/*
 * 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.servicemix.jbi.jaxp;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.xml.namespace.NamespaceContext;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.util.StreamReaderDelegate;

public class ExtendedXMLStreamReader extends StreamReaderDelegate {

    private SimpleNamespaceContext context = new SimpleNamespaceContext();

    public ExtendedXMLStreamReader(XMLStreamReader delegate) {
        super(delegate);
    }

    public NamespaceContext getNamespaceContext() {
        return context;
    }

    public int nextTag() throws XMLStreamException {
        int eventType = next();
        while ((eventType == XMLStreamConstants.CHARACTERS && isWhiteSpace())
                        // skip whitespace
                        || (eventType == XMLStreamConstants.CDATA && isWhiteSpace())
                        // skip whitespace
                        || eventType == XMLStreamConstants.SPACE
                        || eventType == XMLStreamConstants.PROCESSING_INSTRUCTION
                        || eventType == XMLStreamConstants.COMMENT) {
            eventType = next();
        }
        if (eventType != XMLStreamConstants.START_ELEMENT && eventType != XMLStreamConstants.END_ELEMENT) {
            throw new XMLStreamException("expected start or end tag", getLocation());
        }
        return eventType;
    }

    public int next() throws XMLStreamException {
        int next = super.next();
        if (next == START_ELEMENT) {
            context = new SimpleNamespaceContext(context, getNamespaces());
        } else if (next == END_ELEMENT) {
            context = context.getParent();
        }
        return next;
    }

    private Map getNamespaces() {
        Map ns = new HashMap();
        for (int i = 0; i < getNamespaceCount(); i++) {
            ns.put(getNamespacePrefix(i), getNamespaceURI(i));
        }
        return ns;
    }

    public static class SimpleNamespaceContext implements ExtendedNamespaceContext {

        private SimpleNamespaceContext parent;

        private Map namespaces;

        public SimpleNamespaceContext() {
            namespaces = new HashMap();
        }

        public SimpleNamespaceContext(SimpleNamespaceContext parent, Map namespaces) {
            this.parent = parent;
            this.namespaces = namespaces;
        }

        public SimpleNamespaceContext getParent() {
            return parent;
        }

        public Iterator getPrefixes() {
            Set prefixes = new HashSet();
            for (SimpleNamespaceContext context = this; context != null; context = context.parent) {
                prefixes.addAll(context.namespaces.keySet());
            }
            return prefixes.iterator();
        }

        public String getNamespaceURI(String prefix) {
            String uri = (String) namespaces.get(prefix);
            if (uri == null && parent != null) {
                uri = parent.getNamespaceURI(prefix);
            }
            return uri;
        }

        public String getPrefix(String namespaceURI) {
            for (SimpleNamespaceContext context = this; context != null; context = context.parent) {
                for (Iterator it = context.namespaces.keySet().iterator(); it.hasNext();) {
                    Map.Entry entry = (Map.Entry) it.next();
                    if (entry.getValue().equals(namespaceURI)) {
                        return (String) entry.getKey();
                    }
                }
            }
            return null;
        }

        public Iterator getPrefixes(String namespaceURI) {
            Set prefixes = new HashSet();
            for (SimpleNamespaceContext context = this; context != null; context = context.parent) {
                for (Iterator it = context.namespaces.keySet().iterator(); it.hasNext();) {
                    Map.Entry entry = (Map.Entry) it.next();
                    if (entry.getValue().equals(namespaceURI)) {
                        prefixes.add(entry.getKey());
                    }
                }
            }
            return prefixes.iterator();
        }

    }

}
