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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.awt;

import java.util.List;
import java.util.ArrayList;
import sun.util.logging.PlatformLogger;

/**
 * A FocusTraversalPolicy that determines traversal order based on the order
 * of child Components in a Container. From a particular focus cycle root, the
 * policy makes a pre-order traversal of the Component hierarchy, and traverses
 * a Container's children according to the ordering of the array returned by
 * <code>Container.getComponents()</code>. Portions of the hierarchy that are
 * not visible and displayable will not be searched.
 * <p>
 * By default, ContainerOrderFocusTraversalPolicy implicitly transfers focus
 * down-cycle. That is, during normal forward focus traversal, the Component
 * traversed after a focus cycle root will be the focus-cycle-root's default
 * Component to focus. This behavior can be disabled using the
 * <code>setImplicitDownCycleTraversal</code> method.
 * <p>
 * By default, methods of this class will return a Component only if it is
 * visible, displayable, enabled, and focusable. Subclasses can modify this
 * behavior by overriding the <code>accept</code> method.
 * <p>
 * This policy takes into account <a
 * href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal
 * policy providers</a>. When searching for first/last/next/previous Component,
 * if a focus traversal policy provider is encountered, its focus traversal
 * policy is used to perform the search operation.
 *
 * @author David Mendenhall
 *
 * @see Container#getComponents
 * @since 1.4
 */
public class ContainerOrderFocusTraversalPolicy extends FocusTraversalPolicy
 implements java.io.Serializable
{
 private static final PlatformLogger log = PlatformLogger.getLogger("java.awt.ContainerOrderFocusTraversalPolicy");

 final private int FORWARD_TRAVERSAL = 0;
 final private int BACKWARD_TRAVERSAL = 1;

 /*
 * JDK 1.4 serialVersionUID
 */
 private static final long serialVersionUID = 486933713763926351L;

 private boolean implicitDownCycleTraversal = true;

 /**
 * Used by getComponentAfter and getComponentBefore for efficiency. In
 * order to maintain compliance with the specification of
 * FocusTraversalPolicy, if traversal wraps, we should invoke
 * getFirstComponent or getLastComponent. These methods may be overriden in
 * subclasses to behave in a non-generic way. However, in the generic case,
 * these methods will simply return the first or last Components of the
 * sorted list, respectively. Since getComponentAfter and
 * getComponentBefore have already built the list before determining
 * that they need to invoke getFirstComponent or getLastComponent, the
 * list should be reused if possible.
 */
 transient private Container cachedRoot;
 transient private List<Component> cachedCycle;

 /*
 * We suppose to use getFocusTraversalCycle & getComponentIndex methods in order
 * to divide the policy into two parts:
 * 1) Making the focus traversal cycle.
 * 2) Traversing the cycle.
 * The 1st point assumes producing a list of components representing the focus
 * traversal cycle. The two methods mentioned above should implement this logic.
 * The 2nd point assumes implementing the common concepts of operating on the
 * cycle: traversing back and forth, retrieving the initial/default/first/last
 * component. These concepts are described in the AWT Focus Spec and they are
 * applied to the FocusTraversalPolicy in general.
 * Thus, a descendant of this policy may wish to not reimplement the logic of
 * the 2nd point but just override the implementation of the 1st one.
 * A striking example of such a descendant is the javax.swing.SortingFocusTraversalPolicy.
 */
 /*protected*/ private List<Component> getFocusTraversalCycle(Container aContainer) {
 List<Component> cycle = new ArrayList<Component>();
 enumerateCycle(aContainer, cycle);
 return cycle;
 }
 /*protected*/ private int getComponentIndex(List<Component> cycle, Component aComponent) {
 return cycle.indexOf(aComponent);
 }

 private void enumerateCycle(Container container, List<Component> cycle) {
 if (!(container.isVisible() && container.isDisplayable())) {
 return;
 }

 cycle.add(container);

 Component[] components = container.getComponents();
 for (int i = 0; i < components.length; i++) {
 Component comp = components[i];
 if (comp instanceof Container) {
 Container cont = (Container)comp;

 if (!cont.isFocusCycleRoot() && !cont.isFocusTraversalPolicyProvider()) {
 enumerateCycle(cont, cycle);
 continue;
 }
 }
 cycle.add(comp);
 }
 }

 private Container getTopmostProvider(Container focusCycleRoot, Component aComponent) {
 Container aCont = aComponent.getParent();
 Container ftp = null;
 while (aCont != focusCycleRoot && aCont != null) {
 if (aCont.isFocusTraversalPolicyProvider()) {
 ftp = aCont;
 }
 aCont = aCont.getParent();
 }
 if (aCont == null) {
 return null;
 }
 return ftp;
 }

