package org.das2.client;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.das2.datum.CacheTag;
import org.das2.datum.Datum;
import org.das2.datum.DatumRange;
import org.das2.datum.DatumVector;
import org.das2.qds.DDataSet;
import org.das2.qds.DataSetUtil;
import org.das2.qds.JoinDataSet;
import org.das2.qds.MutablePropertyDataSet;
import org.das2.qds.QDataSet;
import org.das2.qds.SemanticOps;
import org.das2.qds.ops.Ops;
import org.das2.qds.util.DataSetBuilder;
import org.das2.stream.PacketDescriptor;
import org.das2.stream.SkeletonDescriptor;
import org.das2.stream.StreamComment;
import org.das2.stream.StreamDescriptor;
import org.das2.stream.StreamException;
import org.das2.stream.StreamHandler;
import org.das2.stream.StreamScalarDescriptor;
import org.das2.stream.StreamYDescriptor;
import org.das2.stream.StreamYScanDescriptor;
import org.das2.stream.StreamZDescriptor;
import org.das2.util.LoggerManager;
import org.das2.util.monitor.NullProgressMonitor;
import org.das2.util.monitor.ProgressMonitor;

/**
 * Read the Das2Stream into a QDataSet.
 * @author jbf
 * @see DataSetStreamHandler which reads into the old model.
 */
public class QDataSetStreamHandler implements StreamHandler {

    private static final Logger logger= LoggerManager.getLogger("das2.dataTransfer");
    
    private Map<Integer,DataSetBuilder> xbuilders;
    private Map<Integer,DataSetBuilder[]> builders;
    
    /**
     * as each id is retired (for example, packet id 01 gets a new definition), put its data into the result.
     */
    private QDataSet jds= null;
    
    private Map<Integer,String> schemes;
    private PacketDescriptor currentPd=null;
    private DataSetBuilder[] currentBuilders;
    private DataSetBuilder currentXBuilder;
    
    private String streamTitle;
    private Map streamProperties;
    
    /**
     * TODO: mission statement, how does this compare to jds?
     */
    private QDataSet ds=null;
    
    //private Object collectionMode= MODE_SPLIT_BY_PACKET_DESCRIPTOR;
    private final Object collectionMode= MODE_SPLIT_BY_NEW_PACKET_DESCRIPTOR;
    
    private ProgressMonitor monitor= new NullProgressMonitor();
    
    private static final String SCHEME_XYZSCATTER= "xyzScatter";
    private static final String SCHEME_PEAKS_AND_AVERAGES= "peaksAndAverages";
        
    public QDataSetStreamHandler() {
        
    }
    
    public void setMonitor( ProgressMonitor monitor ) {
        this.monitor= monitor;
    }
    
    @Override
    public void streamDescriptor(StreamDescriptor sd) throws StreamException {
        logger.log(Level.FINE, "streamDescriptor: {0}", sd);
        xbuilders= new LinkedHashMap<>();
        builders= new LinkedHashMap<>();
        schemes= new LinkedHashMap<>();
        String t= (String) sd.getProperty("title");
        if ( t!=null ) {
            streamTitle= adaptUserProperty( t );
        } else {
            streamTitle= null;
        }
        streamProperties= sd.getProperties();
        
        Object o;
        if ( ( o= sd.getProperty("taskSize") )!=null ) {
            monitor.setTaskSize(  ((Integer)o) );
            monitor.started();
        } else if ( ( o= sd.getProperty("packetCount" ) )!=null ) {
            monitor.setTaskSize( ((Integer)o) );
            monitor.started();
        }
        
    }

    private void putProperty( DataSetBuilder builder, String name, Object value ) {
        if ( value instanceof Datum ) {
            logger.warning("kludge to fix Datum property values");
            value= ((Datum)value).doubleValue(((Datum)value).getUnits());
        }
        if ( SemanticOps.checkPropertyType( name, value, false ) ) {
            builder.putProperty( name, value );
        } else {
            logger.log(Level.WARNING, "property \"{0}\" should be type \"{1}\"", new Object[]{name, SemanticOps.getPropertyType(name)});
        }
    }
    
    private final Pattern ptrn = Pattern.compile("(%\\{)(.+?)(\\})");
    
