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    * must also contain a copy of this document.
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   * info@exolab.org.
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   *
   * 5. Due credit should be given to the Exolab Project (http://www.exolab.org/).
   *
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   * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * Copyright 2000-2004 (C) Intalio, Inc. All Rights Reserved.
   *
   * $Id$
   */
  package org.exolab.castor.xml;
  
  import java.lang.reflect.Array;
  import java.text.MessageFormat;
  import java.util.Enumeration;
  import java.util.List;
  import java.util.Vector;
  
  import org.exolab.castor.mapping.FieldHandler;
  import org.exolab.castor.xml.location.XPathLocation;
  
  /**
   * Handles field validation.
   *
   * @author <a href="mailto:kvisco-at-intalio.com">Keith Visco</a>
   * @version $Revision$ $Date: 2004-10-08 22:58:55 -0600 (Fri, 08 Oct 2004) $
   */
  public class FieldValidator extends Validator {
  
    /**
     * Default value for descriptor names. If a Descriptor XML name value is set to this, then no name
     * has been assigned yet.
     */
    private static final String ERROR_NAME = "-error-if-this-is-used-";
    /** Default minimum occurrance. */
    private static final int DEFAULT_MIN = 0;
    /** Default maximum occurrance. */
    private static final int DEFAULT_MAX = -1;
  
    /** Minimum number of occurrences for this element to pass validation. */
    private int _minOccurs = DEFAULT_MIN;
    /** Maximum number of occurrences for this element to pass validation. */
    private int _maxOccurs = DEFAULT_MAX;
    /** The Field Descriptor describing the field we validate. */
    private XMLFieldDescriptor _descriptor = null;
    /**
     * The actual type validator which is used to validate single instances of the field.
     */
    private TypeValidator _validator = null;
  
    /**
     * Creates a default FieldValidator.
     */
    public FieldValidator() {
      super();
    }
  
    /**
     * Creates a new FieldValidator using the given TypeValidator.
     * 
     * @param validator the TypeValidator to delegate validation to
     */
    public FieldValidator(final TypeValidator validator) {
      super();
      this._validator = validator;
    }
  
    /**
     * Returns the mimimum number of occurances for a given object.
     *
     * @return The mimimum number of occurances for a given object. A zero value denotes no lower
     *         bound (ie. the object is optional).
     */
    public int getMinOccurs() {
      return _minOccurs;
   }
 
   /**
    * Returns the maximum number of occurances for a given object.
    *
    * @return The maximum number of occurances for a given object. A negative value denotes no upper
    *         bound.
    */
   public int getMaxOccurs() {
     return _maxOccurs;
   }
 
   /**
    * Returns the TypeValidator.
    * 
    * @return the TypeValidator.
    */
   public TypeValidator getTypeValidator() {
     return _validator;
   }
 
   /**
    * Returns true if a TypeValidator has been set.
    * 
    * @return true if a TypeValidator has been set.
    */
   public boolean hasTypeValidator() {
     return _validator != null;
   }
 
   /**
    * Sets the mimimum number of occurances for a given object. A zero, or negative value denotes no
    * lower bound (i.e., the object is optional).
    *
    * @param minOccurs the minimum number of times an object must occur in order to be valid.
    */
   public void setMinOccurs(final int minOccurs) {
     this._minOccurs = (minOccurs < 0) ? 0 : minOccurs;
   }
 
   /**
    * Sets the maximum number of occurances for a given object. A negative value denotes no upper
    * bound.
    *
    * @param maxOccurs the maximum number of times an object may occur.
    */
   public void setMaxOccurs(final int maxOccurs) {
     this._maxOccurs = maxOccurs;
   }
 
   /**
    * Sets the field descriptor to use for obtaining information about the field to validate, such as
    * the field name, the field handler, etc.
    *
    * @param descriptor the field descriptor for the field to validate
    */
   public void setDescriptor(final XMLFieldDescriptor descriptor) {
     this._descriptor = descriptor;
   }
 
   public void setValidator(final TypeValidator validator) {
     this._validator = validator;
   }
 
   /**
    * Validates the given Object.
    *
    * @param object the Object that contains the field to validate
    * @param context the ValidationContext
    * @throws ValidationException if validation fails
    */
   public void validate(final Object object, final ValidationContext context)
       throws ValidationException {
     if (_descriptor == null || object == null || context.isValidated(object)) {
       return;
     }
 
     // Don't validate "transient" fields.
     if (_descriptor.isTransient()) {
       return;
     }
 
     FieldHandler handler = _descriptor.getHandler();
     if (handler == null) {
       return;
     }
 
     // Get the value of the field
     Object value = handler.getValue(object);
     if (value == null) {
       if (!_descriptor.isRequired() || _descriptor.isNillable()) {
         return;
       }
       // deal with lenient id/idref validation accordingly, skipping exception handling
       // in this case
       if (_descriptor.isRequired() && _descriptor.getSchemaType() != null
           && _descriptor.getSchemaType().equals("IDREF")
           && context.getInternalContext().getLenientIdValidation()) {
         return;
       }
       StringBuilder buff = new StringBuilder();
       if (!ERROR_NAME.equals(_descriptor.getXMLName())) {
         buff.append(MessageFormat.format(
             resourceBundle.getString("validatorField.error.required.field.whose"),
             new Object[] {_descriptor.getFieldName(), object.getClass().getName(),
                 _descriptor.getXMLName()}));
       } else {
         buff.append(
             MessageFormat.format(resourceBundle.getString("validatorField.error.required.field"),
                 new Object[] {_descriptor.getFieldName(), object.getClass().getName()}));
       }
 
       throw new ValidationException(buff.toString());
     }
 
     if (_descriptor.isReference()) {
       if (_validator != null) {
         _validator.validate(value, context);
       }
       return;
     }
 
