/*   Copyright 2004 The Apache Software Foundation
 *
 *   Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.xmlbeans.impl.validator;

import org.apache.xmlbeans.impl.common.Chars;
import org.apache.xmlbeans.impl.common.IdentityConstraint;
import org.apache.xmlbeans.impl.common.QNameHelper;
import org.apache.xmlbeans.impl.common.ValidationContext;
import org.apache.xmlbeans.impl.common.ValidatorListener.Event;
import org.apache.xmlbeans.impl.common.ValidatorListener;
import org.apache.xmlbeans.impl.common.XmlWhitespace;
import org.apache.xmlbeans.impl.schema.SchemaTypeVisitorImpl;
import org.apache.xmlbeans.impl.schema.SchemaTypeImpl;
import org.apache.xmlbeans.impl.values.NamespaceContext;
import org.apache.xmlbeans.impl.values.JavaUriHolderEx;
import org.apache.xmlbeans.impl.values.JavaBase64HolderEx;
import org.apache.xmlbeans.impl.values.JavaBooleanHolderEx;
import org.apache.xmlbeans.impl.values.XmlDateImpl;
import org.apache.xmlbeans.impl.values.JavaDecimalHolderEx;
import org.apache.xmlbeans.impl.values.JavaDoubleHolderEx;
import org.apache.xmlbeans.impl.values.XmlDurationImpl;
import org.apache.xmlbeans.impl.values.JavaFloatHolderEx;
import org.apache.xmlbeans.impl.values.JavaHexBinaryHolderEx;
import org.apache.xmlbeans.impl.values.JavaBooleanHolder;
import org.apache.xmlbeans.impl.values.XmlQNameImpl;
import org.apache.xmlbeans.impl.values.JavaQNameHolderEx;
import org.apache.xmlbeans.impl.values.JavaStringEnumerationHolderEx;
import org.apache.xmlbeans.impl.values.XmlValueOutOfRangeException;
import org.apache.xmlbeans.impl.values.XmlListImpl;
import org.apache.xmlbeans.GDate;
import org.apache.xmlbeans.GDuration;
import org.apache.xmlbeans.QNameSet;
import org.apache.xmlbeans.XmlQName;
import org.apache.xmlbeans.SchemaAttributeModel;
import org.apache.xmlbeans.SchemaField;
import org.apache.xmlbeans.SchemaLocalAttribute;
import org.apache.xmlbeans.SchemaLocalElement;
import org.apache.xmlbeans.SchemaGlobalElement;
import org.apache.xmlbeans.SchemaParticle;
import org.apache.xmlbeans.SchemaType;
import org.apache.xmlbeans.SchemaTypeLoader;
import org.apache.xmlbeans.XmlError;
import org.apache.xmlbeans.XmlObject;
import org.apache.xmlbeans.XmlOptions;
import org.apache.xmlbeans.SimpleValue;
import org.apache.xmlbeans.SchemaProperty;
import org.apache.xmlbeans.XmlString;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
import javax.xml.namespace.QName;

public final class Validator
    implements ValidatorListener
{
    public Validator (
        SchemaType type, SchemaField field, SchemaTypeLoader globalLoader,
        XmlOptions options, Collection defaultErrorListener )
    {
        options = XmlOptions.maskNull(options);
        _errorListener = (Collection) options.get(XmlOptions.ERROR_LISTENER);

        if (_errorListener == null)
            _errorListener = defaultErrorListener;

        _constraintEngine = new IdentityConstraint(_errorListener, type.isDocumentType());

        _globalTypes = globalLoader;
        _chars = new Chars();
        _rootType = type;
        _rootField = field;

        _vc = new ValidatorVC();
    }

    private class ValidatorVC implements ValidationContext
    {
        public void invalid ( String message )
        {
            Validator.this.emitError( _event, message );
        }

        Event _event;
    }

    public boolean isValid ( )
    {
        return !_invalid && _constraintEngine.isValid();
    }

    private void emitError ( Event event, String msg )
    {
        emitError(event, msg, XmlError.SEVERITY_ERROR);
    }

    private void emitError ( Event event, String msg, int severity )
    {
        _errorState++;

        if (_suspendErrors == 0)
        {
            if (severity == XmlError.SEVERITY_ERROR)
                _invalid = true;

            if (_errorListener != null)
            {
                assert event != null;

                _errorListener.add(
                    XmlError.forCursor( msg, severity, event.getLocationAsCursor() ) );
            }
        }
    }

    private void emitFieldError ( Event event, String msg, QName name )
    {
        emitFieldError( event, msg + " " + QNameHelper.pretty( name ) );
    }

    private void emitFieldError ( Event event, String msg )
    {
        emitFieldError(event, msg, XmlError.SEVERITY_ERROR);
    }

    private void emitFieldError ( Event event, String msg, int severity )
    {
        if (_stateStack != null && _stateStack._field != null)
        {
            msg +=
                " in element " + QNameHelper.pretty( _stateStack._field.getName() );
        }

