/*******************************************************************************
 * Copyright (c) 2001, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 * IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.wst.validation.internal.ui;

import java.lang.reflect.InvocationTargetException;
import java.util.logging.Level;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.jem.util.logger.LogEntry;
import org.eclipse.jem.util.logger.proxy.Logger;
import org.eclipse.jface.preference.PreferencePage;
import org.eclipse.jface.viewers.CheckboxTableViewer;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerSorter;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ScrolledComposite;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.KeyListener;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.MessageBox;
import org.eclipse.swt.widgets.TableItem;
import org.eclipse.swt.widgets.Text;
import org.eclipse.ui.IWorkbench;
import org.eclipse.ui.IWorkbenchPreferencePage;
import org.eclipse.ui.PlatformUI;
import org.eclipse.wst.common.frameworks.internal.ui.WTPUIPlugin;
import org.eclipse.wst.validation.internal.ConfigurationManager;
import org.eclipse.wst.validation.internal.GlobalConfiguration;
import org.eclipse.wst.validation.internal.ProjectConfiguration;
import org.eclipse.wst.validation.internal.ValidationConfiguration;
import org.eclipse.wst.validation.internal.ValidatorMetaData;
import org.eclipse.wst.validation.internal.operations.ValidatorManager;
import org.eclipse.wst.validation.internal.ui.plugin.ValidationUIPlugin;

/**
 * This class and its inner classes are not intended to be subclassed outside of the validation
 * framework.
 */
public class ValidationPreferencePage extends PreferencePage implements IWorkbenchPreferencePage {
	private IValidationPage _pageImpl = null;

	/**
	 * Initially, this interface was created as an abstract class, and getControl() was implemented.
	 * (getProject() could also have been implemented in the abstract class.) However, at runtime, a
	 * NullPointerException was thrown; the inner class had lost its pointer to its enclosing class.
	 * After some experimentation, I discovered that if I changed the parent to an interface, the
	 * enclosing class could be found. (Merely moving the AValidationPage into its own file was
	 * insufficient.)
	 */
	public interface IValidationPage {
		public Composite createPage(Composite parent) throws InvocationTargetException;

		public boolean performOk() throws InvocationTargetException;

		public boolean performDefaults() throws InvocationTargetException;

		public Composite getControl();

		public void dispose();

		public void loseFocus(); // Page is losing focus (event notification)

		public void gainFocus(); // Page is gaining focus (event notification)
	}

	public class InvalidPage implements IValidationPage {
		private Composite page = null;

		private Composite composite = null;
		private GridLayout layout = null;
		private Label messageLabel = null;

		public InvalidPage(Composite parent) {
			page = createPage(parent);
		}

		/**
		 * This page is added to the Properties guide if some internal problem occurred; for
		 * example, the highlighted item in the workbench is not an IProject (according to this
		 * page's plugin.xml, this page is only valid when an IProject is selected).
		 */
		public Composite createPage(Composite parent) {
			// Don't create the default and apply buttons.
			noDefaultAndApplyButton();

			final ScrolledComposite sc1 = new ScrolledComposite(parent, SWT.H_SCROLL | SWT.V_SCROLL);
			sc1.setLayoutData(new GridData(GridData.FILL_BOTH));
			composite = new Composite(sc1, SWT.NONE);
			sc1.setContent(composite);
			layout = new GridLayout();
			composite.setLayout(layout);
			PlatformUI.getWorkbench().getHelpSystem().setHelp(composite, ContextIds.VALIDATION_PROPERTIES_PAGE);

			messageLabel = new Label(composite, SWT.NONE);
			messageLabel.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INVALID_REGISTER));

			composite.setSize(composite.computeSize(SWT.DEFAULT, SWT.DEFAULT));

			return composite;
		}

		public boolean performDefaults() {
			return true;
		}

		/**
		 * Since this page occurs under invalid circumstances, there is nothing to save.
		 */
		public boolean performOk() {
			return true;
		}

		public Composite getControl() {
			return page;
		}

		public void dispose() {
			messageLabel.dispose();
			//			layout.dispose();
			composite.dispose();
		}

