implemented functionality and tests

.gitignore

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+# Compiled class file
+*.class
+
+target
+
+# Log file
+*.log
+
+# BlueJ files
+*.ctxt
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+
+.idea
+*.iml
+
+/.gradle/
+*/.gradle
+/.gradle/
+!gradle-wrapper.jar
+*/out
+*/build
+*/target/**
+*build
+**/resources/pacts
+
+*.DS_Store
+
+#ignore terraform plugins and statefiles
+
+terraform/.terraform
+terraform/.terraform/*
+classes
+
+.terraform

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.test.supermarket</groupId>
+    <artifactId>henrys_groceries</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>11</source>
+                    <target>11</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>1.2.17</version>
+        </dependency>
+    </dependencies>
+</project>

src/main/java/com/test/harrys/InventoryClient.java

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+package com.test.harrys;
+
+import com.test.harrys.basket.ShoppingBasket;
+import com.test.harrys.model.ShoppingListItem;
+
+import java.io.PrintWriter;
+import java.math.BigDecimal;
+import java.util.Scanner;
+import java.util.logging.Logger;
+
+import static com.test.harrys.ShoppingTill.calculateBill;
+import static com.test.harrys.ShoppingTill.getProductPrice;
+import static com.test.harrys.control.InventoryControl.initialiseInventory;
+
+public class InventoryClient extends Thread {
+    private static final String ADD = "add";
+    private static final String BILL = "bill";
+    private static final String RESET ="reset";
+    private static final Logger log = Logger.getLogger(InventoryClient.class.getName());
+    private static final String COMMAND_DELIMITER = " ";
+    public static final String START = "start";
+    public static final String END = "end";
+
+    ShoppingBasket basket = new ShoppingBasket();
+
+    PrintWriter out = new PrintWriter(System.out, true);
+
+    public InventoryClient() {
+        initialiseInventory();
+    }
+
+    /**
+     * starts a thread and sends the
+     * client a set of instructions to use the service
+     */
+    public void run() {
+        Scanner inputS = new Scanner(System.in);
+        userPrompt();
+        while (true) {
+            String input = inputS.nextLine();
+            if (input == null || input.equals("exit")) {
+                break;
+            }
+            processInput(input);
+        }
+    }
+
+    private void displayInventory() {
+        out.println("The inventory consists of :");
+        ShoppingTill.getProductOffering().stream().forEach(item -> out.println(item.getName()));
+    }
+
+    private void userPrompt() {
+        out.println("Enter the word 'exit' to quit");
+        out.println("Enter 'start' to start shopping");
+        out.println("Enter 'add<SPACE><PRODUCT_CODE>' to add a product to the basket eg 'add soup' ");
+        out.println("Enter 'bill' to display bill to customer");
+        out.println("Enter 'end' to settle bill, ends session");
+        out.println("Enter 'reset' to reset all system data to defaults");
+        displayInventory();
+    }
+
+    /**
+     * processes the input by way of interpreting the command sent across
+     * the command string is delimiterred with a space and parsed to determine the command
+     * and the relative parameters, the 1st string in the list is the actual command
+     */
+    private void processInput(String input) {
+        String[] command = input.split(COMMAND_DELIMITER);
+        switch (command[0]) {
+            case START:
+                startShopping();
+                break;
+            case END:
+                endShopping();
+                break;
+            case BILL:
+                displayBill();
+                break;
+            case ADD:
+                addItemToBasket(command[1]);
+                break;
+            case RESET:
+                out.println("Service reset to default state");
+                basket = new ShoppingBasket();
+                break;
+            default:
+                userPrompt();
+                break;
+        }
+    }
+
+    private void endShopping() {
+        displayBill();
+        basket = new ShoppingBasket();
+    }
+
+    private void startShopping() {
+
+    }
+
+
+    /**
+     * adds item to basket
+     * @param productCode
+     */
+    private void addItemToBasket(String productCode) {
+        try{
+            basket.addItem(new ShoppingListItem(productCode));
+            out.println(String.format("added %s to basket, unit price : %s",productCode, getProductPrice(productCode)));
+        }catch (IllegalArgumentException iae){
+            log.warning(iae.getMessage());
+            displayInventory();
+        }
+    }
+
+    private void displayBill(){
+        BigDecimal bill = calculateBill(basket);
+        out.println(String.format("your bill is : %s", bill));
+    }
+
+    public static void main(String[] args) {
+        log.info("The client has been started ");
+        new InventoryClient().start();
+    }
+}