        Validator.this.emitError( event, msg, severity );
    }

    // For XmlEventListener.error

    public void error ( XmlError error )
    {
        _errorState++;

        if (_suspendErrors == 0)
        {
            _invalid = true;

            if (_errorListener != null)
                _errorListener.add( error );
        }
    }

    public void nextEvent ( int kind, Event event )
    {
        resetValues();

        if (_eatContent > 0)
        {
            switch ( kind )
            {
            case END   : _eatContent--; break;
            case BEGIN : _eatContent++; break;
            }
        }
        else
        {
            assert
                kind == BEGIN || kind == ATTR ||
                    kind == END || kind == TEXT || kind == ENDATTRS;

            switch ( kind )
            {
            case BEGIN    : beginEvent(    event ); break;
            case ATTR     : attrEvent(     event ); break;
            case ENDATTRS : endAttrsEvent( event ); break;
            case TEXT     : textEvent(     event ); break;
            case END      : endEvent(      event ); break;
            }
        }
    }

    private void beginEvent ( Event event )
    {
        _localElement = null;
        _wildcardElement = null;
        String message = null;
        State state = topState();

        SchemaType  elementType  = null;
        SchemaField elementField = null;

        if (state == null)
        {
            elementType = _rootType;
            elementField = _rootField;
        }
        else
        {

            QName name = event.getName();

            assert name != null;

            state._isEmpty = false;

            if (state._isNil)
            {
                emitFieldError(event,  "Nil element cannot have element content");
                _eatContent = 1;
                return;
            }

            if (!state._isNil && state._field != null && state._field.isFixed())
            {
                emitFieldError(event, "Element '" + QNameHelper.pretty(state._field.getName()) + "' is fixed and not nil so is not allowed to have element children.");
            }

            if (!state.visit( name ))
            {
                message = findDetailedErrorBegin(state , name);
                if (message != null)
                {
                  emitFieldError(event, message);
                  message = null;
                }
                else
                {
                  emitFieldError(event, "Element not allowed:", name);
                }
                _eatContent = 1;

                return;
            }

            SchemaParticle currentParticle = state.currentParticle();
            _wildcardElement = currentParticle;

            if (currentParticle.getParticleType() == SchemaParticle.WILDCARD)
            {
                //_wildcardElement = currentParticle;
                QNameSet elemWildcardSet = currentParticle.getWildcardSet();

                if (!elemWildcardSet.contains( name ))
                {
                    // Additional processing may be needed to generate more
                    // descriptive messages
                    emitFieldError( event, "Element not allowed:", name );
                    _eatContent = 1;

                    return;
                }

                int wildcardProcess = currentParticle.getWildcardProcess();

                if (wildcardProcess == SchemaParticle.SKIP)
                {
                    _eatContent = 1;
                    return;
                }

                _localElement = _globalTypes.findElement( name );
                elementField = _localElement;

                if (elementField == null)
                {
                    if (wildcardProcess == SchemaParticle.STRICT)
                    {
                        emitFieldError(
                            event, "Element not allowed (strict wildcard, and no definition found):", name );
                    }

                    _eatContent = 1;

                    return;
                }
            }
            else
            {
                assert
                    currentParticle.getParticleType() == SchemaParticle.ELEMENT;

                // If the current element particle name does not match the name
                // of the event, then the current element is a substitute for
                // the current particle. Replace the field with the global
                // element for the replacement

                if (! currentParticle.getName().equals(name))
                {
                    if (((SchemaLocalElement)currentParticle).blockSubstitution())
                    {
                        emitFieldError(event, 
                            "Element substitution not allowed when group head has block='substitution'", name);
                        _eatContent = 1;
                        return;
                    }

                    SchemaGlobalElement newField = _globalTypes.findElement(name);

                    assert newField != null;

                    if (newField != null)
                    {
                        elementField = newField;
                        _localElement = newField;
                    }
                }
                else
                {
                    elementField = (SchemaField) currentParticle;
                }
            }

            elementType = elementField.getType();
        }

        assert elementType != null;

        //
        // the no-type is always invalid (even if there is an xsi:type)
        //

        if (elementType.isNoType())
        {
            emitFieldError(event, "Invalid type.");
            _eatContent = 1;
        }

        //
        // See if the element has an xsi:type on it
        //

        SchemaType xsiType = null;

        if (event.getXsiType( _chars ))
        {
            String value = _chars.asString();

            // Turn off the listener so a public error message
            // does not get generated, but I can see if there was
            // an error through the error state

            int originalErrorState = _errorState;

            _suspendErrors++;

            try
            {
                _vc._event = null;

                xsiType =
                    _globalTypes.findType(
                        XmlQNameImpl.validateLexical( value, _vc, event ) );

            }
            catch ( Throwable t )
            {
                _errorState++;
            }
            finally
            {
                _suspendErrors--;
            }

            if (originalErrorState != _errorState)
            {
                emitFieldError(
                    event, "Invalid xsi:type qname: '" + value + "'" );

                _eatContent = 1;

                return;
            }
            else if (xsiType == null)
            {
                emitError(event,  "Could not find xsi:type: '" + value + "'");

                _eatContent = 1;

                return;
            }
        }

        if (xsiType != null && !xsiType.equals(elementType))
        {
            if (!elementType.isAssignableFrom(xsiType))
            {
                emitFieldError(
                    event,
                    "Type '" + xsiType +
                        "' is not derived from '" + elementType + "'" );

                _eatContent = 1;

                return;
            }

            if (elementType.blockExtension())
            {
                for ( SchemaType t = xsiType ; ! t.equals( elementType ) ;
                      t = t.getBaseType() )
                {
                    if (t.getDerivationType() == SchemaType.DT_EXTENSION)
                    {
                        emitFieldError(
                            event,
                            "Extension type: '" + xsiType +
                                "' may not be substituted for: '" +
                                    elementType + "'" );

