service and controller done

src/main/java/fr/eni/demo/bll/FactureServiceImpl.java

@@ -1,4 +1,36 @@
 package fr.eni.demo.bll;
 
+import fr.eni.demo.bo.Facture;
+import fr.eni.demo.dal.FactureRepository;
+
+import java.util.List;
+
 public class FactureServiceImpl implements FactureService {
+
+  private final FactureRepository factureRepo;
+  public FactureServiceImpl(FactureRepository factureRepo) {
+    this.factureRepo = factureRepo;
+  }
+
+  @Override
+  public List<Facture> getByClient(Long clientId) {
+    if (clientId == null) {
+      throw new IllegalArgumentException("Client id can't be null");
+    }
+    List<Facture> factures = factureRepo.findByClient(clientId);
+    if (factures == null) {
+      throw new IllegalArgumentException("No factures found");
+    };
+    return factures;
+  }
+
+  @Override
+  public List<Facture> getAll() {
+    return factureRepo.findAll();
+  }
+
+  @Override
+  public List<Facture> getUnpayed() {
+    return factureRepo.findByDatePayEmpty();
+  }
 }