/*
* 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.place.shared.PlaceHistoryHandler.Historian;
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;
import com.gwtplatform.mvp.shared.proxy.PlaceRequest;
import com.gwtplatform.mvp.shared.proxy.TokenFormatException;
import com.gwtplatform.mvp.shared.proxy.TokenFormatter;
/**
* Default implementation to be extended of the {@link PlaceManager}.
*
* @see DefaultPlaceManager
*/
public abstract class PlaceManagerImpl implements PlaceManager, ValueChangeHandler<String>, ClosingHandler {
private final EventBus eventBus;
private final TokenFormatter tokenFormatter;
private final Historian historian;
private String currentHistoryToken = "";
private boolean internalError;
private String onLeaveQuestion;
private Command defferedNavigation;
private HandlerRegistration windowClosingHandlerRegistration;
private boolean locked;
private List<PlaceRequest> placeHierarchy = new ArrayList<>();
public PlaceManagerImpl(
EventBus eventBus,
TokenFormatter tokenFormatter,
Historian historian) {
this.eventBus = eventBus;
this.tokenFormatter = tokenFormatter;
this.historian = historian;
registerTowardsHistory();
}
@Override
public String buildHistoryToken(PlaceRequest request) {
return tokenFormatter.toPlaceToken(request);
}
@Override
public String buildRelativeHistoryToken(int level) {
List<PlaceRequest> 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<PlaceRequest> 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 historian.getToken();
}
@Override
public List<PlaceRequest> 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 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 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(ValueChangeEvent<String> event) {
handleTokenChange(event.getValue());
}
private void handleTokenChange(final String historyToken) {
if (locked) {
defferedNavigation = () -> handleTokenChange(historyToken);
return;
}
if (!getLock()) {
return;
}
try {
if (historyToken.trim().isEmpty()) {
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() {
historian.addValueChangeHandler(this);
}
@Override
public void revealCurrentPlace() {
handleTokenChange(historian.getToken());
}
@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 = () -> revealPlace(request, updateBrowserUrl);
return;
}
if (!getLock()) {
return;
}
placeHierarchy.clear();
placeHierarchy.add(request);
doRevealPlace(request, updateBrowserUrl);
}
@Override
public void revealPlaceHierarchy(
final List<PlaceRequest> placeRequestHierarchy) {
if (locked) {
defferedNavigation = () -> 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 = () -> 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 = () -> 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) {
historian.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) {
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<PlaceRequest> 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);
}
}