ecommons/org.eclipse.statet.ecommons.uimisc/src/org/eclipse/statet/ecommons/preferences/ui/ManagedConfigurationBlock.java - gerrit/statet/org.eclipse.statet-commons - Git at Google

 /*=============================================================================#
  # Copyright (c) 2005, 2021 Stephan Wahlbrink and others.
  #
  # This program and the accompanying materials are made available under the
  # terms of the Eclipse Public License 2.0 which is available at
  # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
  # which is available at https://www.apache.org/licenses/LICENSE-2.0.
  #
  # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
  #
  # Contributors:
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
  #=============================================================================*/

 package org.eclipse.statet.ecommons.preferences.ui;

 import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;

 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.IdentityHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;

 import org.osgi.service.prefs.BackingStoreException;

 import org.eclipse.core.databinding.observable.masterdetail.IObservableFactory;
 import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
 import org.eclipse.core.databinding.observable.value.IObservableValue;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.ProjectScope;
 import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.core.runtime.preferences.DefaultScope;
 import org.eclipse.core.runtime.preferences.IEclipsePreferences;
 import org.eclipse.core.runtime.preferences.IEclipsePreferences.IPreferenceChangeListener;
 import org.eclipse.core.runtime.preferences.IScopeContext;
 import org.eclipse.core.runtime.preferences.InstanceScope;
 import org.eclipse.jface.dialogs.IDialogConstants;
 import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.ui.preferences.IWorkbenchPreferenceContainer;
 import org.eclipse.ui.preferences.IWorkingCopyManager;

 import org.eclipse.statet.jcommons.collections.ImCollections;
 import org.eclipse.statet.jcommons.collections.ImList;
 import org.eclipse.statet.jcommons.collections.ImSet;
 import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 import org.eclipse.statet.jcommons.lang.Nullable;

 import org.eclipse.statet.ecommons.databinding.jface.DataBindingSupport;
 import org.eclipse.statet.ecommons.preferences.SettingsChangeNotifier;
 import org.eclipse.statet.ecommons.preferences.core.Preference;
 import org.eclipse.statet.ecommons.preferences.core.PreferenceAccess;
 import org.eclipse.statet.ecommons.preferences.core.PreferenceSetService;
 import org.eclipse.statet.ecommons.resources.core.BuildUtils;
 import org.eclipse.statet.ecommons.runtime.core.StatusChangeListener;


 /**
  * Allows load, save, restore of managed preferences, including:
  * <p><ul>
  * <li>Connected databinding context:<ul>
  *     <li>use {@link #initBindings()} to create dbc</li>
  *     <li>use {@link #createObservable(Object)} to create observables for model</li>
  *     <li>override {@link #addBindings(DataBindingSupport)}) to register bindings</li>
  *   </ul></li>
  *   <li>optional project scope</li>
  *   <li>change settings groups ({@link SettingsChangeNotifier})</li>
  * </ul>
  * Instead of data binding, it is possible to overwrite
  *   {@link #updatePreferences()} and {@link #updateControls()}
  * to map the preferences to UI.
  */
 @NonNullByDefault
 public abstract class ManagedConfigurationBlock extends ConfigurationBlock
 		implements PreferenceAccess, IObservableFactory {


 	private static final String REBUILD_QUALIFIER= "org.eclipse.jdt.ui"; //$NON-NLS-1$
 	private static final String REBUILD_KEY= "preferences_build_requested"; //$NON-NLS-1$


 	protected class PreferenceManager {

 		private final ImList<IScopeContext> lookupOrder;
 		private final @Nullable IScopeContext inheritScope;
 		private final Map<Preference<?>, @Nullable String> preferences;

 		/** Manager for a working copy of the preferences */
 		private final IWorkingCopyManager manager;
 		/** Map saving the project settings, if disabled */
 		private @Nullable Map<Preference<?>, @Nullable Object> disabledProjectSettings;

 		private int rebuildCounter;


 		PreferenceManager(final Map<Preference<?>, @Nullable String> prefs) {
 			this.manager= getContainer().getWorkingCopyManager();
 			this.preferences= prefs;

 			ManagedConfigurationBlock.this.preferenceManager= this;

 			if (ManagedConfigurationBlock.this.project != null) {
 				this.lookupOrder= ImCollections.newList(
 						new ProjectScope(ManagedConfigurationBlock.this.project),
 						InstanceScope.INSTANCE,
 						DefaultScope.INSTANCE );
 				this.inheritScope= null;
 			}
 			else {
 				this.lookupOrder= ImCollections.newList(
 						InstanceScope.INSTANCE,
 						DefaultScope.INSTANCE );
 				this.inheritScope= this.lookupOrder.get(1);
 			}

 			// testIfOptionsComplete();