		public void loseFocus() {
			// This page does not depend on the contents of any other page in the wizard, so do
			// nothing.
		}

		public void gainFocus() {
			// This page does not depend on the contents of any other page in the wizard, so do
			// nothing.
		}
	}

	private class NoValidatorsPage implements IValidationPage {
		private Composite page = null;
		private Composite composite = null;
		private GridLayout layout = null;
		private GridData data = null;
		private Label messageLabel = null;

		public NoValidatorsPage(Composite parent) {
			page = createPage(parent);
		}

		/**
		 * This page is created if an IProject is selected, but that project has no validators
		 * configured (i.e., the page is valid, but an empty list.)
		 */
		public Composite createPage(Composite parent) {
			// Don't create the default and apply buttons.
			noDefaultAndApplyButton();

			// top level group
			final ScrolledComposite sc1 = new ScrolledComposite(parent, SWT.H_SCROLL | SWT.V_SCROLL);
			sc1.setLayoutData(new GridData(GridData.FILL_BOTH));
			composite = new Composite(sc1, SWT.NONE);
			sc1.setContent(composite);
			layout = new GridLayout();
			composite.setLayout(layout);
			data = new GridData(GridData.VERTICAL_ALIGN_FILL | GridData.HORIZONTAL_ALIGN_FILL);
			composite.setLayoutData(data);

			messageLabel = new Label(composite, SWT.NONE);
			messageLabel.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_UI_NO_VALIDATORS_INSTALLED));

			composite.setSize(composite.computeSize(SWT.DEFAULT, SWT.DEFAULT));

			return composite;
		}


		/**
		 * Since there are no validators, there is nothing to save.
		 */
		public boolean performOk() {
			return true;
		}

		public boolean performDefaults() {
			return true;
		}

		public Composite getControl() {
			return page;
		}

		public void dispose() {
			messageLabel.dispose();
			//			layout.dispose();
			//			data.dispose();
			composite.dispose();
		}

		public void loseFocus() {
			// This page does not depend on the contents of any other page in the wizard, so do
			// nothing.
		}

		public void gainFocus() {
			// This page does not depend on the contents of any other page in the wizard, so do
			// nothing.
		}
	}

	private class ValidatorListPage implements IValidationPage {
		private Composite page = null;

		private Composite composite = null;
		CheckboxTableViewer validatorList = null;
		private Button selectAllButton = null;
		private Button deselectAllButton = null;
		private Label emptyRowPlaceholder = null;
		Button valWhenBuildButton = null;
		Button valWhenAutoBuildButton = null;
		private Text maxValProblemsField = null;
		private Label maxValProblemsFieldLabel = null;
		Button overrideButton = null;
		private Label listLabel = null;

		GlobalConfiguration pagePreferences = null; // the values currently on the page, but not
		// necessarily stored yet. Package visibility
		// for the widget listeners (the compiler would
		// have to create a synthetic accessor method in
		// order to access this field)
		private boolean _isAutoBuildEnabled; // initialized in the constructor
		private ValidatorMetaData[] _oldVmd = null; // Cache the enabled validators so that, if
		// there is no change to this list, the
		// expensive task list update can be avoided
		private boolean _allow = false; // Cache the value of the prefence "allow projects to

		// override" so that, when OK is clicked, we can determine
		// if "allow" has changed or not.

		/**
		 * This class is provided for the CheckboxTableViewer in the
		 * ValidationPropertiesPage$ValidatorListPage class.
		 */
		public class ValidationContentProvider implements IStructuredContentProvider {
			/**
			 * Disposes of this content provider. This is called by the viewer when it is disposed.
			 */
			public void dispose() {
				//dispose
			}

