/*
 * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package java.awt;

import java.util.logging.*;

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
Container.getComponents(). Portions of the hierarchy that are
not visible and displayable will not be searched.

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
setImplicitDownCycleTraversal method.

By default, methods of this class with return a Component only if it is
visible, displayable, enabled, and focusable. Subclasses can modify this
behavior by overriding the accept method.

This policy takes into account focus traversal
policy providers.  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 Also:
Container.getComponents
Since:
1.4/**
 * 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 with 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 MutableBoolean found = new MutableBoolean();

    private static final Logger log = Logger.getLogger("java.awt.ContainerOrderFocusTraversalPolicy");

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

    private boolean implicitDownCycleTraversal = true;

    
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.

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 setImplicitDownCycleTraversal method.

If aContainer is focus
traversal policy provider, the focus is always transferred down-cycle.
Params:
aContainer – a focus cycle root of aComponent or a focus traversal policy provider
aComponent – a (possibly indirect) child of aContainer, or
       aContainer itself
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
Returns:
the Component that should receive the focus after aComponent, or
        null if no suitable Component can be found/**
     * 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(Level.FINE)) {
	    log.fine("Looking for next component in " + aContainer  + " for " + 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()) {
            found.value = false;
            Component retval = getComponentAfter(aContainer, aComponent,
                                                 found);
            if (retval != null) {
                if (log.isLoggable(Level.FINE)) {
		    log.fine("After component is " + retval);
		}
                return retval;
            } else if (found.value) {
                if (log.isLoggable(Level.FINE)) {
		    log.fine("Didn't find next component in " + aContainer + " - falling back to the first ");
		}
                return getFirstComponent(aContainer);
            } else {
                if (log.isLoggable(Level.FINE)) {
		    log.fine("After component is null");
		}
                return null;
            }
        }
    }

    private Component getComponentAfter(Container aContainer,
                                        Component aComponent,
                                        MutableBoolean found) {
        if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
            return null;
        }

        if (found.value) {
            if (accept(aContainer)) {
                return aContainer;
            }
        } else if (aContainer == aComponent) {
            found.value = true;
        }

        for (int i = 0; i < aContainer.getComponentCount(); i++) {
            Component comp = aContainer.getComponent(i);
            if ((comp instanceof Container) &&
                !((Container)comp).isFocusCycleRoot()) {
                Component retval = null;
                if (((Container)comp).isFocusTraversalPolicyProvider()) {
                    if (log.isLoggable(Level.FINE)) {
			log.fine("Entering FTP " + comp);
		    }
                    Container cont = (Container) comp;
                    FocusTraversalPolicy policy = cont.getFocusTraversalPolicy();
                    if (log.isLoggable(Level.FINE)) {
			log.fine("FTP contains " + aComponent + ": " + cont.isAncestorOf(aComponent));
		    }
                    if (found.value) {
                        retval = policy.getDefaultComponent(cont);
                        if (log.isLoggable(Level.FINE)) {
			    log.fine("Used FTP for getting default component: " + retval);
			}
                    } else {
                        found.value = cont.isAncestorOf(aComponent);
                        if (found.value)  {
                            if (aComponent == policy.getLastComponent(cont)) {
                            // Reached last component, going to wrap - should switch to next provider
                            retval = null;
                            } else {
                                retval = policy.getComponentAfter(cont, aComponent);
                                if (log.isLoggable(Level.FINE)) {
				    log.fine("FTP found next for the component : " + retval);
				}
                            }
                        }
                    }
                } else {
                    retval = getComponentAfter((Container)comp,
                                                     aComponent,
                                                     found);
                }
                if (retval != null) {
                    return retval;
                }
            } else if (found.value) {
                if (accept(comp)) {
                    return comp;
                }
            } else if (comp == aComponent) {
                found.value = true;
            }

            if (found.value &&
                getImplicitDownCycleTraversal() &&
                (comp instanceof Container) &&
                ((Container)comp).isFocusCycleRoot())
            {
                Container cont = (Container)comp;
                Component retval = cont.getFocusTraversalPolicy().
                    getDefaultComponent(cont);
                if (retval != null) {
                    return retval;
                }
            }
        }

        return null;
    }

    
Returns the Component that should receive the focus before aComponent.
aContainer must be a focus cycle root of aComponent or a focus traversal policy
provider.
Params:
aContainer – a focus cycle root of aComponent or focus traversal policy provider
aComponent – a (possibly indirect) child of aContainer, or
       aContainer itself
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
Returns:
the Component that should receive the focus before aComponent,
        or null if no suitable Component can be found/**
     * 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()) {
            found.value = false;
            Component retval = getComponentBefore(aContainer, aComponent,
                                                  found);
            if (retval != null) {
                if (log.isLoggable(Level.FINE)) {
		    log.fine("Before component is " + retval);
		}
                return retval;
            } else if (found.value) {
                if (log.isLoggable(Level.FINE)) {
		    log.fine("Didn't find before component in " + aContainer + " - falling back to the first ");
		}
                return getLastComponent(aContainer);
            } else {
                if (log.isLoggable(Level.FINE)) {
		    log.fine("Before component is null");
		}
                return null;
            }
        }
    }

    private Component getComponentBefore(Container aContainer,
                                         Component aComponent,
                                         MutableBoolean found) {
        if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
            return null;
        }

