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/**
* Copyright 2013 ArcBees 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 com.gwtplatform.mvp.client.proxy;
import java.util.ArrayList;
import java.util.List;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.GwtEvent;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.History;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.Window.ClosingEvent;
import com.google.gwt.user.client.Window.ClosingHandler;
import com.google.web.bindery.event.shared.EventBus;
import com.google.web.bindery.event.shared.HandlerRegistration;
/**
* Default implementation to be extended of the {@link PlaceManager}.
*
* @see DefaultPlaceManager
*/
public abstract class PlaceManagerImpl implements PlaceManager, ValueChangeHandler, ClosingHandler {
private final EventBus eventBus;
private final TokenFormatter tokenFormatter;
private String currentHistoryToken = "";
private boolean internalError;
private String onLeaveQuestion;
private Command defferedNavigation;
private HandlerRegistration windowClosingHandlerRegistration;
private boolean locked;
private List placeHierarchy = new ArrayList();
public PlaceManagerImpl(EventBus eventBus, TokenFormatter tokenFormatter) {
this.eventBus = eventBus;
this.tokenFormatter = tokenFormatter;
registerTowardsHistory();
}
@Override
public String buildHistoryToken(PlaceRequest request) {
return tokenFormatter.toPlaceToken(request);
}
@Override
public String buildRelativeHistoryToken(int level) {
List placeHierarchyCopy = truncatePlaceHierarchy(level);
if (placeHierarchyCopy.size() == 0) {
return "";
}
return tokenFormatter.toHistoryToken(placeHierarchyCopy);
}
@Override
public String buildRelativeHistoryToken(PlaceRequest request) {
return buildRelativeHistoryToken(request, 0);
}
@Override
public String buildRelativeHistoryToken(PlaceRequest request, int level) {
List placeHierarchyCopy = truncatePlaceHierarchy(level);
placeHierarchyCopy.add(request);
return tokenFormatter.toHistoryToken(placeHierarchyCopy);
}
/**
* If a confirmation question is set (see
* {@link #setOnLeaveConfirmation(String)}), this asks the user if he wants to
* leave the current page.
*
* @return true if the user accepts to leave. false if he refuses.
*/
private boolean confirmLeaveState() {
if (onLeaveQuestion == null) {
return true;
}
boolean confirmed = Window.confirm(onLeaveQuestion);
if (confirmed) {
// User has confirmed, don't ask any more question.
setOnLeaveConfirmation(null);
} else {
NavigationRefusedEvent.fire(this);
setBrowserHistoryToken(currentHistoryToken, false);
}
return confirmed;
}
/**
* Fires the {@link PlaceRequestInternalEvent} for the given
* {@link PlaceRequest}. Do not call this method directly,
* instead call {@link #revealPlace(PlaceRequest)} or a related method.
*
* @param request The {@link PlaceRequest} to fire.
* @param updateBrowserUrl {@code true} If the browser URL should be updated, {@code false}
* otherwise.
*/
protected void doRevealPlace(PlaceRequest request, boolean updateBrowserUrl) {
PlaceRequestInternalEvent requestEvent = new PlaceRequestInternalEvent(request,
updateBrowserUrl);
fireEvent(requestEvent);
if (!requestEvent.isHandled()) {
unlock();
error(tokenFormatter.toHistoryToken(placeHierarchy));
} else if (!requestEvent.isAuthorized()) {
unlock();
illegalAccess(tokenFormatter.toHistoryToken(placeHierarchy));
}
}
/**
* Called whenever an error occurred that requires the error page to be shown
* to the user. This method will detect infinite reveal loops and throw an
* {@link RuntimeException} in that case.
*
* @param invalidHistoryToken The history token that was not recognised.
*/
private void error(String invalidHistoryToken) {
startError();
revealErrorPlace(invalidHistoryToken);
stopError();
}
@Override
public void fireEvent(GwtEvent event) {
getEventBus().fireEventFromSource(event, this);
}
String getBrowserHistoryToken() {
return History.getToken();
}
@Override
public List getCurrentPlaceHierarchy() {
return placeHierarchy;
}
@Override
public PlaceRequest getCurrentPlaceRequest() {
if (placeHierarchy.size() > 0) {
return placeHierarchy.get(placeHierarchy.size() - 1);
} else {
return new PlaceRequest.Builder().build();
}
}
@Override
public void getCurrentTitle(SetPlaceTitleHandler handler) {
getTitle(placeHierarchy.size() - 1, handler);
}
@Override
public EventBus getEventBus() {
return eventBus;
}
@Override
public int getHierarchyDepth() {
return placeHierarchy.size();
}
/**
* Checks that the place manager is not locked and that the user allows the
* application to navigate (see {@link #confirmLeaveState()}. If the
* application is allowed to navigate, this method locks navigation.
