////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2017 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package net.sf.saxon.event;

import net.sf.saxon.expr.parser.ExplicitLocation;
import net.sf.saxon.expr.parser.Location;
import net.sf.saxon.ma.arrays.ArrayItem;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.NodeName;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.SchemaType;
import net.sf.saxon.value.AtomicValue;

/**
 * Implement the "sequence normalization" logic as defined in the XSLT 3.0/XQuery 3.0
 * serialization spec.
 *
 * <p>This class is used only if an ItemSeparator is specified. In the absence of an ItemSeparator,
 * the insertion of a single space performed by the ComplexContentOutputter serves the purpose.</p>
 */

public class SequenceNormalizer extends ProxyReceiver {

    private String separator;
    private int level = 0;
    private boolean first = true;

    public SequenceNormalizer(SequenceReceiver next, String separator) {
        super(next);
        this.separator = separator;
    }

    /**
     * Start of a document node.
     */
    @Override
    public void startDocument(int properties) throws XPathException {
        sep();
        level++;
        getUnderlyingReceiver().startDocument(properties);
    }

    /**
     * Notify the end of a document node
     */
    @Override
    public void endDocument() throws XPathException {
        level--;
        getUnderlyingReceiver().endDocument();
    }

    /**
     * Notify the start of an element
     *  @param elemName   integer code identifying the name of the element within the name pool.
     * @param typeCode   integer code identifying the element's type within the name pool.
     * @param location
     * @param properties properties of the element node
     */
    @Override
    public void startElement(NodeName elemName, SchemaType typeCode, Location location, int properties) throws XPathException {
        sep();
        level++;
        getUnderlyingReceiver().startElement(elemName, typeCode, location, properties);
    }

    /**
     * End of element
     */
    @Override
    public void endElement() throws XPathException {
        level--;
        super.endElement();
    }

    /**
     * Character data
     */
    @Override
    public void characters(CharSequence chars, Location locationId, int properties) throws XPathException {
        sep();
        getUnderlyingReceiver().characters(chars, locationId, properties);
    }

    /**
     * Processing Instruction
     */
    @Override
    public void processingInstruction(String target, CharSequence data, Location locationId, int properties) throws XPathException {
        sep();
        getUnderlyingReceiver().processingInstruction(target, data, locationId, properties);
    }

    /**
     * Output a comment
     */
    @Override
    public void comment(CharSequence chars, Location locationId, int properties) throws XPathException {
        sep();
        getUnderlyingReceiver().comment(chars, locationId, properties);
    }

    /**
     * Append an arbitrary item (node or atomic value) to the output
     *  @param item           the item to be appended
     * @param locationId     the location of the calling instruction, for diagnostics
     * @param copyNamespaces if the item is an element node, this indicates whether its namespaces
 *                       need to be copied. Values are {@link net.sf.saxon.om.NodeInfo#ALL_NAMESPACES},
 *                       {@link net.sf.saxon.om.NodeInfo#LOCAL_NAMESPACES}, {@link net.sf.saxon.om.NodeInfo#NO_NAMESPACES}
     */
    @Override
    public void append(Item item, Location locationId, int copyNamespaces) throws XPathException {
        if (item instanceof ArrayItem) {
            for (Sequence member : (ArrayItem) item) {
                SequenceIterator iter = member.iterate();
                Item it;
                while ((it = iter.next()) != null) {
                    append(it, locationId, copyNamespaces);
                }
            }
        } else {
            sep();
            if (level == 0 && item instanceof AtomicValue) {
                CharSequence cs = item.getStringValueCS();
                getUnderlyingReceiver().characters(cs, locationId, 0);
            } else {
                ((SequenceReceiver) getUnderlyingReceiver()).append(item, locationId, copyNamespaces);
            }
        }
    }

    /**
     * Output the separator, assuming we are at the top level and not at the start
     */

    public void sep() throws XPathException {
        if (level == 0 && !first) {
            getUnderlyingReceiver().characters(separator, ExplicitLocation.UNKNOWN_LOCATION, 0);
        } else {
            first = false;
        }
    }
}

