/*
 * Copyright 2007 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.user.client.ui;

import com.google.gwt.junit.client.GWTTestCase;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * Tests {@link WidgetIterators}.
 */
public class WidgetIteratorsTest extends GWTTestCase {

  /**
   * Provides a class from which to construct mock containers in this test.
   */
  private static class MockWidget implements HasWidgets {
    @Override
    public void add(Widget w) {
      fail("Unexpected call to add(Widget)");
    }

    @Override
    public void clear() {
      fail("Unexpected call to clear()");
    }

    @Override
    public Iterator<Widget> iterator() {
      fail("Unexpected call to iterator()");
      return null;
    }

    @Override
    public boolean remove(Widget w) {
      fail("Unexpected call to remove(Widget)");
      return false;
    }
  }

  @Override
  public String getModuleName() {
    return "com.google.gwt.user.User";
  }

  /**
   * Tests that empty arrays operate properly.
   */
  public void testEmptyArray() {
    final Iterator<Widget> subject = WidgetIterators.createWidgetIterator(
        new MockWidget(), new Widget[] {null, null});
    assertFalse(subject.hasNext());
    assertNextFails(subject);
    assertRemoveFails(subject);
  }

  /**
   * Tests that remove operates properly on an array of widgets that includes
   * <code>null</code>.
   */
  public void testRemove() {
    final int[] expectedRemoveIndex = new int[1];

    final Widget[] widgets = new Widget[] {
        null, createTestWidget(), null, createTestWidget(), null, null};

    final MockWidget mock = new MockWidget() {
      @Override
      public boolean remove(Widget w) {
        assertEquals(widgets[expectedRemoveIndex[0]], w);
        return true;
      }
    };

    final Iterator<Widget> subject = WidgetIterators.createWidgetIterator(mock, widgets);

    expectedRemoveIndex[0] = 1;
    assertTrue(subject.hasNext());
    assertEquals(widgets[1], subject.next());
    subject.remove();
    assertRemoveFails(subject);

    expectedRemoveIndex[0] = 3;
    assertTrue(subject.hasNext());
    assertEquals(widgets[3], subject.next());
    subject.remove();
    assertRemoveFails(subject);

    assertFalse(subject.hasNext());
    assertNextFails(subject);
  }

  /**
   * Tests that the common iteration pattern works on an array of widgets that
   * contains <code>null</code>.
   */
  public void testStandardIteration() {
    final MockWidget mock = new MockWidget();
    final Widget[] widgets = new Widget[] {
        null, createTestWidget(), null, createTestWidget(), null, null};
    final Iterator<Widget> subject = WidgetIterators.createWidgetIterator(mock, widgets);

    assertTrue(subject.hasNext());
    assertEquals(widgets[1], subject.next());

    assertTrue(subject.hasNext());
    assertEquals(widgets[3], subject.next());

    assertFalse(subject.hasNext());
    assertNextFails(subject);
  }

  private void assertNextFails(Iterator<Widget> iterator) {
    try {
      iterator.next();
      fail("Expected NoSuchElementException.");
    } catch (NoSuchElementException e) {
      // This page left intentionally blank.
    }
  }

  private void assertRemoveFails(Iterator<Widget> iterator) {
    try {
      iterator.remove();
      fail("Expected IllegalStateException.");
    } catch (IllegalStateException e) {
      // The page left intentionally blank.
    }
  }

  private Widget createTestWidget() {
    return new Label("Shazam!");
  }
}