chore!: Refactor DTO handling and change response handling when regis…

…tering/connecting an agent and implement tests

backend/src/main/java/rocks/inspectit/gepard/agentmanager/connection/controller/ConnectionController.java

@@ -7,14 +7,14 @@
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
-import rocks.inspectit.gepard.agentmanager.connection.model.dto.ConnectionDto;
+import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
 import rocks.inspectit.gepard.agentmanager.connection.model.dto.CreateConnectionRequest;
 import rocks.inspectit.gepard.agentmanager.connection.model.dto.CreateConnectionResponse;
 import rocks.inspectit.gepard.agentmanager.connection.service.ConnectionService;
 
 /**
  * Controller for handling agent connection requests. Holds the POST endpoint for handling
- * connection requests from agents.
+ * connection requests from agents and the GET endpoints for fetching all or one connection by id.
  */
 @RestController
 @RequestMapping("/api/v1/connections")
@@ -24,18 +24,23 @@ public class ConnectionController {
   private final ConnectionService connectionService;
 
   @PostMapping
-  public ResponseEntity<CreateConnectionResponse> connect(
-      @Valid @RequestBody CreateConnectionRequest connectRequest) {
-    return ResponseEntity.ok(connectionService.handleConnectRequest(connectRequest));
+  public ResponseEntity<Void> connect(@Valid @RequestBody CreateConnectionRequest connectRequest) {
+    CreateConnectionResponse connectionDto = connectionService.handleConnectRequest(connectRequest);
+    return ResponseEntity.created(
+            ServletUriComponentsBuilder.fromCurrentRequest()
+                .path("/{id}")
+                .buildAndExpand(connectionDto.id())
+                .toUri())
+        .build();
   }
 
   @GetMapping
-  public ResponseEntity<List<ConnectionDto>> getConnections() {
+  public ResponseEntity<List<CreateConnectionResponse>> getConnections() {
     return ResponseEntity.ok(connectionService.getConnections());
   }
 
   @GetMapping("/{id}")
-  public ResponseEntity<ConnectionDto> getConnection(@PathVariable UUID id) {
+  public ResponseEntity<CreateConnectionResponse> getConnection(@PathVariable UUID id) {
     return ResponseEntity.ok(connectionService.getConnection(id));
   }
 }

backend/src/main/java/rocks/inspectit/gepard/agentmanager/connection/model/dto/CreateConnectionRequest.java

@@ -2,7 +2,12 @@
 package rocks.inspectit.gepard.agentmanager.connection.model.dto;
 
 import jakarta.validation.constraints.NotNull;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.util.UUID;
 import lombok.Builder;
+import rocks.inspectit.gepard.agentmanager.agent.model.Agent;
+import rocks.inspectit.gepard.agentmanager.connection.model.Connection;
 
 /** Represents a connection request from an agent. */
 @Builder
@@ -12,4 +17,21 @@ public record CreateConnectionRequest(
     @NotNull(message = "Open-Telemetry Version missing.") String otelVersion,
     @NotNull(message = "Process ID is missing.") Long pid,
     @NotNull(message = "Start-Time missing.") Long startTime,
-    @NotNull(message = "Java Version missing.") String javaVersion) {}
+    @NotNull(message = "Java Version missing.") String javaVersion) {
+
+  public static Connection toConnection(CreateConnectionRequest createConnectionRequest) {
+    return Connection.builder()
+        .id(UUID.randomUUID())
+        .registrationTime(LocalDateTime.now())
+        .agent(
+            Agent.builder()
+                .gepardVersion(createConnectionRequest.gepardVersion)
+                .javaVersion(createConnectionRequest.javaVersion)
+                .otelVersion(createConnectionRequest.otelVersion)
+                .pid(createConnectionRequest.pid)
+                .serviceName(createConnectionRequest.serviceName)
+                .startTime(Instant.ofEpochMilli(createConnectionRequest.startTime))
+                .build())
+        .build();
+  }
+}

backend/src/main/java/rocks/inspectit/gepard/agentmanager/connection/model/dto/CreateConnectionResponse.java

@@ -1,24 +1,33 @@
 /* (C) 2024 */
 package rocks.inspectit.gepard.agentmanager.connection.model.dto;
 
+import java.time.LocalDateTime;
 import java.util.UUID;
+import lombok.Builder;
+import rocks.inspectit.gepard.agentmanager.connection.model.Connection;
 
-/**
- * Represents a successful connection response.
- *
- * @param id
- * @param serviceName
- * @param gepardVersion
- * @param otelVersion
- * @param pid
- * @param startTime
- * @param javaVersion
- */
+/** Represents a connection response. */
+@Builder
 public record CreateConnectionResponse(
     UUID id,
+    LocalDateTime registrationTime,
     String serviceName,
     String gepardVersion,
     String otelVersion,
     Long pid,
     Long startTime,
-    String javaVersion) {}
+    String javaVersion) {
+
+  public static CreateConnectionResponse fromConnection(Connection connection) {
+    return CreateConnectionResponse.builder()
+        .id(connection.getId())
+        .registrationTime(connection.getRegistrationTime())
+        .serviceName(connection.getAgent().getServiceName())
+        .gepardVersion(connection.getAgent().getGepardVersion())
+        .otelVersion(connection.getAgent().getOtelVersion())
+        .pid(connection.getAgent().getPid())
+        .startTime(connection.getAgent().getStartTime().toEpochMilli())
+        .javaVersion(connection.getAgent().getJavaVersion())
+        .build();
+  }
+}

backend/src/main/java/rocks/inspectit/gepard/agentmanager/connection/service/ConnectionService.java

