package net.sf.saxon.event;

import net.sf.saxon.Configuration;
import net.sf.saxon.om.NamePool;
import net.sf.saxon.om.Item;
import net.sf.saxon.trans.XPathException;

/**
 * A ProxyReceiver is an Receiver that filters data before passing it to another
 * underlying Receiver.
 */

public abstract class ProxyReceiver extends SequenceReceiver {
    protected Receiver nextReceiver;

    public void setSystemId(String systemId) {
        //noinspection StringEquality
        if (systemId != this.systemId) {
            // use of == rather than equals() is deliberate, since this is only an optimization
            this.systemId = systemId;
            if (nextReceiver != null) {
                nextReceiver.setSystemId(systemId);
            }
        }
    }

     /**
      * Set the underlying receiver. This call is mandatory before using the Receiver.
      * @param receiver the underlying receiver, the one that is to receive events after processing
      * by this filter.
     */

    public void setUnderlyingReceiver(Receiver receiver) {
        if (receiver != nextReceiver) {
            nextReceiver = receiver;
            if (pipelineConfiguration != null) {
                nextReceiver.setPipelineConfiguration(pipelineConfiguration);
            }
        }
    }

    /**
     * Get the underlying Receiver (that is, the next one in the pipeline)
     */

    public Receiver getUnderlyingReceiver() {
        return nextReceiver;
    }


    public void setPipelineConfiguration(PipelineConfiguration pipe) {
        if (pipelineConfiguration != pipe) {
            pipelineConfiguration = pipe;
            if (nextReceiver != null) {
                nextReceiver.setPipelineConfiguration(pipe);
            }
        }
    }

    public Configuration getConfiguration() {
        return pipelineConfiguration.getConfiguration();
    }

    /**
     * Get the namepool for this configuration
     */

    public NamePool getNamePool() {
        return pipelineConfiguration.getConfiguration().getNamePool();
    }

    /**
     * Start of event stream
     */

    public void open() throws XPathException {
        if (nextReceiver == null) {
            throw new IllegalStateException("ProxyReceiver.open(): no underlying receiver provided");
        }
        nextReceiver.open();
    }

    /**
     * End of output
     */

    public void close() throws XPathException {
        // TODO: this isn't safe. It's wrong to assume that because we've finished writing to this
        // receiver, then we've also finished writing to other receivers in the pipe.
        nextReceiver.close();
    }

    /**
     * Start of a document node.
     */

    public void startDocument(int properties) throws XPathException {
        nextReceiver.startDocument(properties);
    }

    /**
     * Notify the end of a document node
     */

    public void endDocument() throws XPathException {
        nextReceiver.endDocument();
    }

    /**
     * Notify the start of an element
     *
     * @param nameCode   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 properties properties of the element node
     */

    public void startElement(int nameCode, int typeCode, int locationId, int properties) throws XPathException {
        nextReceiver.startElement(nameCode, typeCode, locationId, properties);
    }

    /**
     * Notify a namespace. Namespaces are notified <b>after</b> the startElement event, and before
     * any children for the element. The namespaces that are reported are only required
     * to include those that are different from the parent element; however, duplicates may be reported.
     * A namespace must not conflict with any namespaces already used for element or attribute names.
     *
     * @param namespaceCode an integer: the top half is a prefix code, the bottom half a URI code.
     *                      These may be translated into an actual prefix and URI using the name pool. A prefix code of
     *                      zero represents the empty prefix (that is, the default namespace). A URI code of zero represents
     *                      a URI of "", that is, a namespace undeclaration.
     * @throws IllegalStateException: attempt to output a namespace when there is no open element
     *                                start tag
     */

    public void namespace(int namespaceCode, int properties) throws XPathException {
        nextReceiver.namespace(namespaceCode, properties);
    }

    /**
     * Notify an attribute. Attributes are notified after the startElement event, and before any
     * children. Namespaces and attributes may be intermingled.
     *
     * @param nameCode   The name of the attribute, as held in the name pool
     * @param typeCode   The type of the attribute, as held in the name pool
     * @param properties Bit significant value. The following bits are defined:
     *                   <dd>DISABLE_ESCAPING</dd>    <dt>Disable escaping for this attribute</dt>
     *                   <dd>NO_SPECIAL_CHARACTERS</dd>      <dt>Attribute value contains no special characters</dt>
     * @throws IllegalStateException: attempt to output an attribute when there is no open element
     *                                start tag
     */

    public void attribute(int nameCode, int typeCode, CharSequence value, int locationId, int properties)
            throws XPathException {
        nextReceiver.attribute(nameCode, typeCode, value, locationId, properties);
    }

    /**
     * Notify the start of the content, that is, the completion of all attributes and namespaces.
     * Note that the initial receiver of output from XSLT instructions will not receive this event,
     * it has to detect it itself. Note that this event is reported for every element even if it has
     * no attributes, no namespaces, and no content.
     */


    public void startContent() throws XPathException {
        nextReceiver.startContent();
    }

    /**
     * End of element
     */

    public void endElement() throws XPathException {
        nextReceiver.endElement();
    }

    /**
     * Character data
     */

    public void characters(CharSequence chars, int locationId, int properties) throws XPathException {
        nextReceiver.characters(chars, locationId, properties);
    }


    /**
     * Processing Instruction
     */

    public void processingInstruction(String target, CharSequence data, int locationId, int properties) throws XPathException {
        nextReceiver.processingInstruction(target, data, locationId, properties);
    }

    /**
     * Output a comment
     */

    public void comment(CharSequence chars, int locationId, int properties) throws XPathException {
        nextReceiver.comment(chars, locationId, properties);
    }


    /**
     * Set the URI for an unparsed entity in the document.
     */

    public void setUnparsedEntity(String name, String uri, String publicId) throws XPathException {
        nextReceiver.setUnparsedEntity(name, uri, publicId);
    }

    /**
     * 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}
     */

    public void append(Item item, int locationId, int copyNamespaces) throws XPathException {
        if (nextReceiver instanceof SequenceReceiver) {
            ((SequenceReceiver)nextReceiver).append(item, locationId, copyNamespaces);
        } else {
            throw new UnsupportedOperationException("append() method is not supported in this class");
        }
    }

    /**
     * Get the Document Locator
     */

    public LocationProvider getDocumentLocator() {
        return pipelineConfiguration.getLocationProvider();
    }
}

//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (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.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//