			/**
			 * Returns the elements to display in the viewer when its input is set to the given
			 * element. These elements can be presented as rows in a table, items in a list, etc.
			 * The result is not modified by the viewer.
			 * 
			 * @param inputElement
			 *            the input element
			 * @return the array of elements to display in the viewer
			 */
			public java.lang.Object[] getElements(Object inputElement) {
				if (inputElement instanceof ValidatorMetaData[]) {
					// The Collection is the Collection which is returned by ValidatorManager's
					// getConfiguredValidatorMetaData(IProject) call.
					// This Collection is set to be the input of the CheckboxTableViewer in
					// ValidationPropertiesPage$ValidatorListPage's createPage(Composite)
					// method.
					return (ValidatorMetaData[]) inputElement;
				}
				return new Object[0];
			}

			/**
			 * Notifies this content provider that the given viewer's input has been switched to a
			 * different element.
			 * <p>
			 * A typical use for this method is registering the content provider as a listener to
			 * changes on the new input (using model-specific means), and deregistering the viewer
			 * from the old input. In response to these change notifications, the content provider
			 * propagates the changes to the viewer.
			 * </p>
			 * 
			 * @param viewer
			 *            the viewer
			 * @param oldInput
			 *            the old input element, or <code>null</code> if the viewer did not
			 *            previously have an input
			 * @param newInput
			 *            the new input element, or <code>null</code> if the viewer does not have
			 *            an input
			 */
			public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
				//do nothing
			}


		}

		/**
		 * This class is provided for ValidationPropertiesPage$ValidatorListPage's
		 * checkboxTableViewer element.
		 */
		public class ValidationLabelProvider extends LabelProvider {
			/**
			 * Override the LabelProvider's text, by customizing the text for a ValidatorMetaData
			 * element.
			 */
			public String getText(Object element) {
				if (element == null) {
					return ""; //$NON-NLS-1$
				} else if (element instanceof ValidatorMetaData) {
					return ((ValidatorMetaData) element).getValidatorDisplayName();
				} else {
					return super.getText(element);
				}
			}
		}

		/**
		 * This class is used to sort the CheckboxTableViewer elements.
		 */
		public class ValidationViewerSorter extends ViewerSorter {
			/**
			 * Returns a negative, zero, or positive number depending on whether the first element
			 * is less than, equal to, or greater than the second element.
			 * <p>
			 * The default implementation of this method is based on comparing the elements'
			 * categories as computed by the <code>category</code> framework method. Elements
			 * within the same category are further subjected to a case insensitive compare of their
			 * label strings, either as computed by the content viewer's label provider, or their
			 * <code>toString</code> values in other cases. Subclasses may override.
			 * </p>
			 * 
			 * @param viewer
			 *            the viewer
			 * @param e1
			 *            the first element
			 * @param e2
			 *            the second element
			 * @return a negative number if the first element is less than the second element; the
			 *         value <code>0</code> if the first element is equal to the second element;
			 *         and a positive number if the first element is greater than the second element
			 */
			public int compare(Viewer viewer, Object e1, Object e2) {
				// Can't instantiate ViewerSorter because it's abstract, so use this
				// inner class to represent it.
				return super.compare(viewer, e1, e2);
			}
		}

		public ValidatorListPage(Composite parent) throws InvocationTargetException {
			_isAutoBuildEnabled = ValidatorManager.getManager().isGlobalAutoBuildEnabled();
			pagePreferences = new GlobalConfiguration(ConfigurationManager.getManager().getGlobalConfiguration()); // This
			// represents
			// the
			// values
			// on
			// the
			// page
			// that
			// haven't
			// been
			// persisted
			// yet.
			// Start
			// with
			// the
			// last
			// values
			// that
			// were
			// persisted
			// into
			// the
			// current
			// page's
			// starting
			// values.
			_oldVmd = pagePreferences.getEnabledValidators(); // Cache the enabled validators so
			// that, if there is no change to this
			// list, the expensive task list
			// update can be avoided
			_allow = pagePreferences.canProjectsOverride();

			page = createPage(parent);
		}

		public Composite createPage(Composite parent) throws InvocationTargetException {
			// top level group
			final ScrolledComposite sc1 = new ScrolledComposite(parent, SWT.H_SCROLL | SWT.V_SCROLL);
			sc1.setLayoutData(new GridData(GridData.FILL_BOTH));
			composite = new Composite(sc1, SWT.NONE);
			sc1.setContent(composite);
			composite.setLayout(new GridLayout()); // use the layout's default preferences
			PlatformUI.getWorkbench().getHelpSystem().setHelp(composite, ContextIds.VALIDATION_PREFERENCE_PAGE);

