source: trunk/EventBenchConsole/src/de/ugoe/cs/eventbench/data/WindowTree.java @ 1

package de.ugoe.cs.eventbench.data;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * <p>
 * This class provides an the interfaces for window trees.
 * </p>
 * <p>
 * The window tree represents the hierarchical structure of the windows
 * "as it is" currently during a session. It may change during the session due
 * to creation and destruction of windows.
 * </p>
 * <p>
 * The class is implemented as a singleton. The rational behind implementing
 * this class as a singleton is to ease the access of all class that may request
 * information about the windows during the parsing of a session. As the tree
 * may change during the session, it does not make sense to preserve it after a
 * session. Thus, it can just be deleted. Therefore, as long as only one session
 * is parsed at a time, a single instance is sufficient.
 * </p>
 * 
 * @author Steffen Herbold
 */
public class WindowTree {

        /**
         * <p>
         * Handle to the window instance.
         * </p>
         */
        private static WindowTree theInstance = null;

        /**
         * <p>
         * Obtain a handle to the window instance.
         * </p>
         * 
         * @return
         */
        public static WindowTree getInstance() {
                if (theInstance == null) {
                        theInstance = new WindowTree();
                }
                return theInstance;
        }

        /**
         * <p>
         * Resets the tree. Should be used between sessions.
         * </p>
         */
        public static void resetTree() {
                theInstance = null;
        }

        /**
         * <p>
         * Map of all windows that are part of the tree for efficient searching. The
         * keys of the map are the hwnd's of the windows.
         * </p>
         */
        private Map<Integer, WindowTreeNode> nodes;

        /**
         * <p>
         * Creates a new WindowTree.
         * </p>
         * <p>
         * Private, as the class is a singleton.
         * </p>
         */
        private WindowTree() {
                nodes = new HashMap<Integer, WindowTreeNode>();
        }

        /**
         * <p>
         * Adds a new window to the tree.
         * </p>
         * 
         * @param parentHwnd
         *            hwnd of the parent window
         * @param childHwnd
         *            hwnd of the window to be created
         * @param childWindowName
         *            resource id of the window to be created
         * @param resourceId
         *            resource id of the window to be created
         * @param className
         *            class name of the window to be created
         */
        public void add(int parentHwnd, int childHwnd, String childWindowName,
                        int resourceId, String className, boolean isModal) {
                WindowTreeNode parent = nodes.get(parentHwnd);
                WindowTreeNode child = nodes.get(childHwnd);
                if (child == null) {
                        if (parent != null) {
                                child = parent.addChild(childHwnd, childWindowName, resourceId,
                                                className, isModal);
                        } else {
                                child = new WindowTreeNode(childHwnd, null, childWindowName,
                                                resourceId, className, isModal);
                        }
                        nodes.put(childHwnd, child);
                }
        }

        /**
         * <p>
         * Removes a window (defined by its hwnd) from the tree. All children of the
         * window will be removed recursively.
         * </p>
         * 
         * @param hwnd
         *            hwnd of the window to be removed
         * @return number of windows that were removed
         */
        public int remove(int hwnd) {
                int removedCounter = 0;
                WindowTreeNode node = nodes.get(hwnd);
                if (node != null) {
                        List<WindowTreeNode> nodesToBeRemoved = node.remove();
                        for (int i = 0; i < nodesToBeRemoved.size(); i++) {
                                WindowTreeNode nodeToBeRemoved = nodesToBeRemoved.get(i);
                                nodesToBeRemoved.addAll(nodeToBeRemoved.getChildren());
                                nodes.remove(nodeToBeRemoved.getHwnd());
                                removedCounter++;
                        }
                        nodes.remove(hwnd);
                        removedCounter++;
                }
                return removedCounter;
        }

        /**
         * <p>
         * Searches the tree for a window with the specified hwnd and returns its
         * {@link WindowTreeNode}.
         * </p>
         * 
         * @param hwnd
         *            hwnd that is looked for
         * @return {@link WindowTreeNode} of the window with the given hwnd if
         *         found, null otherwise
         */
        public WindowTreeNode find(int hwnd) {
                return nodes.get(hwnd);
        }
        
        /**
         * <p>
         * Returns the number of nodes contained in the WindowTree.
         * </p>
         * 
         * @return number of nodes
         */
        public int size() {
                return nodes.size();
        }
}