                        _eatContent = 1;

                        return;
                    }
                }
            }

            if (elementType.blockRestriction())
            {
                for ( SchemaType t = xsiType ; ! t.equals( elementType ) ;
                      t = t.getBaseType() )
                {
                    if (t.getDerivationType() == SchemaType.DT_RESTRICTION)
                    {
                        emitFieldError(
                            event,
                            "Restriction type: '" + xsiType +
                                "' may not be substituted for: '" +
                                    elementType + "'" );

                        _eatContent = 1;

                        return;
                    }
                }
            }

            if (elementField instanceof SchemaLocalElement)
            {
                SchemaLocalElement sle  = (SchemaLocalElement)elementField;
                _localElement = sle;

                if (sle.blockExtension() || sle.blockRestriction())
                {
                    for ( SchemaType t = xsiType ; ! t.equals( elementType ) ;
                          t = t.getBaseType() )
                    {
                        if ((t.getDerivationType() == SchemaType.DT_RESTRICTION && sle.blockRestriction()) ||
                            (t.getDerivationType() == SchemaType.DT_EXTENSION && sle.blockExtension()))
                        {
                            emitError(
                                event,
                                "Derived type: '" + xsiType +
                                    "' may not be substituted for element '" +
                                    QNameHelper.pretty(sle.getName()) + "'" );

                            _eatContent = 1;

                            return;
                        }
                    }
                }

            }

            elementType = xsiType;
        }

        if (elementField instanceof SchemaLocalElement)
        {
            SchemaLocalElement sle = (SchemaLocalElement)elementField;
            _localElement = sle;

            if (sle.isAbstract())
            {
                emitError(event,  "Element '" + QNameHelper.pretty(sle.getName()) +
                    "' is abstract and cannot be used in an instance.");
                _eatContent = 1;
                return;
            }
        }

        if (elementType != null && elementType.isAbstract())
        {
            emitFieldError(
                event,
                "Abstract type: " + elementType +
                    " cannot be used in an instance" );

            _eatContent = 1;

            return;
        }

        boolean isNil = false;
        boolean hasNil = false;

        if (event.getXsiNil(_chars))
        {
            _vc._event = event;
            isNil = JavaBooleanHolder.validateLexical(_chars.asString(), _vc);
            hasNil = true;
        }
        
        // note in schema spec 3.3.4, you're not even allowed to say xsi:nil="false" if you're not nillable!
        if (hasNil && !elementField.isNillable())
        {
            emitFieldError(event,  "Element has xsi:nil attribute but is not nillable");

            _eatContent = 1;
            return;
        }

        newState( elementType, elementField, isNil );

        // Dispatch this element event to any identity constraints
        // As well as adding any new identity constraints that exist

        _constraintEngine.element(
            event,
            elementType,
            elementField instanceof SchemaLocalElement
                ? ((SchemaLocalElement) elementField).getIdentityConstraints()
                : null );
    }

    private void attrEvent ( Event event )
    {
        QName attrName = event.getName();

        State state = topState();

        if (state._attrs == null)
            state._attrs = new HashSet();

        if (state._attrs.contains( attrName ))
        {
            emitFieldError(
                event,
                "Duplicate attribute: " + QNameHelper.pretty( attrName ) );

            return;
        }

        state._attrs.add( attrName );

        if (!state._canHaveAttrs)
        {
            emitFieldError( event, "Can't have attributes" );
            return;
        }

        SchemaLocalAttribute attrSchema =
            state._attrModel == null
                ? null
                : state._attrModel.getAttribute( attrName );

        if (attrSchema != null)
        {
            _localAttribute = attrSchema;

            if (attrSchema.getUse() == SchemaLocalAttribute.PROHIBITED)
            {
                emitFieldError(
                    event,
                    "Attribute is prohibited: "
                        + QNameHelper.pretty( attrName ) );

                return;
            }

            String value =
                validateSimpleType(
                    attrSchema.getType(), attrSchema, event, false, false );

            _constraintEngine.attr( event, attrName, attrSchema.getType(), value );

            return;
        }

        int wildcardProcess = state._attrModel.getWildcardProcess();
        _wildcardAttribute = state._attrModel;

        if (wildcardProcess == SchemaAttributeModel.NONE)
        {
            emitFieldError(
                event,
                "Attribute not allowed (no wildcards allowed): "
                    + QNameHelper.pretty( attrName ) );

            return;
        }

        QNameSet attrWildcardSet = state._attrModel.getWildcardSet();

        if (!attrWildcardSet.contains( attrName ))
        {
            emitFieldError(
                event,
                "Attribute not allowed: " + QNameHelper.pretty( attrName ) );

            return;
        }

        if (wildcardProcess == SchemaAttributeModel.SKIP)
            return;

        attrSchema = _globalTypes.findAttribute( attrName );
        _localAttribute = attrSchema;

        if (attrSchema == null)
        {
            if (wildcardProcess == SchemaAttributeModel.LAX)
                return;

            assert wildcardProcess == SchemaAttributeModel.STRICT;

            emitFieldError(
                event,
                "Attribute not allowed (strict wildcard, and no definition found): " + QNameHelper.pretty( attrName ) );

            return;
        }

        String value =
            validateSimpleType(
                attrSchema.getType(), attrSchema, event, false, false );