src/main/java/com/test/harrys/ShoppingTill.java

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+package com.test.harrys;
+
+import com.test.harrys.basket.ShoppingBasket;
+import com.test.harrys.model.Product;
+import com.test.harrys.model.ShoppingDiscount;
+import com.test.harrys.model.ShoppingListItem;
+import org.apache.log4j.Logger;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.time.LocalDate;
+import java.time.temporal.ChronoUnit;
+import java.util.*;
+
+
+public class ShoppingTill {
+    final static Logger LOGGER = Logger.getLogger(ShoppingTill.class);
+
+    private static final Set<ShoppingDiscount> discounts = new HashSet<>();
+
+    private static final Set<Product> PRODUCT_SET = new HashSet<>();
+
+    private static final int myNumDecimals = 2;
+
+    /**
+     * get product instance using the code
+     * @param productCode
+     * @return gets product instance
+     */
+    public static Product getProductByCode(String productCode) {
+        return PRODUCT_SET.stream()
+                .filter(product -> product.getProductCode().equals(productCode))
+                .findFirst().orElseThrow(() -> new IllegalArgumentException(
+                        String.format("Cannot find product with product code : [%s] in product offerings",
+                        productCode)));
+    }
+
+    /**
+     * get price of product
+     * @param productCode
+     * @return price of related product
+     */
+    public static BigDecimal getProductPrice(String productCode){
+        return getProductByCode(productCode).getPrice();
+    }
+
+    /**
+     * adds any discounts entries to the invoice if any apply to the items purchased
+     * @param listItem item purchased
+     * @return total discount amount for item purchased
+     */
+    public static BigDecimal calculateDiscountTotal(ShoppingBasket basket, ShoppingListItem listItem){
+        BigDecimal discountAmount = BigDecimal.ZERO;
+        Optional<ShoppingDiscount> shoppingDiscount = discounts.stream()
+                        .filter(discount -> discount.getProductCode().equals(listItem.getProductCode()))
+                        .findFirst();
+        if(shoppingDiscount.isPresent()){
+            discountAmount = shoppingDiscount.get().calculateDiscountAmount(basket);
+        }
+        return discountAmount;
+    }
+
+    static BigDecimal calculateBill(ShoppingBasket basket) {
+        double subTotal = basket.getShoppingListItems().stream().mapToDouble(basketItem ->
+            getProductPrice(basketItem.getProductCode()).doubleValue() * basketItem.getQuantity()).sum();
+        double discountTotal = basket.getShoppingListItems().stream().mapToDouble(items ->
+                calculateDiscountTotal(basket, items).doubleValue()).sum();
+        return BigDecimal.valueOf(subTotal - discountTotal).setScale( myNumDecimals, RoundingMode.HALF_UP);
+    }
+
+    static BigDecimal calculateBill(String[] shoppingList) {
+        ShoppingBasket basket = new ShoppingBasket();
+        Arrays.stream(shoppingList).forEach(p ->  basket.addItem(new ShoppingListItem(p)));
+        return calculateBill(basket);
+    }
+
+    public static void setProductOffering(Set<Product> catalogue) {
+        ShoppingTill.PRODUCT_SET.addAll(catalogue);
+    }
+
+    public static void setDiscounts(Set<ShoppingDiscount> discounts) {
+        ShoppingTill.discounts.clear();
+        ShoppingTill.discounts.addAll(discounts);
+    }
+
+
+    public static Set<Product> getProductOffering() {
+        return Collections.unmodifiableSet(PRODUCT_SET);
+    }
+}
+

src/main/java/com/test/harrys/basket/ShoppingBasket.java

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+package com.test.harrys.basket;
+
+import com.test.harrys.model.ShoppingListItem;
+import org.apache.log4j.Logger;
+
+import java.time.LocalDate;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
+
+/**
+ * @author kay
+ *encapsulates a shopping basket
+ */
+public class ShoppingBasket {
+    private LocalDate shoppingDate;
+
+    final static Logger LOGGER = Logger.getLogger(ShoppingBasket.class);
+
+    private final Set<ShoppingListItem> listItem = new HashSet<>();
+
+    public ShoppingBasket() {
+        shoppingDate = LocalDate.now();
+    }
+
+    /**
+     * adds one or more items of a specific product to a shopping basket
+     * @param item shopping list item
+     */
+    public void addItem(ShoppingListItem item) {
+        if(!listItem.add(item)){
+            listItem.stream().filter(lItem -> lItem.getProductCode().equals(item.getProductCode())).
+                    findAny().ifPresent(lItem -> lItem.increaseQuantity(item.getQuantity()));
+        }
+    }
+
+    public Collection<ShoppingListItem> getShoppingListItems() {
+        return this.listItem;
+    }
+
+    public LocalDate getShoppingDate() {
+        return shoppingDate;
+    }
+
+    public void setShoppingDate(LocalDate shoppingDate) {
+        this.shoppingDate = shoppingDate;
+    }
+}