,
+    TableBody,
+    TableCell,
+    TableHead,
+    TableHeader,
+    TableRow
+} from "@/components/ui/table";
+import {motion} from "framer-motion";
+import {ArrowRight} from "lucide-react";
+import {NewCustomerModal} from "@/components/customers/modal/NewCustomerModal";
+import axios from "axios";
+
+export interface CustomerPhoneNumber {
+    number: string;
+    note: string;
+    creator: string;
+    lastModifier: string;
+    createdAt: string;
+    updatedAt: string;
+}
+
+export interface CustomerNote {
+    text: string;
+    creator: string;
+    lastModifier: string;
+    createdAt: string;
+    updatedAt: string;
+}
+
+export interface Customer {
+    id: string;
+    email: string;
+    name: string;
+    companyName: string;
+    phoneNumbers: CustomerPhoneNumber[];
+    street: string;
+    zip: string;
+    city: string;
+    notes: CustomerNote[];
+    createdAt: string;
+}
+
+export default function CustomersPage() {
+    const router = useRouter();
+    const [customers, setCustomers] = useState<Customer[]>([]);
+    const [search, setSearch] = useState("");
+    const [loading, setLoading] = useState(true);
+    const [page, setPage] = useState(1);
+    const pageSize = 15;
+
+    useEffect(() => {
+        axios.get("/api/customers").then((res) => {
+            setCustomers(res.data);
+            setLoading(false);
+        });
+    }, []);
+
+    const filtered = useMemo(() => {
+        return customers.filter(
+            (c) =>
+                c.name.toLowerCase().includes(search.toLowerCase()) ||
+                c.email.toLowerCase().includes(search.toLowerCase())
+        );
+    }, [customers, search]);
+
+    const paginated = useMemo(() => {
+        const start = (page - 1) * pageSize;
+        return filtered.slice(start, start + pageSize);
+    }, [filtered, page]);
+
+    const totalPages = Math.ceil(filtered.length / pageSize);
+
+    return (
+        <div className="p-6 space-y-6 text-sm overflow-x-auto">
+            <motion.div
+                initial={{opacity: 0}}
+                animate={{opacity: 1}}
+                transition={{duration: 0.3}}
+                className="grid grid-cols-1 md:grid-cols-3 gap-4"
+            >
+                <Card>
+                    <CardContent>
+                        <div className="text-sm text-muted-foreground">Kunden</div>
+                        <div className="text-3xl font-bold">{customers.length}</div>
+                    </CardContent>
+                </Card>
+                <Card>
+                    <CardContent>
+                        <div className="text-sm text-muted-foreground">Demo-Statistik</div>
+                        <div className="text-3xl font-bold">–</div>
+                    </CardContent>
+                </Card>
+                <Card>
+                    <CardContent>
+                        <div className="text-sm text-muted-foreground">Letzte Aktivität</div>
+                        <div className="text-3xl font-bold">–</div>
+                    </CardContent>
+                </Card>
+            </motion.div>
+
+            <motion.div initial={{opacity: 0}} animate={{opacity: 1}} transition={{duration: 0.3}}>
+                <Card>
+                    <CardContent className="space-y-6">
+                        <div className="flex flex-col md:flex-row justify-between items-center gap-4">
+                            <Input placeholder="Suche" value={search} onChange={(e) => setSearch(e.target.value)}/>
+                            <NewCustomerModal/>
+                        </div>
+
+                        {customers.length === 0 && loading ? (
+                            <div className="text-center text-muted-foreground">Lade Kunden...</div>
+                        ) : (
+                            <div className="overflow-x-auto">
+                                <Table className="text-xs min-w-[700px]">
+                                    <TableHeader>
+                                        <TableRow>
+                                            <TableHead>Name</TableHead>
+                                            <TableHead>E-Mail</TableHead>
+                                            <TableHead>Firma</TableHead>
+                                            <TableHead>Telefon</TableHead>
+                                            <TableHead>Straße</TableHead>
+                                            <TableHead>PLZ</TableHead>
+                                            <TableHead>Ort</TableHead>
+                                            <TableHead>Erstellt am</TableHead>
+                                            <TableHead>Aktionen</TableHead>
+                                        </TableRow>
+                                    </TableHeader>
+                                    <TableBody>
+                                        {paginated.map((customer) => (
+                                            <TableRow key={customer.id}>
+                                                <TableCell
+                                                    className="max-w-[180px] truncate">{customer.name}</TableCell>
+                                                <TableCell
+                                                    className="max-w-[180px] truncate">{customer.email}</TableCell>
+                                                <TableCell
+                                                    className="max-w-[180px] truncate">{customer.companyName}</TableCell>
+                                                <TableCell className="max-w-[140px] truncate">
+                                                    {customer.phoneNumbers?.[0]?.number}
+                                                </TableCell>
+                                                <TableCell
+                                                    className="max-w-[180px] truncate">{customer.street}</TableCell>
+                                                <TableCell>{customer.zip}</TableCell>
+                                                <TableCell>{customer.city}</TableCell>
+                                                <TableCell>{new Date(customer.createdAt).toLocaleString()}</TableCell>
+                                                <TableCell>
+                                                    <Button
+                                                        variant="ghost"
+                                                        size="icon"
+                                                        onClick={() => router.push(`/customers/${customer.id}`)}
+                                                    >
+                                                        <ArrowRight className="w-4 h-4"/>
+                                                    </Button>
+                                                </TableCell>
+                                            </TableRow>
+                                        ))}
+                                    </TableBody>
+                                </Table>
+                            </div>
+                        )}
+
+                        <Pagination className="justify-center pt-4">
+                            <PaginationContent>
+                                <PaginationItem>
+                                    <PaginationPrevious
+                                        onClick={() => setPage((p) => Math.max(1, p - 1))}
+                                        className={page === 1 ? "pointer-events-none opacity-50" : ""}
+                                    />
+                                </PaginationItem>
+                                <PaginationItem>
+                                    <PaginationNext
+                                        onClick={() => setPage((p) => Math.min(totalPages, p + 1))}
+                                        className={page === totalPages ? "pointer-events-none opacity-50" : ""}
+                                    />
+                                </PaginationItem>
+                            </PaginationContent>
+                        </Pagination>
+                    </CardContent>
+                </Card>
+            </motion.div>
+        </div>
+    );
+}

internal_frontend/app/layout.tsx

@@ -41,22 +41,21 @@ export default async function RootLayout({
                     }
                 >
                     <AppSidebar/>
-                    <main>
+
-                        <SidebarInset>
+                    <SidebarInset>
-                            <header
+                        <header
-                                className="flex h-16 shrink-0 items-center gap-2 transition-[width,height] ease-linear group-has-data-[collapsible=icon]/sidebar-wrapper:h-12">
+                            className="flex h-16 shrink-0 items-center gap-2 transition-[width,height] ease-linear group-has-data-[collapsible=icon]/sidebar-wrapper:h-12">
-                                <div className="flex items-center gap-2 px-4">
+                            <div className="flex items-center gap-2 px-4">
-                                    <SidebarTrigger className="-ml-1"/>
+                                <SidebarTrigger className="-ml-1"/>
-                                    <Separator
+                                <Separator
-                                        orientation="vertical"
+                                    orientation="vertical"
-                                        className="mr-2 data-[orientation=vertical]:h-4"
+                                    className="mr-2 data-[orientation=vertical]:h-4"
-                                    />
+                                />
-                                    <DynamicBreadcrumb/>
+                                <DynamicBreadcrumb/>
-                                </div>
+                            </div>
-                            </header>
+                        </header>
-                        </SidebarInset>
                         {children}
-                    </main>
+                    </SidebarInset>
                 </SidebarProvider>
             ) : (
                 <LoginScreen/>

internal_frontend/components/app-sidebar.tsx

@@ -5,7 +5,7 @@ import {
     Home,
     Scale,
     User2,
-    Settings
+    Settings, LayoutDashboard
 } from "lucide-react";
 
 import {
@@ -50,6 +50,14 @@ const rheinItems = [
     },
 ];
 