*
* @return true if the place manager can get the lock false otherwise.
*/
private boolean getLock() {
if (locked) {
return false;
}
if (!confirmLeaveState()) {
return false;
}
lock();
return true;
}
@Override
public void getTitle(int index, SetPlaceTitleHandler handler)
throws IndexOutOfBoundsException {
GetPlaceTitleEvent event = new GetPlaceTitleEvent(
placeHierarchy.get(index), handler);
fireEvent(event);
// If nobody took care of the title, indicate it's null
if (!event.isHandled()) {
handler.onSetPlaceTitle(null);
}
}
@Override
public boolean hasPendingNavigation() {
return defferedNavigation != null;
}
/**
* Called whenever the user tries to access an page to which he doesn't have
* access, and we need to reveal the user-defined unauthorized place. This
* method will detect infinite reveal loops and throw an
* {@link RuntimeException} in that case.
*
* @param historyToken The history token that was not recognised.
*/
private void illegalAccess(String historyToken) {
startError();
revealUnauthorizedPlace(historyToken);
stopError();
}
private void lock() {
if (!locked) {
locked = true;
LockInteractionEvent.fire(this, true);
}
}
@Override
public void navigateBack() {
History.back();
}
/**
* Handles change events from {@link History}.
*/
@Override
public void onValueChange(final ValueChangeEvent event) {
if (locked) {
defferedNavigation = new Command() {
@Override
public void execute() {
onValueChange(event);
}
};
return;
}
if (!getLock()) {
return;
}
String historyToken = event.getValue();
try {
if (historyToken.trim().equals("")) {
unlock();
revealDefaultPlace();
} else {
placeHierarchy = tokenFormatter.toPlaceRequestHierarchy(historyToken);
doRevealPlace(getCurrentPlaceRequest(), true);
}
} catch (TokenFormatException e) {
unlock();
error(historyToken);
NavigationEvent.fire(this, null);
}
}
@Override
public void onWindowClosing(ClosingEvent event) {
// The current implementation has a few bugs described below. However these are browser
// bugs, and the workarounds we've experimented with gave worst results than the bug itself.
//
// Here are the current behaviours of different browsers after cancelling navigation
// * Chrome
// - URL bar shows new website (FAIL)
// - Bookmarking uses the title of the webapp, but url of new website (FAIL)
// - Navigating away and then back goes back to the correct webapp page (WORKS)
// * Firefox
// - URL bar shows new website (FAIL)
// - Bookmarking uses the title of the webapp, and url of webapp (WORKS)
// - Navigating away and then back goes back to the correct webapp page (WORKS)
// * IE
// - Untested
//
// Options are to report that upstream in the browsers or to go back to our workarounds in a
// browser-dependent fashion using deferred binding. The workarounds we've experimented with
// consisted of adding a deferred command that used Window.Location.replace to reset the URL
// to the current page. However, this caused infinite loops in some browsers.
//
// See this issue:
// http://code.google.com/p/gwt-platform/issues/detail?id=315
event.setMessage(onLeaveQuestion);
}
void registerTowardsHistory() {
History.addValueChangeHandler(this);
}
@Override
public void revealCurrentPlace() {
History.fireCurrentHistoryState();
}
@Override
public void revealErrorPlace(String invalidHistoryToken) {
revealDefaultPlace();
}
@Override
public void revealPlace(final PlaceRequest request) {
revealPlace(request, true);
}
@Override
public void revealPlace(final PlaceRequest request, final boolean updateBrowserUrl) {
if (locked) {
defferedNavigation = new Command() {
@Override
public void execute() {
revealPlace(request, updateBrowserUrl);
}
};
return;
}
if (!getLock()) {
return;
}
placeHierarchy.clear();
placeHierarchy.add(request);
doRevealPlace(request, updateBrowserUrl);
}
@Override
public void revealPlaceHierarchy(
final List placeRequestHierarchy) {
if (locked) {
defferedNavigation = new Command() {
@Override
public void execute() {
revealPlaceHierarchy(placeRequestHierarchy);
}
};
return;
}
if (!getLock()) {
return;
}
if (placeRequestHierarchy.size() == 0) {
unlock();
revealDefaultPlace();
} else {
placeHierarchy = placeRequestHierarchy;
doRevealPlace(getCurrentPlaceRequest(), true);
}
}
@Override
