package org.apidesign.apifest08.currency;

import java.util.Currency;

import java.util.Hashtable;

import java.util.Map;

/** This is the skeleton class for your API. You need to make it public, so

 * it is accessible to your client code (currently in Task1Test.java) file.

 * <p>

 * Feel free to create additional classes or rename this one, just keep all

 * the API and its implementation in this package. Do not spread it outside

 * to other packages.

 */

public class Convertor {

    private static final Map<String, Float> EXCHANGE_RATES = new Hashtable<String, Float>() { {

            put("CZKUSD", 1/17F);

            put("USDCZK", 17F);

            put("SKKCZK", 100/80F);

            put("CZKSKK", 80/100F);

        }

    };

    private Currency currencyFirst;

    private Currency currencySecond;

    private Convertor(Currency currencyFirst, Currency currencySecond) {

        this.currencyFirst = currencyFirst;

        this.currencySecond = currencySecond;

    }

    public static Convertor getInstanceFor(Currency currencyFirst, Currency currencySecond) {

        return new Convertor(currencyFirst, currencySecond);

    }

    public float convert(float value, Currency toCurrency) {

        if (!toCurrency.equals(currencyFirst) && !toCurrency.equals(currencySecond)) {

            throw new IllegalArgumentException("Unsupported currency for this convertor!: " + toCurrency.getCurrencyCode());

        }

        Float rate = null;

        if (toCurrency.equals(currencyFirst)) {

            rate = EXCHANGE_RATES.get(currencyFirst.getCurrencyCode() + currencySecond.getCurrencyCode());

        }

        if (toCurrency.equals(currencySecond)) {

            rate = EXCHANGE_RATES.get(currencySecond.getCurrencyCode() + currencyFirst.getCurrencyCode());

        }

        if (rate == null) {

            throw new IllegalStateException("Undefinied conversion!");

        }

        return rate*value;

    }

}