/**
* Copyright 2010 Google 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.google.livingstories.client.util;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.DeferredCommand;
import com.google.gwt.user.client.History;
import com.google.gwt.user.client.Window;
import com.google.livingstories.client.FilterSpec;
import com.google.livingstories.client.lsp.Page;
import com.google.livingstories.client.lsp.Page.LoadHandler;
import com.google.livingstories.client.lsp.views.PlayerPage;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
/**
* Class that manages history tokens and navigation.
*
* Note that we use Window.Location.getHash() to get the history token everywhere
* in this class, rather than History.getToken(). We do this because IE has issues
* with firing history change events when the hash is updated programmatically, which
* causes History.getToken to return out of date results.
*/
public class HistoryManager {
public enum HistoryPages {
OVERVIEW {
@Override
public Page getPage(String[] tokens) {
return PageCache.getOverviewPage(new FilterSpec(tokens[1]),
tokens[2].equals("null") ? null : Long.valueOf(tokens[2]));
}
@Override
public String createToken(String... params) {
// name:filterParams:focusedContentItemId (for filterParams see FilterSpec.java)
return name() + ":" + params[0] + ":" + params[1];
}
@Override
public Map<String, String> getDefaultState() {
return new HashMap<String, String>();
}
},
PLAYER {
@Override
public Page getPage(String[] tokens) {
PlayerPage playerPage = new PlayerPage();
playerPage.load(Long.valueOf(tokens[1]));
return playerPage;
}
@Override
public String createToken(String... params) {
// name:contentItemId
return name() + ":" + params[0];
}
@Override
public Map<String, String> getDefaultState() {
return new HashMap<String, String>();
}
};
public abstract Page getPage(String[] pageTokens);
public abstract String createToken(String... params);
public abstract Map<String, String> getDefaultState();
}
public static class HistoryChangeHandler implements ValueChangeHandler<String> {
@Override
public void onValueChange(ValueChangeEvent<String> e) {
if (e.getValue().isEmpty()) {
// Handles the case where the history token is empty (e.g. first visit)
loadMainPage();
return;
}
final String[] newTokens = e.getValue().split(";");
String newPageToken = newTokens[0];
if (page == null || !pageToken.equals(newPageToken)) {
pageToken = newPageToken;
String[] pageParams = newPageToken.split(":");
HistoryPages historyPage = HistoryPages.valueOf(pageParams[0]);
Page newPage = historyPage.getPage(pageParams);
pageState = historyPage.getDefaultState();
if (newPage != page) {
page = newPage;
LivingStoryControls.goToPage(page);
}
}
changeState(newTokens);
if (page.isLoaded()) {
page.onShow();
executeState();
} else {
page.addLoadHandler(new LoadHandler() {
public void onLoad() {
page.onShow();
executeState();
}
});
}
}
private void changeState(String[] tokens) {
pageState.clear();
for (int i = 1; i < tokens.length; i++) {
String[] state = tokens[i].split(":");
pageState.put(state[0], state[1]);
}
}
private void executeState() {
// Prevent state change operations from setting extra tokens
beginBatchStateChange();
for (Entry<String, String> state : pageState.entrySet()) {
page.changeState(state.getKey(), state.getValue());
}
endBatchStateChange();
}
}
private static HistoryChangeHandler historyChangeHandler;
private static String pageToken;
private static Page page;
private static Map<String, String> pageState;
private static boolean batchStateChange = false;
private static boolean initialized = false;
/**
* Convenience method for creating a new history page with the default state.
* This method is a hack to let the player page transition work properly.
*/
public static void newToken(Page page, HistoryPages historyPage, String... params) {
HistoryManager.page = page;
pageToken = historyPage.createToken(params);
pageState = historyPage.getDefaultState();
setToken();
}
/**
* Convenience method for updating the pageToken without changing the page.
*/
public static void newToken(HistoryPages historyPage, String... params) {
pageToken = historyPage.createToken(params);
pageState = historyPage.getDefaultState();
setToken();
}
/**
* Convenience method for creating a new history page with the default state and
* firing a history changed event.
*/
public static void newTokenWithEvent(HistoryPages page, String... params) {
String token = page.createToken(params) + ";";
if (!token.equals(getHash())) {
History.newItem(token);
}
}
/**
* Sets a single state key/value pair without changing the current page.
* Pass in a null as the state value to unset a key.
*/
public static void changeState(String key, String value) {
if (value == null) {
if (value != pageState.remove(key)) {
setToken();
}
} else {
if (!value.equals(pageState.put(key, value))) {
setToken();
}
}
}
public static void beginBatchStateChange() {
batchStateChange = true;
}
public static void endBatchStateChange() {
batchStateChange = false;
setToken();
}
public static String getState(String key) {
return pageState.get(key);
}
public static String getLink(HistoryPages page, String... params) {
String href = Window.Location.getHref().split("#")[0];
return href.concat("#" + getToken(page.createToken(params), page.getDefaultState()));
}
public static String getTokenStringForFocusedContentItem(Long focusedContentItemId) {
return "#" + HistoryPages.OVERVIEW.createToken(
getDefaultFilterSpec().getFilterParams(), focusedContentItemId.toString())
+ ";";
}
private static String getToken(String pageToken, Map<String, String> pageState) {
StringBuilder sb = new StringBuilder(pageToken).append(";");
for (Entry<String, String> entry : pageState.entrySet()) {
sb.append(entry.getKey()).append(":").append(entry.getValue()).append(";");
}
return sb.toString();
}
private static void setToken() {
if (batchStateChange) {
return;
}
String token = getToken(pageToken, pageState);
if (!token.equals(getHash())) {
History.newItem(token, false);
}
}
private static String getHash() {
// In IE, we need to use the location.hash value, since it doesn't fire history
// change events properly so that History.getToken returns the right value.
// In chrome, we can't use location.hash because THAT doesn't return the right value,
// apparently.
return isIE() ? Window.Location.getHash().replaceAll("#", "") : History.getToken();
}
public static void loadMainPage() {
String currentUrl = Window.Location.getHref().split("#")[0];
final String token = HistoryPages.OVERVIEW.createToken(
getDefaultFilterSpec().getFilterParams(), null) + ";";
Window.Location.replace(currentUrl + "#" + token);
Command fireValueChange = new Command() {
@Override
public void execute() {
historyChangeHandler.onValueChange(new ValueChangeEvent<String>(token){});
}
};
if (isIE()) {
// In IE, we need to fire this immediately or we get into an infinite redirect loop.
fireValueChange.execute();
} else {
// In chrome, we need to delay this, otherwise getHash() doesn't return the right value.
DeferredCommand.addCommand(fireValueChange);
}
}
private static FilterSpec getDefaultFilterSpec() {
String defaultPageParams = LivingStoryData.getDefaultPage();
return (defaultPageParams == null || defaultPageParams.isEmpty()) ?
new FilterSpec() : new FilterSpec(defaultPageParams);
}
public static void initialize() {
historyChangeHandler = new HistoryManager.HistoryChangeHandler();
History.addValueChangeHandler(historyChangeHandler);
if (getHash().isEmpty()) {
loadMainPage();
} else {
History.fireCurrentHistoryState();
}
initialized = true;
}
public static boolean isInitialized() {
return initialized;
}
private static native boolean isIE() /*-{
return $wnd.navigator.appName == "Microsoft Internet Explorer";
}-*/;
}