public void revealRelativePlace(final int level) {
if (locked) {
defferedNavigation = new Command() {
@Override
public void execute() {
revealRelativePlace(level);
}
};
return;
}
if (!getLock()) {
return;
}
placeHierarchy = truncatePlaceHierarchy(level);
int hierarchySize = placeHierarchy.size();
if (hierarchySize == 0) {
unlock();
revealDefaultPlace();
} else {
PlaceRequest request = placeHierarchy.get(hierarchySize - 1);
doRevealPlace(request, true);
}
}
@Override
public void revealRelativePlace(PlaceRequest request) {
revealRelativePlace(request, 0);
}
@Override
public void revealRelativePlace(final PlaceRequest request, final int level) {
if (locked) {
defferedNavigation = new Command() {
@Override
public void execute() {
revealRelativePlace(request, level);
}
};
return;
}
if (!getLock()) {
return;
}
placeHierarchy = truncatePlaceHierarchy(level);
placeHierarchy.add(request);
doRevealPlace(request, true);
}
@Override
public void revealUnauthorizedPlace(String unauthorizedHistoryToken) {
revealErrorPlace(unauthorizedHistoryToken);
}
/**
* This method saves the history token, making it possible to correctly restore the browser's
* URL if the user refuses to navigate. (See {@link #onWindowClosing(ClosingEvent)})
*
* @param historyToken The current history token, a string.
*/
private void saveHistoryToken(String historyToken) {
currentHistoryToken = historyToken;
}
void setBrowserHistoryToken(String historyToken, boolean issueEvent) {
History.newItem(historyToken, issueEvent);
}
@Override
public void setOnLeaveConfirmation(String question) {
if (question == null && onLeaveQuestion == null) {
return;
}
if (question != null && onLeaveQuestion == null) {
windowClosingHandlerRegistration = Window.addWindowClosingHandler(this);
}
if (question == null && onLeaveQuestion != null) {
windowClosingHandlerRegistration.removeHandler();
}
onLeaveQuestion = question;
}
/**
* Start revealing an error or unauthorized page. This method will throw an
* exception if an infinite loop is detected.
*
* @see #stopError()
*/
private void startError() {
if (this.internalError) {
throw new RuntimeException(
"Encountered repeated errors resulting in an infinite loop. Make sure all users have access "
+ "to the pages revealed by revealErrorPlace and revealUnauthorizedPlace. (Note that the " +
"default "
+ "implementations call revealDefaultPlace)");
}
internalError = true;
}
/**
* Indicates that an error page has successfully been revealed. Makes it
* possible to detect infinite loops.
*
* @see #startError()
*/
private void stopError() {
internalError = false;
}
@Override
public void unlock() {
if (locked) {
locked = false;
LockInteractionEvent.fire(this, false);
if (hasPendingNavigation()) {
Command navigation = defferedNavigation;
defferedNavigation = null;
navigation.execute();
}
}
}
@Override
public void updateHistory(PlaceRequest request, boolean updateBrowserUrl) {
try {
// Make sure the request match
assert request.hasSameNameToken(getCurrentPlaceRequest()) : "Internal error, PlaceRequest passed to" +
"updateHistory doesn't match the tail of the place hierarchy.";
placeHierarchy.set(placeHierarchy.size() - 1, request);
if (updateBrowserUrl) {
String historyToken = tokenFormatter.toHistoryToken(placeHierarchy);
String browserHistoryToken = getBrowserHistoryToken();
if (browserHistoryToken == null
|| !browserHistoryToken.equals(historyToken)) {
setBrowserHistoryToken(historyToken, false);
}
saveHistoryToken(historyToken);
}
} catch (TokenFormatException e) {
// Do nothing.
}
}
/**
* Returns a modified copy of the place hierarchy based on the specified
* {@code level}.
*
* @param level If negative, take back that many elements from the tail of the
* hierarchy. If positive, keep only that many elements from the head
* of the hierarchy. Passing {@code 0} leaves the hierarchy
* untouched.
*/
private List truncatePlaceHierarchy(int level) {
int size = placeHierarchy.size();
if (level < 0) {
if (-level >= size) {
return new ArrayList();
} else {
return new ArrayList(placeHierarchy.subList(0, size
+ level));
}
} else if (level > 0) {
if (level >= size) {
return new ArrayList(placeHierarchy);
} else {
return new ArrayList(placeHierarchy.subList(0, level));
}
}
return new ArrayList(placeHierarchy);
}
}
