add delete api (#27)

* add delete api

make orphan removal true

make code spotless

* BE: apply spotless changes.

---------

Co-authored-by: Mgrdich <mgotm13@gmail.com>

backend/src/main/java/com/llm_service/llm_service/controller/conversation/ConversationController.java

@@ -90,6 +90,13 @@ public ResponseEntity<List<DiscussionResponse>> continueConversation(
                 .body(discussions.stream().map(conversationApiMapper::map).toList());
     }
 
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteConversation(@PathVariable UUID id) throws ConversationNotFoundException {
+        conversationService.getByID(id).orElseThrow(() -> new ConversationNotFoundException(id));
+        conversationService.delete(id);
+        return ResponseEntity.status(HttpStatus.OK).body(null);
+    }
+
     @ExceptionHandler(ConversationNotFoundException.class)
     public ResponseEntity<String> handleConversationNotFoundException(
             ConversationNotFoundException conversationNotFoundException) {

backend/src/main/java/com/llm_service/llm_service/persistance/entities/ConversationEntity.java

@@ -12,7 +12,7 @@
 @Table(name = "conversation")
 @Data
 public class ConversationEntity extends BaseEntity {
-    @OneToMany(mappedBy = "conversation")
+    @OneToMany(mappedBy = "conversation", orphanRemoval = true)
     private List<DiscussionEntity> discussions;
 
     @Column(name = "title")

backend/src/main/java/com/llm_service/llm_service/service/ConversationService.java

@@ -76,6 +76,10 @@ public List<Discussion> askLLMQuestion(UUID id, ConversationRequest conversation
         return newDiscussions;
     }
 
+    public void delete(UUID id) {
+        conversationPersistenceManager.delete(id);
+    }
+
     private String getPrediction(String text) {
         return llmService.generate(text).toString();
     }