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/*
 * Fabric3
 * Copyright (c) 2009-2015 Metaform Systems
 *
 * 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.
 *
 * Portions originally based on Apache Tuscany 2007
 * licensed under the Apache 2.0 license.
 */
package org.fabric3.spi.introspection.xml;

import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import org.fabric3.api.model.type.ModelObject;

/**
 * Utility functions to support loader implementations.
 */
public final class LoaderUtil {
    private LoaderUtil() {
    }

    /**
     * Advance the stream to the next END_ELEMENT event skipping any nested content.
     *
     * @param reader the reader to advance
     * @throws XMLStreamException if there was a problem reading the stream
     */
    public static void skipToEndElement(XMLStreamReader reader) throws XMLStreamException {
        int depth = 0;
        while (true) {
            int event = reader.next();
            if (event == XMLStreamConstants.START_ELEMENT) {
                depth++;
            } else if (event == XMLStreamConstants.END_ELEMENT) {
                if (depth == 0) {
                    return;
                }
                depth--;
            }
        }
    }

    /**
     * Construct a QName from an XML value.
     *
     * @param text             the text of an XML QName; if null or "" then null will be returned
     * @param defaultNamespace the default namespace to use if none is defined
     * @param context          the context for resolving namespace prefixes
     * @return a QName with the appropriate namespace set
     */
    public static QName getQName(String text, String defaultNamespace, NamespaceContext context) {
        if (text == null || text.length() == 0) {
            return null;
        }

        int index = text.indexOf(':');
        if (index < 1 || index == text.length() - 1) {
            // unqualified form - use the default supplied
            return new QName(defaultNamespace, text);
        } else {
            String prefix = text.substring(0, index);
            String uri = context.getNamespaceURI(prefix);
            String localPart = text.substring(index + 1);
            return new QName(uri, localPart, prefix);
        }
    }

    /**
     * Advances to the next tag in the stream according to the semantics of {@link XMLStreamReader#nextTag()} with the additional behavior that
     * characters, spaces, comments, CDATA, and processing instructions will be recorded on the model object.
     *
     * @param type   the model object
     * @param reader the stream
     * @return the next tag value
     * @throws XMLStreamException if a parsing error occurs
     */
    public static int nextTagRecord(ModelObject type, XMLStreamReader reader) throws XMLStreamException {
        int eventType = reader.next();
        while (true) {
            if (eventType == XMLStreamConstants.CHARACTERS) {
                type.addText(reader.getText());
            } else if (eventType == XMLStreamConstants.SPACE) {
                type.addText(reader.getText());
            } else if (eventType == XMLStreamConstants.COMMENT) {
                type.addComment(reader.getText());
            } else if (eventType == XMLStreamConstants.PROCESSING_INSTRUCTION) {
                // FIXME record
            } else if (eventType == XMLStreamConstants.CDATA) {
                // FIXME record
            } else {
                break;
            }
            eventType = reader.next();
        }
        if (eventType != XMLStreamConstants.START_ELEMENT && eventType != XMLStreamConstants.END_ELEMENT) {
            throw new XMLStreamException("Expected start or end tag", reader.getLocation());
        }
        return eventType;
    }

}