+const customerItems = [
+    {
+        title: "Kundenübersicht",
+        url: "/customers",
+        icon: LayoutDashboard,
+    },
+];
+
 export function AppSidebar() {
     return (
         <Sidebar>
@@ -77,6 +85,27 @@ export function AppSidebar() {
                     </SidebarGroupContent>
                 </SidebarGroup>
 
+                <SidebarGroup>
+                    <SidebarGroupLabel>Kunden</SidebarGroupLabel>
+                    <SidebarGroupContent>
+                        <SidebarMenu className="flex flex-col gap-y-1">
+                            {customerItems.map((item) => (
+                                <SidebarMenuItem key={item.title}>
+                                    <SidebarMenuButton
+                                        asChild
+                                        className="hover:bg-accent hover:text-accent-foreground"
+                                    >
+                                        <a href={item.url}>
+                                            <item.icon/>
+                                            <span>{item.title}</span>
+                                        </a>
+                                    </SidebarMenuButton>
+                                </SidebarMenuItem>
+                            ))}
+                        </SidebarMenu>
+                    </SidebarGroupContent>
+                </SidebarGroup>
+
                 {/* Demos section */}
                 <SidebarGroup>
                     <SidebarGroupLabel>Demos</SidebarGroupLabel>

internal_frontend/components/customers/modal/NewCustomerModal.tsx

@@ -0,0 +1,280 @@
+"use client";
+
+import {useState} from "react";
+import {motion} from "framer-motion";
+import {Trash2} from "lucide-react";
+import {Button} from "@/components/ui/button";
+import {Dialog, DialogContent, DialogHeader, DialogTitle, DialogTrigger,} from "@/components/ui/dialog";
+import {Label} from "@/components/ui/label";
+import {Input} from "@/components/ui/input";
+import {Textarea} from "@/components/ui/textarea";
+import {Progress} from "@/components/ui/progress";
+import {Card, CardContent, CardHeader} from "@/components/ui/card";
+import {CreateCustomerDto, NoteDto, PhoneNumberDto} from "@/services/customers/dtos/createCustomer.dto";
+import {addCustomer} from "@/services/customers/usecases/addCustomer";
+import {validateCustomer} from "@/services/customers/usecases/validateCustomer";
+
+export function NewCustomerModal() {
+    const [step, setStep] = useState(1);
+    const [open, setOpen] = useState(false);
+    const [email, setEmail] = useState("");
+    const [name, setName] = useState("");
+    const [companyName, setCompanyName] = useState("");
+    const [phoneNumbers, setPhoneNumbers] = useState<PhoneNumberDto[]>([{note: "", number: ""}]);
+    const [notes, setNotes] = useState<NoteDto[]>([{text: ""}]);
+    const [street, setStreet] = useState("");
+    const [zip, setZip] = useState("");
+    const [city, setCity] = useState("");
+    const [matches, setMatches] = useState<CustomerMatch[]>([]);
+    const [showDetailModal, setShowDetailModal] = useState(false);
+    const [selectedCustomer] = useState<CustomerMatch | null>(null);
+
+    type CustomerMatch = {
+        id: string;
+        name: string;
+        email: string;
+        companyName: string;
+        street: string;
+        zip: string;
+        city: string;
+    };
+
+    const emailExists = matches.some(m => m.email.toLowerCase() === email.toLowerCase());
+    const companyExists = matches.some(m => m.companyName.toLowerCase() === companyName.toLowerCase());
+    const addressExists = matches.some(m =>
+        m.street.toLowerCase() === street.toLowerCase() &&
+        m.zip.toLowerCase() === zip.toLowerCase() &&
+        m.city.toLowerCase() === city.toLowerCase()
+    );
+
+    const validateField = async () => {
+        try {
+            const result = await validateCustomer({email, companyName, street, zip, city});
+            setMatches(result);
+        } catch (err) {
+            console.error("Validation failed", err);
+        }
+    };
+
+    const handleSubmit = async () => {
+        if (!email || !name || !companyName || !street || !zip || !city) return;
+        const payload: CreateCustomerDto = {email, name, companyName, street, zip, city, phoneNumbers, notes};
+        await addCustomer(payload);
+        location.reload();
+    };
+
+    const renderFormInput = (
+        label: string,
+        value: string,
+        onChange: (value: string) => void,
+        error?: boolean,
+        className?: string
+    ) => (
+        <div className="space-y-2">
+            <Label>{label} *</Label>
+            <Input
+                value={value}
+                onChange={(e) => onChange(e.target.value)}
+                onBlur={validateField}
+                className={error ? "border border-red-500" : className}
+            />
+        </div>
+    );
+
+    const renderCustomerInfo = (customer: CustomerMatch) => (
+        <div className="space-y-1 text-sm">
+            <div><strong>Name:</strong> {customer.name}</div>
+            <div><strong>Firma:</strong> {customer.companyName}</div>
+            <div><strong>E-Mail:</strong> {customer.email}</div>
+            <div><strong>Adresse:</strong> {customer.street}, {customer.zip} {customer.city}</div>
+        </div>
+    );
+
+    const updatePhoneNumber = (i: number, key: keyof PhoneNumberDto, value: string) => {
+        const updated = [...phoneNumbers];
+        updated[i][key] = value;
+        setPhoneNumbers(updated);
+    };
+
+    const removePhoneNumber = (i: number) => {
+        setPhoneNumbers(phoneNumbers.filter((_, idx) => idx !== i));
+    };
+
+    const updateNote = (i: number, value: string) => {
+        const updated = [...notes];
+        updated[i].text = value;
+        setNotes(updated);
+    };
+
+    const renderStepOne = () => (
+        <div className="space-y-4">
+            <div className="space-y-2">
+                {renderFormInput("Name", name, setName)}
+                {renderFormInput("Firma", companyName, setCompanyName, companyExists)}
+                {renderFormInput("E-Mail", email, setEmail, emailExists)}
+                {emailExists && (
+                    <div className="text-red-500 text-sm">Ein Kunde mit dieser E-Mail existiert bereits.</div>
+                )}
+            </div>
+            <div className="space-y-2">
+                <Label>Telefonnummern *</Label>
+                {phoneNumbers.map((p, i) => (
+                    <div key={i} className="grid grid-cols-[2fr_3fr_auto] gap-2 items-center w-full">
+                        <Input
+                            placeholder="Nummer"
+                            value={p.number}
+                            onChange={(e) => updatePhoneNumber(i, "number", e.target.value)}
