/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.shindig.gadgets.rewrite;
import org.apache.commons.lang.StringUtils;
import org.apache.shindig.common.JsonSerializer;
import org.apache.shindig.common.uri.Uri;
import org.apache.shindig.common.xml.DomUtil;
import org.apache.shindig.expressions.Expressions;
import org.apache.shindig.gadgets.Gadget;
import org.apache.shindig.gadgets.GadgetContext;
import org.apache.shindig.gadgets.GadgetException;
import org.apache.shindig.gadgets.MessageBundleFactory;
import org.apache.shindig.gadgets.parse.GadgetHtmlParser;
import org.apache.shindig.gadgets.render.SanitizingGadgetRewriter;
import org.apache.shindig.gadgets.spec.Feature;
import org.apache.shindig.gadgets.spec.MessageBundle;
import org.apache.shindig.gadgets.templates.ContainerTagLibraryFactory;
import org.apache.shindig.gadgets.templates.MessageELResolver;
import org.apache.shindig.gadgets.templates.TagRegistry;
import org.apache.shindig.gadgets.templates.TemplateContext;
import org.apache.shindig.gadgets.templates.TemplateLibrary;
import org.apache.shindig.gadgets.templates.TemplateLibraryFactory;
import org.apache.shindig.gadgets.templates.TemplateParserException;
import org.apache.shindig.gadgets.templates.TemplateProcessor;
import org.apache.shindig.gadgets.templates.TemplateResource;
import org.apache.shindig.gadgets.templates.tags.CompositeTagRegistry;
import org.apache.shindig.gadgets.templates.tags.DefaultTagRegistry;
import org.apache.shindig.gadgets.templates.tags.TagHandler;
import org.apache.shindig.gadgets.templates.tags.TemplateBasedTagHandler;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.inject.Inject;
import com.google.inject.Provider;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import java.io.IOException;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* This ContentRewriter uses a TemplateProcessor to replace os-template
* tag contents of a gadget spec with their rendered equivalents.
*
* Only templates without the @name and @tag attributes are processed
* automatically.
*/
public class TemplateRewriter implements GadgetRewriter {
public final static Set<String> TAGS = ImmutableSet.of("script");
/** Set to true to block auto-processing of templates */
static final String DISABLE_AUTO_PROCESSING_PARAM = "disableAutoProcessing";
/** Specifies what template libraries to load */
static final String REQUIRE_LIBRARY_PARAM = "requireLibrary";
/** Enable client support? **/
static final String CLIENT_SUPPORT_PARAM = "client";
private static final Logger logger = Logger.getLogger(TemplateRewriter.class.getName());
/**
* Provider of the processor. TemplateRewriters are stateless and multithreaded,
* processors are not.
*/
private final Provider<TemplateProcessor> processor;
private final MessageBundleFactory messageBundleFactory;
private final Expressions expressions;
private final TagRegistry baseTagRegistry;
private final TemplateLibraryFactory libraryFactory;
private final ContainerTagLibraryFactory containerTags;
@Inject
public TemplateRewriter(Provider<TemplateProcessor> processor,
MessageBundleFactory messageBundleFactory, Expressions expressions,
TagRegistry baseTagRegistry, TemplateLibraryFactory libraryFactory,
ContainerTagLibraryFactory containerTags) {
this.processor = processor;
this.messageBundleFactory = messageBundleFactory;
this.expressions = expressions;
this.baseTagRegistry = baseTagRegistry;
this.libraryFactory = libraryFactory;
this.containerTags = containerTags;
}
public void rewrite(Gadget gadget, MutableContent content) throws RewritingException {
Feature f = gadget.getSpec().getModulePrefs().getFeatures()
.get("opensocial-templates");
if (f != null && isServerTemplatingEnabled(f)) {
try {
rewriteImpl(gadget, f, content);
} catch (GadgetException ge) {
throw new RewritingException(ge, ge.getHttpStatusCode());
}
}
}
/**
* Disable server-side templating when the feature contains:
* <pre>
* <Param name="disableAutoProcessing">true</Param>
* </pre>
*/
private boolean isServerTemplatingEnabled(Feature f) {
return (!"true".equalsIgnoreCase(f.getParam(DISABLE_AUTO_PROCESSING_PARAM)));
}
private void rewriteImpl(Gadget gadget, Feature f, MutableContent content)
throws GadgetException {
List<TagRegistry> registries = Lists.newArrayList();
List<TemplateLibrary> libraries = Lists.newArrayList();
// TODO: Add View-specific library as Priority 0
// Built-in Java-based tags - Priority 1
registries.add(baseTagRegistry);
TemplateLibrary osmlLibrary = containerTags.getLibrary(gadget.getContext().getContainer());
// OSML Built-in tags - Priority 2
registries.add(osmlLibrary.getTagRegistry());
libraries.add(osmlLibrary);