 			// init disabled settings, if required
 			if (ManagedConfigurationBlock.this.project == null
 					|| hasProjectSpecificSettings(ManagedConfigurationBlock.this.project) ) {
 				this.disabledProjectSettings= null;
 			}
 			else {
 				saveDisabledProjectSettings();
 			}

 			checkRebuild();
 		}


 /* Managing methods ***********************************************************/

 		/**
 		 * Checks, if project specific options exists
 		 *
 		 * @param project to look up
 		 * @return
 		 */
 		boolean hasProjectSpecificSettings(final IProject project) {
 			final IScopeContext projectContext= new ProjectScope(project);
 			for (final Preference<?> pref : this.preferences.keySet()) {
 				if (getInternalValue(pref, projectContext, true) != null) {
 					return true;
 				}
 			}
 			return false;
 		}

 		void setUseProjectSpecificSettings(final boolean enable) {
 			final boolean hasProjectSpecificOption= (this.disabledProjectSettings == null);
 			if (enable != hasProjectSpecificOption) {
 				if (enable) {
 					loadDisabledProjectSettings();
 				} else {
 					saveDisabledProjectSettings();
 				}
 			}
 		}

 		private void saveDisabledProjectSettings() {
 			final Map<Preference<?>, @Nullable Object> projectSettings= new IdentityHashMap<>();
 			for (final Preference<?> pref : this.preferences.keySet()) {
 				projectSettings.put(pref, getValue(pref));
 				setInternalValue(pref, null); // clear project settings
 			}
 			this.disabledProjectSettings= projectSettings;
 		}

 		private void loadDisabledProjectSettings() {
 			final Map<Preference<?>, @Nullable Object> projectSettings= nonNullAssert(this.disabledProjectSettings);
 			for (final Preference<?> key : this.preferences.keySet()) {
 				// Copy values from saved disabled settings to working store
 				setValue((Preference) key, projectSettings.get(key));
 			}
 			this.disabledProjectSettings= null;
 		}

 		boolean processChanges(final boolean saveStore) {
 			final List<Preference<?>> changedPrefs= new ArrayList<>();
 			final boolean needsBuild= getChanges(changedPrefs);
 			if (changedPrefs.isEmpty()) {
 				return true;
 			}

 			boolean doBuild= false;
 			if (needsBuild) {
 				if (checkRebuild()) {
 					final String[] strings= getFullBuildDialogStrings(getProject() == null);
 					if (strings != null) {
 						final MessageDialog dialog= new MessageDialog(getShell(),
 								strings[0], null, strings[1],
 								MessageDialog.QUESTION, new String[] {
 										IDialogConstants.YES_LABEL,
 										IDialogConstants.NO_LABEL,
 										IDialogConstants.CANCEL_LABEL },
 								2 );
 						final int res= dialog.open();
 						if (res == 0) {
 							doBuild= true;
 						}
 						else if (res != 1) {
 							return false; // cancel pressed
 						}
 					}
 				}
 			}
 			if (saveStore) {
 				try {
 					this.manager.applyChanges();
 				}
 				catch (final BackingStoreException e) {
 					logSaveError(e);
 					return false;
 				}
 				if (doBuild) {
 					createRebuild().schedule();
 				}
 			}
 			else {
 				if (doBuild) {
 					getContainer().registerUpdateJob(createRebuild());
 				}
 			}
 			final Set<String> groupIds= new HashSet<>();
 			for (final Preference<?> pref : changedPrefs) {
 				final String groupId= this.preferences.get(pref);
 				if (groupId != null) {
 					groupIds.add(groupId);
 				}
 			}
 			scheduleChangeNotification(groupIds, saveStore);
 			return true;
 		}

 		/**
 		 *
 		 * @param currContext
 		 * @param changedSettings
 		 * @return true, if rebuild is required.
 		 */
 		private boolean getChanges(final List<Preference<?>> changedSettings) {
 			final IScopeContext currContext= this.lookupOrder.get(0);
 			boolean needsBuild= false;
 			for (final Preference<?> key : this.preferences.keySet()) {
 				final String oldValue= getInternalValue(key, currContext, false);
 				final String value= getInternalValue(key, currContext, true);
 				if (value == null) {
 					if (oldValue != null) {
 						changedSettings.add(key);
 						needsBuild |= !oldValue.equals(getInternalValue(key, true));
 					}
 				}
 				else if (!value.equals(oldValue)) {
 					changedSettings.add(key);
 					needsBuild |= (oldValue != null || !value.equals(getInternalValue(key, true)));

 					if (this.inheritScope != null
 							&& value.equals(getInternalValue(key, this.inheritScope, false) )) {
 						final IEclipsePreferences node= getNode(currContext, key.getQualifier(), true);
 						node.remove(key.getKey());
 					}
 				}
 			}
 			return needsBuild;
 		}


 		void loadDefaults() {
 			final IScopeContext defaultScope= DefaultScope.INSTANCE;
 			for (final Preference<?> key : this.preferences.keySet()) {
 				final String defValue= getInternalValue(key, defaultScope, false);
 				setInternalValue(key, defValue);
 			}
 		}

