/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.myfaces.component.validate;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.lang.reflect.Constructor;
  import java.lang.reflect.Method;
  import java.security.AccessController;
  import java.security.PrivilegedActionException;
  import java.security.PrivilegedExceptionAction;
  import java.util.ArrayList;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Set;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  import javax.el.ELContext;
  import javax.el.ValueExpression;
  import javax.el.ValueReference;
  import javax.faces.FacesException;
  import javax.faces.application.FacesMessage;
  import javax.faces.component.UIComponent;
  import javax.faces.component.visit.VisitCallback;
  import javax.faces.component.visit.VisitContext;
  import javax.faces.component.visit.VisitResult;
  import javax.faces.context.FacesContext;
  import javax.faces.validator.BeanValidator;
  import static javax.faces.validator.BeanValidator.EMPTY_VALIDATION_GROUPS_PATTERN;
  import static javax.faces.validator.BeanValidator.MESSAGE_ID;
  import static javax.faces.validator.BeanValidator.VALIDATION_GROUPS_DELIMITER;
  import static javax.faces.validator.BeanValidator.VALIDATOR_FACTORY_KEY;
  import javax.faces.validator.Validator;
  import javax.faces.validator.ValidatorException;
  import javax.validation.ConstraintViolation;
  import javax.validation.MessageInterpolator;
  import javax.validation.Validation;
  import javax.validation.ValidatorFactory;
  import javax.validation.groups.Default;
  import javax.validation.metadata.BeanDescriptor;
  import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFProperty;
  import org.apache.myfaces.shared.util.MessageUtils;
  import org.apache.myfaces.shared.util.MyFacesObjectInputStream;
  import org.apache.myfaces.util.ExternalSpecifications;
  
  /**
   *
   */
  public class WholeBeanValidator implements Validator
  {
      private static final Logger log = Logger.getLogger(WholeBeanValidator.class.getName());
      
      private static final Class<?>[] DEFAULT_VALIDATION_GROUPS_ARRAY = new Class<?>[] { Default.class };
  
      private static final String DEFAULT_VALIDATION_GROUP_NAME = "javax.validation.groups.Default";
      
      private static final String CANDIDATE_COMPONENT_VALUES_MAP = "oam.WBV.candidatesMap";
      
      private static final String BEAN_VALIDATION_FAILED = "oam.WBV.validationFailed";
  
      private Class<?>[] validationGroupsArray;
  
      @Override
      public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException
      {
          if (context == null)
          {
              throw new NullPointerException("context");
          }
          if (component == null)
          {
              throw new NullPointerException("component");
          }
  
          ValueExpression valueExpression = component.getValueExpression("value");
          if (valueExpression == null)
          {
             log.warning("cannot validate component with empty value: " 
                     + component.getClientId(context));
             return;
         }
 
         Object base = valueExpression.getValue(context.getELContext());
                 
         Class<?> valueBaseClass = base.getClass();
         if (valueBaseClass == null)
         {
             return;
         }
 
         // Initialize Bean Validation.
         ValidatorFactory validatorFactory = createValidatorFactory(context);
         javax.validation.Validator validator = createValidator(validatorFactory, context, 
                 (ValidateWholeBeanComponent)component);
         BeanDescriptor beanDescriptor = validator.getConstraintsForClass(valueBaseClass);
         if (!beanDescriptor.isBeanConstrained())
         {
             return;
         }
         
         // Note that validationGroupsArray was initialized when createValidator was called
         Class[] validationGroupsArray = this.validationGroupsArray;
 
         // Delegate to Bean Validation.
         
         // TODO: Use validator.validate(...) over the copy instance.
         