     // Prevent endless loop! Have we seen this object yet?
     if (context != null) {
       if (context.isValidated(object)) {
         return;
       }
       // -- mark object as processed
       context.addValidated(object);
     }
 
     // We are now ready to do actual validation
 
     Class type = value.getClass();
     int size = 1;
     long occurence = -1;
 
     try {
       if (type.isArray()) {
         // We don't validate Byte array types
         if (type.getComponentType() != Byte.TYPE) {
           size = Array.getLength(value);
           if (_validator != null) {
             for (int i = 0; i < size; i++) {
               occurence = i + 1;
               _validator.validate(Array.get(value, i), context);
             }
           } else {
             for (int i = 0; i < size; i++) {
               super.validate(Array.get(value, i), context);
             }
           }
         }
       } else if (value instanceof Enumeration) {
         // <NOTE>
         // The following code should be changed to use CollectionHandler
         // </NOTE>
         size = 0;
         for (Enumeration enumeration = (Enumeration) value; enumeration.hasMoreElements();) {
           ++size;
           validateInstance(context, enumeration.nextElement());
         }
       } else if (value instanceof Vector) {
         Vector vector = (Vector) value;
         size = vector.size();
         for (int i = 0; i < size; i++) {
           occurence = i + 1;
           validateInstance(context, vector.elementAt(i));
         }
       } else if (value instanceof List) {
         List list = (List) value;
         size = list.size();
         for (int i = 0; i < size; i++) {
           occurence = i + 1;
           validateInstance(context, list.get(i));
         }
       } else {
         validateInstance(context, value);
       }
     } catch (ValidationException vx) {
       // -- add additional validation information
       String err = MessageFormat.format(resourceBundle.getString("validatorField.error.exception"),
           new Object[] {_descriptor.getFieldName(), object.getClass().getName()});
       ValidationException validationException = new ValidationException(err, vx);
       addLocationInformation(_descriptor, validationException, occurence);
       throw validationException;
     }
 
     // Check sizes of collection
 
     // Check minimum.
     // If any items exist (size != 0) or the descriptor is marked as
     // required then we need to report the error. Otherwise size == 0 and
     // field is not required, so no error.
     if (size < _minOccurs && (size != 0 || _descriptor.isRequired())) {
       StringBuilder buff = new StringBuilder();
       if (!ERROR_NAME.equals(_descriptor.getXMLName())) {
         buff.append(MessageFormat.format(
             resourceBundle.getString("validatorField.error.exception.min.occurs.whose"),
             new Object[] {_minOccurs, _descriptor.getFieldName(), object.getClass().getName(),
                 _descriptor.getXMLName()}));
       } else {
         buff.append(MessageFormat.format(
             resourceBundle.getString("validatorField.error.exception.min.occurs"),
             new Object[] {_minOccurs, _descriptor.getFieldName(), object.getClass().getName()}));
       }
       throw new ValidationException(buff.toString());
     }
 
     // Check maximum.
     if (_maxOccurs >= 0 && size > _maxOccurs) {
       StringBuilder buff = new StringBuilder();
       if (!ERROR_NAME.equals(_descriptor.getXMLName())) {
         buff.append(MessageFormat.format(
             resourceBundle.getString("validatorField.error.exception.max.occurs.whose"),
             new Object[] {_maxOccurs, _descriptor.getFieldName(), object.getClass().getName(),
                 _descriptor.getXMLName()}));
       } else {
         buff.append(MessageFormat.format(
             resourceBundle.getString("validatorField.error.exception.max.occurs"),
             new Object[] {_maxOccurs, _descriptor.getFieldName(), object.getClass().getName()}));
       }
 
       throw new ValidationException(buff.toString());
     }
 
     if (context != null) {
       context.removeValidated(object);
     }
   }
 
   /**
    * Validate an individual instance.
    * 
    * @param context the validation context.
    * @param value The instance to validate.
    * @throws ValidationException if validation fails
    */
   private void validateInstance(final ValidationContext context, final Object value)
       throws ValidationException {
     if (_validator != null) {
       _validator.validate(value, context);
     } else {
       super.validate(value, context);
     }
   }
 
   /**
    * Adds location information to the {@link ValidationException} instance.
    * 
    * @param fieldDescriptor The {@link XMLFieldDescriptor} instance whose has been responsible for
    *        generating the error.
    * @param e The {@link ValidationException} to enrich.
    * @param occurence If greater than 0, denotes the position of the invalid collection value.
    */
   private void addLocationInformation(final XMLFieldDescriptor fieldDescriptor,
       final ValidationException e, final long occurence) {
     XPathLocation loc = (XPathLocation) e.getLocation();
     if (loc == null) {
       loc = new XPathLocation();
       e.setLocation(loc);
       String xmlName = fieldDescriptor.getXMLName();
       if (occurence > 0) {
         xmlName += "[" + occurence + "]";
       }
       if (fieldDescriptor.getNodeType() == NodeType.Attribute) {
         loc.addAttribute(xmlName);
       } else {
         loc.addChild(xmlName);
       }
     }
   }
 
 }