+                        />
+                        <Input
+                            placeholder="Notiz"
+                            value={p.note}
+                            onChange={(e) => updatePhoneNumber(i, "note", e.target.value)}
+                        />
+                        <Button variant="ghost" size="icon" onClick={() => removePhoneNumber(i)}>
+                            <Trash2 className="w-4 h-4"/>
+                        </Button>
+                    </div>
+                ))}
+                <Button
+                    variant="outline"
+                    size="sm"
+                    onClick={() => setPhoneNumbers([...phoneNumbers, {note: "", number: ""}])}
+                >
+                    + Telefonnummer hinzufügen
+                </Button>
+            </div>
+        </div>
+    );
+
+    const renderStepTwo = () => (
+        <div className="space-y-4">
+            <div className="grid grid-cols-12 gap-4">
+                <div className="col-span-6">
+                    {renderFormInput("Straße", street, setStreet, addressExists)}
+                </div>
+                <div className="col-span-3">
+                    {renderFormInput("PLZ", zip, setZip, addressExists)}
+                </div>
+                <div className="col-span-3">
+                    {renderFormInput("Ort", city, setCity, addressExists)}
+                </div>
+            </div>
+            <div className="space-y-2">
+                <Label>Notizen</Label>
+                {notes.map((note, i) => (
+                    <div key={i} className="flex items-start gap-2">
+                        <Textarea
+                            placeholder={`Notiz ${i + 1}`}
+                            value={note.text}
+                            rows={3}
+                            className="w-full resize-y"
+                            onChange={(e) => updateNote(i, e.target.value)}
+                        />
+                        <Button
+                            type="button"
+                            variant="ghost"
+                            size="icon"
+                            onClick={() => setNotes(notes.filter((_, idx) => idx !== i))}
+                        >
+                            <Trash2 className="w-4 h-4"/>
+                        </Button>
+                    </div>
+                ))}
+                <Button
+                    type="button"
+                    onClick={() => setNotes([...notes, {text: ""}])}
+                    variant="outline"
+                    size="sm"
+                >
+                    + Notiz hinzufügen
+                </Button>
+            </div>
+        </div>
+    );
+
+    const renderDuplicationCard = () => (
+        <motion.div initial={{opacity: 0}} animate={{opacity: 1}} transition={{duration: 0.3}} className="mt-6">
+            <Card
+                className={emailExists ? "border-red-500 bg-red-100 dark:bg-red-900/20" : "border-yellow-500 bg-yellow-100 dark:bg-yellow-900/20"}>
+                <CardHeader className="text-sm font-semibold">
+                    {matches.length} mögliche Duplikate gefunden
+                </CardHeader>
+                <CardContent>
+                    <Button variant="outline" size="sm" className="w-full"
+                            onClick={() => setShowDetailModal(true)}>Details</Button>
+                </CardContent>
+            </Card>
+        </motion.div>
+    );
+
+    return (
+        <>
+            <Dialog open={open} onOpenChange={setOpen}>
+                <DialogTrigger asChild>
+                    <Button onClick={() => {
+                        setOpen(true);
+                        setStep(1);
+                    }}>Neue Kunde</Button>
+                </DialogTrigger>
+                <DialogContent className="w-full max-w-5xl max-h-[95vh] overflow-y-auto">
+                    <DialogHeader><DialogTitle>Neuen Kunden anlegen</DialogTitle></DialogHeader>
+                    <div className="mb-4">
+                        <div className="text-xs font-semibold mb-2">Schritt {step} von 2</div>
+                        <Progress value={step === 1 ? 50 : 100}/>
+                    </div>
+
+                    {step === 1 ? renderStepOne() : renderStepTwo()}
+                    {matches.length > 0 && renderDuplicationCard()}
+
+                    <div className="flex justify-between mt-6">
+                        <Button variant="secondary" disabled={step === 1} onClick={() => setStep(step - 1)}>
+                            Zurück
+                        </Button>
+                        {step === 1 ? (
+                            <Button
+                                onClick={() => setStep(2)}
+                                disabled={!email || !name || !companyName || phoneNumbers.length === 0 || !phoneNumbers.some(p => p.number.trim()) || emailExists}
+                            >
+                                Weiter
+                            </Button>
+                        ) : (
+                            <Button onClick={handleSubmit} disabled={!street || !zip || !city}>
+                                Anlegen
+                            </Button>
+                        )}
+                    </div>
+                </DialogContent>
+            </Dialog>
+
+            <Dialog open={showDetailModal} onOpenChange={setShowDetailModal}>
+                <DialogContent className="max-w-3xl max-h-[90vh] overflow-y-auto space-y-4">
+                    <DialogHeader>
+                        <DialogTitle>Kundendetails</DialogTitle>
+                    </DialogHeader>
+                    {matches.length === 1 ? (
+                        renderCustomerInfo(matches[0])
+                    ) : (
+                        <div className="space-y-4">
+                            {matches.map((customer) => (
+                                <Card key={customer.id}>
+                                    <CardContent className="pt-4">
+                                        {renderCustomerInfo(customer)}
+                                    </CardContent>
+                                </Card>
+                            ))}
+                            {selectedCustomer && (
+                                <motion.div
+                                    initial={{opacity: 0, y: 10}}
+                                    animate={{opacity: 1, y: 0}}
+                                    className="p-4 border rounded-md bg-muted"
+                                >
+                                    {renderCustomerInfo(selectedCustomer)}
+                                </motion.div>
+                            )}
+                        </div>
+                    )}
+                </DialogContent>
+            </Dialog>
+        </>
+    );
+}