         Boolean beanValidationFailed = (Boolean) context.getViewRoot().getTransientStateHelper()
                 .getTransient(BEAN_VALIDATION_FAILED);
         
         if (Boolean.TRUE.equals(beanValidationFailed))
         {
             // JSF 2.3 Skip class level validation
             return;
         }
         
         Map<String, Object> candidatesMap = (Map<String, Object>) context.getViewRoot()
                 .getTransientStateHelper().getTransient(CANDIDATE_COMPONENT_VALUES_MAP);
         if (candidatesMap != null)
         {
             Object copy = createBeanCopy(base);
             
             UpdateBeanCopyCallback callback = new UpdateBeanCopyCallback(this, base, copy, candidatesMap);
             context.getViewRoot().visitTree(
                     VisitContext.createVisitContext(context, candidatesMap.keySet(), null), 
                     callback);
             
             Set constraintViolations = validator.validate(copy, validationGroupsArray);
             if (!constraintViolations.isEmpty())
             {
                 Set<FacesMessage> messages = new LinkedHashSet<FacesMessage>(constraintViolations.size());
                 for (Object violation: constraintViolations)
                 {
                     ConstraintViolation constraintViolation = (ConstraintViolation) violation;
                     String message = constraintViolation.getMessage();
                     Object[] args = new Object[]{ message, MessageUtils.getLabel(context, component) };
                     FacesMessage msg = MessageUtils.getMessage(FacesMessage.SEVERITY_ERROR, MESSAGE_ID, args, context);
                     messages.add(msg);
                 }
                 throw new ValidatorException(messages);
             }
         }
     }
     
     private Object createBeanCopy(Object base)
     {
         Object copy = null;
         try
         {
             copy = base.getClass().newInstance();
         }
         catch (Exception ex)
         {
             Logger.getLogger(WholeBeanValidator.class.getName()).log(Level.FINEST, null, ex);
         }
         
         if (base instanceof Serializable)
         {
             copy = copySerializableObject(base);
         }
         else if(base instanceof Cloneable)
         { 
             Method cloneMethod;
             try
             {
                 cloneMethod = base.getClass().getMethod("clone");
                 copy = cloneMethod.invoke(base);
             }
             catch (Exception ex) 
             {
                 Logger.getLogger(WholeBeanValidator.class.getName()).log(Level.FINEST, null, ex);
             }
         }
         else
         {
             Class<?> clazz = base.getClass();
             try
             {
                 Constructor<?> copyConstructor = clazz.getConstructor(clazz);
                 if (copyConstructor != null)
                 {
                     copy = copyConstructor.newInstance(base);
                 }
             }
             catch (Exception ex)
             {
                 Logger.getLogger(WholeBeanValidator.class.getName()).log(Level.FINEST, null, ex);
             }
         }
         
         if (copy == null)
         {
             throw new FacesException("Cannot create copy for wholeBeanValidator: "+base.getClass().getName());
         }
         
         return copy;
     }
     
     private Object copySerializableObject(Object base)
     {
         Object copy = null;
         try 
         {
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
             ObjectOutputStream oos = new ObjectOutputStream(baos);
             oos.writeObject(base);
             oos.flush();
             oos.close();
             baos.close();
             byte[] byteData = baos.toByteArray();
             ByteArrayInputStream bais = new ByteArrayInputStream(byteData);
             try 
             {
                 copy = new MyFacesObjectInputStream(bais).readObject();
             }
             catch (ClassNotFoundException e)
             {
                 //e.printStackTrace();
             }
         }
         catch (IOException e) 
         {
             //e.printStackTrace();
         }
         return copy;
     }    
     
     private javax.validation.Validator createValidator(final ValidatorFactory validatorFactory, 
             FacesContext context, ValidateWholeBeanComponent component)
     {
         // Set default validation group when setValidationGroups has not been called.
         // The null check is there to prevent it from happening twice.
         if (validationGroupsArray == null)
         {
             postSetValidationGroups(component);
         }
 
         return validatorFactory //
                 .usingContext() //
                 .messageInterpolator(new FacesMessageInterpolator(
                         validatorFactory.getMessageInterpolator(), context)) //
                 .getValidator();
 