        _constraintEngine.attr( event, attrName, attrSchema.getType(), value );
    }

    private void endAttrsEvent ( Event event )
    {
        State state = topState();

        if (state._attrModel != null)
        {
            SchemaLocalAttribute[] attrs = state._attrModel.getAttributes();

            for ( int i = 0 ; i < attrs.length ; i++ )
            {
                SchemaLocalAttribute sla = attrs[ i ];

                if (state._attrs == null ||
                        !state._attrs.contains( sla.getName() ))
                {
                    if (sla.getUse() == SchemaLocalAttribute.REQUIRED)
                    {
                        emitFieldError(
                            event, "Expected attribute: ", sla.getName() );
                    }
                    else if (sla.isDefault() || sla.isFixed())
                    {
                        _constraintEngine.attr(event, sla.getName(), sla.getType(), sla.getDefaultText());

                        // We don't need to validate attribute defaults because this is done at compiletime.
                        /*
                        String value = sla.getDefaultText();
                        SchemaType type = sla.getType();

                        if (XmlQName.type.isAssignableFrom(type))
                        {
                            emitFieldError(
                                event, 
                                "Default QName values are unsupported for attribute: " + 
                                    QNameHelper.pretty(sla.getName()), 
                                XmlError.SEVERITY_INFO);
                        }

                        else 
                        {
                            validateSimpleType(
                                type, sla.getDefaultText(), event );

                            _constraintEngine.attr( event, type, value );
                        }
                        */
                    }
                }
            }
        }
    }

    private void endEvent ( Event event )
    {
        _localElement = null;
        _wildcardElement = null;
        String message = null;
        State state = topState();

        if (!state._isNil)
        {
            if (!state.end())
            {

                message = findDetailedErrorEnd(state);

                if (message != null)
                {
                  emitFieldError(event, message);
                }
                else
                {
                  emitFieldError(event, "Expected element(s)");
                }
            }

            // This end event has no text, use this fact to pass no text to
            // handleText

            if (state._isEmpty)
                handleText( event, true, state._field );
        }

        popState( event );

        _constraintEngine.endElement( event );
    }

    private void textEvent ( Event event )
    {
        State state = topState();

        if (state._isNil)
            emitFieldError(event, "Nil element cannot have simple content");
        else
            handleText( event, false, state._field );

        state._isEmpty = false;
    }


    private void handleText (
        Event event, boolean emptyContent, SchemaField field )
    {
        State state = topState();

        if (!state._sawText)
        {
            if (state._hasSimpleContent)
            {
                String value =
                    validateSimpleType(
                        state._type, field, event, emptyContent, true );

                _constraintEngine.text( event, state._type, value, false );
            }
            else if (state._canHaveMixedContent)
            {
                // handles cvc-elt.5.2.2.2.1, checking mixed content against fixed.
                // if we see <mixedType>a</b>c</mixedType>, we validate against
                // the first 'a' text and we check the content of mixedType to
                // be empty in beginElem().  we don't care about checking against
                // the 'c' text since there will already be an error for <b/>
                String value =
                    validateSimpleType(
                        XmlString.type, field, event, emptyContent, true );

                _constraintEngine.text( event, XmlString.type, value, false );
            }
            else if (emptyContent)
            {
                _constraintEngine.text( event, state._type, null, true );
            }
            else
                _constraintEngine.text( event, state._type, "", false);
        }

        if (!emptyContent && !state._canHaveMixedContent && 
            !event.textIsWhitespace() && !state._hasSimpleContent)
        {
            if (field instanceof SchemaLocalElement) 
            {
                SchemaLocalElement e = (SchemaLocalElement)field;
                emitError(event, "Element: '" + QNameHelper.pretty(e.getName()) + "' cannot have mixed content.");
            }
            else
                emitError( event, "Can't have mixed content" );
        }

        if (!emptyContent)
            state._sawText = true;
    }

    private String findDetailedErrorBegin(State state, QName qName)
    {
        String message = null;
        SchemaProperty[] eltProperties = state._type.getElementProperties();

        ArrayList expectedNames = new ArrayList();
        ArrayList optionalNames = new ArrayList();

        for (int ii = 0; ii < eltProperties.length; ii++)
        {
            //Get the element from the schema
            SchemaProperty sProp = eltProperties[ii];

            // test if the element is valid
            if (state.test(sProp.getName()))
            {
                if (0 == BigInteger.ZERO.compareTo(sProp.getMinOccurs()))
                    optionalNames.add(sProp.getName());
                else
                    expectedNames.add(sProp.getName());
            }
        }

        List names = (expectedNames.size() > 0 ? expectedNames : optionalNames);

        if (names.size() > 0)
        {
            StringBuffer buf = new StringBuffer();
            for (Iterator iter = names.iterator(); iter.hasNext(); )
            {
                buf.append(QNameHelper.pretty((QName)iter.next()));
                buf.append(" ");
            }

            message = "Expected element" + (names.size()>1 ? "s " : " ") +
                      buf.toString() + "at the end of the content";
        }

        return message;
    }

    private String findDetailedErrorEnd(State state)
    {
        SchemaProperty[] eltProperties  = state._type.getElementProperties();
        String message = null;