internal_frontend/components/ui/dialog.tsx

@@ -0,0 +1,143 @@
+"use client"
+
+import * as React from "react"
+import * as DialogPrimitive from "@radix-ui/react-dialog"
+import { XIcon } from "lucide-react"
+
+import { cn } from "@/lib/utils"
+
+function Dialog({
+  ...props
+}: React.ComponentProps<typeof DialogPrimitive.Root>) {
+  return <DialogPrimitive.Root data-slot="dialog" {...props} />
+}
+
+function DialogTrigger({
+  ...props
+}: React.ComponentProps<typeof DialogPrimitive.Trigger>) {
+  return <DialogPrimitive.Trigger data-slot="dialog-trigger" {...props} />
+}
+
+function DialogPortal({
+  ...props
+}: React.ComponentProps<typeof DialogPrimitive.Portal>) {
+  return <DialogPrimitive.Portal data-slot="dialog-portal" {...props} />
+}
+
+function DialogClose({
+  ...props
+}: React.ComponentProps<typeof DialogPrimitive.Close>) {
+  return <DialogPrimitive.Close data-slot="dialog-close" {...props} />
+}
+
+function DialogOverlay({
+  className,
+  ...props
+}: React.ComponentProps<typeof DialogPrimitive.Overlay>) {
+  return (
+    <DialogPrimitive.Overlay
+      data-slot="dialog-overlay"
+      className={cn(
+        "data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 fixed inset-0 z-50 bg-black/50",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function DialogContent({
+  className,
+  children,
+  showCloseButton = true,
+  ...props
+}: React.ComponentProps<typeof DialogPrimitive.Content> & {
+  showCloseButton?: boolean
+}) {
+  return (
+    <DialogPortal data-slot="dialog-portal">
+      <DialogOverlay />
+      <DialogPrimitive.Content
+        data-slot="dialog-content"
+        className={cn(
+          "bg-background data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 fixed top-[50%] left-[50%] z-50 grid w-full max-w-[calc(100%-2rem)] translate-x-[-50%] translate-y-[-50%] gap-4 rounded-lg border p-6 shadow-lg duration-200 sm:max-w-lg",
+          className
+        )}
+        {...props}
+      >
+        {children}
+        {showCloseButton && (
+          <DialogPrimitive.Close
+            data-slot="dialog-close"
+            className="ring-offset-background focus:ring-ring data-[state=open]:bg-accent data-[state=open]:text-muted-foreground absolute top-4 right-4 rounded-xs opacity-70 transition-opacity hover:opacity-100 focus:ring-2 focus:ring-offset-2 focus:outline-hidden disabled:pointer-events-none [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-4"
+          >
+            <XIcon />
+            <span className="sr-only">Close</span>
+          </DialogPrimitive.Close>
+        )}
+      </DialogPrimitive.Content>
+    </DialogPortal>
+  )
+}
+
+function DialogHeader({ className, ...props }: React.ComponentProps<"div">) {
+  return (
+    <div
+      data-slot="dialog-header"
+      className={cn("flex flex-col gap-2 text-center sm:text-left", className)}
+      {...props}
+    />
+  )
+}
+
+function DialogFooter({ className, ...props }: React.ComponentProps<"div">) {
+  return (
+    <div
+      data-slot="dialog-footer"
+      className={cn(
+        "flex flex-col-reverse gap-2 sm:flex-row sm:justify-end",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function DialogTitle({
+  className,
+  ...props
+}: React.ComponentProps<typeof DialogPrimitive.Title>) {
+  return (
+    <DialogPrimitive.Title
+      data-slot="dialog-title"
+      className={cn("text-lg leading-none font-semibold", className)}
+      {...props}
+    />
+  )
+}
+
+function DialogDescription({
+  className,
+  ...props
+}: React.ComponentProps<typeof DialogPrimitive.Description>) {
+  return (
+    <DialogPrimitive.Description
+      data-slot="dialog-description"
+      className={cn("text-muted-foreground text-sm", className)}
+      {...props}
+    />
+  )
+}
+
+export {
+  Dialog,
+  DialogClose,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogOverlay,
+  DialogPortal,
+  DialogTitle,
+  DialogTrigger,
+}

internal_frontend/components/ui/label.tsx

@@ -0,0 +1,24 @@
+"use client"
+
+import * as React from "react"
+import * as LabelPrimitive from "@radix-ui/react-label"
+
+import { cn } from "@/lib/utils"
+
+function Label({
+  className,
+  ...props
+}: React.ComponentProps<typeof LabelPrimitive.Root>) {
+  return (
+    <LabelPrimitive.Root
+      data-slot="label"
+      className={cn(
+        "flex items-center gap-2 text-sm leading-none font-medium select-none group-data-[disabled=true]:pointer-events-none group-data-[disabled=true]:opacity-50 peer-disabled:cursor-not-allowed peer-disabled:opacity-50",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Label }

internal_frontend/components/ui/pagination.tsx

@@ -0,0 +1,127 @@
+import * as React from "react"
+import {
+  ChevronLeftIcon,
+  ChevronRightIcon,
+  MoreHorizontalIcon,
+} from "lucide-react"
+
+import { cn } from "@/lib/utils"
+import { Button, buttonVariants } from "@/components/ui/button"
+
+function Pagination({ className, ...props }: React.ComponentProps<"nav">) {
+  return (
+    <nav
+      role="navigation"
+      aria-label="pagination"
+      data-slot="pagination"
+      className={cn("mx-auto flex w-full justify-center", className)}
+      {...props}
+    />
+  )
+}
+
+function PaginationContent({
+  className,
+  ...props
+}: React.ComponentProps<"ul">) {
+  return (
+    <ul
+      data-slot="pagination-content"
+      className={cn("flex flex-row items-center gap-1", className)}
+      {...props}
+    />
+  )
+}
+
+function PaginationItem({ ...props }: React.ComponentProps<"li">) {
+  return <li data-slot="pagination-item" {...props} />
+}
+
+type PaginationLinkProps = {
+  isActive?: boolean
+} & Pick<React.ComponentProps<typeof Button>, "size"> &
+  React.ComponentProps<"a">
+
+function PaginationLink({
+  className,
+  isActive,
+  size = "icon",
+  ...props
+}: PaginationLinkProps) {
+  return (
+    <a
+      aria-current={isActive ? "page" : undefined}
+      data-slot="pagination-link"
+      data-active={isActive}
+      className={cn(
+        buttonVariants({
+          variant: isActive ? "outline" : "ghost",
+          size,
+        }),
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function PaginationPrevious({
+  className,
+  ...props
+}: React.ComponentProps<typeof PaginationLink>) {
+  return (
+    <PaginationLink
+      aria-label="Go to previous page"
+      size="default"
+      className={cn("gap-1 px-2.5 sm:pl-2.5", className)}
+      {...props}
+    >
+      <ChevronLeftIcon />
+      <span className="hidden sm:block">Previous</span>
+    </PaginationLink>
+  )
+}
+
+function PaginationNext({
+  className,
+  ...props
+}: React.ComponentProps<typeof PaginationLink>) {
+  return (
+    <PaginationLink
+      aria-label="Go to next page"
+      size="default"
+      className={cn("gap-1 px-2.5 sm:pr-2.5", className)}
+      {...props}
+    >
+      <span className="hidden sm:block">Next</span>
+      <ChevronRightIcon />
+    </PaginationLink>
+  )
+}
+
+function PaginationEllipsis({
+  className,
+  ...props
+}: React.ComponentProps<"span">) {
+  return (
+    <span
+      aria-hidden
+      data-slot="pagination-ellipsis"
+      className={cn("flex size-9 items-center justify-center", className)}
+      {...props}
+    >
+      <MoreHorizontalIcon className="size-4" />
+      <span className="sr-only">More pages</span>
+    </span>
+  )
+}
+
+export {
+  Pagination,
+  PaginationContent,
+  PaginationLink,
+  PaginationItem,
+  PaginationPrevious,
+  PaginationNext,
+  PaginationEllipsis,
+}

internal_frontend/components/ui/progress.tsx

@@ -0,0 +1,31 @@
+"use client"
+
+import * as React from "react"
+import * as ProgressPrimitive from "@radix-ui/react-progress"
+
+import { cn } from "@/lib/utils"
+
+function Progress({
+  className,
+  value,
+  ...props
+}: React.ComponentProps<typeof ProgressPrimitive.Root>) {
+  return (
+    <ProgressPrimitive.Root
+      data-slot="progress"
+      className={cn(
+        "bg-primary/20 relative h-2 w-full overflow-hidden rounded-full",
+        className
+      )}
+      {...props}
+    >
+      <ProgressPrimitive.Indicator
+        data-slot="progress-indicator"
+        className="bg-primary h-full w-full flex-1 transition-all"
+        style={{ transform: `translateX(-${100 - (value || 0)}%)` }}
+      />
+    </ProgressPrimitive.Root>
+  )
+}
+
+export { Progress }