     }
 
 
     /**
      * Get the ValueReference from the ValueExpression.
      *
      * @param valueExpression The ValueExpression for value.
      * @param context The FacesContext.
      * @return A ValueReferenceWrapper with the necessary information about the ValueReference.
      */
     private ValueReference getValueReference(
             final ValueExpression valueExpression, final FacesContext context)
     {
         ELContext elCtx = context.getELContext();
         
         return _ValueReferenceResolver.resolve(valueExpression, elCtx);
     }
 
     /**
      * This method creates ValidatorFactory instances or retrieves them from the container.
      *
      * Once created, ValidatorFactory instances are stored in the container under the key
      * VALIDATOR_FACTORY_KEY for performance.
      *
      * @param context The FacesContext.
      * @return The ValidatorFactory instance.
      * @throws FacesException if no ValidatorFactory can be obtained because: a) the
      * container is not a Servlet container or b) because Bean Validation is not available.
      */
     private ValidatorFactory createValidatorFactory(FacesContext context)
     {
         Map<String, Object> applicationMap = context.getExternalContext().getApplicationMap();
         Object attr = applicationMap.get(VALIDATOR_FACTORY_KEY);
         if (attr instanceof ValidatorFactory)
         {
             return (ValidatorFactory) attr;
         }
         else
         {
             synchronized (this)
             {
                 if (ExternalSpecifications.isBeanValidationAvailable())
                 {
                     ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
                     applicationMap.put(VALIDATOR_FACTORY_KEY, factory);
                     return factory;
                 }
                 else
                 {
                     throw new FacesException("Bean Validation is not present");
                 }
             }
         }
     }
 
     /**
      * Fully initialize the validation groups if needed.
      * If no validation groups are specified, the Default validation group is used.
      */
     private void postSetValidationGroups(ValidateWholeBeanComponent component)
     {
         String validationGroups = getValidationGroups(component);
         if (validationGroups == null || validationGroups.matches(EMPTY_VALIDATION_GROUPS_PATTERN))
         {
             this.validationGroupsArray = DEFAULT_VALIDATION_GROUPS_ARRAY;
         }
         else
         {
             String[] classes = validationGroups.split(VALIDATION_GROUPS_DELIMITER);
             List<Class<?>> validationGroupsList = new ArrayList<Class<?>>(classes.length);
 
             for (String clazz : classes)
             {
                 clazz = clazz.trim();
                 if (!clazz.isEmpty())
                 {
                     Class<?> theClass = null;
                     ClassLoader cl = null;
                     if (System.getSecurityManager() != null) 
                     {
                         try 
                         {
                             cl = AccessController.doPrivileged(new PrivilegedExceptionAction<ClassLoader>()
                                     {
                                         public ClassLoader run() throws PrivilegedActionException
                                         {
                                             return Thread.currentThread().getContextClassLoader();
                                         }
                                     });
                         }
                         catch (PrivilegedActionException pae)
                         {
                             throw new FacesException(pae);
                         }
                     }
                     else
                     {
                         cl = Thread.currentThread().getContextClassLoader();
                     }
                     
                     try
                     {                        
                         // Try WebApp ClassLoader first
                         theClass = Class.forName(clazz,false,cl);
                     }
                     catch (ClassNotFoundException ignore)
                     {
                         try
                         {
                             // fallback: Try ClassLoader for BeanValidator (i.e. the myfaces.jar lib)
                             theClass = Class.forName(clazz,false, BeanValidator.class.getClassLoader());
                         }
                         catch (ClassNotFoundException e)
                         {
                             throw new RuntimeException("Could not load validation group", e);
                         }                        
                     }
                     // the class was found
                     validationGroupsList.add(theClass);
                 }
             }
                     
             this.validationGroupsArray = validationGroupsList.toArray(new Class[validationGroupsList.size()]);
         }
     }
 
     /**
      * Get the Bean Validation validation groups.
      * @return The validation groups String.
      */
     @JSFProperty
     public String getValidationGroups(ValidateWholeBeanComponent component)
     {
         return component.getValidationGroups();
     }
 