			Composite validatorGroup = new Composite(composite, SWT.NONE);
			GridLayout validatorGroupLayout = new GridLayout();
			validatorGroupLayout.numColumns = 2;
			validatorGroup.setLayout(validatorGroupLayout);
			PlatformUI.getWorkbench().getHelpSystem().setHelp(validatorGroup, ContextIds.VALIDATION_PREFERENCE_PAGE);

			GridData overrideData = new GridData(GridData.FILL_HORIZONTAL);
			overrideData.horizontalSpan = 2;
			overrideButton = new Button(validatorGroup, SWT.CHECK);
			overrideButton.setLayoutData(overrideData);
			overrideButton.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_BUTTON_OVERRIDE));
			overrideButton.setEnabled(true);
			overrideButton.addSelectionListener(new SelectionAdapter() {
				public void widgetSelected(SelectionEvent e) {
					pagePreferences.setCanProjectsOverride(overrideButton.getSelection());
					try {
						updateWidgets();
					} catch (InvocationTargetException exc) {
						displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
					}
				}
			});
			PlatformUI.getWorkbench().getHelpSystem().setHelp(overrideButton, ContextIds.VALIDATION_PREFERENCE_PAGE_OVERRIDE);

			emptyRowPlaceholder = new Label(validatorGroup, SWT.NONE);
			emptyRowPlaceholder.setLayoutData(new GridData());

			GridData valWhenBuildData = new GridData(GridData.FILL_HORIZONTAL);
			valWhenBuildData.horizontalSpan = 2;
			valWhenBuildButton = new Button(validatorGroup, SWT.CHECK);
			valWhenBuildButton.setLayoutData(valWhenBuildData);
			valWhenBuildButton.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_BUTTON_FULL));
			valWhenBuildButton.addSelectionListener(new SelectionAdapter() {
				public void widgetSelected(SelectionEvent e) {
					pagePreferences.setBuildValidate(valWhenBuildButton.getSelection());
					valWhenBuildButton.setFocus();
				}
			});

			GridData valWhenAutoBuildData = new GridData(GridData.FILL_HORIZONTAL);
			valWhenAutoBuildData.horizontalSpan = 2;
			valWhenAutoBuildButton = new Button(validatorGroup, SWT.CHECK);
			valWhenAutoBuildButton.setLayoutData(valWhenAutoBuildData);
			valWhenAutoBuildButton.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_BUTTON_AUTO));
			valWhenAutoBuildButton.addSelectionListener(new SelectionAdapter() {
				public void widgetSelected(SelectionEvent e) {
					pagePreferences.setAutoValidate(valWhenAutoBuildButton.getSelection());
					valWhenAutoBuildButton.setFocus();
				}
			});

			listLabel = new Label(validatorGroup, SWT.NONE);
			GridData listLabelData = new GridData(GridData.FILL_HORIZONTAL);
			listLabelData.horizontalSpan = 2;
			listLabel.setLayoutData(listLabelData);
			listLabel.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_VALLIST_TITLE));

			GridData validatorListData = new GridData(GridData.FILL_HORIZONTAL);
			validatorListData.horizontalSpan = 2;
			validatorList = CheckboxTableViewer.newCheckList(validatorGroup, SWT.BORDER);
			validatorList.getTable().setLayoutData(validatorListData);
			validatorList.setLabelProvider(new ValidationLabelProvider());
			validatorList.setContentProvider(new ValidationContentProvider());
			validatorList.setSorter(new ValidationViewerSorter());
			validatorList.setInput(pagePreferences.getValidators());
			validatorList.getTable().addSelectionListener(new SelectionAdapter() {
				public void widgetSelected(SelectionEvent e) {
					pagePreferences.setEnabledValidators(ValidationConfiguration.convertToArray(validatorList.getCheckedElements()));
					try {
						updateWidgets();
					} catch (InvocationTargetException exc) {
						displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
					}
				}

