/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 2003 The Apache Software Foundation.  All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* 3. The end-user documentation included with the redistribution,
*    if any, must include the following acknowledgment:
*       "This product includes software developed by the
*        Apache Software Foundation (http://www.apache.org/)."
*    Alternately, this acknowledgment may appear in the software itself,
*    if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" must
*    not be used to endorse or promote products derived from this
*    software without prior written permission. For written
*    permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache
*    XMLBeans", nor may "Apache" appear in their name, without prior
*    written permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 2000-2003 BEA Systems
* Inc., <http://www.bea.com/>. For more information on the Apache Software
* Foundation, please see <http://www.apache.org/>.
*/

package org.apache.xmlbeans.impl.marshal;

import org.apache.xmlbeans.XmlRuntimeException;
import org.apache.xmlbeans.impl.common.XsTypeConverter;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import java.util.Collection;

final class MarshalStreamUtils
{
    static final String XSI_NS = "http://www.w3.org/2001/XMLSchema-instance";
    static final String XSI_TYPE_ATTR = "type";
    static final String XSI_NIL_ATTR = "nil";

    //more efficient (hopefully) version of XmlStreamReader.getElementText()
    //TODO: plenty of room for optimizations here...
    static CharSequence getContent(XMLStreamReader reader, Collection errors)
        throws XMLStreamException
    {
        assert reader.isStartElement();

        reader.next(); //move past start element

        String content = null;
        StringBuffer buf = null;

        FOL:
        for (int state = reader.getEventType(); ; state = reader.next()) {
            switch (state) {
                case XMLStreamReader.END_DOCUMENT:
                    throw new XmlRuntimeException("unexpected end of XML");
                case XMLStreamReader.END_ELEMENT:
                    if (content == null) {
                        content = "";
                    }
                    reader.next(); // eat the matching end elem
                    break FOL;
                case XMLStreamReader.START_ELEMENT:
                    //TODO: better error handling
                    errors.add("skipping unexpected child element");
                    skipElement(reader);
                    break;
                case XMLStreamReader.CHARACTERS:
                    if (content == null) {
                        content = reader.getText();
                    } else {
                        if (buf == null) {
                            buf = new StringBuffer(content);
                        }
                        buf.append(reader.getText());
                    }
                    break;
                case XMLStreamReader.PROCESSING_INSTRUCTION:
                case XMLStreamReader.COMMENT:
                    break;
                default:
                    throw new AssertionError("unexpected xml state " + state);
            }

            if (!reader.hasNext()) {
                throw new XmlRuntimeException("unexpected end of xml stream");
            }

        }

        if (buf == null) {
            assert (content != null) ;
            return content;
        } else {
            return buf.toString();
        }

    }


    /**
     * special marker qname object used to indicate that we noticed
     * an xsi:nil="true" value while we were looking for an xsi:type attribute
     *
     * note that such a value would never be returned by getXsiType since
     * it is illegal to declare types in the instance namespace.
     */
    static QName XSI_NIL_MARKER = new QName(XSI_NS, "unused");

    //TODO: REVIEW: reconsider this approach
    //and what about the other xsi attributes?
    static QName getXsiType(final XMLStreamReader reader, Collection errors)
    {
        assert reader.isStartElement();

        final int att_cnt = reader.getAttributeCount();
        for (int att_idx = 0; att_idx < att_cnt; att_idx++) {
            if (!XSI_NS.equals(reader.getAttributeNamespace(att_idx)))
                continue;

            final String lname = reader.getAttributeLocalName(att_idx);
            if (XSI_NIL_ATTR.equals(lname)) {
                final String att_val = reader.getAttributeValue(att_idx);
                boolean is_nil = XsTypeConverter.lexBoolean(att_val, errors);
                if (is_nil) return XSI_NIL_MARKER;
            } else if (XSI_TYPE_ATTR.equals(lname)) {
                final String type_str = reader.getAttributeValue(att_idx);
                return XsTypeConverter.lexQName(type_str, errors,
                                                reader.getNamespaceContext());
            }
        }

        return null;
    }

    /**
     * go to next start element.  if reader is sitting on a start element
     * then no advancing will be done.  returns false if we hit and end element,
     * otherwise returns true
     *
     * @param reader
     * @return
     */
    static boolean advanceToNextStartElement(XMLStreamReader reader)
    {
        try {
            for (int state = reader.getEventType();
                 reader.hasNext();
                 state = reader.next()) {
                switch (state) {
                    case XMLStreamReader.END_DOCUMENT:
                        throw new XmlRuntimeException("unexpected end of XML");
                    case XMLStreamReader.END_ELEMENT:
                        return false;
                    case XMLStreamReader.START_ELEMENT:
                        return true;
                    case XMLStreamReader.CHARACTERS:
                        //TODO: what about mixed content models
                    case XMLStreamReader.PROCESSING_INSTRUCTION:
                    case XMLStreamReader.COMMENT:
                        break;
                    default:
                        throw new AssertionError("unexpected xml state " + state);
                }
            }
        }
        catch (XMLStreamException e) {
            throw new XmlRuntimeException(e);
        }

        throw new XmlRuntimeException("unexpected end of xml stream");
    }

    /**
     * Skip current element node and all its contents.
     * Reader must be on start element.
     * Skips to the matching end element (not past it).
     * We are just counting start/end -- the parser is
     * dealing with well-formedness.
     *
     * @param reader
     */
    static void skipElement(XMLStreamReader reader)
    {
        assert reader.isStartElement();

        int cnt = -1;

        //TODO: seem to be rechecking assertion, why not skip one ahead...

        try {
            for (int state = reader.getEventType(); reader.hasNext();
                 state = reader.next()) {
                switch (state) {
                    case XMLStreamReader.END_DOCUMENT:
                        //should not happen for well-formed xml
                        throw new XmlRuntimeException("unexpected end of xml document");
                    case XMLStreamReader.END_ELEMENT:
                        if (cnt == 0) {
                            return;
                        } else {
                            cnt--;
                        }
                        break;
                    case XMLStreamReader.START_ELEMENT:
                        cnt++;
                        break;
                    default:
                        break;
                }
            }
        }
        catch (XMLStreamException e) {
            throw new XmlRuntimeException(e);
        }

        //should not happen for well-formed xml
        throw new XmlRuntimeException("unexpected end of xml stream");
    }


    public static boolean isXsiNilTrue(XMLStreamReader reader,
                                       int att_idx,
                                       Collection errors)
    {
        final String lname = reader.getAttributeLocalName(att_idx);
        System.out.println("lname = " + lname);
        if (!XSI_NIL_ATTR.equals(lname))
            return false;

        if (!XSI_NS.equals(reader.getAttributeNamespace(att_idx)))
            return false;

        final String att_val = reader.getAttributeValue(att_idx);
        return XsTypeConverter.lexBoolean(att_val, errors);
    }


}