package fumokmm.test.factory;

import java.util.*;
import org.junit.*;
import static org.junit.Assert.*;
import static org.hamcrest.CoreMatchers.*;

public class FactoryTest {

  static abstract class Alphabet {
    abstract String whoAmI();
  }
  static class A extends Alphabet {
    @Override String whoAmI() { return "I'm A!"; }
  }
  static class B extends Alphabet {
    @Override String whoAmI() { return "I'm B!"; }
  }
  static class C extends Alphabet {
    @Override String whoAmI() { return "I'm C!"; }
  }

  static interface Animal {}
  static class Cat implements Animal {}
  static class Dog implements Animal {}

  static class Factory<T> {
    private Map<Class<? extends T>, T> instanceMap =
      new HashMap<Class<? extends T>, T>();

    public <U extends T> U getOrCreate(Class<U> clazz) {
      if (! instanceMap.containsKey(clazz)) {
        try {
          instanceMap.put(clazz, clazz.newInstance());
        } catch (InstantiationException e) {
          e.printStackTrace();
        } catch (IllegalAccessException e) {
          e.printStackTrace();
        }
      }
      return clazz.cast(instanceMap.get(clazz));
    }
  }

  // 以下テスト

  Factory<Alphabet> factory;

  @Before
  public void setup() {
    factory = new Factory<Alphabet>();
  }

  @Test
  public void createするテスト() {
    A a = factory.getOrCreate(A.class);
    assertThat(a instanceof A, is(true));

    B b = factory.getOrCreate(B.class);
    assertThat(b instanceof B, is(true));

    C c = factory.getOrCreate(C.class);
    assertThat(c instanceof C, is(true));
  }

  @Test
  public void AlphabetとしてCreateするテスト() {
    Alphabet someAlp = factory.getOrCreate(A.class);
    assertThat(someAlp.whoAmI(), is("I'm A!"));
    assertThat(someAlp instanceof A, is(true));

    someAlp = factory.getOrCreate(B.class);
    assertThat(someAlp.whoAmI(), is("I'm B!"));
    assertThat(someAlp instanceof B, is(true));
  }

  @Test
  public void Factoryの使い分けのテスト() {
    // Animal用のFactory
    Factory<Animal> aniFactory = new Factory<Animal>();
    aniFactory.getOrCreate(Cat.class);
    aniFactory.getOrCreate(Dog.class);

    //aniFactory.getOrCreate(A.class);
    // => コンパイルエラー：aniFactoryは Animal を extends (implements) したクラスのみ生成可能
  }

  @Test
  public void インスタンスは同じファクトリ内で使い回されるテスト() {
    assertThat("最初はサイズ0", factory.instanceMap.size(), is(0));
    A a1 = factory.getOrCreate(A.class);
    assertThat("Aを生成＆取得", factory.instanceMap.size(), is(1));
    factory.getOrCreate(B.class);
    assertThat("Bを生成＆取得", factory.instanceMap.size(), is(2));
    A a2 = factory.getOrCreate(A.class);
    assertThat("Aは既に取得済みなので増えない", factory.instanceMap.size(), is(2));
    assertSame("同じオブジェクトのはず", a1, a2);
  }

}