        ArrayList expectedNames = new ArrayList();
        ArrayList optionalNames = new ArrayList();

        for (int ii = 0; ii < eltProperties.length; ii++)
        {
            //Get the element from the schema
            SchemaProperty sProp = eltProperties[ii];

            // test if the element is valid
            if (state.test(sProp.getName()))
            {
                if (0 == BigInteger.ZERO.compareTo(sProp.getMinOccurs()))
                    optionalNames.add(sProp.getName());
                else
                    expectedNames.add(sProp.getName());
            }
        }

        List names = (expectedNames.size() > 0 ? expectedNames : optionalNames);

        if (names.size() > 0)
        {
            StringBuffer buf = new StringBuffer();
            for (Iterator iter = names.iterator(); iter.hasNext(); )
            {
                buf.append(QNameHelper.pretty((QName)iter.next()));
                buf.append(" ");
            }

            message = "Expected element" + (names.size()>1 ? "s " : " ") +
                      buf.toString() + "at the end of the content";
        }

        return message;
    }


    private final class State
    {
        boolean visit ( QName name )
        {
            return _canHaveElements && _visitor.visit( name );
        }

        boolean test( QName name )
        {
            return _canHaveElements && _visitor.testValid( name );
        }

        boolean end ( )
        {
            return !_canHaveElements || _visitor.visit( null );
        }

        SchemaParticle currentParticle ( )
        {
            assert _visitor != null;
            return _visitor.currentParticle();
        }

        SchemaType  _type;
        SchemaField _field;

        boolean _canHaveAttrs;
        boolean _canHaveMixedContent;
        boolean _hasSimpleContent;

        boolean _sawText;
        boolean _isEmpty;
        boolean _isNil;

        SchemaTypeVisitorImpl _visitor;
        boolean _canHaveElements;

        SchemaAttributeModel _attrModel;

        HashSet _attrs;

        State _next;
    }

    private void newState ( SchemaType type, SchemaField field, boolean isNil )
    {
        State state = new State();

        state._type = type;
        state._field = field;
        state._isEmpty = true;
        state._isNil = isNil;

        if (type.isSimpleType())
        {
            state._hasSimpleContent = true;
        }
        else
        {
            state._canHaveAttrs = true;
            state._attrModel = type.getAttributeModel();

            switch ( type.getContentType() )
            {
            case SchemaType.EMPTY_CONTENT :
                break;

            case SchemaType.SIMPLE_CONTENT :
                state._hasSimpleContent = true;
                break;

            case SchemaType.MIXED_CONTENT :
                state._canHaveMixedContent = true;
                // Fall through

            case SchemaType.ELEMENT_CONTENT :

                SchemaParticle particle = type.getContentModel();

                state._canHaveElements = particle != null;

                if (state._canHaveElements)
                    state._visitor = initVisitor( particle );

                break;

            default :
                throw new RuntimeException( "Unexpected content type" );
            }
        }

        pushState( state );
    }

    private void popState ( Event e )
    {
        if (_stateStack._visitor != null)
        {
            poolVisitor( _stateStack._visitor );
            _stateStack._visitor = null;
        }

        _stateStack = _stateStack._next;
    }

    private void pushState ( State state )
    {
        state._next = _stateStack;
        _stateStack = state;
    }

    private LinkedList _visitorPool = new LinkedList();

    private void poolVisitor( SchemaTypeVisitorImpl visitor )
    {
        _visitorPool.add( visitor );
    }

    private SchemaTypeVisitorImpl initVisitor( SchemaParticle particle )
    {
        if (_visitorPool.isEmpty())
            return new SchemaTypeVisitorImpl( particle );

        SchemaTypeVisitorImpl result =
            (SchemaTypeVisitorImpl) _visitorPool.removeLast();

        result.init( particle );

        return result;
    }

    private State topState ( )
    {
        return _stateStack;
    }

    //
    // Simple Type Validation
    //
    // emptyContent means that you can't use the event to get text: there is
    // no text, but you can use the event to do prefix resolution (in the case
    // where the default is a qname)
    //

    private String validateSimpleType (
        SchemaType type, SchemaField field, Event event,
        boolean emptyContent, boolean canApplyDefault )
    {
        if (!type.isSimpleType() &&
                type.getContentType() != SchemaType.SIMPLE_CONTENT)
        {
            assert false;
            // throw new RuntimeException( "Not a simple type" );
            return null; // should never happen
        }

        //
        // the no-type is always invalid
        //

        if (type.isNoType())
        {
            emitError(event, "Invalid type.");
            return null;
        }

        // Get the value as a string (as normalized by the white space rule
        // TODO - will want to optimize this later

        String value = "";

        if (!emptyContent)
        {
            event.getText( _chars, type.getWhiteSpaceRule() );
            value = _chars.asString();
        }

        // See if I can apply a default/fixed value

        if (value.length() == 0 && canApplyDefault && field != null &&
                (field.isDefault() || field.isFixed()))
        {
            if (XmlQName.type.isAssignableFrom(type))
            {
                emitError(
                    event,
                    "Default QName values are unsupported for " +
                        QNameHelper.readable(type) + " - ignoring.",
                    XmlError.SEVERITY_INFO);

                return null;
            }

            String defaultValue =
                XmlWhitespace.collapse(
                    field.getDefaultText(), type.getWhiteSpaceRule() );