 		// DEBUG
 		private void testIfOptionsComplete() {
 			for (final Preference<?> key : this.preferences.keySet()) {
 				if (getInternalValue(key, false) == null) {
 					System.out.println("preference option missing: " + key + " (" + this.getClass().getName() +')');  //$NON-NLS-1$//$NON-NLS-2$
 				}
 			}
 		}

 		private IEclipsePreferences getNode(final IScopeContext context, final String qualifier, final boolean useWorkingCopy) {
 			final IEclipsePreferences node= context.getNode(qualifier);
 			if (useWorkingCopy && context != DefaultScope.INSTANCE) {
 				return this.manager.getWorkingCopy(node);
 			}
 			return node;
 		}

 		private @Nullable String getInternalValue(final Preference<?> pref, final IScopeContext context, final boolean useWorkingCopy) {
 			final IEclipsePreferences node= getNode(context, pref.getQualifier(), useWorkingCopy);
 			return node.get(pref.getKey(), null);
 		}

 		private @Nullable String getInternalValue(final Preference<?> pref, final boolean ignoreTopScope) {
 			for (int i= ignoreTopScope ? 1 : 0; i < this.lookupOrder.size(); i++) {
 				final String value= getInternalValue(pref, this.lookupOrder.get(i), true);
 				if (value != null) {
 					return value;
 				}
 			}
 			return null;
 		}

 		private <T> void setInternalValue(final Preference<T> pref, final @Nullable String value) {
 			final IEclipsePreferences node= getNode(this.lookupOrder.get(0), pref.getQualifier(), true);
 			if (value != null) {
 				node.put(pref.getKey(), value);
 			}
 			else {
 				node.remove(pref.getKey());
 			}
 		}


 		private <T> void setValue(final Preference<T> pref, final @Nullable T value) {
 			final IEclipsePreferences node= getNode(this.lookupOrder.get(0), pref.getQualifier(), true);
 			final String storeValue;
 			if (value == null
 					|| (storeValue= pref.usage2Store(value)) == null) {
 				node.remove(pref.getKey());
 				return;
 			}
 			node.put(pref.getKey(), storeValue);
 		}

 		private <T> T getValue(final Preference<T> pref) {
 			IEclipsePreferences node= null;
 			for (int i= 0; i < this.lookupOrder.size(); i++) {
 				final IEclipsePreferences nodeToCheck= getNode(this.lookupOrder.get(i), pref.getQualifier(), true);
 				if (nodeToCheck.get(pref.getKey(), null) != null) {
 					node= nodeToCheck;
 					break;
 				}
 			}

 			final String storeValue= (node != null) ? node.get(pref.getKey(), null) : null;
 			return pref.store2Usage(storeValue);
 		}


 		private boolean checkRebuild() {
 			final int counter= this.manager.getWorkingCopy(DefaultScope.INSTANCE.getNode(REBUILD_QUALIFIER))
 					.getInt(REBUILD_KEY, 0);
 			if (counter > this.rebuildCounter) {
 				this.rebuildCounter= counter;
 				return false;
 			}
 			return true;
 		}

 		private Job createRebuild() {
 			this.rebuildCounter++;
 			this.manager.getWorkingCopy(DefaultScope.INSTANCE.getNode(REBUILD_QUALIFIER))
 					.putInt(REBUILD_KEY, this.rebuildCounter);
 			return BuildUtils.getBuildJob(getProject());
 		}

 	}


 	private final @Nullable IProject project;
 	private @Nullable PreferenceManager preferenceManager;

 	private DataBindingSupport dataBinding;
 	private @Nullable StatusChangeListener statusListener;

 	private Composite pageComposite;


 	protected ManagedConfigurationBlock(final @Nullable IProject project) {
 		this(project, null, null);
 	}

 	protected ManagedConfigurationBlock(final @Nullable IProject project,
 			final @Nullable StatusChangeListener statusListener) {
 		this(project, null, statusListener);
 	}

 	protected ManagedConfigurationBlock(final @Nullable IProject project,
 			final String title,
 			final @Nullable StatusChangeListener statusListener) {
 		super(title);
 		this.project= project;
 		this.statusListener= statusListener;
 	}


 	protected void setStatusListener(final StatusChangeListener listener) {
 		this.statusListener= listener;
 	}


 	public final @Nullable IProject getProject() {
 		return this.project;
 	}

 	@Override
 	public void createContents(final Composite pageComposite,
 			final IWorkbenchPreferenceContainer container, final IPreferenceStore preferenceStore) {
 		this.pageComposite= pageComposite;
 		super.createContents(pageComposite, container, preferenceStore);
 	}

 	/**
 	 * initialize preference management
 	 *
 	 * @param container
 	 * @param prefs map with preference objects as key and their settings group id as optional value
 	 */
 	protected void setupPreferenceManager(final Map<Preference<?>, @Nullable String> prefs) {
 		new PreferenceManager(prefs);
 	}

 	protected void initBindings() {
 		this.dataBinding= new DataBindingSupport(this.pageComposite);
 		addBindings(this.dataBinding);

 		this.dataBinding.installStatusListener(this.statusListener);
 	}

 	protected DataBindingSupport getDataBinding() {
 		return this.dataBinding;
 	}

 	protected void addBindings(final DataBindingSupport db) {
 	}

 	/**
 	 * Point to hook, before the managed preference values are saved to store.
 	 * E.g. you can set some additional (or all) values.
 	 */
 	protected void updatePreferences() {
 	}