internal_frontend/components/ui/table.tsx

@@ -0,0 +1,116 @@
+"use client"
+
+import * as React from "react"
+
+import { cn } from "@/lib/utils"
+
+function Table({ className, ...props }: React.ComponentProps<"table">) {
+  return (
+    <div
+      data-slot="table-container"
+      className="relative w-full overflow-x-auto"
+    >
+      <table
+        data-slot="table"
+        className={cn("w-full caption-bottom text-sm", className)}
+        {...props}
+      />
+    </div>
+  )
+}
+
+function TableHeader({ className, ...props }: React.ComponentProps<"thead">) {
+  return (
+    <thead
+      data-slot="table-header"
+      className={cn("[&_tr]:border-b", className)}
+      {...props}
+    />
+  )
+}
+
+function TableBody({ className, ...props }: React.ComponentProps<"tbody">) {
+  return (
+    <tbody
+      data-slot="table-body"
+      className={cn("[&_tr:last-child]:border-0", className)}
+      {...props}
+    />
+  )
+}
+
+function TableFooter({ className, ...props }: React.ComponentProps<"tfoot">) {
+  return (
+    <tfoot
+      data-slot="table-footer"
+      className={cn(
+        "bg-muted/50 border-t font-medium [&>tr]:last:border-b-0",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function TableRow({ className, ...props }: React.ComponentProps<"tr">) {
+  return (
+    <tr
+      data-slot="table-row"
+      className={cn(
+        "hover:bg-muted/50 data-[state=selected]:bg-muted border-b transition-colors",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function TableHead({ className, ...props }: React.ComponentProps<"th">) {
+  return (
+    <th
+      data-slot="table-head"
+      className={cn(
+        "text-foreground h-10 px-2 text-left align-middle font-medium whitespace-nowrap [&:has([role=checkbox])]:pr-0 [&>[role=checkbox]]:translate-y-[2px]",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function TableCell({ className, ...props }: React.ComponentProps<"td">) {
+  return (
+    <td
+      data-slot="table-cell"
+      className={cn(
+        "p-2 align-middle whitespace-nowrap [&:has([role=checkbox])]:pr-0 [&>[role=checkbox]]:translate-y-[2px]",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+function TableCaption({
+  className,
+  ...props
+}: React.ComponentProps<"caption">) {
+  return (
+    <caption
+      data-slot="table-caption"
+      className={cn("text-muted-foreground mt-4 text-sm", className)}
+      {...props}
+    />
+  )
+}
+
+export {
+  Table,
+  TableHeader,
+  TableBody,
+  TableFooter,
+  TableHead,
+  TableRow,
+  TableCell,
+  TableCaption,
+}

internal_frontend/components/ui/textarea.tsx

@@ -0,0 +1,18 @@
+import * as React from "react"
+
+import { cn } from "@/lib/utils"
+
+function Textarea({ className, ...props }: React.ComponentProps<"textarea">) {
+  return (
+    <textarea
+      data-slot="textarea"
+      className={cn(
+        "border-input placeholder:text-muted-foreground focus-visible:border-ring focus-visible:ring-ring/50 aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive dark:bg-input/30 flex field-sizing-content min-h-16 w-full rounded-md border bg-transparent px-3 py-2 text-base shadow-xs transition-[color,box-shadow] outline-none focus-visible:ring-[3px] disabled:cursor-not-allowed disabled:opacity-50 md:text-sm",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Textarea }

internal_frontend/lib/api/callApi.ts

@@ -0,0 +1,28 @@
+// lib/api/callApi.ts
+import {serverCall} from "@/lib/api/serverCall";
+
+export async function callApi<TResponse, TRequest = unknown>(
+    path: string,
+    method: "GET" | "POST" | "PUT" | "DELETE" | "PATCH",
+    body?: TRequest
+): Promise<TResponse> {
+    const res = await serverCall(path, method, body);
+
+    const contentType = res.headers.get("content-type") ?? "";
+    const isJson = contentType.includes("application/json");
+
+    const rawBody = isJson ? await res.json() : await res.text();
+
+    console.log(`[api ${path}] Response:`, res.status, rawBody);
+
+    if (!res.ok) {
+        const errorMessage = isJson
+            ? (rawBody?.message ?? rawBody?.errors?.join(", ")) ?? "Unbekannter Fehler"
+            : String(rawBody);
+
+        console.error(`[api ${path}] Error:`, errorMessage);
+        throw new Error(errorMessage);
+    }
+
+    return rawBody as TResponse;
+}

internal_frontend/lib/api/serverCall.ts

@@ -0,0 +1,28 @@
+// lib/callBackendApi.ts
+import {getServerSession} from "next-auth";
+import {authOptions} from "@/lib/auth/authOptions";
+
+export async function serverCall(
+    path: string,
+    method: "GET" | "POST" | "PUT" | "DELETE" | "PATCH",
+    body?: unknown
+): Promise<Response> {
+    const url = `${process.env.INTERNAL_BACKEND_URL ?? "http://localhost:8080/api"}${path}`;
+    const session = await getServerSession(authOptions);
+
+    const headers: Record<string, string> = {
+        "Content-Type": "application/json",
+    };
+
+    if (session != null) {
+        headers["Authorization"] = `Bearer ${session.accessToken}`;
+    }
+
+    console.log("[api] Calling backend API: ", method, url, body);
+
+    return fetch(url, {
+        method,
+        headers,
+        body: body ? JSON.stringify(body) : undefined,
+    });
+}

internal_frontend/lib/auth/authOptions.ts

@@ -15,10 +15,10 @@ const {
     NEXTAUTH_SECRET,
 } = process.env;
 
-if (!KEYCLOAK_CLIENT_ID) throw new Error("Missing KEYCLOAK_CLIENT_ID");
+// if (!KEYCLOAK_CLIENT_ID) throw new Error("Missing KEYCLOAK_CLIENT_ID");
-if (!KEYCLOAK_CLIENT_SECRET) throw new Error("Missing KEYCLOAK_CLIENT_SECRET");
+// if (!KEYCLOAK_CLIENT_SECRET) throw new Error("Missing KEYCLOAK_CLIENT_SECRET");
-if (!KEYCLOAK_ISSUER) throw new Error("Missing KEYCLOAK_ISSUER");
+// if (!KEYCLOAK_ISSUER) throw new Error("Missing KEYCLOAK_ISSUER");
-if (!NEXTAUTH_SECRET) throw new Error("Missing NEXTAUTH_SECRET");
+// if (!NEXTAUTH_SECRET) throw new Error("Missing NEXTAUTH_SECRET");
 
 console.log("[auth] Using Keycloak provider:");
 console.log("  - Client ID:", KEYCLOAK_CLIENT_ID);
@@ -42,8 +42,8 @@ async function isTokenValid(token: string): Promise<boolean> {
 export const authOptions: NextAuthOptions = {
     providers: [
         KeycloakProvider({
-            clientId: KEYCLOAK_CLIENT_ID,
+            clientId: KEYCLOAK_CLIENT_ID as string,
-            clientSecret: KEYCLOAK_CLIENT_SECRET,
+            clientSecret: KEYCLOAK_CLIENT_SECRET as string,
             issuer: KEYCLOAK_ISSUER,
         }),
     ],

internal_frontend/lib/breadcrumb-map.ts

@@ -4,5 +4,6 @@ export const breadcrumbMap: Record<string, string> = {
     'settings': 'Settings',
     'demo': 'Demo',
     'users': 'User Management',
+    'customers': 'Kundenübersicht',
     // Add more mappings as needed
 };

