hw1

src/main/kotlin/orders/Order.kt

@@ -17,29 +17,38 @@ class Order(
      * If the product is null, it should be ignored.
      */
     fun addProduct(product: Product?) {
+        product?.let {
+            _products.add(it)
+        }
         // TODO: add product to _products, ignore null
     }
 
     /**
      * Removes the first product matching [productId].
      */
     fun removeProductById(productId: Int) {
+        _products.removeIf { it.id == productId }
         // TODO: remove product from _products by id
     }
 
     /**
      * Returns the total price of all products in the order.
      */
     override fun calculateTotal(): Int {
-        // TODO: sum the prices of all products
-        return 0
+        return  _products.sumOf { it.price }
     }
 
     /**
      * Marks the order as paid.
      * Throws [IllegalStateException] if the order has no products.
      */
     fun pay() {
+        if(products.isNotEmpty()){
+            status = OrderStatus.Paid
+        }
+        else{
+            throw IllegalStateException("Order has no products")
+        }
         // TODO: throw if _products is empty, otherwise set status to Paid
     }
 
@@ -48,6 +57,7 @@ class Order(
      * If [reason] is null, use "Unknown reason".
      */
     fun cancel(reason: String?) {
+        status = OrderStatus.Cancelled(reason = reason ?: "Unknown reason")
         // TODO: set status to Cancelled with reason (default "Unknown reason" if null)
     }
 }

src/main/kotlin/orders/OrderExtensions.kt

@@ -14,5 +14,11 @@ fun Order.applyDiscount(
     discountPercent: Int,
     logger: ((String) -> Unit)? = null
 ) {
+    products.forEach { product ->
+        removeProductById(product.id)
+        val discountedProduct = product.copy(price = product.price * (100 - discountPercent) / 100)
+        addProduct(discountedProduct)
+        logger?.invoke("${product.price}")
+    }
     // TODO: apply discount to each product using extension + scoped functions
 }

src/main/kotlin/orders/OrderProcessor.kt

@@ -8,6 +8,9 @@ package orders
  *   - Cancelled -> "Order {id} is cancelled: {reason}"
  */
 fun processOrder(order: Order): String {
-    // TODO: use when to return the appropriate string
-    return ""
+    return when(order.status){
+        is OrderStatus.Cancelled -> "Order ${order.id} is cancelled ${(order.status as OrderStatus.Cancelled).reason}"
+        OrderStatus.Created -> "Order ${order.id} is created"
+        OrderStatus.Paid -> "Order ${order.id} is paid"
+    }
 }