 	@Override
 	public boolean performOk(final int flags) {
 		final PreferenceManager preferenceManager= this.preferenceManager;
 		if (preferenceManager != null) {
 			updatePreferences();
 			return preferenceManager.processChanges((flags & SAVE_STORE) != 0);
 		}
 		return true;
 	}

 	@Override
 	public void performDefaults() {
 		final PreferenceManager preferenceManager= this.preferenceManager;
 		if (preferenceManager != null) {
 			preferenceManager.loadDefaults();
 			updateControls();
 		}
 	}


 /* */

 	/**
 	 * Checks, if project specific options exists
 	 *
 	 * @param project to look up
 	 * @return
 	 */
 	public boolean hasProjectSpecificOptions(final IProject project) {
 		final PreferenceManager preferenceManager= this.preferenceManager;
 		if (project != null && preferenceManager != null) {
 			return preferenceManager.hasProjectSpecificSettings(project);
 		}
 		return false;
 	}

 	@Override
 	public void setUseProjectSpecificSettings(final boolean enable) {
 		super.setUseProjectSpecificSettings(enable);
 		final PreferenceManager preferenceManager= this.preferenceManager;
 		if (this.project != null && preferenceManager != null) {
 			preferenceManager.setUseProjectSpecificSettings(enable);
 		}
 	}

 	protected void updateControls() {
 		if (this.dataBinding != null) {
 			this.dataBinding.getContext().updateTargets();
 		}
 	}


 /* Access preference values ***************************************************/

 	@Override
 	public ImList<IScopeContext> getPreferenceContexts() {
 		final PreferenceManager preferenceManager= nonNullAssert(this.preferenceManager);

 		return preferenceManager.lookupOrder;
 	}

 	/**
 	 * Returns the value for the specified preference.
 	 *
 	 * @param pref preference key
 	 * @return value of the preference
 	 */
 	@Override
 	@SuppressWarnings("unchecked")
 	public <T> T getPreferenceValue(final Preference<T> pref) {
 		assert (pref != null);
 		final PreferenceManager preferenceManager= nonNullAssert(this.preferenceManager);

 		final Map<Preference<?>, @Nullable Object> projectSettings= preferenceManager.disabledProjectSettings;
 		if (projectSettings != null) {
 			return (T)projectSettings.get(pref);
 		}
 		return preferenceManager.getValue(pref);
 	}

 	/**
 	 * Sets a preference value in the default store.
 	 *
 	 * @param key preference key
 	 * @param value new value
 	 * @return old value
 	 */
 	@SuppressWarnings("unchecked")
 	public <T> T setPrefValue(final Preference<T> key, final T value) {
 		final PreferenceManager preferenceManager= nonNullAssert(this.preferenceManager);

 		final Map<Preference<?>, @Nullable Object> projectSettings= preferenceManager.disabledProjectSettings;
 		if (projectSettings != null) {
 			return (T) projectSettings.put(key, value);
 		}
 		final T oldValue= getPreferenceValue(key);
 		preferenceManager.setValue(key, value);
 		return oldValue;
 	}

 	public void setPrefValues(final Map<Preference<?>, Object> map) {
 		for (final Entry<Preference<?>, Object> entry : map.entrySet()) {
 			setPrefValue((Preference)entry.getKey(), entry.getValue());
 		}
 	}

 	/**
 	 * Not (yet) supported
 	 */
 	@Override
 	public void addPreferenceNodeListener(final String nodeQualifier, final IPreferenceChangeListener listener) {
 		throw new UnsupportedOperationException();
 	}

 	/**
 	 * Not (yet) supported
 	 */
 	@Override
 	public void removePreferenceNodeListener(final String nodeQualifier, final IPreferenceChangeListener listener) {
 		throw new UnsupportedOperationException();
 	}

 	/**
 	 * Not (yet) supported
 	 */
 	@Override
 	public void addPreferenceSetListener(final PreferenceSetService.ChangeListener listener,
 			final ImSet<String> qualifiers) {
 		throw new UnsupportedOperationException();
 	}

 	/**
 	 * Not (yet) supported
 	 */
 	@Override
 	public void removePreferenceSetListener(final PreferenceSetService.ChangeListener listener) {
 		throw new UnsupportedOperationException();
 	}


 	@Override
 	public IObservableValue createObservable(final Object target) {
 		return createObservable((Preference<?>) target);
 	}

 	public <T> IObservableValue<T> createObservable(final Preference<T> pref) {
 		return new AbstractObservableValue<T>() {
 			@Override
 			public Object getValueType() {
 				return pref.getUsageType();
 			}
 			@Override
 			protected void doSetValue(final T value) {
 				setPrefValue(pref, value);
 			}
 			@Override
 			protected T doGetValue() {
 				return getPreferenceValue(pref);
 			}
 			@Override
 			public synchronized void dispose() {
 				super.dispose();
 			}
 		};
 	}

