Codility: task3: e-commerce service/build_simple_aggregator_for_report

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>home.com</groupId>
+    <artifactId>codility</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+   <!-- <properties>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <maven.compiler.source>1.8</maven.compiler.source>
+    </properties>-->
+
+    <dependencies>
+        <!-- junit -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.6.1</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

src/main/java/task2_stack_transaction/Solution.java

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+package task2_stack_transaction;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Solution {
+    int top;
+
+    List<Integer> stack;
+    public Solution() {
+        // write your code in Java SE 8
+        stack = new ArrayList<>();
+    }
+
+    public void push(int value) {
+        top = value;
+        stack.add(top);
+    }
+
+    public int top() {
+        return top;
+    }
+
+    public void pop() {
+        if (stack.isEmpty()){
+            return;
+        }
+        stack.remove(stack.size()-1);
+        top = stack.get(stack.size()-1);
+    }
+
+    public void begin() {
+
+    }
+
+    public boolean rollback() {
+        return false;
+    }
+
+    public boolean commit() {
+        return false;
+    }
+
+    public static void test() {
+        // Define your tests here
+        Solution sol = new Solution();
+        sol.push(5);
+        sol.push(2);
+        assert sol.top() == 2 : "top() should be 2";
+        sol.pop();
+        assert sol.top() == 5 : "top() should be 5";
+
+        Solution sol2 = new Solution();
+        assert sol2.top() == 0;
+        sol2.pop();
+    }
+};

src/main/java/task2_stack_transaction/main.java

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+package task2_stack_transaction;
+
+public class main {
+    public static void main(String[] args){
+        System.out.println("Test");
+        Solution.test();
+    }
+}

src/main/java/task3_streams/EURExchangeService.java

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+package task3_streams;
+
+import java.math.BigDecimal;
+import java.util.Optional;
+
+public class EURExchangeService implements ExchangeService {
+    @Override
+    public Optional<BigDecimal> rate(String currency) {
+        Optional<BigDecimal> result = Optional.empty();
+        switch (currency){
+            case "USD": result = Optional.of(new BigDecimal("1.13"));
+                        break;
+            case "UAH": result = Optional.of(new BigDecimal("29.50"));
+                        break;
+            case "RUB": result = Optional.of(new BigDecimal("71.40"));
+                break;
+            default: break;
+        }
+        return result;
+    }
+}

src/main/java/task3_streams/ExchangeService.java

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+package task3_streams;
+
+import java.math.BigDecimal;
+import java.util.Optional;
+
+public interface ExchangeService {
+    Optional<BigDecimal> rate(String currency);
+}

src/main/java/task3_streams/SimpleSoldProduct.java

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+package task3_streams;
+
+import java.math.BigDecimal;
+
+public class SimpleSoldProduct {
+    private final String name;
+    private final BigDecimal price;
+
+    public SimpleSoldProduct(String name, BigDecimal price) {
+        this.name = name;
+        this.price = price;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    @Override
+    public String toString() {
+        return "task3_streams.SimpleSoldProduct{" +
+                "name='" + name + '\'' +
+                ", price=" + price +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        SimpleSoldProduct that = (SimpleSoldProduct) o;
+
+        if (name != null ? !name.equals(that.name) : that.name != null) return false;
+        return price != null ? price.equals(that.price) : that.price == null;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = name != null ? name.hashCode() : 0;
+        result = 31 * result + (price != null ? price.hashCode() : 0);
+        return result;
+    }
+}

src/main/java/task3_streams/SoldProduct.java

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+package task3_streams;
+
+import java.math.BigDecimal;
+
+public class SoldProduct {
+    String name;
+    BigDecimal price;
+    String currency;
+
+    public SoldProduct(String name, BigDecimal price, String currency) {
+        this.name = name;
+        this.price = price;
+        this.currency = currency;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public String getCurrency() {
+        return currency;
+    }
+
+    @Override
+    public String toString() {
+        return "task3_streams.SoldProduct{" +
+                "name='" + name + '\'' +
+                ", price=" + price +
+                ", currency='" + currency + '\'' +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        SoldProduct that = (SoldProduct) o;
+
+        if (name != null ? !name.equals(that.name) : that.name != null) return false;
+        if (price != null ? !price.equals(that.price) : that.price != null) return false;
+        return currency != null ? currency.equals(that.currency) : that.currency == null;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = name != null ? name.hashCode() : 0;
+        result = 31 * result + (price != null ? price.hashCode() : 0);
+        result = 31 * result + (currency != null ? currency.hashCode() : 0);
+        return result;
+    }
+}