				public void widgetDefaultSelected(SelectionEvent e) {
					try {
						performDefaults();
					} catch (InvocationTargetException exc) {
						displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
					}
				}
			});

			selectAllButton = new Button(validatorGroup, SWT.PUSH);
			selectAllButton.setLayoutData(new GridData());
			selectAllButton.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_BUTTON_SELECTALL));
			selectAllButton.addSelectionListener(new SelectionAdapter() {
				public void widgetSelected(SelectionEvent e) {
					try {
						performSelectAll();
					} catch (InvocationTargetException exc) {
						displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
					}
				}
			});
			PlatformUI.getWorkbench().getHelpSystem().setHelp(selectAllButton, ContextIds.VALIDATION_PREFERENCE_PAGE);

			deselectAllButton = new Button(validatorGroup, SWT.PUSH);
			deselectAllButton.setLayoutData(new GridData());
			deselectAllButton.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_BUTTON_DESELECTALL));
			deselectAllButton.addSelectionListener(new SelectionAdapter() {
				public void widgetSelected(SelectionEvent e) {
					try {
						performDeselectAll();
					} catch (InvocationTargetException exc) {
						displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
					}
				}
			});
			PlatformUI.getWorkbench().getHelpSystem().setHelp(deselectAllButton, ContextIds.VALIDATION_PREFERENCE_PAGE);

			Composite buttonGroup = new Composite(composite, SWT.NONE);
			GridLayout buttonGroupLayout = new GridLayout();
			buttonGroupLayout.numColumns = 2;
			buttonGroup.setLayout(buttonGroupLayout);
			buttonGroup.setLayoutData(new GridData(GridData.HORIZONTAL_ALIGN_FILL));

			maxValProblemsFieldLabel = new Label(buttonGroup, SWT.NONE);
			maxValProblemsFieldLabel.setLayoutData(new GridData());
			maxValProblemsFieldLabel.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_LBL_MAXMSGS));

			maxValProblemsField = new Text(buttonGroup, SWT.SINGLE | SWT.BORDER);
			maxValProblemsField.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
			maxValProblemsField.addKeyListener(new KeyListener() {
				/**
				 * Sent when a key is pressed on the system keyboard.
				 * 
				 * @param e
				 *            an event containing information about the key press
				 */
				public void keyPressed(KeyEvent e) {
					//do nothing
				}

				/**
				 * Sent when a key is released on the system keyboard.
				 * 
				 * @param e
				 *            an event containing information about the key release
				 */
				public void keyReleased(KeyEvent e) {
					try {
						pagePreferences.setMaximumNumberOfMessages(checkInteger());
					} catch (InvocationTargetException exc) {
						displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
					}
				}
			});
			PlatformUI.getWorkbench().getHelpSystem().setHelp(maxValProblemsField, ContextIds.VALIDATION_PREFERENCE_PAGE_MAX_MESSAGES);

			// Have to set the tab order or only the first checkbox in a Composite can
			// be tab-ed to. (Seems to apply only to checkboxes. Have to use the arrow
			// key to navigate the checkboxes.)
			validatorGroup.setTabList(new Control[]{overrideButton, valWhenBuildButton, valWhenAutoBuildButton, validatorList.getTable(), selectAllButton, deselectAllButton});

			updateWidgets();

			composite.setSize(composite.computeSize(SWT.DEFAULT, SWT.DEFAULT));

			return composite;
		}

		protected int checkInteger() throws InvocationTargetException {
			GlobalConfiguration gp = ConfigurationManager.getManager().getGlobalConfiguration();
			String text = maxValProblemsField.getText();
			if (text == null) {
				setErrorMessage(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_ERROR_INT));
				return gp.getMaximumNumberOfMessages();
			}
			try {
				Integer tempInt = new Integer(text.trim());

