public class Invoice

package zda;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.HashMap;


public class Invoice
{

    private Contractor client;
    private LocalDate dateOfIssue;

    private String nr;

    private static class Identifier
    {
        static int currentNumber = 0;
        static int currentMonth = 0;
        static int currentYear = 0;

        static String generateNr()
        {
            LocalDate ld = LocalDate.now();

            int year = ld.getYear();
            int month = ld.getMonthValue();
            if (year > currentYear)
            {
                currentYear = year;
                currentMonth = ld.getMonthValue();
                currentNumber = 0;
            } else if (month > currentMonth)
            {
                currentMonth = month;
                currentNumber = 0;
            }

            return (++currentNumber) + "/" + currentMonth + "/" + currentYear;

        }
    }

    public enum Measure
    {
        QTY, M, L, KG, M2
    }

    public enum VAT
    {
        s23(.23), s08(.08), s05(.05), s00(.0);

        public double rate;
        public String str;

        VAT(double rate)
        {
            this.rate = rate;
            this.str = String.format("%.0f%%", 100 * rate);
        }
    }

    private class Position
    {
        private int position;
        private String name;
        private Measure mmasure;
        private double quantity;
        private double unitPriceWithoutTax;
        private VAT tax;

        public Position(String name, Measure mmasure, double quantity, double price, VAT tax)
        {
            this.name = name;
            this.mmasure = mmasure;
            this.quantity = quantity;
            this.unitPriceWithoutTax = price;
            this.tax = tax;
            this.position = positions.size() + 1;
        }

        public double getValue()
        {
            return quantity * unitPriceWithoutTax;
        }

        public double getTax()
        {
            double d = quantity * unitPriceWithoutTax * tax.rate;
            d = Math.round(d * 100) / 100.;
            return d;
        }

        @Override
        public String toString()
        {
            return String.format("%5d | %30s | %10s | %10s | %10s | %10s | %10.2f", position, name, mmasure, quantity,
                    unitPriceWithoutTax, tax.str, getValue() + getTax());
        }
    }

    public static String heading()
    {
        return String.format("%5s | %30s | %10s | %10s | %10s | %10s | %10s", "LP.", "name", "mmasure", "quantity",
                "Unit price.", "tax", "price with tax");
    }

    private ArrayList<Position> positions = new ArrayList<Position>();

    public void addPosition(String name, Measure m, double quantity, double price, VAT tax)
    {
        if (closed)
            return;

        Position p = new Position(name, m, quantity, price, tax);
        positions.add(p);
        double d = subtotals.get(tax);
        d += p.getTax();
        subtotals.put(tax, d);
        sumWithTax += p.getValue();
        sumPayment += p.getValue() + p.getTax();
    }

    private boolean closed = false;

    public void close()
    {
        closed = true;
    }

    private HashMap<VAT, Double> subtotals = new HashMap<>();
    private double sumWithTax = 0;
    private double sumPayment = 0;

    public Invoice(Contractor c)
    {
        nr = Identifier.generateNr();
        client = c;
        dateOfIssue = LocalDate.now();

        for (VAT v : VAT.values())
        {
            subtotals.put(v, 0.);
        }
    }

    @Override
    public String toString()
    {
        String invoice = "---------------------------------------------\n";
        invoice += (closed ? "C-" : "O-") + "invoice no." + nr + "\n";
        invoice += "from date " + dateOfIssue.format(DateTimeFormatter.ofPattern("d-M-y")) + "\n";
        invoice += "\nFor: \n" + client + "\n\n";
        invoice += heading() + "\n";
        for (Position p : positions)
        {
            invoice += p.toString() + "\n";
        }
        invoice += "\n";
        invoice += String.format("%-15s: %10.2f\n", "Sum without tax", sumWithTax);
        for (HashMap.Entry<VAT, Double> e : subtotals.entrySet())
        {
            if (e.getValue() > 0)
                invoice += String.format("%-15s: %10.2f\n", "SUM " + e.getKey().str, e.getValue());
        }
        invoice += String.format("%27s\n", "+ ----------");
        invoice += String.format("%-15s: %10.2f\n", "sum to pay", sumPayment);
        invoice += "---------------------------------------------\n";
        return invoice;
    }

}