 /*
 * Checks if a new focus cycle takes place and returns a Component to traverse focus to.
 * @param comp a possible focus cycle root or policy provider
 * @param traversalDirection the direction of the traversal
 * @return a Component to traverse focus to if {@code comp} is a root or provider
 * and implicit down-cycle is set, otherwise {@code null}
 */
 private Component getComponentDownCycle(Component comp, int traversalDirection) {
 Component retComp = null;

 if (comp instanceof Container) {
 Container cont = (Container)comp;

 if (cont.isFocusCycleRoot()) {
 if (getImplicitDownCycleTraversal()) {
 retComp = cont.getFocusTraversalPolicy().getDefaultComponent(cont);

 if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Transfered focus down-cycle to " + retComp +
 " in the focus cycle root " + cont);
 }
 } else {
 return null;
 }
 } else if (cont.isFocusTraversalPolicyProvider()) {
 retComp = (traversalDirection == FORWARD_TRAVERSAL ?
 cont.getFocusTraversalPolicy().getDefaultComponent(cont) :
 cont.getFocusTraversalPolicy().getLastComponent(cont));

 if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Transfered focus to " + retComp + " in the FTP provider " + cont);
 }
 }
 }
 return retComp;
 }

 /**
 * Returns the Component that should receive the focus after aComponent.
 * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
 * <p>
 * By default, ContainerOrderFocusTraversalPolicy implicitly transfers
 * focus down-cycle. That is, during normal forward focus traversal, the
 * Component traversed after a focus cycle root will be the focus-cycle-
 * root's default Component to focus. This behavior can be disabled using
 * the <code>setImplicitDownCycleTraversal</code> method.
 * <p>
 * If aContainer is <a href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
 * traversal policy provider</a>, the focus is always transferred down-cycle.
 *
 * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
 * @param aComponent a (possibly indirect) child of aContainer, or
 * aContainer itself
 * @return the Component that should receive the focus after aComponent, or
 * null if no suitable Component can be found
 * @throws IllegalArgumentException if aContainer is not a focus cycle
 * root of aComponent or focus traversal policy provider, or if either aContainer or
 * aComponent is null
 */
 public Component getComponentAfter(Container aContainer, Component aComponent) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Searching in " + aContainer + " for component after " + aComponent);
 }

 if (aContainer == null || aComponent == null) {
 throw new IllegalArgumentException("aContainer and aComponent cannot be null");
 }
 if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
 throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");

 } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
 throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
 }

 synchronized(aContainer.getTreeLock()) {

 if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 return null;
 }

 // Before all the ckecks below we first see if it's an FTP provider or a focus cycle root.
 // If it's the case just go down cycle (if it's set to "implicit").
 Component comp = getComponentDownCycle(aComponent, FORWARD_TRAVERSAL);
 if (comp != null) {
 return comp;
 }

 // See if the component is inside of policy provider.
 Container provider = getTopmostProvider(aContainer, aComponent);
 if (provider != null) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Asking FTP " + provider + " for component after " + aComponent);
 }

 // FTP knows how to find component after the given. We don't.
 FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
 Component afterComp = policy.getComponentAfter(provider, aComponent);

 // Null result means that we overstepped the limit of the FTP's cycle.
 // In that case we must quit the cycle, otherwise return the component found.
 if (afterComp != null) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### FTP returned " + afterComp);
 }
 return afterComp;
 }
 aComponent = provider;
 }

 List<Component> cycle = getFocusTraversalCycle(aContainer);