				// no exception? It's an int, then.
				if (tempInt.intValue() <= 0) {
					setErrorMessage(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_ERROR_INT));
					return gp.getMaximumNumberOfMessages();
				}
				setErrorMessage(null);
				return Integer.valueOf(maxValProblemsField.getText().trim()).intValue();
			} catch (NumberFormatException exc) {
				setErrorMessage(ResourceHandler.getExternalizedMessage(ResourceConstants.PREF_ERROR_INT));
				return gp.getMaximumNumberOfMessages();
			}
		}

		protected void updateWidgets() throws InvocationTargetException {
			// Need to update even the widgets that do not change based on another
			// widgets because of performDefaults(). If performDefaults() is selected,
			// then the pagePreferences values are reset, and these widgets
			// might also need to be updated.
			overrideButton.setSelection(pagePreferences.canProjectsOverride());

			maxValProblemsField.setText(String.valueOf(pagePreferences.getMaximumNumberOfMessages()));

			updateTable();

			boolean valEnabled = (pagePreferences.numberOfEnabledValidators() > 0);
			valWhenBuildButton.setEnabled(valEnabled);
			valWhenBuildButton.setSelection(pagePreferences.isBuildValidate() && valEnabled);

			boolean incValEnabled = (pagePreferences.numberOfEnabledIncrementalValidators() > 0);
			valWhenAutoBuildButton.setEnabled(_isAutoBuildEnabled && incValEnabled);
			valWhenAutoBuildButton.setSelection(pagePreferences.isAutoValidate() && incValEnabled && _isAutoBuildEnabled);

			updateHelp();
		}

		protected void updateTable() throws InvocationTargetException {
			TableItem[] items = validatorList.getTable().getItems();
			for (int i = 0; i < items.length; i++) {
				TableItem item = items[i];
				ValidatorMetaData vmd = (ValidatorMetaData) item.getData();

				// Should the validator be enabled? Read the user's preferences from last time,
				// if they exist, and set from that. If they don't exist, use the Validator class'
				// default value.
				validatorList.setChecked(vmd, pagePreferences.isEnabled(vmd));
			}
		}

		public boolean performOk() throws InvocationTargetException {
			storeValues();
			updateTaskList();
			return true;
		}

		public boolean performDefaults() throws InvocationTargetException {
			pagePreferences.resetToDefault();
			updateWidgets();
			checkInteger(); // clear the "max must be a positive integer" message if it exists
			getDefaultsButton().setFocus();
			return true;
		}

		public boolean performSelectAll() throws InvocationTargetException {
			validatorList.setAllChecked(true);
			pagePreferences.setEnabledValidators(ValidationConfiguration.convertToArray(validatorList.getCheckedElements()));
			updateWidgets();
			selectAllButton.setFocus();
			return true;
		}

		public boolean performDeselectAll() throws InvocationTargetException {
			validatorList.setAllChecked(false);
			pagePreferences.setEnabledValidators(ValidationConfiguration.convertToArray(validatorList.getCheckedElements()));
			updateWidgets();
			deselectAllButton.setFocus();
			return true;
		}

		protected void updateHelp() {
			// never disable this widget because users don't expect the preference page to alter
			// based on workbench contents
			PlatformUI.getWorkbench().getHelpSystem().setHelp(valWhenBuildButton, ContextIds.VALIDATION_PREFERENCE_PAGE_REBUILD_ENABLED);

			// never disable this widget because users don't expect the preference page to alter
			// based on workbench contents
			PlatformUI.getWorkbench().getHelpSystem().setHelp(valWhenAutoBuildButton, ContextIds.VALIDATION_PREFERENCE_PAGE_AUTO_ENABLED);
		}

		/*
		 * Store the current values of the controls into the preference store.
		 */
		private void storeValues() throws InvocationTargetException {
			pagePreferences.setCanProjectsOverride(overrideButton.getSelection());

			// If the manual build button is disabled because no validators are selected in the
			// task list, don't overwrite the user's preference.
			if (valWhenBuildButton.isEnabled()) {
				pagePreferences.setBuildValidate(valWhenBuildButton.getSelection());
			}