        for (int i = aContainer.getComponentCount() - 1; i >= 0; i--) {
            Component comp = aContainer.getComponent(i);
            if (comp == aComponent) {
                found.value = true;
            } else if ((comp instanceof Container) &&
                !((Container)comp).isFocusCycleRoot()) {
                Component retval = null;
                if (((Container)comp).isFocusTraversalPolicyProvider()) {
                    if (log.isLoggable(Level.FINE)) {
			log.fine("Entering FTP " + comp);
		    }
                    Container cont = (Container) comp;
                    FocusTraversalPolicy policy = cont.getFocusTraversalPolicy();
                    if (log.isLoggable(Level.FINE)) {
			log.fine("FTP contains " + aComponent + ": " + cont.isAncestorOf(aComponent));
		    }
                    if (found.value) {
                        retval = policy.getLastComponent(cont);
                        if (log.isLoggable(Level.FINE)) {
			    log.fine("Used FTP for getting last component: " + retval);
			}
                    } else {
                        found.value = cont.isAncestorOf(aComponent);
                        if (found.value) {
                            if (aComponent == policy.getFirstComponent(cont)) {
                                retval = null;
                            } else {
                                retval = policy.getComponentBefore(cont, aComponent);
                                if (log.isLoggable(Level.FINE)) {
				    log.fine("FTP found previous for the component : " + retval);
				}
                            }
                        }
                    }
                } else {
                    retval = getComponentBefore((Container)comp,
                                                      aComponent,
                                                      found);
                }
                if (retval != null) {
                    return retval;
                }
            } else if (found.value) {
                if (accept(comp)) {
                    return comp;
                }
            }
        }

        if (found.value) {
            if (accept(aContainer)) {
                return aContainer;
            }
        } else if (aContainer == aComponent) {
            found.value = true;
        }

        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.
Params:
aContainer – the focus cycle root or focus traversal policy provider whose first
       Component is to be returned
Throws:
IllegalArgumentException – if aContainer is null
Returns:
the first Component in the traversal cycle of aContainer,
        or null if no suitable Component can be found/**
     * 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) {
        if (aContainer == null) {
            throw new IllegalArgumentException("aContainer cannot be null");
        }

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

            if (accept(aContainer)) {
                return aContainer;
            }

            for (int i = 0; i < aContainer.getComponentCount(); i++) {
                Component comp = aContainer.getComponent(i);
                if (comp instanceof Container &&
                    !((Container)comp).isFocusCycleRoot())
                {
                    Component retval = null;
                    Container cont = (Container)comp;
                    if (cont.isFocusTraversalPolicyProvider()) {
                        FocusTraversalPolicy policy = cont.getFocusTraversalPolicy();
                        retval = policy.getDefaultComponent(cont);
                    } else {
                        retval = getFirstComponent((Container)comp);
                    }
                    if (retval != null) {
                        return retval;
                    }
                } else if (accept(comp)) {
                    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.
Params:
aContainer – the focus cycle root or focus traversal policy provider whose last
       Component is to be returned
Throws:
IllegalArgumentException – if aContainer is null
Returns:
the last Component in the traversal cycle of aContainer,
        or null if no suitable Component can be found/**
     * 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) {
        if (aContainer == null) {
            throw new IllegalArgumentException("aContainer cannot be null");
        }
        if (log.isLoggable(Level.FINE)) {
	    log.fine("Looking for the last component in " + aContainer);
	}

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

            for (int i = aContainer.getComponentCount() - 1; i >= 0; i--) {
                Component comp = aContainer.getComponent(i);
                if (comp instanceof Container &&
                    !((Container)comp).isFocusCycleRoot())
                {
                    Component retval = null;
                    Container cont = (Container)comp;
                    if (cont.isFocusTraversalPolicyProvider()) {
                        if (log.isLoggable(Level.FINE)) {
			    log.fine("\tEntering FTP " + cont);
			}
                        FocusTraversalPolicy policy = cont.getFocusTraversalPolicy();
                        retval = policy.getLastComponent(cont);
                    } else {
                        if (log.isLoggable(Level.FINE)) {
			    log.fine("\tEntering sub-container");
			}
                        retval = getLastComponent((Container)comp);
                    }
                    if (retval != null) {
                        if (log.isLoggable(Level.FINE)) {
			    log.fine("\tFound last component : " + retval);
			}
                        return retval;
                    }
                } else if (accept(comp)) {
                    return comp;
                }
            }

            if (accept(aContainer)) {
                return aContainer;
            }
        }

        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 getFirstComponent.
Params:
aContainer – the focus cycle root or focus traversal policy provider whose default
       Component is to be returned
Throws:
IllegalArgumentException – if aContainer is null
See Also:
getFirstComponent
Returns:
the default Component in the traversal cycle of aContainer,
        or null if no suitable Component can be found/**
     * 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 true, 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 false,
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 true.
Params:
implicitDownCycleTraversal – whether this
       ContainerOrderFocusTraversalPolicy transfers focus down-cycle
       implicitly
See Also:
getImplicitDownCycleTraversal
getFirstComponent/**
     * 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 true, 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 false,
the next Component in the focus traversal cycle rooted at the specified
focus cycle root will be traversed instead.
See Also:
setImplicitDownCycleTraversal
getFirstComponent
Returns:
whether this ContainerOrderFocusTraversalPolicy transfers focus
        down-cycle implicitly/**
     * 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.
Params:
aComponent – the Component whose fitness as a focus owner is to
       be tested
Returns:
true if aComponent is visible, displayable,
        enabled, and focusable; false otherwise/**
     * 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;
    }

}


class MutableBoolean {
    boolean value = false;
}