/*
* Copyright 2011 JBoss, by Red Hat, Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jboss.errai.databinding.client;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import org.jboss.errai.common.client.api.Assert;
import org.jboss.errai.databinding.client.api.Convert;
import org.jboss.errai.databinding.client.api.Converter;
import org.jboss.errai.databinding.client.api.DataBinder;
import org.jboss.errai.databinding.client.api.InitialState;
import org.jboss.errai.databinding.client.api.PropertyChangeEvent;
import org.jboss.errai.databinding.client.api.PropertyChangeHandler;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.ui.HasText;
import com.google.gwt.user.client.ui.HasValue;
import com.google.gwt.user.client.ui.Widget;
/**
* Manages bindings and acts in behalf of a {@link BindableProxy} to keep the target model and bound widgets in sync.
* <p>
* An agent will:
* <ul>
* <li>Carry out an initial state sync between the bound widgets and the target model, if specified (see
* {@link DataBinder#DataBinder(Object, InitialState)})</li>
*
* <li>Update the bound widget when a setter method is invoked on the model (see
* {@link #updateWidgetAndFireEvent(String, Object, Object)}). Works for widgets that either implement {@link HasValue}
* or {@link HasText})</li>
*
* <li>Update the bound widgets when a non-accessor method is invoked on the model (by comparing all bound properties to
* detect changes). See {@link #updateWidgetsAndFireEvents()}. Works for widgets that either implement {@link HasValue}
* or {@link HasText})</li>
*
* <li>Update the target model in response to value change events (only works for bound widgets that implement
* {@link HasValue})</li>
* <ul>
*
* @author Christian Sadilek <csadilek@redhat.com>
*
* @param <T>
* The type of the target model being proxied.
*
*/
@SuppressWarnings({ "rawtypes", "unchecked" })
public final class BindableProxyAgent<T> implements HasPropertyChangeHandlers {
final Map<String, PropertyType> propertyTypes = new HashMap<String, PropertyType>();
final Map<String, Widget> bindings = new HashMap<String, Widget>();
final Map<String, DataBinder> binders = new HashMap<String, DataBinder>();
final Map<String, Converter> converters = new HashMap<String, Converter>();
final Map<String, HandlerRegistration> handlerRegistrations = new HashMap<String, HandlerRegistration>();
final Map<String, Object> knownValues = new HashMap<String, Object>();
PropertyChangeHandlerSupport propertyChangeHandlerSupport = new PropertyChangeHandlerSupport();
final BindableProxy<T> proxy;
final T target;
final InitialState initialState;
BindableProxyAgent(BindableProxy<T> proxy, T target, InitialState initialState) {
this.proxy = proxy;
this.target = target;
this.initialState = initialState;
}
/**
* Makes the settings of this BindableProxyAgent match those of the given agent.
* <p>
* IMPORTANT NOTE: this is currently implemented by sharing the PropertyChangeHandler registrations with the given
* agent. You should discard all references to the "other" agent after calling this method.
*
* @param other
* the agent to copy/share settings from. Should not be used after you pass it to this method.
*/
public void copyStateFrom(BindableProxyAgent<T> other) {
for (String boundProperty : other.getBoundProperties()) {
bind(other.getWidget(boundProperty), boundProperty, other.getConverter(boundProperty));
}
propertyChangeHandlerSupport = other.propertyChangeHandlerSupport;
}
/**
* Copies the values of all properties to be able to compare them in case they change outside a setter method.
*/
void copyValues() {
for (String property : propertyTypes.keySet()) {
knownValues.put(property, proxy.get(property));
}
}
/**
* Returns a set of the currently bound property names.
*
* @return bound properties, an empty set if no properties have been bound.
*/
public Set<String> getBoundProperties() {
return bindings.keySet();
}
/**
* Returns the widget currently bound to the provided property (see {@link #bind(Widget, String, Converter)}).
*
* @param property
* the name of the model property
* @return the widget currently bound to the provided property or null if no widget was bound to the property.
*/
public Widget getWidget(final String property) {
return bindings.get(property);
}
/**
* Returns the converter used for the binding of the provided property (see {@link #bind(Widget, String, Converter)}).
*
* @param property
* the name of the model property
* @return the converter used for the bound property or null if the property was not bound or no converter was
* specified for the binding.