NodeList templateElements = content.getDocument()
.getElementsByTagName(GadgetHtmlParser.OSML_TEMPLATE_TAG);
ImmutableList.Builder<Element> builder = ImmutableList.builder();
for (int i = 0; i < templateElements.getLength(); i++) {
builder.add((Element) templateElements.item(i));
}
List<Element> templates = builder.build();
// User-defined custom tags - Priority 3
registries.add(registerCustomTags(templates));
// User-defined libraries - Priority 4
loadTemplateLibraries(gadget.getContext(), f, registries, libraries);
TagRegistry registry = new CompositeTagRegistry(registries);
TemplateContext templateContext = new TemplateContext(gadget, content.getPipelinedData());
boolean needsFeature = executeTemplates(templateContext, content, templates, registry);
// Check if a feature param overrides our guess at whether the client-side
// feature is needed.
String clientOverride = f.getParam(CLIENT_SUPPORT_PARAM);
if ("true".equalsIgnoreCase(clientOverride)) {
needsFeature = true;
} else if ("false".equalsIgnoreCase(clientOverride)) {
needsFeature = false;
}
Element head = (Element) DomUtil.getFirstNamedChildNode(
content.getDocument().getDocumentElement(), "head");
postProcess(templateContext, needsFeature, head, templates, libraries);
}
/**
* Post-processes the gadget content after rendering templates.
*
* @param templateContext TemplateContext to operate on
* @param needsFeature Should the templates feature be made available to
* client?
* @param head Head element of the gadget's document
* @param libraries Keeps track of all libraries, and which got used
* @param allTemplates A list of all the template nodes
* @param libraries A list of all registered libraries
*/
private void postProcess(TemplateContext templateContext, boolean needsFeature, Element head,
List<Element> allTemplates, List<TemplateLibrary> libraries) {
// Inject all the needed library assets.
// TODO: inject library assets that aren't used on the server, but will
// be needed on the client
for (TemplateResource resource : templateContext.getResources()) {
injectTemplateLibraryAssets(resource, head);
}
// If we don't need the feature, remove it and all templates from the gadget
if (!needsFeature) {
templateContext.getGadget().removeFeature("opensocial-templates");
for (Element template : allTemplates) {
Node parent = template.getParentNode();
if (parent != null) {
parent.removeChild(template);
}
}
} else {
// If the feature is to be kept, inject the libraries.
// Library assets will be generated on the client.
// TODO: only inject the templates, not the full scripts/styles
for (TemplateLibrary library : libraries) {
injectTemplateLibrary(library, head);
}
}
}
private void loadTemplateLibraries(GadgetContext context,
Feature f, List<TagRegistry> registries, List<TemplateLibrary> libraries) throws GadgetException {
Collection<String> urls = f.getParams().get(REQUIRE_LIBRARY_PARAM);
if (urls != null) {
for (String url : urls) {
Uri uri = Uri.parse(url.trim());
uri = context.getUrl().resolve(uri);
try {
TemplateLibrary library = libraryFactory.loadTemplateLibrary(context, uri);
registries.add(library.getTagRegistry());
libraries.add(library);
} catch (TemplateParserException te) {
// Suppress exceptions due to malformed template libraries
logger.log(Level.WARNING, null, te);
}
}
}
}
private void injectTemplateLibraryAssets(TemplateResource resource, Element head) {
Element contentElement;
switch (resource.getType()) {
case JAVASCRIPT:
contentElement = head.getOwnerDocument().createElement("script");
contentElement.setAttribute("type", "text/javascript");
break;
case STYLE:
contentElement = head.getOwnerDocument().createElement("style");
contentElement.setAttribute("type", "text/css");
break;
default:
throw new IllegalStateException("Unhandled type");
}
if (resource.isSafe()) {
SanitizingGadgetRewriter.bypassSanitization(contentElement, false);
}
contentElement.setTextContent(resource.getContent());
head.appendChild(contentElement);
}
private void injectTemplateLibrary(TemplateLibrary library, Element head) {
try {
String libraryContent = library.serialize();
if (StringUtils.isEmpty(libraryContent)) {
return;
}
Element scriptElement = head.getOwnerDocument().createElement("script");
scriptElement.setAttribute("type", "text/javascript");
StringBuilder buffer = new StringBuilder();
buffer.append("opensocial.template.Loader.loadContent(");
JsonSerializer.appendString(buffer, library.serialize());
buffer.append(',');
JsonSerializer.appendString(buffer, library.getLibraryUri().toString());
buffer.append(");");
scriptElement.setTextContent(buffer.toString());
head.appendChild(scriptElement);
} catch (IOException ioe) {
// This should never happen.