internal_frontend/lib/ui/showError.ts

@@ -0,0 +1,16 @@
+// lib/ui/showError.ts
+import {toast} from "sonner";
+
+export function showError(error: unknown, fallback = "Ein unbekannter Fehler ist aufgetreten") {
+    let message: string;
+
+    if (error instanceof Error) {
+        message = error.message;
+    } else if (typeof error === "string") {
+        message = error;
+    } else {
+        message = fallback;
+    }
+
+    toast.error(message);
+}

internal_frontend/package-lock.json

@@ -11,9 +11,12 @@
         "@radix-ui/react-collapsible": "^1.1.11",
         "@radix-ui/react-dialog": "^1.1.14",
         "@radix-ui/react-dropdown-menu": "^2.1.15",
+        "@radix-ui/react-label": "^2.1.7",
+        "@radix-ui/react-progress": "^1.1.7",
         "@radix-ui/react-separator": "^1.1.7",
         "@radix-ui/react-slot": "^1.2.3",
         "@radix-ui/react-tooltip": "^1.2.7",
+        "axios": "^1.10.0",
         "class-variance-authority": "^0.7.1",
         "clsx": "^2.1.1",
         "framer-motion": "^12.22.0",
@@ -24,7 +27,9 @@
         "next-themes": "^0.4.6",
         "react": "^19.0.0",
         "react-dom": "^19.0.0",
-        "tailwind-merge": "^3.3.1"
+        "sonner": "^2.0.6",
+        "tailwind-merge": "^3.3.1",
+        "zustand": "^5.0.6"
       },
       "devDependencies": {
         "@eslint/eslintrc": "^3",
@@ -1308,6 +1313,29 @@
         }
       }
     },
+    "node_modules/@radix-ui/react-label": {
+      "version": "2.1.7",
+      "resolved": "https://registry.npmjs.org/@radix-ui/react-label/-/react-label-2.1.7.tgz",
+      "integrity": "sha512-YT1GqPSL8kJn20djelMX7/cTRp/Y9w5IZHvfxQTVHrOqa2yMl7i/UfMqKRU5V7mEyKTrUVgJXhNQPVCG8PBLoQ==",
+      "license": "MIT",
+      "dependencies": {
+        "@radix-ui/react-primitive": "2.1.3"
+      },
+      "peerDependencies": {
+        "@types/react": "*",
+        "@types/react-dom": "*",
+        "react": "^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc",
+        "react-dom": "^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc"
+      },
+      "peerDependenciesMeta": {
+        "@types/react": {
+          "optional": true
+        },
+        "@types/react-dom": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/@radix-ui/react-menu": {
       "version": "2.1.15",
       "resolved": "https://registry.npmjs.org/@radix-ui/react-menu/-/react-menu-2.1.15.tgz",
@@ -1451,6 +1479,30 @@
         }
       }
     },
+    "node_modules/@radix-ui/react-progress": {
+      "version": "1.1.7",
+      "resolved": "https://registry.npmjs.org/@radix-ui/react-progress/-/react-progress-1.1.7.tgz",
+      "integrity": "sha512-vPdg/tF6YC/ynuBIJlk1mm7Le0VgW6ub6J2UWnTQ7/D23KXcPI1qy+0vBkgKgd38RCMJavBXpB83HPNFMTb0Fg==",
+      "license": "MIT",
+      "dependencies": {
+        "@radix-ui/react-context": "1.1.2",
+        "@radix-ui/react-primitive": "2.1.3"
+      },
+      "peerDependencies": {
+        "@types/react": "*",
+        "@types/react-dom": "*",
+        "react": "^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc",
+        "react-dom": "^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc"
+      },
+      "peerDependenciesMeta": {
+        "@types/react": {
+          "optional": true
+        },
+        "@types/react-dom": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/@radix-ui/react-roving-focus": {
       "version": "1.1.10",
       "resolved": "https://registry.npmjs.org/@radix-ui/react-roving-focus/-/react-roving-focus-1.1.10.tgz",
@@ -2892,6 +2944,12 @@
         "node": ">= 0.4"
       }
     },
+    "node_modules/asynckit": {
+      "version": "0.4.0",
+      "resolved": "https://registry.npmjs.org/asynckit/-/asynckit-0.4.0.tgz",
+      "integrity": "sha512-Oei9OH4tRh0YqU3GxhX79dM/mwVgvbZJaSNaRk+bshkj0S5cfHcgYakreBjrHwatXKbz+IoIdYLxrKim2MjW0Q==",
+      "license": "MIT"
+    },
     "node_modules/available-typed-arrays": {
       "version": "1.0.7",
       "resolved": "https://registry.npmjs.org/available-typed-arrays/-/available-typed-arrays-1.0.7.tgz",
@@ -2918,6 +2976,17 @@
         "node": ">=4"
       }
     },
+    "node_modules/axios": {
+      "version": "1.10.0",
+      "resolved": "https://registry.npmjs.org/axios/-/axios-1.10.0.tgz",
+      "integrity": "sha512-/1xYAC4MP/HEG+3duIhFr4ZQXR4sQXOIe+o6sdqzeykGLx6Upp/1p8MHqhINOvGeP7xyNHe7tsiJByc4SSVUxw==",
+      "license": "MIT",
+      "dependencies": {
+        "follow-redirects": "^1.15.6",
+        "form-data": "^4.0.0",
+        "proxy-from-env": "^1.1.0"
+      }
+    },
     "node_modules/axobject-query": {
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/axobject-query/-/axobject-query-4.1.0.tgz",
@@ -2993,7 +3062,6 @@
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/call-bind-apply-helpers/-/call-bind-apply-helpers-1.0.2.tgz",
       "integrity": "sha512-Sp1ablJ0ivDkSzjcaJdxEunN5/XvksFJ2sMBFfq6x0ryhQV/2b/KwFe21cMpmHtPOSij8K99/wSfoEuTObmuMQ==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "es-errors": "^1.3.0",
@@ -3149,6 +3217,18 @@
         "simple-swizzle": "^0.2.2"
       }
     },
+    "node_modules/combined-stream": {
+      "version": "1.0.8",
+      "resolved": "https://registry.npmjs.org/combined-stream/-/combined-stream-1.0.8.tgz",
+      "integrity": "sha512-FQN4MRfuJeHf7cBbBMJFXhKSDq+2kAArBlmRBvcvFE5BB1HZKXtSFASDhdlz9zOYwxh8lDdnvmMOe/+5cdoEdg==",
+      "license": "MIT",
+      "dependencies": {
+        "delayed-stream": "~1.0.0"
+      },
+      "engines": {
+        "node": ">= 0.8"
+      }
+    },
     "node_modules/concat-map": {
       "version": "0.0.1",
       "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
@@ -3309,6 +3389,15 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/delayed-stream": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/delayed-stream/-/delayed-stream-1.0.0.tgz",
+      "integrity": "sha512-ZySD7Nf91aLB0RxL4KGrKHBXl7Eds1DAmEdcoVawXnLD7SDhpNgtuII2aAkg7a7QS41jxPSZ17p4VdGnMHk3MQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=0.4.0"
+      }
+    },
     "node_modules/detect-libc": {
       "version": "2.0.4",
       "resolved": "https://registry.npmjs.org/detect-libc/-/detect-libc-2.0.4.tgz",
@@ -3342,7 +3431,6 @@
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/dunder-proto/-/dunder-proto-1.0.1.tgz",
       "integrity": "sha512-KIN/nDJBQRcXw0MLVhZE9iQHmG68qAVIBg9CqmUYjmQIhgij9U5MFvrqkUL5FbtyyzZuOeOt0zdeRe4UY7ct+A==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "call-bind-apply-helpers": "^1.0.1",
@@ -3447,7 +3535,6 @@
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/es-define-property/-/es-define-property-1.0.1.tgz",
       "integrity": "sha512-e3nRfgfUZ4rNGL232gUgX06QNyyez04KdjFrF+LTRoOXmrOgFKDg4BCdsjW8EnT69eqdYGmRpJwiPVYNrCaW3g==",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">= 0.4"
@@ -3457,7 +3544,6 @@
       "version": "1.3.0",
       "resolved": "https://registry.npmjs.org/es-errors/-/es-errors-1.3.0.tgz",
       "integrity": "sha512-Zf5H2Kxt2xjTvbJvP2ZWLEICxA6j+hAmMzIlypy4xcBg1vKVnx89Wy0GbS+kf5cwCVFFzdCFh2XSCFNULS6csw==",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">= 0.4"
@@ -3495,7 +3581,6 @@
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/es-object-atoms/-/es-object-atoms-1.1.1.tgz",
       "integrity": "sha512-FGgH2h8zKNim9ljj7dankFPcICIK9Cp5bm+c2gQSYePhpaG5+esrLODihIorn+Pe6FGJzWhXQotPv73jTaldXA==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "es-errors": "^1.3.0"