*/
public Converter getConverter(final String property) {
return converters.get(property);
}
/**
* Returns the {@link InitialState} configured when the proxy was created.
*
* @return initial state, can be null.
*/
public InitialState getInitialState() {
return initialState;
}
/**
* Binds the provided widget to the specified property (or property chain) of the model instance associated with this
* proxy (see {@link #setModel(Object, InitialState)}).
*
* @param widget
* the widget to bind to, must not be null.
* @param property
* the property of the model to bind the widget to, must not be null.
* @param converter
* the converter to use for this binding, null if default conversion should be used.
*/
public void bind(final Widget widget, final String property, final Converter converter) {
validatePropertyExpr(property);
if (property.indexOf(".") > 0) {
createNestedBinders(widget, property, converter);
bindings.put(property, widget);
return;
}
if (!propertyTypes.containsKey(property)) {
throw new NonExistingPropertyException(property);
}
unbind(property);
if (bindings.containsValue(widget)) {
throw new WidgetAlreadyBoundException("Widget already bound to a different property!");
}
bindings.put(property, widget);
converters.put(property, converter);
if (widget instanceof HasValue) {
handlerRegistrations.put(property, ((HasValue) widget).addValueChangeHandler(new ValueChangeHandler() {
@Override
public void onValueChange(ValueChangeEvent event) {
Object oldValue = proxy.get(property);
Object newValue =
Convert.toModelValue(propertyTypes.get(property).getType(), widget, event.getValue(), converter);
proxy.set(property, newValue);
firePropertyChangeEvent(property, oldValue, newValue);
}
}));
}
syncState(widget, property, initialState);
}
/**
* Creates a data binder for a nested property to support property chains. The nested data binder is initialized with
* the current value of the specified property, or with a new instance of the property type if the value is null. The
* proxy's value for this property is then replaced with the proxy managed by the nested data binder.
*
* @param widget
* the widget to bind to, must not be null.
* @param property
* the property of the model to bind the widget to, must not be null. The property must be of a @Bindable
* type.
* @param converter
* the converter to use for this binding, null if default conversion should be used.
*/
private void createNestedBinders(final Widget widget, final String property, final Converter converter) {
int dotPos = property.indexOf(".");
if (dotPos > 0) {
String bindableProperty = property.substring(0, dotPos);
if (!propertyTypes.containsKey(bindableProperty)) {
throw new NonExistingPropertyException(bindableProperty);
}
if (!propertyTypes.get(bindableProperty).isBindable()) {
throw new RuntimeException("The type of property " + bindableProperty + " ("
+ propertyTypes.get(bindableProperty).getType().getName() + ") is not a @Bindable type!");
}
DataBinder<Object> binder = binders.get(bindableProperty);
if (binder == null) {
if (proxy.get(bindableProperty) == null) {
binder = DataBinder.forType(propertyTypes.get(bindableProperty).getType(), initialState);
}
else {
binder = DataBinder.forModel(proxy.get(bindableProperty), initialState);
}
binders.put(bindableProperty, binder);
}
binder.bind(widget, property.substring(dotPos + 1), converter);
proxy.set(bindableProperty, binder.getModel());
}
}
private void validatePropertyExpr(String property) {
if (property.startsWith(".") || property.endsWith(".")) {
throw new RuntimeException("Binding expression (property chain) cannot start or end with '.' :" + property);
}
}
/**
* Unbinds all properties.
*/
public void unbind() {
for (DataBinder binder : binders.values()) {
binder.unbind();
}
binders.clear();
for (Object reg : handlerRegistrations.keySet()) {
(handlerRegistrations.get(reg)).removeHandler();
}
handlerRegistrations.clear();
bindings.clear();
converters.clear();
}
/**
* Unbinds the property with the given name.
*
* @param property
* the name of the model property to unbind, must not be null.
*/
public void unbind(final String property) {
validatePropertyExpr(property);
int dotPos = property.indexOf(".");
if (dotPos > 0) {
String bindableProperty = property.substring(0, dotPos);
DataBinder binder = binders.get(bindableProperty);
if (binder != null) {
binder.unbind(property.substring(dotPos + 1));
}
}
bindings.remove(property);
converters.remove(property);
HandlerRegistration reg = handlerRegistrations.remove(property);
if (reg != null) {
reg.removeHandler();
}
}
/**
* Updates all bound widgets if necessary (if a bound property's value has changed). This method is invoked in case a
* bound property changed outside the property's write method (when using a non accessor method).