src/main/java/task3_streams/SoldProductsAggregate.java

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+package task3_streams;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+public class SoldProductsAggregate {
+    List<SimpleSoldProduct> products;
+    BigDecimal total;
+
+    public SoldProductsAggregate(List<SimpleSoldProduct> products, BigDecimal total) {
+        this.products = products;
+        this.total = total;
+    }
+
+    public List<SimpleSoldProduct> getProducts() {
+        return products;
+    }
+
+    public BigDecimal getTotal() {
+        return total;
+    }
+
+    @Override
+    public String toString() {
+        return "task3_streams.SoldProductsAggregate{" +
+                "products=" + products +
+                ", total=" + total +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        SoldProductsAggregate that = (SoldProductsAggregate) o;
+
+        if (products != null ? !products.equals(that.products) : that.products != null) return false;
+        return total != null ? total.equals(that.total) : that.total == null;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = products != null ? products.hashCode() : 0;
+        result = 31 * result + (total != null ? total.hashCode() : 0);
+        return result;
+    }
+}

src/main/java/task3_streams/SoldProductsAggregator.java

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+package task3_streams;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collector;
+import java.util.stream.Stream;
+
+public class SoldProductsAggregator {
+
+    private final EURExchangeService exchangeService;
+
+    SoldProductsAggregator(EURExchangeService EURExchangeService) {
+        this.exchangeService = EURExchangeService;
+    }
+
+    SoldProductsAggregate aggregate(Stream<SoldProduct> products) {
+
+        Collector<SimpleSoldProduct, List<SimpleSoldProduct>, SoldProductsAggregate> soldProductsCollector =
+            Collector.of(ArrayList<SimpleSoldProduct>::new,
+                         List::add,
+                         (l1, l2) -> {l1.addAll(l2); return l1;},
+                         (l)->new SoldProductsAggregate(l,
+                            new BigDecimal(l.stream().mapToDouble(p->p.getPrice().doubleValue()).sum()).setScale(2, RoundingMode.HALF_EVEN))
+                         );
+
+       return products.map(p ->
+                new SimpleSoldProduct(p.name,
+                        p.price.divide(exchangeService.rate(p.currency).filter(r -> r.compareTo(BigDecimal.ZERO)>0).orElse(BigDecimal.ONE), 2, RoundingMode.HALF_EVEN))
+        ).collect(soldProductsCollector);
+    }
+
+}

src/test/java/task3_streams/SoldProductsAggregatorTest.java

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+package task3_streams;
+
+import org.junit.Before;
+import org.junit.Test;
+import task3_streams.*;
+
+import java.math.BigDecimal;
+import java.util.Arrays;
+import java.util.List;
+
+public class SoldProductsAggregatorTest {
+
+    private EURExchangeService exchangeService;
+
+    @Before
+    public  void init(){
+      exchangeService = new EURExchangeService();
+    }
+
+    @Test
+    public void aggregate() throws Exception {
+        SoldProductsAggregate soldProductsAggregate;
+
+        List<SimpleSoldProduct> simpleSoldProducts = Arrays.asList(
+                new SimpleSoldProduct("Monitor", new BigDecimal("200.53")),
+                new SimpleSoldProduct("PC", new BigDecimal(("523.30"))),
+                new SimpleSoldProduct("Keyboard", new BigDecimal("15.00")),
+                new SimpleSoldProduct("Mouse", new BigDecimal("2.35")));
+
+        List<SoldProduct> soldProducts = Arrays.asList(
+                new SoldProduct("Monitor", new BigDecimal("200.53"), "USD"),
+                new SoldProduct("PC", new BigDecimal(("10523.30")), "UAH"),
+                new SoldProduct("Keyboard", new BigDecimal("15.00"), "USD"),
+                new SoldProduct("Mouse", new BigDecimal("282.35"), "RUB"));
+
+        SoldProductsAggregator soldAgg = new SoldProductsAggregator(exchangeService);
+        soldProductsAggregate = soldAgg.aggregate(soldProducts.stream());
+        System.out.println(soldProductsAggregate);
+        //assertEquals(2000.55, soldProductsAggregate.getTotal().doubleValue(), 2.00);
+    }
+
+}