    private String adaptUserProperty( String s ) {
        Matcher m = ptrn.matcher(s);
        while (m.find()) {
            // Group indices are not as expected, 0 = entire match, 1 = 1st group, etc.
            if (!m.group(2).contains("USER_PROPERTIES")) {
                s = String.format("%sUSER_PROPERTIES.%s%s", s.substring(0, m.end(1)),
                        s.substring(m.start(2), m.end(2)),
                        s.substring(m.start(3), s.length()));
                m = ptrn.matcher(s);
            }
        }
        return s;
    }
    
    private Object findProperty( StreamYScanDescriptor sd, String d2sName ) {
        Object o= sd.getProperty(d2sName);
        if ( o==null ) {
            String n= sd.getName();
            o= streamProperties.get( n + "." + d2sName );
        }
        if ( o==null ) {
            o= streamProperties.get( d2sName );
        }
        // look for macros which refer to the properties.  These will become
        // USER_PROPERTIES, and the macro needs to use that name.
        if ( o instanceof String ) {
            o= adaptUserProperty((String)o);
        }
        return o;
    }

    private Object findProperty( StreamScalarDescriptor sd, String d2sName ) {
        Object o= sd.getProperty(d2sName);
        if ( o==null ) {
            String n= sd.getName();
            o= streamProperties.get( n + "." + d2sName );
        }
        if ( o==null ) {
            o= streamProperties.get( d2sName );
        }
        return o;
    }
    
    @Override
    public void packetDescriptor(PacketDescriptor pd) throws StreamException {
        logger.log(Level.FINE, "packetDescriptor: {0}", pd);
        createBuilders(pd);
    }

    @Override
    public void packet(PacketDescriptor pd, Datum xTag, DatumVector[] vectors) throws StreamException {
        if ( pd!=currentPd ) {
            if ( currentPd!=null && collectionMode==MODE_SPLIT_BY_PACKET_DESCRIPTOR ) {
                collectDataSet();
                createBuilders(currentPd);
            }
            logger.log(Level.FINE, "packet type changed: {0}", pd.getYDescriptor(0).getSizeBytes());
            currentXBuilder= xbuilders.get(pd.getId());
            currentBuilders= builders.get(pd.getId());
            currentPd= pd;
        }
        
        currentXBuilder.nextRecord(xTag);
        
        for ( int i=0; i<pd.getYCount(); i++ ) {
            if (currentBuilders[i].rank()==1 ) {
                currentBuilders[i].nextRecord(vectors[i].get(0));
            } else {
                currentBuilders[i].nextRecord(vectors[i]);
            }
        }
        
    }
    
    public static final Object MODE_SPLIT_BY_PACKET_DESCRIPTOR = "splitByPacketDescriptor";
    public static final Object MODE_SPLIT_BY_NEW_PACKET_DESCRIPTOR = "splitByNewPacketDescriptor";
    
    @Override
    public void streamClosed(StreamDescriptor sd) throws StreamException {
        logger.finest("got streamClosed");
    }

    @Override
    public void streamException(StreamException se) throws StreamException {
        logger.finest("got streamException");
    }

    @Override
    public void streamComment(StreamComment sc) throws StreamException {
        logger.log(Level.FINEST, "got stream comment: {0}", sc);

        if (sc.getType().equals(StreamComment.TYPE_TASK_SIZE)) {
            if (!monitor.isCancelled()) {
                monitor.setTaskSize(Integer.parseInt(sc.getValue()));
                monitor.started();
            }
            return;
        }

        if (sc.getType().equals(StreamComment.TYPE_TASK_PROGRESS)) {
            if (monitor.getTaskSize() != -1 && !monitor.isCancelled()) {
                monitor.setTaskProgress(Long.parseLong(sc.getValue()));
            }
            return;
        }

        if (sc.getType().matches(StreamComment.TYPE_LOG)) {
            String level = sc.getType().substring(4);
            Level l = Level.parse(level.toUpperCase());
            if (l.intValue() > Level.FINE.intValue()) {
                logger.log(Level.FINE, sc.getValue());
            } else {
                logger.log(l, sc.getValue());
            }
            monitor.setProgressMessage(sc.getValue());
        }
    }
    
