package org.apidesign.apifest08.test;

import java.util.Currency;

import junit.framework.TestCase;

import org.apidesign.apifest08.currency.Convertor;

import org.apidesign.apifest08.currency.exceptions.InvalidCurrencyException;

import org.apidesign.apifest08.currency.exceptions.UnknownConvertorException;

/**

 * Finish the Convertor API, and then write bodies of methods inside of this class to match the given tasks. To fullfil

 * your task, use the API define in the <code>org.apidesign.apifest08.currency</code> package. Do not you reflection, or

 * other hacks as your code shall run without any runtime permissions.

 */

public class Task1Test extends TestCase {

  public Task1Test(String testName) {

    super(testName);

  }

  @Override

  protected void setUp() throws Exception {

  }

  @Override

  protected void tearDown() throws Exception {

  }

  //

  // Imagine that there are three parts of the whole system:

  // 1. there is someone who knows the current exchange rate

  // 2. there is someone who wants to do the conversion

  // 3. there is the API between 1. and 2. which allows them to communicate

  // Please design such API

  //

  /**

   * Create convertor that understands two currencies, CZK and USD. Make 1 USD == 17 CZK. This is a method provided for

   * #1 group - e.g. those that know the exchange rate. They somehow need to create the objects from the API and tell

   * them the exchange rate. The API itself knows nothing about any rates, before the createCZKtoUSD method is called.

   * Creation of the convertor shall not require subclassing of any class or interface on the client side.

   * @return prepared convertor ready for converting USD to CZK and CZK to USD

   */

  public static Convertor createCZKtoUSD() {

    // set exchange rates

    Convertor.setConvertorRates(Currency.getInstance("USD"), Currency.getInstance("CZK"), 17d, 1d);

    // create new instance

    Convertor convertor = null;

    try {

      convertor = Convertor.getConvertorInstance(Currency.getInstance("USD"), Currency.getInstance("CZK"));

    } catch (UnknownConvertorException e) {

      e.printStackTrace();

    }

    return convertor;

  }

  /**

   * Create convertor that understands two currencies, CZK and SKK. Make 100 SKK == 80 CZK. Again this is method for the

   * #1 group - it knows the exchange rate, and needs to use the API to create objects with the exchange rate. Anyone

   * shall be ready to call this method without any other method being called previously. The API itself shall know

   * nothing about any rates, before this method is called. Creation of the convertor shall not require subclassing of

   * any class or interface on the client side.

   * @return prepared convertor ready for converting SKK to CZK and CZK to SKK

   */

  public static Convertor createSKKtoCZK() {

    // set exchange rates

    Convertor.setConvertorRates(Currency.getInstance("SKK"), Currency.getInstance("CZK"), 80d, 100d);

    // create new instance

    Convertor convertor = null;

    try {

      convertor = Convertor.getConvertorInstance(Currency.getInstance("SKK"), Currency.getInstance("CZK"));

    } catch (UnknownConvertorException e) {

      e.printStackTrace();

    }

    return convertor;

  }

  //

  // now the methods for group #2 follow:

  // this group knows nothing about exchange rates, but knows how to use

  // the API to do conversions. It somehow (by calling one of the factory

  // methods) gets objects from the API and uses them to do the conversions.

  //

  /**

   * Use the convertor from <code>createCZKtoUSD</code> method and do few conversions with it.

   */

  public void testCurrencyCZKUSD() throws Exception {

    Convertor c = createCZKtoUSD();

    // convert $5 to CZK using c:

    double result = c.convert(5, Currency.getInstance("USD"), Currency.getInstance("CZK"));

    assertEquals("Result is not 85 CZK", 85.0, result);

    // convert $8 to CZK

    result = c.convert(8, Currency.getInstance("USD"), Currency.getInstance("CZK"));

    assertEquals("Result is not 136 CZK", 136.0, result);

    // convert 1003CZK to USD

    result = c.convert(1003, Currency.getInstance("CZK"), Currency.getInstance("USD"));

    assertEquals("Result is not 59 USD", 59.0, result);

  }

  /**

   * Use the convertor from <code>createSKKtoCZK</code> method and do few conversions with it.

   */

  public void testCurrencySKKCZK() throws Exception {

    Convertor c = createSKKtoCZK();

    // convert 16CZK using c:

    double result = c.convert(16, Currency.getInstance("CZK"), Currency.getInstance("SKK"));

    assertEquals("Result is not 20 SKK", 20.0, result);

    // convert 500SKK to CZK

    result = c.convert(500, Currency.getInstance("SKK"), Currency.getInstance("CZK"));

    assertEquals("Result is not 400 CZK", 400.0, result);

  }

  /**

   * Verify that the CZK to USD convertor knows nothing about SKK.

   */

  public void testCannotConvertToSKKwithCZKUSDConvertor() throws Exception {

    Convertor c = createCZKtoUSD();

    boolean exceptionThrown = false;

    // convert $5 to SKK, the API shall say this is not possible

    try {

      c.convert(5, Currency.getInstance("USD"), Currency.getInstance("SKK"));

      exceptionThrown = false;

    } catch (InvalidCurrencyException e) {

      exceptionThrown = true;

    }

    assertEquals("It should be impossible to convert to SKK with USD->CZK convertor", true, exceptionThrown);

    // convert 500 SKK to CZK, the API shall say this is not possible

    try {

      c.convert(500, Currency.getInstance("SKK"), Currency.getInstance("CZK"));

      exceptionThrown = false;

    } catch (InvalidCurrencyException e) {

      exceptionThrown = true;

    }

    assertEquals("It should be impossible to convert from SKK with USD->CZK convertor", true, exceptionThrown);

  }

  /**

   * Verify that the CZK to SKK convertor knows nothing about USD.

   */

  public void testCannotConvertToSKKwithSKKCZKConvertor() throws Exception {

    Convertor c = createSKKtoCZK();

    boolean exceptionThrown = false;

    // convert $5 to SKK, the API shall say this is not possible

    try {

      c.convert(5, Currency.getInstance("USD"), Currency.getInstance("SKK"));

      exceptionThrown = false;

    } catch (InvalidCurrencyException e) {

      exceptionThrown = true;

    }

    assertEquals("It should be impossible to convert form USD with SKK->CZK convertor", true, exceptionThrown);

    // convert 500 CZK to USD, the API shall say this is not possible

    try {

      c.convert(500, Currency.getInstance("CZK"), Currency.getInstance("USD"));

      exceptionThrown = false;

    } catch (InvalidCurrencyException e) {

      exceptionThrown = true;

    }

    assertEquals("It should be impossible to convert to USD with SKK->CZK convertor", true, exceptionThrown);

  }

}