     /**
      * Set the Bean Validation validation groups.
      * @param validationGroups The validation groups String, separated by
      *                         {@link BeanValidator#VALIDATION_GROUPS_DELIMITER}.
      */
     public void setValidationGroups(ValidateWholeBeanComponent component, final String validationGroups)
     {
         component.setValidationGroups(validationGroups);
     }
 
     /**
      * Note: Before 2.1.5/2.0.11 there was another strategy for this point to minimize
      * the instances used, but after checking this with a profiler, it is more expensive to
      * call FacesContext.getCurrentInstance() than create this object for bean validation.
      * 
      * Standard MessageInterpolator, as described in the JSR-314 spec.
      */
     private static class FacesMessageInterpolator implements MessageInterpolator
     {
         private final FacesContext facesContext;
         private final MessageInterpolator interpolator;
 
         public FacesMessageInterpolator(final MessageInterpolator interpolator, final FacesContext facesContext)
         {
             this.interpolator = interpolator;
             this.facesContext = facesContext;
         }
 
         public String interpolate(final String s, final MessageInterpolator.Context context)
         {
             Locale locale = facesContext.getViewRoot().getLocale();
             return interpolator.interpolate(s, context, locale);
         }
 
         public String interpolate(final String s, final MessageInterpolator.Context context, final Locale locale)
         {
             return interpolator.interpolate(s, context, locale);
         }
     }
 
     private static class UpdateBeanCopyCallback implements VisitCallback
     {
         private WholeBeanValidator validator;
         private Object wholeBeanBase;
         private Object wholeBeanBaseCopy;
         private Map<String, Object> candidateValuesMap;
 
         public UpdateBeanCopyCallback(WholeBeanValidator validator, Object wholeBeanBase, Object wholeBeanBaseCopy,
                 Map<String, Object> candidateValuesMap)
         {
             this.validator = validator;
             this.wholeBeanBase = wholeBeanBase;
             this.wholeBeanBaseCopy = wholeBeanBaseCopy;
             this.candidateValuesMap = candidateValuesMap;
         }
 
         @Override
         public VisitResult visit(VisitContext context, UIComponent target)
         {
             // The idea is follow almost the same algorithm used by Bean Validation. This 
             // algorithm calculates the base of the ValueExpression used by the component.
             // Then a simple equals() check will do the trick to decide when to call
             // setValue and affect the model. If the base is the same than the value returned by
             // f:validateWholeBean, you are affecting to same instance.
             
             ValueExpression valueExpression = target.getValueExpression("value");
             if (valueExpression == null)
             {
                 log.warning("cannot validate component with empty value: " 
                         + target.getClientId(context.getFacesContext()));
                 return VisitResult.ACCEPT;
             }
 
             // Obtain a reference to the to-be-validated object and the property name.
             ValueReference reference = validator.getValueReference(
                     valueExpression, context.getFacesContext());
             if (reference == null)
             {
                 return VisitResult.ACCEPT;
             }
             
             Object base = reference.getBase();
             if (base == null)
             {
                 return VisitResult.ACCEPT;
             }
 
             Object referenceProperty = reference.getProperty();
             if (!(referenceProperty instanceof String))
             {
                 // if the property is not a String, the ValueReference does not
                 // point to a bean method, but e.g. to a value in a Map, thus we 
                 // can exit bean validation here
                 return VisitResult.ACCEPT;
             }
                         
             // If the base of the EL expression is the same to the base of the one in f:validateWholeBean
             if (base == this.wholeBeanBase || base.equals(this.wholeBeanBase))
             {
                 // Do the trick over ELResolver and apply it to the copy.
                 ELContext elCtxDecorator = new _ELContextDecorator(context.getFacesContext().getELContext(),
                         new CopyBeanInterceptorELResolver(context.getFacesContext().getApplication().getELResolver(),
                             this.wholeBeanBase, this.wholeBeanBaseCopy));
                 
                 valueExpression.setValue(elCtxDecorator, candidateValuesMap.get(
                         target.getClientId(context.getFacesContext())));
             }
             
             return VisitResult.ACCEPT;
         }
     }
 }