    
    public void createBuilders( PacketDescriptor pd ) {
        DataSetBuilder[] lbuilders= new DataSetBuilder[pd.getYCount()];
        for ( int i=0; i<pd.getYCount(); i++ ) {
            SkeletonDescriptor sd= pd.getYDescriptor(i);
            logger.log(Level.FINER, "got packet: {0}", sd);
            DataSetBuilder builder;
            if ( sd instanceof StreamYScanDescriptor ) {
                StreamYScanDescriptor yscan= (StreamYScanDescriptor)sd;
                builder= new DataSetBuilder(2,1000,yscan.getNItems());
                putProperty( builder, QDataSet.UNITS, yscan.getZUnits() );
                putProperty( builder, QDataSet.NAME, yscan.getName() );
                putProperty( builder, QDataSet.LABEL, findProperty( yscan, "zLabel" ) ); // any of the following may return null.
                putProperty( builder, QDataSet.TITLE, findProperty( yscan, "zSummary" ) );
                putProperty( builder, QDataSet.VALID_MIN, findProperty( yscan, "zValidMin" ) );
                putProperty( builder, QDataSet.VALID_MAX, findProperty( yscan, "zValidMax" ) );
                DatumRange zRange= (DatumRange)findProperty( yscan, "zRange" );
                if ( zRange!=null ) {
                    putProperty( builder, QDataSet.TYPICAL_MIN, zRange.min().doubleValue( zRange.getUnits() ) );
                    putProperty( builder, QDataSet.TYPICAL_MAX, zRange.max().doubleValue( zRange.getUnits() ) );
                }                
                putProperty( builder, QDataSet.FILL_VALUE, findProperty( yscan, "zFill" ) );
                putProperty( builder, QDataSet.SCALE_TYPE, findProperty( yscan, "zScaleType" ) );
                DDataSet ytags= DDataSet.wrap( yscan.getYTags() );
                ytags.putProperty( QDataSet.UNITS, yscan.getYUnits() );
                ytags.putProperty( QDataSet.SCALE_TYPE, findProperty( yscan, "yScaleType") );
                DatumRange yRange= (DatumRange)findProperty( yscan, "yRange" );
                if ( yRange!=null ) {
                    ytags.putProperty( QDataSet.TYPICAL_MIN, yRange.min().doubleValue( yRange.getUnits() ) );
                    ytags.putProperty( QDataSet.TYPICAL_MAX, yRange.max().doubleValue( yRange.getUnits() ) );
                }                
                ytags.putProperty( QDataSet.LABEL, findProperty( yscan, "yLabel" ));
                ytags.putProperty( QDataSet.TITLE, findProperty( yscan, "ySummary" ));
                Object o= findProperty( yscan, "yTagWidth" );
                if ( o!=null ) {
                    if ( o instanceof Datum ) {
                        o= DataSetUtil.asDataSet( (Datum)o );
                        ytags.putProperty( QDataSet.CADENCE, o );
                    } else {
                        logger.warning("property yTagWidth should be a Datum");
                    }
                }
                putProperty( builder, QDataSet.DEPEND_1, ytags );
                String checkOperation= (String)yscan.getProperty( "operation" );
                String checkSource= (String)yscan.getProperty( "source" ); 
                if ( checkSource!=null && !yscan.getName().equals(checkSource) ) {  // support the new format using the old format.
                    if ( checkOperation.equals("BIN_MAX") ) {
                        putProperty( builder, QDataSet.NAME, checkSource + ".max" );
                    } else if ( checkOperation.equals("BIN_AVG") ) {
                        putProperty( builder, QDataSet.NAME, checkSource + ".avg" );
                    }else if ( checkOperation.equals("BIN_MIN") ) {
                        putProperty( builder, QDataSet.NAME, checkSource + ".min" );
                    }
                }
                