 	/**
 	 * Changes requires full build, this method should be overwritten
 	 * and return the Strings for the dialog.
 	 *
 	 * @param workspaceSettings true, if settings for workspace; false, if settings for project.
 	 * @return
 	 */
 	protected String @Nullable [] getFullBuildDialogStrings(final boolean workspaceSettings) {
 		return null;
 	}

 }
	/*=============================================================================#
	# Copyright (c) 2005, 2021 Stephan Wahlbrink and others.
	#
	# This program and the accompanying materials are made available under the
	# terms of the Eclipse Public License 2.0 which is available at
	# https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
	# which is available at https://www.apache.org/licenses/LICENSE-2.0.
	#
	# SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
	#
	# Contributors:
	# Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
	#=============================================================================*/

	package org.eclipse.statet.ecommons.preferences.ui;

	import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;

	import java.util.ArrayList;
	import java.util.HashSet;
	import java.util.IdentityHashMap;
	import java.util.List;
	import java.util.Map;
	import java.util.Map.Entry;
	import java.util.Set;

	import org.osgi.service.prefs.BackingStoreException;

	import org.eclipse.core.databinding.observable.masterdetail.IObservableFactory;
	import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
	import org.eclipse.core.databinding.observable.value.IObservableValue;
	import org.eclipse.core.resources.IProject;
	import org.eclipse.core.resources.ProjectScope;
	import org.eclipse.core.runtime.jobs.Job;
	import org.eclipse.core.runtime.preferences.DefaultScope;
	import org.eclipse.core.runtime.preferences.IEclipsePreferences;
	import org.eclipse.core.runtime.preferences.IEclipsePreferences.IPreferenceChangeListener;
	import org.eclipse.core.runtime.preferences.IScopeContext;
	import org.eclipse.core.runtime.preferences.InstanceScope;
	import org.eclipse.jface.dialogs.IDialogConstants;
	import org.eclipse.jface.dialogs.MessageDialog;
	import org.eclipse.jface.preference.IPreferenceStore;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.ui.preferences.IWorkbenchPreferenceContainer;
	import org.eclipse.ui.preferences.IWorkingCopyManager;

	import org.eclipse.statet.jcommons.collections.ImCollections;
	import org.eclipse.statet.jcommons.collections.ImList;
	import org.eclipse.statet.jcommons.collections.ImSet;
	import org.eclipse.statet.jcommons.lang.NonNullByDefault;
	import org.eclipse.statet.jcommons.lang.Nullable;

	import org.eclipse.statet.ecommons.databinding.jface.DataBindingSupport;
	import org.eclipse.statet.ecommons.preferences.SettingsChangeNotifier;
	import org.eclipse.statet.ecommons.preferences.core.Preference;
	import org.eclipse.statet.ecommons.preferences.core.PreferenceAccess;
	import org.eclipse.statet.ecommons.preferences.core.PreferenceSetService;
	import org.eclipse.statet.ecommons.resources.core.BuildUtils;
	import org.eclipse.statet.ecommons.runtime.core.StatusChangeListener;


	/**
	* Allows load, save, restore of managed preferences, including:
	* <p><ul>
	* <li>Connected databinding context:<ul>
	* <li>use {@link #initBindings()} to create dbc</li>
	* <li>use {@link #createObservable(Object)} to create observables for model</li>
	* <li>override {@link #addBindings(DataBindingSupport)}) to register bindings</li>
	* </ul></li>
	* <li>optional project scope</li>
	* <li>change settings groups ({@link SettingsChangeNotifier})</li>
	* </ul>
	* Instead of data binding, it is possible to overwrite
	* {@link #updatePreferences()} and {@link #updateControls()}
	* to map the preferences to UI.
	*/
	@NonNullByDefault
	public abstract class ManagedConfigurationBlock extends ConfigurationBlock
	implements PreferenceAccess, IObservableFactory {


	private static final String REBUILD_QUALIFIER= "org.eclipse.jdt.ui"; //$NON-NLS-1$
	private static final String REBUILD_KEY= "preferences_build_requested"; //$NON-NLS-1$


	protected class PreferenceManager {

	private final ImList<IScopeContext> lookupOrder;
	private final @Nullable IScopeContext inheritScope;
	private final Map<Preference<?>, @Nullable String> preferences;

	/** Manager for a working copy of the preferences */
	private final IWorkingCopyManager manager;
	/** Map saving the project settings, if disabled */
	private @Nullable Map<Preference<?>, @Nullable Object> disabledProjectSettings;

	private int rebuildCounter;


	PreferenceManager(final Map<Preference<?>, @Nullable String> prefs) {
	this.manager= getContainer().getWorkingCopyManager();
	this.preferences= prefs;

