/*
    * 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.commons.jxpath.ri.axes;
  
  import java.util.Iterator;
  
  import org.apache.commons.jxpath.ri.EvalContext;
  import org.apache.commons.jxpath.ri.InfoSetUtil;
  import org.apache.commons.jxpath.ri.compiler.Expression;
  import org.apache.commons.jxpath.ri.compiler.NameAttributeTest;
  import org.apache.commons.jxpath.ri.model.NodePointer;
  import org.apache.commons.jxpath.ri.model.beans.PropertyOwnerPointer;
  import org.apache.commons.jxpath.ri.model.beans.PropertyPointer;
  
  /**
   * EvalContext that checks predicates.
   */
  public class PredicateContext extends EvalContext {
  
      private final Expression expression;
      private boolean done;
      private Expression nameTestExpression;
      private PropertyPointer dynamicPropertyPointer;
  
      /**
       * Constructs a new PredicateContext.
       *
       * @param parentContext parent context
       * @param expression    compiled Expression
       */
      public PredicateContext(final EvalContext parentContext, final Expression expression) {
          super(parentContext);
          this.expression = expression;
          if (expression instanceof NameAttributeTest) {
              nameTestExpression = ((NameAttributeTest) expression).getNameTestExpression();
          }
      }
  
      @Override
      public NodePointer getCurrentNodePointer() {
          if (position == 0 && !setPosition(1)) {
              return null;
          }
          if (dynamicPropertyPointer != null) {
              return dynamicPropertyPointer.getValuePointer();
          }
          return parentContext.getCurrentNodePointer();
      }
  
      @Override
      public boolean nextNode() {
          if (done) {
              return false;
          }
          while (parentContext.nextNode()) {
              if (setupDynamicPropertyPointer()) {
                  final Object pred = nameTestExpression.computeValue(parentContext);
                  final String propertyName = InfoSetUtil.stringValue(pred);
                  // At this point it would be nice to say:
                  // dynamicPropertyPointer.setPropertyName(propertyName)
                  // and then: dynamicPropertyPointer.isActual().
                  // However some PropertyPointers, e.g. DynamicPropertyPointer
                  // will declare that any property you ask for is actual.
                  // That's not acceptable for us: we really need to know
                  // if the property is currently declared. Thus,
                  // we'll need to perform a search.
                  boolean ok = false;
                  final String[] names = dynamicPropertyPointer.getPropertyNames();
                  for (final String name : names) {
                      if (name.equals(propertyName)) {
                          ok = true;
                          break;
                      }
                  }
                  if (ok) {
                      dynamicPropertyPointer.setPropertyName(propertyName);
                      position++;
                      return true;
                  }
              } else {
                  Object pred = expression.computeValue(parentContext);
                  if (pred instanceof Iterator) {
                      if (!((Iterator) pred).hasNext()) {
                          return false;
                     }
                     pred = ((Iterator) pred).next();
                 }
                 if (pred instanceof NodePointer) {
                     pred = ((NodePointer) pred).getNode();
                 }
                 if (pred instanceof Number) {
                     final int pos = (int) InfoSetUtil.doubleValue(pred);
                     position++;
                     done = true;
                     return parentContext.setPosition(pos);
                 }
                 if (InfoSetUtil.booleanValue(pred)) {
                     position++;
                     return true;
                 }
             }
         }
         return false;
     }
 
     @Override
     public boolean nextSet() {
         reset();
         return parentContext.nextSet();
     }
 
     @Override
     public void reset() {
         super.reset();
         parentContext.reset();
         done = false;
     }
 
     @Override
     public boolean setPosition(final int position) {
         if (nameTestExpression == null) {
             return setPositionStandard(position);
         }
         if (dynamicPropertyPointer == null && !setupDynamicPropertyPointer()) {
             return setPositionStandard(position);
         }
         if (position < 1 || position > dynamicPropertyPointer.getLength()) {
             return false;
         }
         dynamicPropertyPointer.setIndex(position - 1);
         return true;
     }
 
     /**
      * Basic setPosition
      *
      * @param position to set
      * @return whether valid
      */
     private boolean setPositionStandard(final int position) {
         if (this.position > position) {
             reset();
         }
         while (this.position < position) {
             if (!nextNode()) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Used for an optimized access to dynamic properties using the "map[@name = 'name']" syntax
      *
      * @return whether valid
      */
     private boolean setupDynamicPropertyPointer() {
         if (nameTestExpression == null) {
             return false;
         }
         NodePointer parent = parentContext.getCurrentNodePointer();
         if (parent == null) {
             return false;
         }
         parent = parent.getValuePointer();
         if (!(parent instanceof PropertyOwnerPointer)) {
             return false;
         }
         dynamicPropertyPointer = (PropertyPointer) ((PropertyOwnerPointer) parent).getPropertyPointer().clone();
         return true;
     }
 }