			// If the auto build button is disabled because no validators are selected in the
			// task list, or because auto-build is disabled, don't overwrite the user's preference.
			if (valWhenAutoBuildButton.isEnabled()) {
				pagePreferences.setAutoValidate(valWhenAutoBuildButton.getSelection());
			}

			pagePreferences.setMaximumNumberOfMessages(checkInteger());
			pagePreferences.setEnabledValidators(ValidationConfiguration.convertToArray(validatorList.getCheckedElements()));

			pagePreferences.passivate();
			pagePreferences.store();
			// If the projects aren't allowed to override, clear their settings.
			if (!pagePreferences.canProjectsOverride()) {
				IWorkspace workspace = ResourcesPlugin.getWorkspace();
				IProject[] projects = workspace.getRoot().getProjects();
				for (int i = 0; i < projects.length; i++) {
					IProject project = projects[i];
					try {
						if (project.isOpen()) {
							if (ConfigurationManager.getManager().isMigrated(project)) {
								ProjectConfiguration prjp = ConfigurationManager.getManager().getProjectConfiguration(project);
								prjp.setDoesProjectOverride(false);
								prjp.passivate();
								prjp.store();
							}
						}
					} catch (InvocationTargetException exc) {
						displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
					}
				}
			}

		}

		private void updateTaskList() {
			IWorkspace workspace = ResourcesPlugin.getWorkspace();
			IProject[] projects = workspace.getRoot().getProjects();
			boolean allowChanged = (pagePreferences.canProjectsOverride() != _allow);
			for (int i = 0; i < projects.length; i++) {
				IProject project = projects[i];
				try {
					if (project.isOpen()) {
						ProjectConfiguration prjp = ConfigurationManager.getManager().getProjectConfiguration(project);
						if (!prjp.doesProjectOverride() && (prjp.hasEnabledValidatorsChanged(_oldVmd, allowChanged) || ValidatorManager.getManager().isMessageLimitExceeded(project))) {
							// If the project used to override the preferences, and the preferences
							// make that impossible now, then update the task list.
							//
							// If the preferences allow projects to override, and they don't, and if
							// the validators have changed, then update the task list.
							ValidatorManager.getManager().updateTaskList(project); // Do not remove
							// the exceeded
							// message; only
							// ValidationOperation
							// should do that
							// because it's
							// about to run
							// validation. If
							// the limit is
							// increased,
							// messages may
							// still be
							// missing, so
							// don't remove
							// the "messages
							// may be
							// missing"
							// message.
						}
					}
				} catch (InvocationTargetException exc) {
					displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
				}
			}
		}

		public Composite getControl() {
			return page;
		}

		public void dispose() {
			listLabel.dispose();
			overrideButton.dispose();
			maxValProblemsField.dispose();
			maxValProblemsFieldLabel.dispose();
			valWhenAutoBuildButton.dispose();
			valWhenBuildButton.dispose();
			emptyRowPlaceholder.dispose();
			deselectAllButton.dispose();
			selectAllButton.dispose();
			validatorList.getTable().dispose();
			//			validatorList.dispose();
			//			layout.dispose();
			//			data.dispose();
			composite.dispose();
		}

		public void loseFocus() {
			// This page does not need to cache anything before it loses focus.
		}

		public void gainFocus() {
			// This page depends on the Workbench Preference page, so update the value of the
			// isAutoBuild (in case the workbench page's value has changed), and then update
			// this page's widgets.
			try {
				_isAutoBuildEnabled = ValidatorManager.getManager().isGlobalAutoBuildEnabled();
				updateWidgets();
			} catch (InvocationTargetException exc) {
				displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
			}
		}
	}

	/*
	 * @see PreferencePage#createContents(Composite)
	 */
	protected Control createContents(Composite parent) {
		try {
			GlobalConfiguration gp = ConfigurationManager.getManager().getGlobalConfiguration();
			if (gp.numberOfValidators() == 0) {
				_pageImpl = new NoValidatorsPage(parent);
			} else {
				try {
					_pageImpl = new ValidatorListPage(parent);
				} catch (InvocationTargetException exc) {
					_pageImpl = new InvalidPage(parent);
					displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
				} catch (Throwable exc) {
					_pageImpl = new InvalidPage(parent);
					displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
				}
			}
		} catch (InvocationTargetException exc) {
			_pageImpl = new InvalidPage(parent);
			displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
		} catch (Throwable exc) {
			_pageImpl = new InvalidPage(parent);
			displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
		}