// BUGBUG - should validate defaultValue at compile time
            return
                validateSimpleType( type, defaultValue, event )
                    ? defaultValue
                    : null;
        }

        if (!validateSimpleType( type, value, event ))
            return null;

        if (field != null && field.isFixed())
        {
// TODO - fixed value should have been cooked at compile time
            String fixedValue =
                XmlWhitespace.collapse(
                    field.getDefaultText(), type.getWhiteSpaceRule() );

            if (!validateSimpleType( type, fixedValue, event ))
                return null;

            XmlObject val = type.newValue( value );
            XmlObject def = type.newValue( fixedValue );

            if (!val.valueEquals( def ))
            {
                // BUGBUG - make this more verbose

                emitError(
                    event,
                    "Value not equal to fixed value. " + value );

                return null;
            }
        }

        return value;
    }

    private boolean validateSimpleType (
        SchemaType type, String value, Event event )
    {
        if (!type.isSimpleType() &&
                type.getContentType() != SchemaType.SIMPLE_CONTENT)
        {
            assert false;
            throw new RuntimeException( "Not a simple type" );
        }

        int retState = _errorState;

        switch ( type.getSimpleVariety() )
        {
        case SchemaType.ATOMIC : validateAtomicType( type, value, event );break;
        case SchemaType.UNION  : validateUnionType(  type, value, event );break;
        case SchemaType.LIST   : validateListType(   type, value, event );break;

        default : throw new RuntimeException( "Unexpected simple variety" );
        }

        return retState == _errorState;
    }

    private void validateAtomicType (
        SchemaType type, String value, Event event )
    {
        // Now we should have only an atomic type to validate

        assert type.getSimpleVariety() == SchemaType.ATOMIC;

        // Record the current error state to see if any new errors are made
        int errorState = _errorState;
        _vc._event = event;

        switch ( type.getPrimitiveType().getBuiltinTypeCode() )
        {
        case SchemaType.BTC_ANY_SIMPLE :
        {
            // Always valid!
            break;
        }
        case SchemaType.BTC_STRING :
        {
            JavaStringEnumerationHolderEx.validateLexical( value, type, _vc );
            _stringValue = value;
            break;
        }
        case SchemaType.BTC_DECIMAL :
        {
            JavaDecimalHolderEx.validateLexical( value, type, _vc );

            if (errorState == _errorState)
            {
                _decimalValue = new BigDecimal( value );
                JavaDecimalHolderEx.validateValue( _decimalValue, type, _vc );
            }

            break;
        }
        case SchemaType.BTC_BOOLEAN :
        {
            _booleanValue = JavaBooleanHolderEx.validateLexical( value, type, _vc );
            break;
        }
        case SchemaType.BTC_FLOAT :
        {
            float f =
                JavaFloatHolderEx.validateLexical( value, type, _vc );

            if (errorState == _errorState)
                JavaFloatHolderEx.validateValue( f, type, _vc );

            _floatValue = f;
            break;
        }
        case SchemaType.BTC_DOUBLE :
        {
            double d =
                JavaDoubleHolderEx.validateLexical( value, type, _vc );

            if (errorState == _errorState)
                JavaDoubleHolderEx.validateValue( d, type, _vc );

            _doubleValue = d;
            break;
        }
        case SchemaType.BTC_QNAME :
        {
            QName n =
                JavaQNameHolderEx.validateLexical(
                    value, type, _vc, event );

            if (errorState == _errorState)
                JavaQNameHolderEx.validateValue( n, type, _vc );

            _qnameValue = n;
            break;
        }
        case SchemaType.BTC_ANY_URI :
        {
            JavaUriHolderEx.validateLexical( value, type, _vc );
            _stringValue = value;
            break;
        }
        case SchemaType.BTC_DATE_TIME :
        case SchemaType.BTC_TIME :
        case SchemaType.BTC_DATE :
        case SchemaType.BTC_G_YEAR_MONTH :
        case SchemaType.BTC_G_YEAR :
        case SchemaType.BTC_G_MONTH_DAY :
        case SchemaType.BTC_G_DAY :
        case SchemaType.BTC_G_MONTH :
        {
            GDate d = XmlDateImpl.validateLexical( value, type, _vc );

            if (d != null)
                XmlDateImpl.validateValue( d, type, _vc );

            _gdateValue = d;
            break;
        }
        case SchemaType.BTC_DURATION :
        {
            GDuration d = XmlDurationImpl.validateLexical( value, type, _vc );

            if (d != null)
                XmlDurationImpl.validateValue( d, type, _vc );

            _gdurationValue = d;
            break;
        }
        case SchemaType.BTC_BASE_64_BINARY :
        {
            byte[] v =
                JavaBase64HolderEx.validateLexical( value, type, _vc );

            if (v != null)
                JavaBase64HolderEx.validateValue( v, type, _vc );

            _byteArrayValue = v;
            break;
        }
        case SchemaType.BTC_HEX_BINARY :
        {
            byte[] v =
                JavaHexBinaryHolderEx.validateLexical( value, type, _vc );

            if (v != null)
                JavaHexBinaryHolderEx.validateValue( v, type, _vc );

            _byteArrayValue = v;
            break;
        }
        case SchemaType.BTC_NOTATION :
            // Unimplemented. 
            break;

        default :
            throw new RuntimeException( "Unexpected primitive type code" );
        }
    }

    private void validateListType (
        SchemaType type, String value, Event event )
    {
        int errorState = _errorState;

        if (!type.matchPatternFacet( value ))
        {
            emitError(
                event,
                "List '" + value + "' does not match pattern for " + QNameHelper.readable(type) );
        }