	ManagedConfigurationBlock.this.preferenceManager= this;

	if (ManagedConfigurationBlock.this.project != null) {
	this.lookupOrder= ImCollections.newList(
	new ProjectScope(ManagedConfigurationBlock.this.project),
	InstanceScope.INSTANCE,
	DefaultScope.INSTANCE );
	this.inheritScope= null;
	}
	else {
	this.lookupOrder= ImCollections.newList(
	InstanceScope.INSTANCE,
	DefaultScope.INSTANCE );
	this.inheritScope= this.lookupOrder.get(1);
	}

	// testIfOptionsComplete();

	// init disabled settings, if required
	if (ManagedConfigurationBlock.this.project == null
	\|\| hasProjectSpecificSettings(ManagedConfigurationBlock.this.project) ) {
	this.disabledProjectSettings= null;
	}
	else {
	saveDisabledProjectSettings();
	}

	checkRebuild();
	}


	/* Managing methods ***********************************************************/

	/**
	* Checks, if project specific options exists
	*
	* @param project to look up
	* @return
	*/
	boolean hasProjectSpecificSettings(final IProject project) {
	final IScopeContext projectContext= new ProjectScope(project);
	for (final Preference<?> pref : this.preferences.keySet()) {
	if (getInternalValue(pref, projectContext, true) != null) {
	return true;
	}
	}
	return false;
	}

	void setUseProjectSpecificSettings(final boolean enable) {
	final boolean hasProjectSpecificOption= (this.disabledProjectSettings == null);
	if (enable != hasProjectSpecificOption) {
	if (enable) {
	loadDisabledProjectSettings();
	} else {
	saveDisabledProjectSettings();
	}
	}
	}

	private void saveDisabledProjectSettings() {
	final Map<Preference<?>, @Nullable Object> projectSettings= new IdentityHashMap<>();
	for (final Preference<?> pref : this.preferences.keySet()) {
	projectSettings.put(pref, getValue(pref));
	setInternalValue(pref, null); // clear project settings
	}
	this.disabledProjectSettings= projectSettings;
	}

	private void loadDisabledProjectSettings() {
	final Map<Preference<?>, @Nullable Object> projectSettings= nonNullAssert(this.disabledProjectSettings);
	for (final Preference<?> key : this.preferences.keySet()) {
	// Copy values from saved disabled settings to working store
	setValue((Preference) key, projectSettings.get(key));
	}
	this.disabledProjectSettings= null;
	}

	boolean processChanges(final boolean saveStore) {
	final List<Preference<?>> changedPrefs= new ArrayList<>();
	final boolean needsBuild= getChanges(changedPrefs);
	if (changedPrefs.isEmpty()) {
	return true;
	}

	boolean doBuild= false;
	if (needsBuild) {
	if (checkRebuild()) {
	final String[] strings= getFullBuildDialogStrings(getProject() == null);
	if (strings != null) {
	final MessageDialog dialog= new MessageDialog(getShell(),
	strings[0], null, strings[1],
	MessageDialog.QUESTION, new String[] {
	IDialogConstants.YES_LABEL,
	IDialogConstants.NO_LABEL,
	IDialogConstants.CANCEL_LABEL },
	2 );
	final int res= dialog.open();
	if (res == 0) {
	doBuild= true;
	}
	else if (res != 1) {
	return false; // cancel pressed
	}
	}
	}
	}
	if (saveStore) {
	try {
	this.manager.applyChanges();
	}
	catch (final BackingStoreException e) {
	logSaveError(e);
	return false;
	}
	if (doBuild) {
	createRebuild().schedule();
	}
	}
	else {
	if (doBuild) {
	getContainer().registerUpdateJob(createRebuild());
	}
	}
	final Set<String> groupIds= new HashSet<>();
	for (final Preference<?> pref : changedPrefs) {
	final String groupId= this.preferences.get(pref);
	if (groupId != null) {
	groupIds.add(groupId);
	}
	}
	scheduleChangeNotification(groupIds, saveStore);
	return true;
	}

	/**
	*
	* @param currContext
	* @param changedSettings
	* @return true, if rebuild is required.
	*/
	private boolean getChanges(final List<Preference<?>> changedSettings) {
	final IScopeContext currContext= this.lookupOrder.get(0);
	boolean needsBuild= false;
	for (final Preference<?> key : this.preferences.keySet()) {
	final String oldValue= getInternalValue(key, currContext, false);
	final String value= getInternalValue(key, currContext, true);
	if (value == null) {
	if (oldValue != null) {
	changedSettings.add(key);
	needsBuild \|= !oldValue.equals(getInternalValue(key, true));
	}
	}
	else if (!value.equals(oldValue)) {
	changedSettings.add(key);
	needsBuild \|= (oldValue != null \|\| !value.equals(getInternalValue(key, true)));

	if (this.inheritScope != null
	&& value.equals(getInternalValue(key, this.inheritScope, false) )) {
	final IEclipsePreferences node= getNode(currContext, key.getQualifier(), true);
	node.remove(key.getKey());
	}
	}
	}
	return needsBuild;
	}


	void loadDefaults() {
	final IScopeContext defaultScope= DefaultScope.INSTANCE;
	for (final Preference<?> key : this.preferences.keySet()) {
	final String defValue= getInternalValue(key, defaultScope, false);
	setInternalValue(key, defValue);
	}
	}