		return _pageImpl.getControl();
	}

	/*
	 * @see IWorkbenchPreferencePage#init(IWorkbench)
	 */
	public void init(IWorkbench workbench) {
		//init
	}

	protected void noDefaultAndApplyButton() {
		super.noDefaultAndApplyButton();
	}

	/**
	 * Performs special processing when this page's Defaults button has been pressed.
	 * <p>
	 * This is a framework hook method for sublcasses to do special things when the Defaults button
	 * has been pressed. Subclasses may override, but should call <code>super.performDefaults</code>.
	 * </p>
	 */
	protected void performDefaults() {
		super.performDefaults();

		try {
			_pageImpl.performDefaults();
		} catch (InvocationTargetException exc) {
			displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
		} catch (Throwable exc) {
			displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
		}
	}

	/**
	 * When the user presses the "OK" or "Apply" button on the Properties Guide/Properties Page,
	 * respectively, some processing is performed by this PropertyPage. If the page is found, and
	 * completes successfully, true is returned. Otherwise, false is returned, and the guide doesn't
	 * finish.
	 */
	public boolean performOk() {
		try {
			return _pageImpl.performOk();
		} catch (InvocationTargetException exc) {
			displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
			return false;
		} catch (Throwable exc) {
			displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
			return false;
		}
	}

	/**
	 * Since the pages are inner classes of a child PreferencePage, not a PreferencePage itself,
	 * DialogPage's automatic disposal of its children's widgets cannot be used. Instead, dispose of
	 * each inner class' widgets explicitly.
	 */
	public void dispose() {
		super.dispose();
		try {
			if (_pageImpl != null) {
				_pageImpl.dispose();
			}
		} catch (Throwable exc) {
			displayAndLogError(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_TITLE), ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_INTERNAL_PAGE), exc);
		}
	}

	private void logError(Throwable exc) {
		Logger logger = WTPUIPlugin.getLogger();
		if (logger.isLoggingLevel(Level.SEVERE)) {
			LogEntry entry = ValidationUIPlugin.getLogEntry();
			entry.setSourceIdentifier("ValidationPreferencePage.displayAndLogError"); //$NON-NLS-1$
			entry.setMessageTypeIdentifier(ResourceConstants.VBF_EXC_INTERNAL_PAGE);
			entry.setTargetException(exc);
			logger.write(Level.SEVERE, entry);

			if (exc instanceof InvocationTargetException) {
				if (((InvocationTargetException) exc).getTargetException() != null) {
					entry.setTargetException(((InvocationTargetException) exc).getTargetException());
					logger.write(Level.SEVERE, entry);
				}
			}
		}
	}

	/**
	 * package visibility because if this method is private, then the compiler needs to create a
	 * synthetic accessor method for the internal classes, and that can have performance
	 * implications.
	 */
	void displayAndLogError(String title, String message, Throwable exc) {
		logError(exc);
		displayMessage(title, message, org.eclipse.swt.SWT.ICON_ERROR);
	}

	private void displayMessage(String title, String message, int iIconType) {
		MessageBox messageBox = new MessageBox(getShell(), org.eclipse.swt.SWT.OK | iIconType | org.eclipse.swt.SWT.APPLICATION_MODAL);
		messageBox.setMessage(message);
		messageBox.setText(title);
		messageBox.open();
	}

	/**
	 * @see org.eclipse.jface.dialogs.IDialogPage#setVisible(boolean)
	 */
	public void setVisible(boolean visible) {
		super.setVisible(visible);
		if (_pageImpl == null)
			return;
		if (visible) {
			_pageImpl.gainFocus();
		} else {
			_pageImpl.loseFocus();
		}
	}

	/**
	 * @see org.eclipse.jface.preference.PreferencePage#getDefaultsButton()
	 */
	protected Button getDefaultsButton() {
		return super.getDefaultsButton();
	}
}