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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2015 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.evpull;

import net.sf.saxon.Configuration;
import net.sf.saxon.lib.Logger;
import net.sf.saxon.om.NamePool;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.pattern.NodeKindTest;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.util.FastStringBuffer;
import net.sf.saxon.type.Type;
import net.sf.saxon.value.AtomicValue;

/**
 * Diagnostic class to display the sequence of events reported by an EventIterator
 */
public class PullEventTracer implements EventIterator {

    private EventIterator base;
    private String label = ("PET" + hashCode()).substring(0, 8) + ": ";
    private Logger out;
    //@SuppressWarnings({"FieldCanBeLocal"})
    private NamePool pool;

    /**
     * Create a tracer for pull events
     *
     * @param base   the event iterator whose events are to be traced
     * @param config the Saxon configuration
     */

    public PullEventTracer(EventIterator base, Configuration config) {
        this.base = base;
        pool = config.getNamePool();
        out = config.getLogger();
    }


    /**
     * Get the next event in the sequence
     *
     * @return the next event, or null when the sequence is exhausted. Note that since an EventIterator is
     *         itself a PullEvent, this method may return a nested iterator.
     * @throws net.sf.saxon.trans.XPathException
     *          if a dynamic evaluation error occurs
     */

    /*@Nullable*/
    public PullEvent next() throws XPathException {
        PullEvent pe = base.next();
        if (pe == null) {
            return null;
        }
        if (pe instanceof StartDocumentEvent) {
            out.info(label + "StartDocument");
            label = "  " + label;
        } else if (pe instanceof StartElementEvent) {
            out.info(label + "StartElement " + ((StartElementEvent) pe).getElementName().getDisplayName());
            label = "  " + label;
        } else if (pe instanceof EndDocumentEvent) {
            label = label.substring(2);
            out.info(label + "EndDocument");
        } else if (pe instanceof EndElementEvent) {
            label = label.substring(2);
            out.info(label + "EndElement");
        } else if (pe instanceof NodeInfo) {
            FastStringBuffer fsb = new FastStringBuffer(FastStringBuffer.C64);
            fsb.append(label);
            int kind = ((NodeInfo) pe).getNodeKind();
            fsb.append(NodeKindTest.toString(kind));
            if (kind == Type.ELEMENT || kind == Type.ATTRIBUTE) {
                fsb.append(' ');
                fsb.append(((NodeInfo) pe).getDisplayName());
            }
            fsb.append(" \"");
            fsb.append(((NodeInfo) pe).getStringValueCS());
            fsb.append('"');
            out.info(fsb.toString());
        } else if (pe instanceof AtomicValue) {
            out.info(label + Type.displayTypeName((AtomicValue) pe) + ' ' + pe);
        } else if (pe instanceof EventIterator) {
            out.info(label + "** NESTED ITERATOR **");
        } else {
            out.info(label + pe.getClass().getName());
        }

        return pe;
    }


    /**
     * Determine whether the EventIterator returns a flat sequence of events, or whether it can return
     * nested event iterators
     *
     * @return true if the next() method is guaranteed never to return an EventIterator
     */

    public boolean isFlatSequence() {
        return base.isFlatSequence();
    }

    /**
     * Main method for testing only
     *
     * @param args not used
     * @throws Exception
     */

//    public static void main(String[] args) throws Exception {
//        Configuration config = new Configuration();
//        DocumentInfo doc = config.buildDocument(new StreamSource(new File("c:/MyJava/samples/data/books.xml")));
//        PipelineConfiguration pipe = config.makePipelineConfiguration();
//        pipe.setHostLanguage(Configuration.XQUERY);
//        EventIterator e = new Decomposer(new SingletonEventIterator(doc.getDocumentNode()), pipe);
//        e = EventStackIterator.flatten(e);
//        e = new PullEventTracer(e, config);
//        while (true) {
//            PullEvent pe = e.next();
//            if (pe == null) {
//                break;
//            }
//        }
//    }
}