	// DEBUG
	private void testIfOptionsComplete() {
	for (final Preference<?> key : this.preferences.keySet()) {
	if (getInternalValue(key, false) == null) {
	System.out.println("preference option missing: " + key + " (" + this.getClass().getName() +')'); //$NON-NLS-1$//$NON-NLS-2$
	}
	}
	}

	private IEclipsePreferences getNode(final IScopeContext context, final String qualifier, final boolean useWorkingCopy) {
	final IEclipsePreferences node= context.getNode(qualifier);
	if (useWorkingCopy && context != DefaultScope.INSTANCE) {
	return this.manager.getWorkingCopy(node);
	}
	return node;
	}

	private @Nullable String getInternalValue(final Preference<?> pref, final IScopeContext context, final boolean useWorkingCopy) {
	final IEclipsePreferences node= getNode(context, pref.getQualifier(), useWorkingCopy);
	return node.get(pref.getKey(), null);
	}

	private @Nullable String getInternalValue(final Preference<?> pref, final boolean ignoreTopScope) {
	for (int i= ignoreTopScope ? 1 : 0; i < this.lookupOrder.size(); i++) {
	final String value= getInternalValue(pref, this.lookupOrder.get(i), true);
	if (value != null) {
	return value;
	}
	}
	return null;
	}

	private <T> void setInternalValue(final Preference<T> pref, final @Nullable String value) {
	final IEclipsePreferences node= getNode(this.lookupOrder.get(0), pref.getQualifier(), true);
	if (value != null) {
	node.put(pref.getKey(), value);
	}
	else {
	node.remove(pref.getKey());
	}
	}


	private <T> void setValue(final Preference<T> pref, final @Nullable T value) {
	final IEclipsePreferences node= getNode(this.lookupOrder.get(0), pref.getQualifier(), true);
	final String storeValue;
	if (value == null
	\|\| (storeValue= pref.usage2Store(value)) == null) {
	node.remove(pref.getKey());
	return;
	}
	node.put(pref.getKey(), storeValue);
	}

	private <T> T getValue(final Preference<T> pref) {
	IEclipsePreferences node= null;
	for (int i= 0; i < this.lookupOrder.size(); i++) {
	final IEclipsePreferences nodeToCheck= getNode(this.lookupOrder.get(i), pref.getQualifier(), true);
	if (nodeToCheck.get(pref.getKey(), null) != null) {
	node= nodeToCheck;
	break;
	}
	}

	final String storeValue= (node != null) ? node.get(pref.getKey(), null) : null;
	return pref.store2Usage(storeValue);
	}


	private boolean checkRebuild() {
	final int counter= this.manager.getWorkingCopy(DefaultScope.INSTANCE.getNode(REBUILD_QUALIFIER))
	.getInt(REBUILD_KEY, 0);
	if (counter > this.rebuildCounter) {
	this.rebuildCounter= counter;
	return false;
	}
	return true;
	}

	private Job createRebuild() {
	this.rebuildCounter++;
	this.manager.getWorkingCopy(DefaultScope.INSTANCE.getNode(REBUILD_QUALIFIER))
	.putInt(REBUILD_KEY, this.rebuildCounter);
	return BuildUtils.getBuildJob(getProject());
	}

	}


	private final @Nullable IProject project;
	private @Nullable PreferenceManager preferenceManager;

	private DataBindingSupport dataBinding;
	private @Nullable StatusChangeListener statusListener;

	private Composite pageComposite;


	protected ManagedConfigurationBlock(final @Nullable IProject project) {
	this(project, null, null);
	}

	protected ManagedConfigurationBlock(final @Nullable IProject project,
	final @Nullable StatusChangeListener statusListener) {
	this(project, null, statusListener);
	}

	protected ManagedConfigurationBlock(final @Nullable IProject project,
	final String title,
	final @Nullable StatusChangeListener statusListener) {
	super(title);
	this.project= project;
	this.statusListener= statusListener;
	}


	protected void setStatusListener(final StatusChangeListener listener) {
	this.statusListener= listener;
	}


	public final @Nullable IProject getProject() {
	return this.project;
	}

	@Override
	public void createContents(final Composite pageComposite,
	final IWorkbenchPreferenceContainer container, final IPreferenceStore preferenceStore) {
	this.pageComposite= pageComposite;
	super.createContents(pageComposite, container, preferenceStore);
	}

	/**
	* initialize preference management
	*
	* @param container
	* @param prefs map with preference objects as key and their settings group id as optional value
	*/
	protected void setupPreferenceManager(final Map<Preference<?>, @Nullable String> prefs) {
	new PreferenceManager(prefs);
	}

	protected void initBindings() {
	this.dataBinding= new DataBindingSupport(this.pageComposite);
	addBindings(this.dataBinding);

	this.dataBinding.installStatusListener(this.statusListener);
	}

	protected DataBindingSupport getDataBinding() {
	return this.dataBinding;
	}

	protected void addBindings(final DataBindingSupport db) {
	}

	/**
	* Point to hook, before the managed preference values are saved to store.
	* E.g. you can set some additional (or all) values.
	*/
	protected void updatePreferences() {
	}