        String[] items = XmlListImpl.split_list(value);

        
        int i;
        XmlObject o;

        if ((o = type.getFacet( SchemaType.FACET_LENGTH )) != null)
        {
            if ((i = ((SimpleValue)o).getIntValue()) != items.length)
            {
                emitError(
                    event,
                    "List (" + value + ") does not have " + i +
                        " items per length facet for " + QNameHelper.readable(type));
            }
        }

        if ((o = type.getFacet( SchemaType.FACET_MIN_LENGTH )) != null)
        {
            if ((i = ((SimpleValue)o).getIntValue()) > items.length)
            {
                emitError(
                    event,
                    "List (" + value + ") has only " + items.length +
                        " items, fewer than min length facet (" + i + ") for " + QNameHelper.readable(type) );
            }
        }
        
        if ((o = type.getFacet( SchemaType.FACET_MAX_LENGTH )) != null)
        {
            if ((i = ((SimpleValue)o).getIntValue()) < items.length)
            {
                emitError(
                    event,
                    "List (" + value + ") has " + items.length +
                        " items, more than max length facet (" + i + ") for " + QNameHelper.readable(type) );
            }
        }

        SchemaType itemType = type.getListItemType();
        _listValue = new ArrayList();
        _listTypes = new ArrayList();

        for ( i = 0 ; i < items.length ; i++ )
        {
            validateSimpleType(
                itemType, items[i], event );
            addToList(itemType);
        }

        // If no errors up to this point, then I can create an
        // XmlList from this value and campare it again enums.

        if (errorState == _errorState)
        {
            if (type.getEnumerationValues() != null)
            {
                // Lists which contain QNames will need a resolver

                NamespaceContext.push(
                    new NamespaceContext( event ) );

                try
                {
                    XmlObject listValue = ( (SchemaTypeImpl) type).newValidatingValue( value );
                }
                catch (XmlValueOutOfRangeException e)
                {
                    emitError(
                        event,
                        "List value (" + value +
                            ") is not a valid enumeration value for " + QNameHelper.readable(type));
                }
                finally
                {
                    NamespaceContext.pop();
                }
            }
        }
    }

    private void validateUnionType (
        SchemaType type, String value, Event event )
    {
        // TODO - if xsi:type is specified on a union, it selects
        // that union member type

        if (!type.matchPatternFacet( value ))
        {
            emitError(
                event,
                "Union '" + value + "' does not match pattern for " + QNameHelper.readable(type));
        }

        int currentWsr = SchemaType.WS_PRESERVE;
        String currentValue = value;

        SchemaType[] types = type.getUnionMemberTypes();

        int originalState = _errorState;

        int i;
        for ( i = 0 ; i < types.length ; i++ )
        {
            int memberWsr = types[ i ].getWhiteSpaceRule();

            if (memberWsr == SchemaType.WS_UNSPECIFIED)
                memberWsr = SchemaType.WS_PRESERVE;

            if (memberWsr != currentWsr)
            {
                currentWsr = memberWsr;
                currentValue = XmlWhitespace.collapse( value, currentWsr );
            }

            int originalErrorState = _errorState;

            _suspendErrors++;

            try
            {
                validateSimpleType( types[ i ], currentValue, event );
            }
            finally
            {
                _suspendErrors--;
            }

            if (originalErrorState == _errorState)
            {
                _unionType = types[i];
                break;
            }
        }

        _errorState = originalState;

        if (i >= types.length)
        {
            emitError(
                event,
                "Union '" + value + "' does not match any members of " + QNameHelper.readable(type) );
        }
        else
        {
            XmlObject[] unionEnumvals = type.getEnumerationValues();

            if (unionEnumvals != null)
            {
                // Unions which contain QNames will need a resolver

                NamespaceContext.push( new NamespaceContext( event ) );

                try
                {
                    XmlObject unionValue = type.newValue( value );

                    for ( i = 0 ; i < unionEnumvals.length ; i++ )
                    {
                        if (unionValue.valueEquals( unionEnumvals[ i ] ))
                            break;
                    }

                    if (i >= unionEnumvals.length)
                    {
                        emitError(
                            event,
                            "Union '" + value +
                                "' is not a valid enumeration value for " + QNameHelper.readable(type) );
                    }
                }
                catch (XmlValueOutOfRangeException e)
                {
                    // actually, the current union code always ends up here when invalid
                    emitError(
                        event,
                        "Union '" + value +
                            "' is not a valid enumeration value for " + QNameHelper.readable(type) );
                }
                finally
                {
                    NamespaceContext.pop();
                }
            }
        }
    }

    private void addToList(SchemaType type)
    {
        if (type.getSimpleVariety() != SchemaType.ATOMIC)
            return;

        if (type.getUnionMemberTypes().length>0 && getUnionType()!=null)
        {
            type = getUnionType();
            _unionType = null;
        }

