Add Decorator

src/decorator/Annotation.txt

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+##############################
+#         Decorator          #
+##############################
+
+
+
+
+
+##### Language - EN
+
+- In the code example, we want a tax to have another tax in it, that is, a compound tax, that way it would be simple using decorator.
+
+- We decorate tax A with tax B, decorate tax B with tax C, and so on.
+
+- Whenever we realize that we have behaviors that can be composed of behaviors from other classes involved in the same hierarchy,
+as was the case with taxes, which may consist of other taxes. Decorator introduces flexibility in the composition of these behaviors,
+just choose at the moment of instantiation, which instances will be used to perform the work.
+
+
+##### Language - PT-BR
+
+- No exemplo do código, nós queremos que um imposto possa ter outro imposto nele, ou seja, imposto composto, dessa forma ficaria simples usando decorator.
+
+- Decoramos um imposto A com o imposto B, decoramos imposto B com um imposto C, e assim por diante.
+
+- Sempre que percebemos que temos comportamentos que podem ser compostos por comportamentos de outras classes envolvidas em uma mesma hierarquia, 
+como foi o caso dos impostos, que podem ser composto por outros impostos. O Decorator introduz a flexibilidade na composição desses comportamentos, 
+bastando escolher no momento da instanciação, quais instancias serão utilizadas para realizar o trabalho.

src/decorator/Budget.java

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+package decorator;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import templateMethod.Item;
+
+public class Budget {
+
+	private double value;
+	private final List<Item> items;
+
+	public Budget(double value) {
+		super();
+		this.value = value;
+		items = new ArrayList<Item>();
+	}
+
+	public double getValue() {
+		return value;
+	}
+
+	public void addItem(Item item) {
+		items.add(item);
+	}
+
+	public List<Item> getItems() {
+		return Collections.unmodifiableList(items);// unmodifiableList -> Return a List immutable.
+	}
+
+}

src/decorator/ComplexTaxTest.java

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+package decorator;
+
+public class ComplexTaxTest {
+
+	public static void main(String[] args) {
+		System.out.println("--------------------------------------------- Begin Test for Complex Tax");
+
+
+		Budget budget = new Budget(500);
+
+
+		// Tax in % = 0.2 + 0.1 + 0.06 (INSS + ICMS + ABCD)
+		// Calculate: 500 * 0.36 = 180%
+		Tax taxValue = new TaxINSS(new TaxICMS(new TaxABCD()));
+		System.out.println("Compound Tax Value: " + taxValue.calculate(budget) + "%");//180.0%
+
+
+		System.out.println("--------------------------------------------- End Test for Complex Tax");
+	}
+
+}

src/decorator/ConditionalTaxTemplate.java

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+package decorator;
+
+public abstract class ConditionalTaxTemplate extends Tax{
+
+	@Override
+	public double calculate(Budget budget) {
+
+		if(mustUseMaxTaxAplly(budget)) {
+			return maxTaxAplly(budget) + calculateOtherTax(budget); // Aplly Max Tax + calculateOtherTax
+		} else {
+			return minTaxAplly(budget) + calculateOtherTax(budget); // Aplly Min Tax + calculateOtherTax
+		}
+
+	}
+
+	// Protected for only children to see
+	protected abstract boolean mustUseMaxTaxAplly(Budget budget);
+
+	protected abstract double maxTaxAplly(Budget budget);
+
+	protected abstract double minTaxAplly(Budget budget);
+
+}

src/decorator/Tax.java

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+package decorator;
+
+public abstract class Tax {
+
+	protected Tax otherTax;
+
+	// Constructor for otherTax for compound tax
+	public Tax(Tax otherTax) {
+		this.otherTax = otherTax;
+	}
+
+	public Tax() {
+
+	}
+
+	public abstract double calculate(Budget budget);
+
+	protected double calculateOtherTax(Budget budget) {
+		// Tax that is not compounded must return the value 0
+		if (this.otherTax == null)
+			return 0.0d;
+		else
+			return otherTax.calculate(budget); //Calculate other tax, always compound tax.
+	}
+
+}

src/decorator/TaxABCD.java

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+package decorator;
+
+public class TaxABCD extends ConditionalTaxTemplate {
+
+	// If item in the list is greater than 100 it returns true
+	private boolean thereIsAnItemGreaterThan100InTheBudget(Budget budget) {
+		return budget.getItems().stream()
+			.anyMatch(i -> {
+				if (i.getValue() > 100) {
+					return true;
+				}
+				return false;
+			});
+	}
+
+	@Override
+	protected boolean mustUseMaxTaxAplly(Budget budget) {
+		return budget.getValue() > 500 && thereIsAnItemGreaterThan100InTheBudget(budget);
+	}
+
+	@Override
+	protected double maxTaxAplly(Budget budget) {
+		return budget.getValue() * 0.15;
+	}
+
+	@Override
+	protected double minTaxAplly(Budget budget) {
+		return budget.getValue() * 0.06;
+	}
+
+}

src/decorator/TaxEFGH.java

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+package decorator;
+
+public class TaxEFGH extends ConditionalTaxTemplate {
+
+	@Override
+	protected boolean mustUseMaxTaxAplly(Budget budget) {
+		return budget.getValue() > 500;
+	}
+
+	@Override
+	protected double maxTaxAplly(Budget budget) {
+		return budget.getValue() * 0.10;
+	}
+
+	@Override
+	protected double minTaxAplly(Budget budget) {
+		return budget.getValue() * 0.06;
+	}
+
+}

src/decorator/TaxICMS.java

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+package decorator;
+
+public class TaxICMS extends Tax {
+
+	public TaxICMS (Tax otherTax) {
+		super(otherTax);
+	}
+
+	public TaxICMS () {
+	}
+
+	@Override
+	public double calculate(Budget budget) {
+		return (budget.getValue() * 0.1) + (calculateOtherTax(budget));
+	}
+
+}

src/decorator/TaxINSS.java

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+package decorator;
+
+public class TaxINSS extends Tax {
+
+	public TaxINSS(Tax otherTax) {
+		super(otherTax);
+	}
+
+	public TaxINSS() {
+		super();
+	}
+
+	@Override
+	public double calculate(Budget budget) {
+		return (budget.getValue() * 0.2) + (calculateOtherTax(budget));
+	}
+
+}