@@ -3508,7 +3593,6 @@
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/es-set-tostringtag/-/es-set-tostringtag-2.1.0.tgz",
       "integrity": "sha512-j6vWzfrGVfyXxge+O0x5sh6cvxAog0a/4Rdd2K36zCMV5eJ+/+tOAngRO8cODMNWbVRdVlmGZQL2YS3yR8bIUA==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "es-errors": "^1.3.0",
@@ -4115,6 +4199,26 @@
       "dev": true,
       "license": "ISC"
     },
+    "node_modules/follow-redirects": {
+      "version": "1.15.9",
+      "resolved": "https://registry.npmjs.org/follow-redirects/-/follow-redirects-1.15.9.tgz",
+      "integrity": "sha512-gew4GsXizNgdoRyqmyfMHyAmXsZDk6mHkSxZFCzW9gwlbtOW44CDtYavM+y+72qD/Vq2l550kMF52DT8fOLJqQ==",
+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://github.com/sponsors/RubenVerborgh"
+        }
+      ],
+      "license": "MIT",
+      "engines": {
+        "node": ">=4.0"
+      },
+      "peerDependenciesMeta": {
+        "debug": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/for-each": {
       "version": "0.3.5",
       "resolved": "https://registry.npmjs.org/for-each/-/for-each-0.3.5.tgz",
@@ -4131,6 +4235,22 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/form-data": {
+      "version": "4.0.3",
+      "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.3.tgz",
+      "integrity": "sha512-qsITQPfmvMOSAdeyZ+12I1c+CKSstAFAwu+97zrnWAbIr5u8wfsExUzCesVLC8NgHuRUqNN4Zy6UPWUTRGslcA==",
+      "license": "MIT",
+      "dependencies": {
+        "asynckit": "^0.4.0",
+        "combined-stream": "^1.0.8",
+        "es-set-tostringtag": "^2.1.0",
+        "hasown": "^2.0.2",
+        "mime-types": "^2.1.12"
+      },
+      "engines": {
+        "node": ">= 6"
+      }
+    },
     "node_modules/framer-motion": {
       "version": "12.22.0",
       "resolved": "https://registry.npmjs.org/framer-motion/-/framer-motion-12.22.0.tgz",
@@ -4162,7 +4282,6 @@
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/function-bind/-/function-bind-1.1.2.tgz",
       "integrity": "sha512-7XHNxH7qX9xG5mIwxkhumTox/MIRNcOgDrxWsMt2pAr23WHp6MrRlN7FBSFpCpr+oVO0F744iUgR82nJMfG2SA==",
-      "dev": true,
       "license": "MIT",
       "funding": {
         "url": "https://github.com/sponsors/ljharb"
@@ -4203,7 +4322,6 @@
       "version": "1.3.0",
       "resolved": "https://registry.npmjs.org/get-intrinsic/-/get-intrinsic-1.3.0.tgz",
       "integrity": "sha512-9fSjSaos/fRIVIp+xSJlE6lfwhES7LNtKaCBIamHsjr2na1BiABJPo0mOjjz8GJDURarmCPGqaiVg5mfjb98CQ==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "call-bind-apply-helpers": "^1.0.2",
@@ -4237,7 +4355,6 @@
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/get-proto/-/get-proto-1.0.1.tgz",
       "integrity": "sha512-sTSfBjoXBp89JvIKIefqw7U2CCebsc74kiY6awiGogKtoSGbgjYE/G/+l9sF3MWFPNc9IcoOC4ODfKHfxFmp0g==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "dunder-proto": "^1.0.1",
@@ -4325,7 +4442,6 @@
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/gopd/-/gopd-1.2.0.tgz",
       "integrity": "sha512-ZUKRh6/kUFoAiTAtTYPZJ3hw9wNxx+BIBOijnlG9PnrJsCcSjs1wyyD6vJpaYtgnzDrKYRSqf3OO6Rfa93xsRg==",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">= 0.4"
@@ -4404,7 +4520,6 @@
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/has-symbols/-/has-symbols-1.1.0.tgz",
       "integrity": "sha512-1cDNdwJ2Jaohmb3sg4OmKaMBwuC48sYni5HUw2DvsC8LjGTLK9h+eb1X6RyuOHe4hT0ULCW68iomhjUoKUqlPQ==",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">= 0.4"
@@ -4417,7 +4532,6 @@
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/has-tostringtag/-/has-tostringtag-1.0.2.tgz",
       "integrity": "sha512-NqADB8VjPFLM2V0VvHUewwwsw0ZWBaIdgo+ieHtK3hasLz4qeCRjYcqfB6AQrBggRKppKF8L52/VqdVsO47Dlw==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "has-symbols": "^1.0.3"
@@ -4433,7 +4547,6 @@
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/hasown/-/hasown-2.0.2.tgz",
       "integrity": "sha512-0hJU9SCPvmMzIBdZFqNPXWa6dqh7WdH0cII9y+CyS8rG3nL48Bclra9HmKhVVUHyPWNH5Y7xDwAB7bfgSjkUMQ==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "function-bind": "^1.1.2"
@@ -5393,7 +5506,6 @@
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/math-intrinsics/-/math-intrinsics-1.1.0.tgz",
       "integrity": "sha512-/IXtbwEk5HTPyEwyKX6hGkYXxM9nbj64B+ilVJnC/R6B0pH5G4V3b0pVbL7DBj4tkhBAppbQUlf6F6Xl9LHu1g==",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">= 0.4"
@@ -5423,6 +5535,27 @@
         "node": ">=8.6"
       }
     },
+    "node_modules/mime-db": {
+      "version": "1.52.0",
+      "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.52.0.tgz",
+      "integrity": "sha512-sPU4uV7dYlvtWJxwwxHD0PuihVNiE7TyAbQ5SWxDCB9mUYvOgroQOwYQQOKPJ8CIbE+1ETVlOoK1UC2nU3gYvg==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 0.6"
+      }
+    },
+    "node_modules/mime-types": {
+      "version": "2.1.35",
+      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.35.tgz",
+      "integrity": "sha512-ZDY+bPm5zTTF+YpCrAU9nK0UgICYPT0QtT1NZWFv4s++TNkcgVaT0g6+4R2uI4MjQjzysHB1zxuWL50hzaeXiw==",
+      "license": "MIT",
+      "dependencies": {
+        "mime-db": "1.52.0"
+      },
+      "engines": {
+        "node": ">= 0.6"
+      }
+    },
     "node_modules/minimatch": {
       "version": "3.1.2",
       "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.2.tgz",
@@ -6050,6 +6183,12 @@
         "react-is": "^16.13.1"
       }
     },
+    "node_modules/proxy-from-env": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/proxy-from-env/-/proxy-from-env-1.1.0.tgz",
+      "integrity": "sha512-D+zkORCbA9f1tdWRK0RaCR3GPv50cMxcrz4X8k5LTSUD1Dkw47mKJEZQNunItRTkWwgtaUSo1RVFRIG9ZXiFYg==",
+      "license": "MIT"
+    },
     "node_modules/punycode": {
       "version": "2.3.1",
       "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.1.tgz",
@@ -6572,6 +6711,16 @@
         "is-arrayish": "^0.3.1"
       }
     },
+    "node_modules/sonner": {
+      "version": "2.0.6",
+      "resolved": "https://registry.npmjs.org/sonner/-/sonner-2.0.6.tgz",
+      "integrity": "sha512-yHFhk8T/DK3YxjFQXIrcHT1rGEeTLliVzWbO0xN8GberVun2RiBnxAjXAYpZrqwEVHBG9asI/Li8TAAhN9m59Q==",
+      "license": "MIT",
+      "peerDependencies": {
+        "react": "^18.0.0 || ^19.0.0 || ^19.0.0-rc",
+        "react-dom": "^18.0.0 || ^19.0.0 || ^19.0.0-rc"
+      }
+    },
     "node_modules/source-map-js": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
@@ -7305,6 +7454,35 @@
       "funding": {
         "url": "https://github.com/sponsors/sindresorhus"
       }
+    },
+    "node_modules/zustand": {
+      "version": "5.0.6",
+      "resolved": "https://registry.npmjs.org/zustand/-/zustand-5.0.6.tgz",
+      "integrity": "sha512-ihAqNeUVhe0MAD+X8M5UzqyZ9k3FFZLBTtqo6JLPwV53cbRB/mJwBI0PxcIgqhBBHlEs8G45OTDTMq3gNcLq3A==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=12.20.0"
+      },
+      "peerDependencies": {
+        "@types/react": ">=18.0.0",
+        "immer": ">=9.0.6",
+        "react": ">=18.0.0",
+        "use-sync-external-store": ">=1.2.0"
+      },
+      "peerDependenciesMeta": {
+        "@types/react": {
+          "optional": true
+        },
+        "immer": {
+          "optional": true
+        },
+        "react": {
+          "optional": true
+        },
+        "use-sync-external-store": {
+          "optional": true
+        }
+      }
     }
   }
 }

