add historical prices and getters for highest and lowest price with p…

…ropper null handling

src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Stock.java

@@ -7,7 +7,7 @@
 /**
  * Represents a stock of a company in the {@link Exchange}.
  * <p>
- * Each {@code Stock} has a unique symbol, a company name, and a history of sales prices.
+ * Each stock has a unique symbol, a company name, and a history of sales prices.
  * You can retrieve the current price or add new prices as the market changes.
  * </p>
  */
@@ -17,7 +17,7 @@ public class Stock {
   private List<BigDecimal> prices = new ArrayList<>();
 
   /**
-   * Constructs a new {@code Stock} with the given symbol, company name, and initial sales price.
+   * Constructs a new stock with the given symbol, company name, and initial sales price.
    * @param symbol symbol the unique stock symbol (e.g., "AAPL")
    * @param company company the company name (e.g., "Apple Inc.")
    * @param salesPrice salesPrice the initial sales price of the stock
@@ -45,7 +45,22 @@ public BigDecimal getSalesPrice() {
    *
    * @param salesPrice the new sales price to add
    */
-  public void addNewSalesPrices(BigDecimal salesPrice) {
+  public void addNewSalesPrice(BigDecimal salesPrice) {
     prices.add(salesPrice);
   }
+
+  public List<BigDecimal> getHistoricalPrices() {
+    return List.copyOf(prices);
+  }
+
+  public BigDecimal getHighestPrice() {
+    return prices.stream().max(BigDecimal::compareTo).orElse(BigDecimal.ZERO);
+  }
+  public BigDecimal getLowestPrice() {
+    return prices.stream().min(BigDecimal::compareTo).orElse(BigDecimal.ZERO);
+  }
+
+  public BigDecimal getLatestPrice() {
+    return prices.isEmpty() ? BigDecimal.ZERO : prices.get(prices.size() - 1);
+  }
 }

src/test/java/edu/ntnu/idi/idatt2003/gruppe42/Model/StockTest.java

@@ -20,7 +20,7 @@ void stockPropertiesTest() {
   void addNewPriceTest() {
     Stock stock = new Stock("AAPL", "Apple Inc.", new BigDecimal("100"));
     BigDecimal newPrice = new BigDecimal("110");
-    stock.addNewSalesPrices(newPrice);
+    stock.addNewSalesPrice(newPrice);
 
     assertEquals(0, newPrice.compareTo(stock.getSalesPrice()));
   }