}
}
/**
* Register templates with a "tag" attribute.
*/
private TagRegistry registerCustomTags(List<Element> allTemplates) {
ImmutableSet.Builder<TagHandler> handlers = ImmutableSet.builder();
for (Element template : allTemplates) {
// Only process templates with a tag attribute
if (template.getAttribute("tag").length() == 0) {
continue;
}
// TODO: split() is a regex compile, and should be avoided
String [] nameParts = template.getAttribute("tag").split(":");
// At this time, we only support
if (nameParts.length != 2) {
continue;
}
String namespaceUri = template.lookupNamespaceURI(nameParts[0]);
if (namespaceUri != null) {
handlers.add(new TemplateBasedTagHandler(template, namespaceUri, nameParts[1]));
}
}
return new DefaultTagRegistry(handlers.build());
}
/**
* Processes and renders inline templates.
* @return Do we think the templates feature is still needed on the client?
*/
private boolean executeTemplates(TemplateContext templateContext, MutableContent content,
List<Element> allTemplates, TagRegistry registry) throws GadgetException {
Map<String, Object> pipelinedData = content.getPipelinedData();
// If true, client-side processing will be needed
boolean needsFeature = false;
List<Element> templates = Lists.newArrayList();
for (Element element : allTemplates) {
String tag = element.getAttribute("tag");
String require = element.getAttribute("require");
if (!checkRequiredData(require, pipelinedData.keySet())) {
// Can't be processed on the server at all; keep client-side processing
needsFeature = true;
} else if ("".equals(tag)) {
templates.add(element);
}
}
if (!templates.isEmpty()) {
Gadget gadget = templateContext.getGadget();
MessageBundle bundle = messageBundleFactory.getBundle(gadget.getSpec(),
gadget.getContext().getLocale(), gadget.getContext().getIgnoreCache());
MessageELResolver messageELResolver = new MessageELResolver(expressions, bundle);
int autoUpdateID = 0;
for (Element template : templates) {
DocumentFragment result = processor.get().processTemplate(
template, templateContext, messageELResolver, registry);
// TODO: sanitized renders should ignore this value
if ("true".equals(template.getAttribute("autoUpdate"))) {
// autoUpdate requires client-side processing.
needsFeature = true;
Element span = template.getOwnerDocument().createElement("span");
String id = "template_auto" + (autoUpdateID++);
span.setAttribute("id", "_T_" + id);
template.setAttribute("name", id);
template.getParentNode().insertBefore(span, template);
span.appendChild(result);
} else {
template.getParentNode().insertBefore(result, template);
template.getParentNode().removeChild(template);
}
}
MutableContent.notifyEdit(content.getDocument());
}
return needsFeature;
}
/**
* Checks that all the required data is available at rewriting time.
* @param requiredData A string of comma-separated data set names
* @param availableData A map of available data sets
* @return true if all required data sets are present, false otherwise
*/
private static boolean checkRequiredData(String requiredData, Set<String> availableData) {
if ("".equals(requiredData)) {
return true;
}
StringTokenizer st = new StringTokenizer(requiredData, ",");
while (st.hasMoreTokens()) {
if (!availableData.contains(st.nextToken().trim())) {
return false;
}
}
return true;
}
}