 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Cycle is " + cycle + ", component is " + aComponent);
 }

 int index = getComponentIndex(cycle, aComponent);

 if (index < 0) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
 }
 return getFirstComponent(aContainer);
 }

 for (index++; index < cycle.size(); index++) {
 comp = cycle.get(index);
 if (accept(comp)) {
 return comp;
 } else if ((comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null) {
 return comp;
 }
 }

 if (aContainer.isFocusCycleRoot()) {
 this.cachedRoot = aContainer;
 this.cachedCycle = cycle;

 comp = getFirstComponent(aContainer);

 this.cachedRoot = null;
 this.cachedCycle = null;

 return comp;
 }
 }
 return null;
 }

 /**
 * Returns the Component that should receive the focus before aComponent.
 * aContainer must be a focus cycle root of aComponent or a <a
 * href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal policy
 * provider</a>.
 *
 * @param aContainer a focus cycle root of aComponent or focus traversal policy provider
 * @param aComponent a (possibly indirect) child of aContainer, or
 * aContainer itself
 * @return the Component that should receive the focus before aComponent,
 * or null if no suitable Component can be found
 * @throws IllegalArgumentException if aContainer is not a focus cycle
 * root of aComponent or focus traversal policy provider, or if either aContainer or
 * aComponent is null
 */
 public Component getComponentBefore(Container aContainer, Component aComponent) {
 if (aContainer == null || aComponent == null) {
 throw new IllegalArgumentException("aContainer and aComponent cannot be null");
 }
 if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
 throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");

 } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
 throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
 }

 synchronized(aContainer.getTreeLock()) {

 if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 return null;
 }

 // See if the component is inside of policy provider.
 Container provider = getTopmostProvider(aContainer, aComponent);
 if (provider != null) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Asking FTP " + provider + " for component after " + aComponent);
 }

 // FTP knows how to find component after the given. We don't.
 FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
 Component beforeComp = policy.getComponentBefore(provider, aComponent);

 // Null result means that we overstepped the limit of the FTP's cycle.
 // In that case we must quit the cycle, otherwise return the component found.
 if (beforeComp != null) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### FTP returned " + beforeComp);
 }
 return beforeComp;
 }
 aComponent = provider;

 // If the provider is traversable it's returned.
 if (accept(aComponent)) {
 return aComponent;
 }
 }

 List<Component> cycle = getFocusTraversalCycle(aContainer);

 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Cycle is " + cycle + ", component is " + aComponent);
 }

 int index = getComponentIndex(cycle, aComponent);

 if (index < 0) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
 }
 return getLastComponent(aContainer);
 }

 Component comp = null;
 Component tryComp = null;

 for (index--; index>=0; index--) {
 comp = cycle.get(index);
 if (comp != aContainer && (tryComp = getComponentDownCycle(comp, BACKWARD_TRAVERSAL)) != null) {
 return tryComp;
 } else if (accept(comp)) {
 return comp;
 }
 }

 if (aContainer.isFocusCycleRoot()) {
 this.cachedRoot = aContainer;
 this.cachedCycle = cycle;

 comp = getLastComponent(aContainer);

 this.cachedRoot = null;
 this.cachedCycle = null;

 return comp;
 }
 }
 return null;
 }

 /**
 * Returns the first Component in the traversal cycle. This method is used
 * to determine the next Component to focus when traversal wraps in the
 * forward direction.
 *
 * @param aContainer the focus cycle root or focus traversal policy provider whose first
 * Component is to be returned
 * @return the first Component in the traversal cycle of aContainer,
 * or null if no suitable Component can be found
 * @throws IllegalArgumentException if aContainer is null
 */
 public Component getFirstComponent(Container aContainer) {
 List<Component> cycle;

 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Getting first component in " + aContainer);
 }
 if (aContainer == null) {
 throw new IllegalArgumentException("aContainer cannot be null");

 }

 synchronized(aContainer.getTreeLock()) {

 if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 return null;
 }

 if (this.cachedRoot == aContainer) {
 cycle = this.cachedCycle;
 } else {
 cycle = getFocusTraversalCycle(aContainer);
 }

 if (cycle.size() == 0) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Cycle is empty");
 }
 return null;
 }
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Cycle is " + cycle);
 }

 for (Component comp : cycle) {
 if (accept(comp)) {
 return comp;
 } else if (comp != aContainer &&
 (comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null)
 {
 return comp;
 }
 }
 }
 return null;
 }