        _listTypes.add(type);

        switch ( type.getPrimitiveType().getBuiltinTypeCode() )
        {
            case SchemaType.BTC_ANY_SIMPLE :
                {
                    _listValue.add(_stringValue);
                    break;
                }
            case SchemaType.BTC_STRING :
                {
                    _listValue.add(_stringValue);
                    _stringValue = null;
                    break;
                }
            case SchemaType.BTC_DECIMAL :
                {
                    _listValue.add( _decimalValue );
                    _decimalValue = null;
                    break;
                }
            case SchemaType.BTC_BOOLEAN :
                {
                    _listValue.add(_booleanValue ? Boolean.TRUE : Boolean.FALSE);
                    _booleanValue = false;
                    break;
                }
            case SchemaType.BTC_FLOAT :
                {
                    _listValue.add(new Float(_floatValue));
                    _floatValue = 0;
                    break;
                }
            case SchemaType.BTC_DOUBLE :
                {
                    _listValue.add(new Double(_doubleValue));
                    _doubleValue = 0;
                    break;
                }
            case SchemaType.BTC_QNAME :
                {
                    _listValue.add(_qnameValue);
                    _qnameValue = null;
                    break;
                }
            case SchemaType.BTC_ANY_URI :
                {
                    _listTypes.add(_stringValue);
                    break;
                }
            case SchemaType.BTC_DATE_TIME :
            case SchemaType.BTC_TIME :
            case SchemaType.BTC_DATE :
            case SchemaType.BTC_G_YEAR_MONTH :
            case SchemaType.BTC_G_YEAR :
            case SchemaType.BTC_G_MONTH_DAY :
            case SchemaType.BTC_G_DAY :
            case SchemaType.BTC_G_MONTH :
                {
                    _listValue.add(_gdateValue);
                    _gdateValue = null;
                    break;
                }
            case SchemaType.BTC_DURATION :
                {
                    _listValue.add(_gdurationValue);
                    _gdurationValue = null;
                    break;
                }
            case SchemaType.BTC_BASE_64_BINARY :
                {
                    _listValue.add(_byteArrayValue);
                    _byteArrayValue = null;
                    break;
                }
            case SchemaType.BTC_HEX_BINARY :
                {
                    _listValue.add(_byteArrayValue);
                    _byteArrayValue = null;
                    break;
                }
            case SchemaType.BTC_NOTATION :
                {
                    _listValue.add(_stringValue);
                    _stringValue = null;
                    break;
                }

            default :
                throw new RuntimeException( "Unexpected primitive type code" );
        }
    }

    //
    // Members of the validator class
    //

    private boolean            _invalid;
    private SchemaType         _rootType;
    private SchemaField        _rootField;
    private SchemaTypeLoader   _globalTypes;
    private Chars              _chars;
    private State              _stateStack;
    private int                _errorState;
    private Collection         _errorListener;
    private ValidatorVC        _vc;
    private int                _suspendErrors;
    private IdentityConstraint _constraintEngine;
    private int                _eatContent;

    private SchemaLocalElement   _localElement;
    private SchemaParticle       _wildcardElement;
    private SchemaLocalAttribute _localAttribute;
    private SchemaAttributeModel _wildcardAttribute;
    private SchemaType           _unionType;

    // Strongly typed values
    private String _stringValue;
    private BigDecimal _decimalValue;
    private boolean _booleanValue;
    private float _floatValue;
    private double _doubleValue;
    private QName _qnameValue;
    private GDate _gdateValue;
    private GDuration _gdurationValue;
    private byte[] _byteArrayValue;
    private List _listValue;
    private List _listTypes;

    private void resetValues()
    {
        _localAttribute = null;
        _wildcardAttribute = null;
        _stringValue = null;
        _decimalValue = null;
        _booleanValue = false;
        _floatValue = 0;
        _doubleValue = 0;
        _qnameValue = null;
        _gdateValue = null;
        _gdurationValue = null;
        _byteArrayValue = null;
        _listValue = null;
        _listTypes = null;
        _unionType = null;
        _localAttribute = null;
    }

    public SchemaLocalElement getCurrentElement()
    {
        if (_localElement != null)
            return _localElement;

        // it means the element is to be skiped and it doesn't have a known SchemaLocalElement
        if (_eatContent>0)
            return null;

        //try getting it from the stack (this should happen after END)
        if (_stateStack!=null && _stateStack._field instanceof SchemaLocalElement )
            return (SchemaLocalElement)_stateStack._field;

        return null;
    }

    public SchemaParticle getCurrentWildcardElement()
    {
        return _wildcardElement;
    }

    public SchemaLocalAttribute getCurrentAttribute()
    {
        return _localAttribute;
    }

    public SchemaAttributeModel getCurrentWildcardAttribute()
    {
        return _wildcardAttribute;
    }

    public String getStringValue()
    {
        return _stringValue;
    }

    public BigDecimal getDecimalValue()
    {
        return _decimalValue;
    }

    public boolean getBooleanValue()
    {
        return _booleanValue;
    }

    public float getFloatValue()
    {
        return _floatValue;
    }

    public double getDoubleValue()
    {
        return _doubleValue;
    }

    public QName getQNameValue()
    {
        return _qnameValue;
    }

    public GDate getGDateValue()
    {
        return _gdateValue;
    }

    public GDuration getGDurationValue()
    {
        return _gdurationValue;
    }

    public byte[] getByteArrayValue()
    {
        return _byteArrayValue;
    }

    public List getListValue()
    {
        return _listValue;
    }

    public List getListTypes()
    {
        return _listTypes;
    }

    public SchemaType getUnionType()
    {
        return _unionType;
    }
}