/*
 * Copyright 2000-2010 JetBrains s.r.o.
 *
 * 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.intellij.ui;

import com.intellij.openapi.util.Pair;
import com.intellij.util.Function;
import gnu.trove.THashSet;
import org.jetbrains.annotations.NotNull;

import java.awt.*;
import java.util.Collections;
import java.util.Set;

public class ExcludingTraversalPolicy extends FocusTraversalPolicy {
  private final FocusTraversalPolicy myWrappee;
  private final Set<Component> myExcludes = new THashSet<Component>();
  private final Set<String> myRecursionGuard = new THashSet<String>();

  public ExcludingTraversalPolicy(Component... excludes) {
    this(KeyboardFocusManager.getCurrentKeyboardFocusManager().getDefaultFocusTraversalPolicy(), excludes);
  }

  public ExcludingTraversalPolicy(@NotNull FocusTraversalPolicy wrappee, Component... excludes) {
    myWrappee = wrappee;
    Collections.addAll(myExcludes, excludes);
  }

  public void exclude(Component c) {
    myExcludes.add(c);
  }

  @Override
  public Component getComponentAfter(Container aContainer, Component aComponent) {
    try {
      if (!myRecursionGuard.add("getComponentAfter")) return null;

      return traverse(aContainer, aComponent, new Function<Pair<Container, Component>, Component>() {
        public Component fun(Pair<Container, Component> param) {
          return myWrappee.getComponentAfter(param.first, param.second);
        }
      });
    }
    finally {
      myRecursionGuard.clear();
    }
  }

  @Override
  public Component getComponentBefore(Container aContainer, Component aComponent) {
    try {
      if (!myRecursionGuard.add("getComponentBefore")) return null;

      return traverse(aContainer, aComponent, new Function<Pair<Container, Component>, Component>() {
        public Component fun(Pair<Container, Component> param) {
          return myWrappee.getComponentBefore(param.first, param.second);
        }
      });
    }
    finally {
      myRecursionGuard.clear();
    }
  }

  private Component traverse(Container aContainer, Component aComponent, Function<Pair<Container, Component>, Component> func) {
    Set<Component> loopGuard = new THashSet<Component>();
    do {
      if (!loopGuard.add(aComponent)) return null;
      aComponent = func.fun(Pair.create(aContainer, aComponent));
    }
    while (aComponent != null && myExcludes.contains(aComponent));
    return aComponent;
  }

  @Override
  public Component getFirstComponent(Container aContainer) {
    try {
      if (!myRecursionGuard.add("getFirstComponent")) return null;

      Component result = myWrappee.getFirstComponent(aContainer);
      if (result == null) return null;
      return myExcludes.contains(result) ? getComponentAfter(aContainer, result) : result;
    }
    finally {
      myRecursionGuard.clear();
    }
  }

  @Override
  public Component getLastComponent(Container aContainer) {
    try {
      if (!myRecursionGuard.add("getLastComponent")) return null;

      Component result = myWrappee.getLastComponent(aContainer);
      if (result == null) return null;
      return myExcludes.contains(result) ? getComponentBefore(aContainer, result) : result;
    }
    finally {
      myRecursionGuard.clear();
    }
  }

  @Override
  public Component getDefaultComponent(Container aContainer) {
    try {
      if (!myRecursionGuard.add("getDefaultComponent")) return null;

      return getFirstComponent(aContainer);
    }
    finally {
      myRecursionGuard.clear();
    }
  }
}