Add TransactionArchive

src/main/java/TransactionArchive.java

@@ -0,0 +1,40 @@
+import java.util.ArrayList;
+import java.util.stream.Collectors;
+import java.util.List;
+
+public class TransactionArchive {
+    private List<Transaction> transactions;
+
+    public TransactionArchive() {
+        this.transactions = new ArrayList<>();
+    }
+
+    public boolean add(Transaction transaction) {
+        if (transaction == null) {
+            throw new IllegalArgumentException("Should not be null"); // Eller NullPointerExeption?
+        }
+
+        return transactions.add(transaction);
+
+    }
+
+    public boolean isEmpty() {
+        return transactions.isEmpty();
+    }
+
+    public List<Transaction> getTransactions(int week) {
+        return transactions.stream().filter(transaction -> transaction.getWeek() == week).collect(Collectors.toList());
+    }
+
+    public List<Purchase> getPurchase(int week) {
+        return transactions.stream().filter(transaction -> transaction.getWeek() == week).filter(purchase -> transactions instanceof Purchase).map(transaction -> (Purchase) transaction).collect(Collectors.toList());
+    }
+
+    public List<Sale> getSale(int week) {
+        return transactions.stream().filter(transaction -> transaction.getWeek() == week).filter(sale -> transactions instanceof Sale).map(transaction -> (Sale) transaction).collect(Collectors.toList());
+    }
+
+    public int countDistinctWeeks() {
+        return (int) transactions.stream().map(Transaction::getWeek).distinct().count();
+    }
+}