            } else if ( sd instanceof StreamYDescriptor ) {
                StreamScalarDescriptor multiy= (StreamScalarDescriptor)sd;
                builder= new DataSetBuilder(1,1000);
                putProperty( builder, QDataSet.UNITS, multiy.getUnits() );
                putProperty( builder, QDataSet.NAME, multiy.getName() );
                putProperty( builder, QDataSet.LABEL, findProperty( multiy, "yLabel" ) ); // any of the following may return null.
                putProperty( builder, QDataSet.FORMAT, findProperty( multiy, "yFormat" ) );
                putProperty( builder, QDataSet.TITLE, findProperty( multiy, "ySummary" ) );
                putProperty( builder, QDataSet.VALID_MIN, findProperty( multiy, "yValidMin" ) );
                putProperty( builder, QDataSet.VALID_MAX, findProperty( multiy, "yValidMax" ) );
                DatumRange yRange= (DatumRange)findProperty( multiy, "yRange" );
                if ( yRange!=null ) {
                    putProperty( builder, QDataSet.TYPICAL_MIN, yRange.min().doubleValue( yRange.getUnits() ) );
                    putProperty( builder, QDataSet.TYPICAL_MAX, yRange.max().doubleValue( yRange.getUnits() ) );
                }                
                putProperty( builder, QDataSet.SCALE_TYPE, findProperty( multiy, "yScaleType" ) );
                putProperty( builder, QDataSet.FILL_VALUE, findProperty( multiy, "yFill" ) );

            } else if ( sd instanceof StreamZDescriptor ) {
                StreamScalarDescriptor multiy= (StreamScalarDescriptor)sd;
                builder= new DataSetBuilder(1,1000);
                putProperty( builder, QDataSet.UNITS, multiy.getUnits() );
                putProperty( builder, QDataSet.NAME, multiy.getName() );
                putProperty( builder, QDataSet.LABEL, findProperty( multiy, "zLabel" ) ); // any of the following may return null.
                putProperty( builder, QDataSet.FORMAT, findProperty( multiy, "zFormat" ) );
                putProperty( builder, QDataSet.TITLE, findProperty( multiy, "zSummary" ) );
                putProperty( builder, QDataSet.VALID_MIN, findProperty( multiy, "zValidMin" ) );
                putProperty( builder, QDataSet.VALID_MAX, findProperty( multiy, "zValidMax" ) );
                DatumRange zRange= (DatumRange)findProperty( multiy, "zRange" );
                if ( zRange!=null ) {
                    putProperty( builder, QDataSet.TYPICAL_MIN, zRange.min().doubleValue( zRange.getUnits() ) );
                    putProperty( builder, QDataSet.TYPICAL_MAX, zRange.max().doubleValue( zRange.getUnits() ) );
                }                
                putProperty( builder, QDataSet.SCALE_TYPE, findProperty( multiy, "zScaleType" ) );
                putProperty( builder, QDataSet.FILL_VALUE, findProperty( multiy, "zFill" ) );
                
            } else {
                throw new IllegalArgumentException("not supported: "+sd);
            }
            lbuilders[i]= builder;
        }
        
        if ( pd.getYCount()==2 && pd.getYDescriptor(0) instanceof StreamYDescriptor && pd.getYDescriptor(1) instanceof StreamZDescriptor ) {
            this.schemes.put( pd.getId(), SCHEME_XYZSCATTER );
        } else {
            this.schemes.put( pd.getId(), "" );
        }
        
        
        DataSetBuilder xbuilder= new DataSetBuilder(1,1000);
        xbuilder.putProperty( QDataSet.UNITS, pd.getXDescriptor().getUnits() );
        
        Object o;
        
        o= pd.getProperty( "xLabel" );
        if ( o==null ) o=streamProperties.get("xLabel");
        xbuilder.putProperty( QDataSet.LABEL, o );
        
        o= pd.getProperty( "xTagWidth" );
        if ( o==null ) o=streamProperties.get("xTagWidth" );
        if ( o!=null ) {
            if ( o instanceof Datum ) {
                xbuilder.putProperty( QDataSet.CADENCE, DataSetUtil.asDataSet( (Datum)o ) );
            } else {
                logger.warning("property xTagWidth should be a Datum");
            }
        }
        o= pd.getProperty("monotonicXTags");
        if ( o==null ) o= streamProperties.get("monotonicXTags");
        if ( "true".equals( o ) ) {
            xbuilder.putProperty( QDataSet.MONOTONIC, Boolean.TRUE );
        }
        
        DataSetBuilder retirex= xbuilders.put( pd.getId(), xbuilder );
        DataSetBuilder[] retireb= this.builders.put( pd.getId(), lbuilders );
        if ( retirex!=null ) {
            jds= Ops.join( jds, collectDataSet( retirex, retireb ) );
        }
        
