refactor code, add interfaces for services

src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java

@@ -2,6 +2,7 @@ package com.faf223.expensetrackerfaf.service;
 
 import com.faf223.expensetrackerfaf.model.Credential;
 import com.faf223.expensetrackerfaf.model.Expense;
+import com.faf223.expensetrackerfaf.model.IMoneyTransaction;
 import com.faf223.expensetrackerfaf.repository.CredentialRepository;
 import com.faf223.expensetrackerfaf.repository.ExpenseRepository;
 import lombok.RequiredArgsConstructor;
@@ -13,16 +14,16 @@ import java.util.Optional;
 
 @Service
 @RequiredArgsConstructor
-public class ExpenseService {
+public class ExpenseService implements ITransactionService {
 
     private final ExpenseRepository expenseRepository;
     private final CredentialRepository credentialRepository;
 
-    public void createOrUpdateExpense(Expense expense) {
-        expenseRepository.save(expense);
+    public void createOrUpdate(IMoneyTransaction expense) {
+        expenseRepository.save((Expense) expense);
     }
 
-    public List<Expense> getExpensesByEmail(String email) {
+    public List<Expense> getTransactionsByEmail(String email) {
 
         Optional<Credential> credential = credentialRepository.findByEmail(email);
         if (credential.isPresent()) {
@@ -32,11 +33,11 @@ public class ExpenseService {
         return new ArrayList<>();
     }
 
-    public List<Expense> getExpenses() {
+    public List<Expense> getTransactions() {
         return expenseRepository.findAll();
     }
 
-    public Expense getExpenseById(long id) {
+    public Expense getTransactionById(long id) {
         return expenseRepository.findById(id).orElse(null);
     }
 }