/**
* 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.hadoop.gateway.filter.rewrite.impl.html;
import net.htmlparser.jericho.Attribute;
import net.htmlparser.jericho.Attributes;
import net.htmlparser.jericho.EndTag;
import net.htmlparser.jericho.Segment;
import net.htmlparser.jericho.StartTag;
import net.htmlparser.jericho.StreamedSource;
import net.htmlparser.jericho.Tag;
import org.apache.hadoop.gateway.filter.rewrite.i18n.UrlRewriteMessages;
import org.apache.hadoop.gateway.i18n.messages.MessagesFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
import java.io.Reader;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Stack;
public abstract class HtmlFilterReaderBase extends Reader {
private static final UrlRewriteMessages LOG = MessagesFactory.get( UrlRewriteMessages.class );
private Document document;
private Stack<Level> stack;
private Reader reader;
private StreamedSource parser;
private Iterator<Segment> iterator;
private int lastSegEnd;
private int offset;
private StringWriter writer;
private StringBuffer buffer;
protected HtmlFilterReaderBase( Reader reader ) throws IOException, ParserConfigurationException {
this.reader = reader;
document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
stack = new Stack<Level>();
parser = new StreamedSource( reader );
iterator = parser.iterator();
writer = new StringWriter();
buffer = writer.getBuffer();
offset = 0;
}
protected abstract String filterAttribute( QName elementName, QName attributeName, String attributeValue, String ruleName );
protected abstract String filterText( QName elementName, String text, String ruleName );
@Override
public int read( char[] destBuffer, int destOffset, int destCount ) throws IOException {
int count = 0;
int available = buffer.length() - offset;
if( available == 0 ) {
if( iterator.hasNext() ) {
iterator.next();
processCurrentSegment();
available = buffer.length() - offset;
} else {
count = -1;
}
}
if( available > 0 ) {
count = Math.min( destCount, available );
buffer.getChars( offset, offset + count, destBuffer, destOffset );
offset += count;
if( offset == buffer.length() ) {
offset = 0;
buffer.setLength( 0 );
}
}
return count;
}
private void processCurrentSegment() {
Segment segment = parser.getCurrentSegment();
// If this tag is inside the previous tag (e.g. a server tag) then
// ignore it as it was already output along with the previous tag.
if( segment.getEnd() <= lastSegEnd ) {
return;
}
lastSegEnd = segment.getEnd();
if( segment instanceof Tag ) {
if( segment instanceof StartTag ) {
processStartTag( (StartTag)segment );
} else if ( segment instanceof EndTag ) {
processEndTag( (EndTag)segment );
} else {
writer.write( segment.toString() );
}
} else {
processText( segment );
}
}
private void processEndTag( EndTag tag ) {
while( !stack.isEmpty() ) {
Level popped = stack.pop();
if( popped.getTag().getName().equalsIgnoreCase( tag.getName() ) ) {
break;
}
}
writer.write( tag.toString() );
}
private void processStartTag( StartTag tag ) {
if( "<".equals( tag.getTagType().getStartDelimiter() ) ) {
Element e = document.createElement( tag.getNameSegment().toString() );
stack.push( new Level( tag ) );
writer.write( "<" );
writer.write( tag.getNameSegment().toString() );
Attributes attributes = tag.getAttributes();
if( !attributes.isEmpty() ) {
for( Attribute attribute : attributes ) {
processAttribute( attribute );
}
}
if( tag.toString().trim().endsWith( "/>" ) || tag.isEmptyElementTag() ) {
stack.pop();
writer.write( "/>" );
} else {
writer.write( ">" );
}
} else {
writer.write( tag.toString() );
}
}
private void processAttribute( Attribute attribute ) {
String inputValue = attribute.getValue();
String outputValue = inputValue;
try {
Level tag = stack.peek();
outputValue = filterAttribute( tag.getQName(), tag.getQName( attribute.getName() ), inputValue, null );
if( outputValue == null ) {
outputValue = inputValue;
}
} catch ( Exception e ) {
LOG.failedToFilterAttribute( attribute.getName(), e );
}
writer.write( " " );
writer.write( attribute.getName() );
writer.write( "=" );
writer.write( attribute.getQuoteChar() );
writer.write( outputValue );
writer.write( attribute.getQuoteChar() );
}
private void processText( Segment segment ) {
String inputValue = segment.toString();
String outputValue = inputValue;
try {
if( stack.isEmpty() ) {
// This can happen for whitespace outside of the root element.
//outputValue = filterText( null, inputValue );
} else {
outputValue = filterText( stack.peek().getQName(), inputValue, null );
}
if( outputValue == null ) {
outputValue = inputValue;
}
} catch ( Exception e ) {
LOG.failedToFilterValue( inputValue, null, e );
}
writer.write( outputValue );
}
@Override
public void close() throws IOException {
parser.close();
reader.close();
writer.close();
stack.clear();
}
private String getNamespace( String prefix ) {
String namespace = null;
for( Level level : stack ) {
namespace = level.getNamespace( prefix );
if( namespace != null ) {
break;
}
}
return namespace;
}
private static class Level {
private StartTag tag;
private QName name;
private Map<String,String> namespaces;
private Level( StartTag tag ) {
this.tag = tag;
this.name = null;
this.namespaces = null;
}
private StartTag getTag() {
return tag;
}
private QName getQName() {
if( name == null ) {
name = getQName( tag.getName() );
}
return name;
}
private String getNamespace( String prefix ) {
return getNamespaces().get( prefix );
}
private QName getQName( String name ) {
String prefix;
String local;
int colon = ( name == null ? -1 : name.indexOf( ':' ) );
if( colon < 0 ) {
prefix = "";
local = name;
} else {
prefix = name.substring( 0, colon );
local = ( colon + 1 < name.length() ? name.substring( colon + 1 ) : "" );
}
String namespace = ( prefix == null ) ? null : getNamespace( prefix );
return new QName( namespace, local, prefix );
}
private Map<String,String> getNamespaces() {
if( namespaces == null ) {
namespaces = new HashMap<String,String>();
parseNamespaces();
}
return namespaces;
}
private void parseNamespaces() {
Attributes attributes = tag.getAttributes();
if( attributes != null ) {
for( Attribute attribute : tag.getAttributes() ) {
String name = attribute.getName();
if( name.toLowerCase().startsWith( "xmlns" ) ) {
int colon = name.indexOf( ":", 5 );
String prefix;
if( colon == 0 ) {
prefix = "";
} else {
prefix = name.substring( colon );
}
namespaces.put( prefix, attribute.getValue() );
}
}
}
}
}
}