*
* @param <P>
* The property type of the changed property.
*/
void updateWidgetsAndFireEvents() {
for (String property : propertyTypes.keySet()) {
Object knownValue = knownValues.get(property);
Object actualValue = proxy.get(property);
if ((knownValue == null && actualValue != null) ||
(knownValue != null && !knownValue.equals(actualValue))) {
DataBinder nestedBinder = binders.get(property);
if (nestedBinder != null) {
nestedBinder.setModel(actualValue, InitialState.FROM_MODEL);
proxy.set(property, nestedBinder.getModel());
}
updateWidgetAndFireEvent(property, knownValue, actualValue);
}
}
}
/**
* Updates a bound widget and fires the corresponding {@link PropertyChangeEvent}.
*
* @param <P>
* The property type of the changed property.
* @param property
* The name of the property that changed. Must not be null.
* @param oldValue
* The old value of the property.
* @param newValue
* The new value of the property.
*/
<P> void updateWidgetAndFireEvent(final String property, final P oldValue, final P newValue) {
Widget widget = bindings.get(property);
if (widget instanceof HasValue) {
HasValue hv = (HasValue) widget;
Object widgetValue =
Convert.toWidgetValue(widget, propertyTypes.get(property).getType(), newValue, converters.get(property));
hv.setValue(widgetValue);
}
else if (widget instanceof HasText) {
HasText ht = (HasText) widget;
Object widgetValue =
Convert
.toWidgetValue(String.class, propertyTypes.get(property).getType(), newValue, converters.get(property));
ht.setText((String) widgetValue);
}
firePropertyChangeEvent(property, oldValue, newValue);
}
/**
* Fires a property change event.
*
* @param <P>
* The property type of the changed property.
* @param property
* The name of the property that changed. Must not be null.
* @param oldValue
* The old value of the property.
* @param newValue
* The new value of the property.
*/
private <P> void firePropertyChangeEvent(final String property, final P oldValue, final P newValue) {
PropertyChangeEvent<P> event = new PropertyChangeEvent<P>(proxy, Assert.notNull(property), oldValue, newValue);
propertyChangeHandlerSupport.notifyHandlers(event);
knownValues.put(property, newValue);
}
/**
* Synchronizes the state of the provided widgets and model property based on the value of the provided {@link InitialState}.
*
* @param widget
* The widget to synchronize. Must not be null.
* @param property
* The name of the model property that should be synchronized. Must not be null.
* @param initialState
* Specifies the origin of the initial state of both model and UI widget. If null, no state
* synchronization should be carried out.
*/
private void syncState(final Widget widget, final String property, final InitialState initialState) {
Assert.notNull(widget);
Assert.notNull(property);
if (initialState != null) {
Object value = proxy.get(property);
if (widget instanceof HasValue) {
value = initialState.getInitialValue(value, ((HasValue) widget).getValue());
}
else if (widget instanceof HasText) {
value = initialState.getInitialValue(value, ((HasText) widget).getText());
}
if (initialState == InitialState.FROM_MODEL) {
updateWidgetAndFireEvent(property, knownValues.get(property), value);
}
else if (initialState == InitialState.FROM_UI) {
proxy.set(property, value);
firePropertyChangeEvent(property, knownValues.get(property), value);
}
}
}
@Override
public void addPropertyChangeHandler(PropertyChangeHandler handler) {
propertyChangeHandlerSupport.addPropertyChangeHandler(handler);
}
@Override
public <P> void addPropertyChangeHandler(String name, PropertyChangeHandler<P> handler) {
propertyChangeHandlerSupport.addPropertyChangeHandler(name, handler);
}
@Override
public void removePropertyChangeHandler(PropertyChangeHandler handler) {
propertyChangeHandlerSupport.removePropertyChangeHandler(handler);
}
@Override
public void removePropertyChangeHandler(String name, PropertyChangeHandler handler) {
propertyChangeHandlerSupport.removePropertyChangeHandler(name, handler);
}
}