internal_frontend/package.json

@@ -12,9 +12,12 @@
     "@radix-ui/react-collapsible": "^1.1.11",
     "@radix-ui/react-dialog": "^1.1.14",
     "@radix-ui/react-dropdown-menu": "^2.1.15",
+    "@radix-ui/react-label": "^2.1.7",
+    "@radix-ui/react-progress": "^1.1.7",
     "@radix-ui/react-separator": "^1.1.7",
     "@radix-ui/react-slot": "^1.2.3",
     "@radix-ui/react-tooltip": "^1.2.7",
+    "axios": "^1.10.0",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "framer-motion": "^12.22.0",
@@ -25,7 +28,9 @@
     "next-themes": "^0.4.6",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
-    "tailwind-merge": "^3.3.1"
+    "sonner": "^2.0.6",
+    "tailwind-merge": "^3.3.1",
+    "zustand": "^5.0.6"
   },
   "devDependencies": {
     "@eslint/eslintrc": "^3",

internal_frontend/services/customers/dtos/createCustomer.dto.ts

@@ -0,0 +1,19 @@
+export interface PhoneNumberDto {
+    number: string;
+    note: string;
+}
+
+export interface NoteDto {
+    text: string;
+}
+
+export interface CreateCustomerDto {
+    email: string;
+    name: string;
+    companyName: string;
+    phoneNumbers: PhoneNumberDto[];
+    street: string;
+    zip: string;
+    city: string;
+    notes: NoteDto[];
+}

internal_frontend/services/customers/entities/customer.ts

@@ -0,0 +1,32 @@
+export interface PhoneNumber {
+    number: string;
+    note: string;
+    createdBy: string;
+    createdAt: string;
+    updatedBy: string;
+    updatedAt: string;
+}
+
+export interface Note {
+    text: string;
+    createdBy: string;
+    createdAt: string;
+    updatedBy: string;
+    updatedAt: string;
+}
+
+export interface Customer {
+    id: string;
+    email: string;
+    name: string;
+    companyName: string;
+    phoneNumbers: PhoneNumber[];
+    street: string;
+    zip: string;
+    city: string;
+    notes: Note[];
+    createdBy: string;
+    createdAt: string;
+    updatedBy: string;
+    updatedAt: string;
+}

internal_frontend/services/customers/repositories/customerRepository.ts

@@ -0,0 +1,13 @@
+import {Customer} from "@/services/customers/entities/customer";
+import {CreateCustomerDto} from "@/services/customers/dtos/createCustomer.dto";
+import {callApi} from "@/lib/api/callApi";
+
+export class CustomerRepository {
+    static async getAll(): Promise<Customer[]> {
+        return await callApi<Customer[]>("/customers", "GET");
+    }
+
+    static async create(payload: CreateCustomerDto): Promise<void> {
+        await callApi<void, CreateCustomerDto>("/customers", "POST", payload);
+    }
+}

internal_frontend/services/customers/usecases/addCustomer.ts

@@ -0,0 +1,21 @@
+"use server";
+
+import {CreateCustomerDto} from "@/services/customers/dtos/createCustomer.dto";
+import {CustomerRepository} from "@/services/customers/repositories/customerRepository";
+
+export async function addCustomer(params: CreateCustomerDto): Promise<void> {
+    const {email, name, companyName, street, zip, city, phoneNumbers, notes} = params;
+
+    const payload: CreateCustomerDto = {
+        email,
+        name,
+        companyName,
+        street,
+        zip,
+        city,
+        phoneNumbers,
+        notes: notes.map(({text}) => ({text})),
+    };
+
+    await CustomerRepository.create(payload);
+}

internal_frontend/services/customers/usecases/validateCustomer.ts

@@ -0,0 +1,15 @@
+"use server";
+
+import {callApi} from "@/lib/api/callApi";
+import {Customer} from "@/app/customers/page";
+import {customerRoutes} from "@/app/api/customers/customerRoutes";
+
+export async function validateCustomer(input: {
+    email: string;
+    companyName: string;
+    street: string;
+    zip: string;
+    city: string;
+}): Promise<Customer[]> {
+    return await callApi<Customer[]>(customerRoutes.validate, "POST", input);
+}