1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/task2/solution05/src/org/apidesign/apifest08/currency/ConvertorImpl.java	Wed Oct 01 10:43:05 2008 +0200
     1.3 @@ -0,0 +1,56 @@
     1.4 +package org.apidesign.apifest08.currency;
     1.5 +
     1.6 +/**
     1.7 + * ConvetorImpl it the basic implementaion of Convertor interface.
     1.8 + * @see Convertor Convertor for more details.
     1.9 + * The 100 pences makes 1 amount of the currency.
    1.10 + *
    1.11 + * @author jindra
    1.12 + */
    1.13 +final class ConvertorImpl implements Convertor {
    1.14 +
    1.15 +    private static final double P_TO_AM = 100;
    1.16 +    private double exchangeRate;
    1.17 +
    1.18 +    ConvertorImpl(double exchangeRate) {
    1.19 +        this.exchangeRate = exchangeRate;
    1.20 +    }
    1.21 +
    1.22 +    public Amount convert(Amount amount) {
    1.23 +        verifyInput(amount);
    1.24 +        double result = convertToDouble(amount) * exchangeRate;
    1.25 +        return convertToAmount(result);
    1.26 +    }
    1.27 +
    1.28 +    public Amount convertBack(Amount amount) {
    1.29 +        if (amount == null) {
    1.30 +            throw new IllegalArgumentException("Amount must be not null");
    1.31 +        }
    1.32 +        double result = convertToDouble(amount) / exchangeRate;
    1.33 +        return convertToAmount(result);
    1.34 +    }
    1.35 +
    1.36 +    private double convertToDouble(Amount amount) {
    1.37 +        double am = amount.getAmount();
    1.38 +        double pc = amount.getPence();
    1.39 +        return am + (pc / P_TO_AM);
    1.40 +    }
    1.41 +
    1.42 +    private Amount convertToAmount(double result) {
    1.43 +        long resultAm = Math.round(Math.floor(result));
    1.44 +        long resultPc = Math.round(Math.floor((result * P_TO_AM - resultAm * P_TO_AM)));
    1.45 +        return new Amount(resultAm, resultPc);
    1.46 +    }
    1.47 +
    1.48 +    private void verifyInput(Amount amount) {
    1.49 +        if (amount == null) {
    1.50 +            throw new IllegalArgumentException("Amount must be not null");
    1.51 +        }
    1.52 +        if (amount.getPence() < 0) {
    1.53 +            throw new IllegalArgumentException("Pences must not be negative");
    1.54 +        }
    1.55 +        if (amount.getPence() > P_TO_AM) {
    1.56 +            throw new IllegalArgumentException("Pences must not be over P_TO_AM");
    1.57 +        }
    1.58 +    }
    1.59 +}