@@ -9,8 +9,6 @@
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Service;
 import rocks.inspectit.gepard.agentmanager.connection.model.Connection;
-import rocks.inspectit.gepard.agentmanager.connection.model.ConnectionDtoMapper;
-import rocks.inspectit.gepard.agentmanager.connection.model.dto.ConnectionDto;
 import rocks.inspectit.gepard.agentmanager.connection.model.dto.CreateConnectionRequest;
 import rocks.inspectit.gepard.agentmanager.connection.model.dto.CreateConnectionResponse;
 
@@ -20,37 +18,40 @@
 @RequiredArgsConstructor
 public class ConnectionService {
 
-  private final ConnectionDtoMapper connectionDtoMapper;
-
   private final HashMap<UUID, Connection> connectionCache = new HashMap<>();
 
   /**
    * Handles a connection request from an agent.
    *
-   * @param connectRequest
-   * @return
+   * @param connectRequest The request for the new connection to be created.
+   * @return CreateConnectionResponse The response containing all saved information.
    */
   public CreateConnectionResponse handleConnectRequest(CreateConnectionRequest connectRequest) {
-    Connection connection = connectionDtoMapper.toConnection(connectRequest);
+    Connection connection = CreateConnectionRequest.toConnection(connectRequest);
     connectionCache.put(connection.getId(), connection);
 
-    return connectionDtoMapper.toCreateConnectionResponse(connection);
+    return CreateConnectionResponse.fromConnection(connection);
   }
 
-  public List<ConnectionDto> getConnections() {
-    return connectionCache.values().stream().map(ConnectionDto::fromConnection).toList();
+  /**
+   * Returns all connections in the cache.
+   *
+   * @return List<CreateConnectionResponse> All connections from the cache.
+   */
+  public List<CreateConnectionResponse> getConnections() {
+    return connectionCache.values().stream().map(CreateConnectionResponse::fromConnection).toList();
   }
 
   /**
-   * Returns a connection by its id.
+   * Returns a connection from the cache by its id.
    *
    * @param id The id of the connection.
-   * @return ReadConnectionDTO The connection.
+   * @return ConnectionDto The connection.
    */
-  public ConnectionDto getConnection(UUID id) {
+  public CreateConnectionResponse getConnection(UUID id) {
     if (!connectionCache.containsKey(id)) {
       throw new NoSuchElementException("No connection with id " + id + " found in cache.");
     }
-    return ConnectionDto.fromConnection(connectionCache.get(id));
+    return CreateConnectionResponse.fromConnection(connectionCache.get(id));
   }
 }

backend/src/main/java/rocks/inspectit/gepard/agentmanager/exception/ApiError.java

@@ -4,12 +4,5 @@
 import java.time.LocalDateTime;
 import java.util.List;
 
-/**
- * Represents an error that occurred during an API request.
- *
- * @param path
- * @param errors
- * @param statusCode
- * @param timestamp
- */
+/** Represents an error that occurred during an API request. */
 public record ApiError(String path, List<String> errors, int statusCode, LocalDateTime timestamp) {}

backend/src/test/java/rocks/inspectit/gepard/agentmanager/connection/controller/ConnectionControllerTest.java

@@ -4,19 +4,20 @@
 import static org.mockito.Mockito.when;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
-import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
-import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import java.time.LocalDateTime;
 import java.util.UUID;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
 import org.springframework.boot.test.mock.mockito.MockBean;
 import org.springframework.http.MediaType;
 import org.springframework.test.web.servlet.MockMvc;
-import rocks.inspectit.gepard.agentmanager.connection.model.dto.ConnectionDto;
+import rocks.inspectit.gepard.agentmanager.connection.model.Connection;
 import rocks.inspectit.gepard.agentmanager.connection.model.dto.CreateConnectionRequest;
+import rocks.inspectit.gepard.agentmanager.connection.model.dto.CreateConnectionResponse;
 import rocks.inspectit.gepard.agentmanager.connection.service.ConnectionService;
 
 @WebMvcTest(controllers = ConnectionController.class)
@@ -58,12 +59,20 @@ void connect_whenEverythingIsValid_shouldReturnOk() throws Exception {
             .javaVersion("11.0.12")
             .build();
 
+    Connection connection = CreateConnectionRequest.toConnection(createConnectionRequest);
+    when(connectionService.handleConnectRequest(createConnectionRequest))
+        .thenReturn(CreateConnectionResponse.fromConnection(connection));
+
     mockMvc
         .perform(
             post("/api/v1/connections")
                 .contentType(MediaType.APPLICATION_JSON)
                 .content(objectMapper.writeValueAsString(createConnectionRequest)))
-        .andExpect(status().isOk());
+        .andExpect(status().isCreated())
+        .andExpect(header().exists("Location"))
+        .andExpect(
+            header()
+                .string("Location", "http://localhost/api/v1/connections/" + connection.getId()));
   }
 
   @Test
@@ -77,8 +86,9 @@ void get_connections_whenEverythingIsValid_shouldReturnOk() throws Exception {
   @Test
   void get_connection_whenEverythingIsValid_shouldReturnOk() throws Exception {
     UUID uuid = UUID.randomUUID();
-    ConnectionDto connection =
-        new ConnectionDto(uuid, "service name", "5", "7", 42L, 123456789L, "22");
+    CreateConnectionResponse connection =
+        new CreateConnectionResponse(
+            uuid, LocalDateTime.now(), "service name", "5", "7", 42L, 123456789L, "22");
     when(connectionService.getConnection(uuid)).thenReturn(connection);
 
     mockMvc