    }
    
    private static QDataSet collectDataSet( DataSetBuilder currentXBuilder, DataSetBuilder[] currentBuilders ) {
        QDataSet xds1= currentXBuilder.getDataSet();
        QDataSet ds1;
        if ( currentBuilders.length==1 ) {
            ds1= currentBuilders[0].getDataSet();
        } else {
            ds1= null;
            for (DataSetBuilder currentBuilder : currentBuilders) {
                DDataSet ds= currentBuilder.getDataSet();
                ds1 = Ops.bundle(ds1, ds );
            }
            if ( currentBuilders.length==2 ) {
                // look for bundles.
                String prefix= (String)Ops.unbundle(ds1,0).property("NAME");
                String name1= (String)Ops.unbundle(ds1,1).property("NAME");
                if ( name1.equals( prefix + ".max" ) || ( prefix.equals("") && name1.equals("peaks") ) ) {
                    QDataSet max= Ops.unbundle(ds1,1);
                    max= Ops.putProperty( max, QDataSet.NAME, name1.replaceAll("\\.","_") );
                    max= Ops.putProperty( max, QDataSet.BUNDLE_1, null );
                    max= Ops.link( xds1, max );
                    ds1= Ops.unbundle(ds1,0);
                    ds1= Ops.putProperty( ds1, QDataSet.BIN_MAX, max );
                    ds1= Ops.putProperty( ds1, QDataSet.BUNDLE_1, null );
                } else if ( name1.equals( prefix + ".min" ) ) {
                    QDataSet min= Ops.unbundle(ds1,1);
                    min= Ops.putProperty( min, QDataSet.NAME, name1.replaceAll("\\.","_") );
                    min= Ops.putProperty( min, QDataSet.BUNDLE_1, null );
                    min= Ops.link( xds1, min );
                    ds1= Ops.unbundle(ds1,0);
                    ds1= Ops.putProperty( ds1, QDataSet.BIN_MIN, min );
                    ds1= Ops.putProperty( ds1, QDataSet.BUNDLE_1, null );
                }
            }
        }
        
        if ( ds1 instanceof MutablePropertyDataSet && !((MutablePropertyDataSet)ds1).isImmutable() ) {
            ((MutablePropertyDataSet)ds1).putProperty( QDataSet.DEPEND_0, xds1 );
        } else {
            ds1= Ops.link( xds1, ds1 );
        }
        
        return ds1;
        
    }
    
    /**
     * TODO: mission statement
     */
    public void collectDataSet( ) {
        QDataSet xds1= currentXBuilder.getDataSet();
        QDataSet ds1;
        if ( currentBuilders.length==1 ) {
            ds1= currentBuilders[0].getDataSet();
        } else {
            ds1= null;
            for (DataSetBuilder currentBuilder : currentBuilders) {
                ds1 = Ops.bundle(ds1, currentBuilder.getDataSet());
            }
            if ( currentBuilders.length==2 ) {
                // look for bundles.
                
                String name0= (String)Ops.unbundle(ds1,0).property("NAME");
                String name1= (String)Ops.unbundle(ds1,1).property("NAME");
                String prefix;
                int ip= name0.lastIndexOf('.');
                if ( ip>-1 ) {
                    prefix= name0.substring(0,ip);
                } else {
                    prefix= name0;
                }
                
                if ( ds1.rank()==3 && 
                        ( ( name0.equals( prefix + ".avg" ) && name1.equals( prefix + ".max" ) )
                            || ( name0.equals( prefix ) && name1.equals( prefix + ".max" ) ) 
                            || ( prefix.equals("") && name1.equals("peaks") ) ) ) {
                    QDataSet max= Ops.unbundle(ds1,1);
                    max= Ops.putProperty( max, QDataSet.NAME, name1.replaceAll("\\.","_") );
                    max= Ops.putProperty( max, QDataSet.BUNDLE_1, null );
                    max= Ops.link( xds1, max );
                    ds1= Ops.unbundle(ds1,0);
                    ds1= Ops.putProperty( ds1, QDataSet.BIN_MAX, max );
                    ds1= Ops.putProperty( ds1, QDataSet.BUNDLE_1, null );
                } else if ( ds1.rank()==3 && name1.equals( prefix + ".min" ) ) {
                    QDataSet min= Ops.unbundle(ds1,1);
                    min= Ops.putProperty( min, QDataSet.NAME, name1.replaceAll("\\.","_") );
                    min= Ops.putProperty( min, QDataSet.BUNDLE_1, null );
                    min= Ops.link( xds1, min );
                    ds1= Ops.unbundle(ds1,0);
                    ds1= Ops.putProperty( ds1, QDataSet.BIN_MIN, min );
                    ds1= Ops.putProperty( ds1, QDataSet.BUNDLE_1, null );
                }
            }
        }
        