	@Override
	public boolean performOk(final int flags) {
	final PreferenceManager preferenceManager= this.preferenceManager;
	if (preferenceManager != null) {
	updatePreferences();
	return preferenceManager.processChanges((flags & SAVE_STORE) != 0);
	}
	return true;
	}

	@Override
	public void performDefaults() {
	final PreferenceManager preferenceManager= this.preferenceManager;
	if (preferenceManager != null) {
	preferenceManager.loadDefaults();
	updateControls();
	}
	}


	/* */

	/**
	* Checks, if project specific options exists
	*
	* @param project to look up
	* @return
	*/
	public boolean hasProjectSpecificOptions(final IProject project) {
	final PreferenceManager preferenceManager= this.preferenceManager;
	if (project != null && preferenceManager != null) {
	return preferenceManager.hasProjectSpecificSettings(project);
	}
	return false;
	}

	@Override
	public void setUseProjectSpecificSettings(final boolean enable) {
	super.setUseProjectSpecificSettings(enable);
	final PreferenceManager preferenceManager= this.preferenceManager;
	if (this.project != null && preferenceManager != null) {
	preferenceManager.setUseProjectSpecificSettings(enable);
	}
	}

	protected void updateControls() {
	if (this.dataBinding != null) {
	this.dataBinding.getContext().updateTargets();
	}
	}


	/* Access preference values ***************************************************/

	@Override
	public ImList<IScopeContext> getPreferenceContexts() {
	final PreferenceManager preferenceManager= nonNullAssert(this.preferenceManager);

	return preferenceManager.lookupOrder;
	}

	/**
	* Returns the value for the specified preference.
	*
	* @param pref preference key
	* @return value of the preference
	*/
	@Override
	@SuppressWarnings("unchecked")
	public <T> T getPreferenceValue(final Preference<T> pref) {
	assert (pref != null);
	final PreferenceManager preferenceManager= nonNullAssert(this.preferenceManager);

	final Map<Preference<?>, @Nullable Object> projectSettings= preferenceManager.disabledProjectSettings;
	if (projectSettings != null) {
	return (T)projectSettings.get(pref);
	}
	return preferenceManager.getValue(pref);
	}

	/**
	* Sets a preference value in the default store.
	*
	* @param key preference key
	* @param value new value
	* @return old value
	*/
	@SuppressWarnings("unchecked")
	public <T> T setPrefValue(final Preference<T> key, final T value) {
	final PreferenceManager preferenceManager= nonNullAssert(this.preferenceManager);

	final Map<Preference<?>, @Nullable Object> projectSettings= preferenceManager.disabledProjectSettings;
	if (projectSettings != null) {
	return (T) projectSettings.put(key, value);
	}
	final T oldValue= getPreferenceValue(key);
	preferenceManager.setValue(key, value);
	return oldValue;
	}

	public void setPrefValues(final Map<Preference<?>, Object> map) {
	for (final Entry<Preference<?>, Object> entry : map.entrySet()) {
	setPrefValue((Preference)entry.getKey(), entry.getValue());
	}
	}

	/**
	* Not (yet) supported
	*/
	@Override
	public void addPreferenceNodeListener(final String nodeQualifier, final IPreferenceChangeListener listener) {
	throw new UnsupportedOperationException();
	}

	/**
	* Not (yet) supported
	*/
	@Override
	public void removePreferenceNodeListener(final String nodeQualifier, final IPreferenceChangeListener listener) {
	throw new UnsupportedOperationException();
	}

	/**
	* Not (yet) supported
	*/
	@Override
	public void addPreferenceSetListener(final PreferenceSetService.ChangeListener listener,
	final ImSet<String> qualifiers) {
	throw new UnsupportedOperationException();
	}

	/**
	* Not (yet) supported
	*/
	@Override
	public void removePreferenceSetListener(final PreferenceSetService.ChangeListener listener) {
	throw new UnsupportedOperationException();
	}


	@Override
	public IObservableValue createObservable(final Object target) {
	return createObservable((Preference<?>) target);
	}

	public <T> IObservableValue<T> createObservable(final Preference<T> pref) {
	return new AbstractObservableValue<T>() {
	@Override
	public Object getValueType() {
	return pref.getUsageType();
	}
	@Override
	protected void doSetValue(final T value) {
	setPrefValue(pref, value);
	}
	@Override
	protected T doGetValue() {
	return getPreferenceValue(pref);
	}
	@Override
	public synchronized void dispose() {
	super.dispose();
	}
	};
	}

	/**
	* Changes requires full build, this method should be overwritten
	* and return the Strings for the dialog.
	*
	* @param workspaceSettings true, if settings for workspace; false, if settings for project.
	* @return
	*/
	protected String @Nullable [] getFullBuildDialogStrings(final boolean workspaceSettings) {
	return null;
	}

	}