Feat: Refactored transactionarchive + testing

Replaced for loops with streams, centralized concrete getters via get transactions, and added parameter guarding. Also updated test class.

src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/engine/TransactionArchive.java

@@ -3,11 +3,15 @@
 import edu.ntnu.idi.idatt2003.g40.mappe.model.Purchase;
 import edu.ntnu.idi.idatt2003.g40.mappe.model.Sale;
 import edu.ntnu.idi.idatt2003.g40.mappe.model.Transaction;
+import edu.ntnu.idi.idatt2003.g40.mappe.utils.Validator;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 /**
- * Stores completed transactions.
+ * Stores completed transactions in an {@link ArrayList} object.
+ *
+ * @version 1.1.0
  */
 public final class TransactionArchive {
 
@@ -20,6 +24,7 @@ public final class TransactionArchive {
    * Creates an empty transaction archive.
    */
   public TransactionArchive() {
+    // Empty constructor.
   }
 
   /**
@@ -28,8 +33,13 @@ public TransactionArchive() {
    * @param transaction the transaction to add
    *
    * @return true if the transaction was added
+   *
+   * @throws IllegalArgumentException if transaction is null
    */
   public boolean add(final Transaction transaction) {
+    if (transaction == null) {
+      throw new IllegalArgumentException("Transaction cannot be null!");
+    }
     return transactions.add(transaction);
   }
 
@@ -48,24 +58,27 @@ public boolean isEmpty() {
    * @param week the week number
    *
    * @return list of transactions from the given week
+   *
+   * @throws IllegalArgumentException if week is less than 1.
    */
   public List<Transaction> getTransactions(final int week) {
-    List<Transaction> result = new ArrayList<>();
-    for (Transaction transaction : transactions) {
-      if (transaction.getWeek() == week) {
-        result.add(transaction);
-      }
+    if (!Validator.VALID_WEEK.isValid(Integer.toString(week))) {
+      throw new IllegalArgumentException(
+              Validator.VALID_WEEK.getErrorMessage()
+      );
     }
-    return result;
+    return transactions.stream()
+            .filter(transaction -> transaction.getWeek() == week)
+            .toList();
   }
 
   /**
-   * Returns all transactions.
+   * Returns an un-mutable reference to the transactions list.
    *
-   * @return list of transactions from the given week
+   * @return unmodifiable version of list.
    */
   public List<Transaction> getTransactions() {
-    return transactions;
+    return Collections.unmodifiableList(transactions);
   }
 
   /**
@@ -74,16 +87,15 @@ public List<Transaction> getTransactions() {
    * @param week the week number
    *
    * @return list of purchases from the given week
+   *
+   * @throws IllegalArgumentException if week is less than 1.
    */
-  public List<Purchase> getPurchases(final int week) {
-    List<Purchase> result = new ArrayList<>();
-    for (Transaction transaction : transactions) {
-      if (transaction instanceof Purchase purchase
-              && transaction.getWeek() == week) {
-        result.add(purchase);
-      }
-    }
-    return result;
+  public List<Purchase> getPurchases(final int week)
+          throws IllegalArgumentException {
+    return getTransactions(week).stream()
+            .filter(Purchase.class::isInstance)
+            .map(Purchase.class::cast)
+            .toList();
   }
 
   /**
@@ -92,15 +104,15 @@ public List<Purchase> getPurchases(final int week) {
    * @param week the week number
    *
    * @return list of sales from the given week
+   *
+   * @throws IllegalArgumentException if week is less than 1.
    */
-  public List<Sale> getSales(final int week) {
-    List<Sale> result = new ArrayList<>();
-    for (Transaction transaction : transactions) {
-      if (transaction instanceof Sale sale && transaction.getWeek() == week) {
-        result.add(sale);
-      }
-    }
-    return result;
+  public List<Sale> getSales(final int week)
+          throws IllegalArgumentException {
+    return getTransactions(week).stream()
+            .filter(Sale.class::isInstance)
+            .map(Sale.class::cast)
+            .toList();
   }
 
   /**
@@ -109,13 +121,9 @@ public List<Sale> getSales(final int week) {
    * @return number of distinct weeks
    */
   public int countDistinctWeeks() {
-    List<Integer> weeks = new ArrayList<>();
-    for (Transaction transaction : transactions) {
-      int week = transaction.getWeek();
-      if (!weeks.contains(week)) {
-        weeks.add(week);
-      }
-    }
-    return weeks.size();
+    return (int) transactions.stream()
+            .map(Transaction::getWeek)
+            .distinct()
+            .count();
   }
 }