 /**
 * Returns the last Component in the traversal cycle. This method is used
 * to determine the next Component to focus when traversal wraps in the
 * reverse direction.
 *
 * @param aContainer the focus cycle root or focus traversal policy provider whose last
 * Component is to be returned
 * @return the last Component in the traversal cycle of aContainer,
 * or null if no suitable Component can be found
 * @throws IllegalArgumentException if aContainer is null
 */
 public Component getLastComponent(Container aContainer) {
 List<Component> cycle;
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Getting last component in " + aContainer);
 }

 if (aContainer == null) {
 throw new IllegalArgumentException("aContainer cannot be null");
 }

 synchronized(aContainer.getTreeLock()) {

 if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 return null;
 }

 if (this.cachedRoot == aContainer) {
 cycle = this.cachedCycle;
 } else {
 cycle = getFocusTraversalCycle(aContainer);
 }

 if (cycle.size() == 0) {
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Cycle is empty");
 }
 return null;
 }
 if (log.isLoggable(PlatformLogger.Level.FINE)) {
 log.fine("### Cycle is " + cycle);
 }

 for (int i= cycle.size() - 1; i >= 0; i--) {
 Component comp = cycle.get(i);
 if (accept(comp)) {
 return comp;
 } else if (comp instanceof Container && comp != aContainer) {
 Container cont = (Container)comp;
 if (cont.isFocusTraversalPolicyProvider()) {
 Component retComp = cont.getFocusTraversalPolicy().getLastComponent(cont);
 if (retComp != null) {
 return retComp;
 }
 }
 }
 }
 }
 return null;
 }

 /**
 * Returns the default Component to focus. This Component will be the first
 * to receive focus when traversing down into a new focus traversal cycle
 * rooted at aContainer. The default implementation of this method
 * returns the same Component as <code>getFirstComponent</code>.
 *
 * @param aContainer the focus cycle root or focus traversal policy provider whose default
 * Component is to be returned
 * @return the default Component in the traversal cycle of aContainer,
 * or null if no suitable Component can be found
 * @see #getFirstComponent
 * @throws IllegalArgumentException if aContainer is null
 */
 public Component getDefaultComponent(Container aContainer) {
 return getFirstComponent(aContainer);
 }

 /**
 * Sets whether this ContainerOrderFocusTraversalPolicy transfers focus
 * down-cycle implicitly. If <code>true</code>, during normal forward focus
 * traversal, the Component traversed after a focus cycle root will be the
 * focus-cycle-root's default Component to focus. If <code>false</code>,
 * the next Component in the focus traversal cycle rooted at the specified
 * focus cycle root will be traversed instead. The default value for this
 * property is <code>true</code>.
 *
 * @param implicitDownCycleTraversal whether this
 * ContainerOrderFocusTraversalPolicy transfers focus down-cycle
 * implicitly
 * @see #getImplicitDownCycleTraversal
 * @see #getFirstComponent
 */
 public void setImplicitDownCycleTraversal(boolean implicitDownCycleTraversal) {
 this.implicitDownCycleTraversal = implicitDownCycleTraversal;
 }

 /**
 * Returns whether this ContainerOrderFocusTraversalPolicy transfers focus
 * down-cycle implicitly. If <code>true</code>, during normal forward focus
 * traversal, the Component traversed after a focus cycle root will be the
 * focus-cycle-root's default Component to focus. If <code>false</code>,
 * the next Component in the focus traversal cycle rooted at the specified
 * focus cycle root will be traversed instead.
 *
 * @return whether this ContainerOrderFocusTraversalPolicy transfers focus
 * down-cycle implicitly
 * @see #setImplicitDownCycleTraversal
 * @see #getFirstComponent
 */
 public boolean getImplicitDownCycleTraversal() {
 return implicitDownCycleTraversal;
 }

 /**
 * Determines whether a Component is an acceptable choice as the new
 * focus owner. By default, this method will accept a Component if and
 * only if it is visible, displayable, enabled, and focusable.
 *
 * @param aComponent the Component whose fitness as a focus owner is to
 * be tested
 * @return <code>true</code> if aComponent is visible, displayable,
 * enabled, and focusable; <code>false</code> otherwise
 */
 protected boolean accept(Component aComponent) {
 if (!aComponent.canBeFocusOwner()) {
 return false;
 }

 // Verify that the Component is recursively enabled. Disabling a
 // heavyweight Container disables its children, whereas disabling
 // a lightweight Container does not.
 if (!(aComponent instanceof Window)) {
 for (Container enableTest = aComponent.getParent();
 enableTest != null;
 enableTest = enableTest.getParent())
 {
 if (!(enableTest.isEnabled() || enableTest.isLightweight())) {
 return false;
 }
 if (enableTest instanceof Window) {
 break;
 }
 }
 }

 return true;
 }
}