        if ( ds1 instanceof MutablePropertyDataSet && !((MutablePropertyDataSet)ds1).isImmutable() ) {
            ((MutablePropertyDataSet)ds1).putProperty( QDataSet.DEPEND_0, xds1 );
        } else {
            ds1= Ops.link( xds1, ds1 );
        }
        
        if ( ds==null ) {
            ds= ds1;
        } else {
            ds= Ops.join( ds, ds1 );
        }
        
    }
        
    /**
     * return the dataset collected by the handler, or null if no records have been received.
     * @return the dataset collected by the handler, or null if no records have been received.
     */
    public QDataSet getDataSet() {
          
        if ( collectionMode==MODE_SPLIT_BY_PACKET_DESCRIPTOR ) {
            if ( currentXBuilder==null ) return null;
            collectDataSet();
        } else {
            if ( currentXBuilder==null ) return null;
            int nbuilders= builders.size();
            if ( nbuilders==1 ) {
                collectDataSet();
                if ( jds!=null ) { // TODO: the structure of this changed, so that "ds" should probably be renamed with a new mission statement.
                    if ( ds==null ) {
                        ds= jds;
                    } else {
                        jds= (JoinDataSet)Ops.join( jds, ds );
                        ds= jds;
                    }
                }
            } else {
                for ( Entry<Integer,DataSetBuilder[]> e: builders.entrySet() ) {
                    int id= e.getKey();
                    currentBuilders= e.getValue();
                    currentXBuilder= xbuilders.get(id);
                    QDataSet ds1= collectDataSet( currentXBuilder, currentBuilders );
                    jds= (JoinDataSet)Ops.join( jds, ds1 );
                }
                ds= jds;
            }
        }
        if ( ds==null ) return null;
        
        if ( ds instanceof JoinDataSet ) {
            if ( ds.length()<2 ) {
                //TODO: consider slice
            } else {
                if ( appendable( ds.slice(0), ds.slice(1) ) ) {
                    ds= jds.slice(0);
                    for ( int i=1; i<jds.length(); i++ ) {
                        ds= Ops.append( ds, jds.slice(i) );
                    }
                }
            }
        }
        
        ds= Ops.putProperty( ds, QDataSet.TITLE, streamTitle );
        Object oxCacheRange= streamProperties.get( "xCacheRange" );
        if ( oxCacheRange!=null ) {
            Object oxCacheResolution= streamProperties.get("xCacheResolution");
            try {
                CacheTag ct;
                if ( oxCacheResolution!=null ) {
                    ct= new CacheTag( (DatumRange)oxCacheRange, (Datum)oxCacheResolution );
                } else {
                    ct= new CacheTag( (DatumRange)oxCacheRange, null );
                }
                ds= Ops.putProperty( ds, QDataSet.CACHE_TAG, ct );
            } catch ( RuntimeException ex) {
                logger.log(Level.SEVERE, "unable to use properties for cacheTag", ex);
            }
        }
        String renderer= (String) streamProperties.get( "renderer" );
        if ( renderer!=null ) {
            ds= Ops.putProperty( ds, QDataSet.RENDER_TYPE, renderer );
        }
                
        ds= Ops.putProperty( ds, QDataSet.USER_PROPERTIES, streamProperties );
        
        return ds;
    }

    /**
     * check if data is a join of dissimilar spectrograms or similar bundles.  TODO: this is not a thorough
     * test.
     * @param s0
     * @param s1
     * @return true if the two can be appended.
     */
    private boolean appendable(QDataSet s0, QDataSet s1) {
        if ( s0.rank()==s1.rank() ) {
            if ( s0.rank()==1 || ( SemanticOps.isBundle(s0) && SemanticOps.isBundle(s1) && s0.length(0)==s1.length(0) ) ) {
                return true;
            }
        }
        return false;
    }
    
}