/*
    * 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.jexl3.parser;
  
  import org.apache.commons.jexl3.JexlArithmetic;
  import org.apache.commons.jexl3.JexlCache;
  import org.apache.commons.jexl3.JexlContext.NamespaceFunctor;
  import org.apache.commons.jexl3.JexlInfo;
  import org.apache.commons.jexl3.JxltEngine;
  import org.apache.commons.jexl3.introspection.JexlMethod;
  import org.apache.commons.jexl3.introspection.JexlPropertyGet;
  import org.apache.commons.jexl3.introspection.JexlPropertySet;
  
  /**
   * Base class for parser nodes - holds an 'image' of the token for later use.
   *
   * @since 2.0
   */
  public abstract class JexlNode extends SimpleNode implements JexlCache.Reference {
      /**
       * A marker interface for constants.
       * @param <T> the literal type
       */
      public interface Constant<T> {
          T getLiteral();
      }
      /**
       * Marker interface for cachable function calls.
       */
      public interface Funcall {}
  
      /**
       * Marker interface for nodes hosting a JxltExpression.
       */
      public interface JxltHandle {
          /** @return the expression source. */
          String getExpressionSource();
  
          /**@return the expression instance, should be a TemplateEngine.TemplateExpression. */
          JxltEngine.Expression getExpression();
  
          /**
           * Sets the template expression.
           * @param expr a TemplateEngine.TemplateExpression instance
           */
          void setExpression(JxltEngine.Expression expr);
      }
  
      @Override
      public Object getCache() {
          return jjtGetValue();
      }
  
      @Override
      public void setCache(Object cache) {
          jjtSetValue(cache);
      }
  
      /**
       * An info bound to its node.
       * <p>Used to parse expressions for templates.
       */
      public static class Info extends JexlInfo {
          JexlNode node;
  
          /**
           * Default ctor.
           * @param jnode the node
           */
          public Info(final JexlNode jnode) {
              this(jnode, jnode.jexlInfo());
          }
  
          /**
           * Copy ctor.
           * @param jnode the node
           * @param info the
           */
          public Info(final JexlNode jnode, final JexlInfo info) {
              this(jnode, info.getName(), info.getLine(), info.getColumn());
          }
  
          /**
           * Full detail ctor.
           * @param jnode the node
          * @param name the file name
          * @param l the line
          * @param c the column
          */
         private Info(final JexlNode jnode, final String name, final int l, final int c) {
             super(name, l, c);
             node = jnode;
         }
 
         @Override
         public JexlInfo at(final int l, final int c) {
             return new Info(node, getName(), l, c);
         }
 
         @Override
         public JexlInfo detach() {
             node = null;
             return this;
         }
 
         /**
          * @return the node this info is bound to
          */
         public JexlNode getNode() {
             return node;
         }
     }
 
     /**
      */
     private static final long serialVersionUID = 1L;
 
     // line + column encoded: up to 4096 columns (ie 20 bits for line + 12 bits for column)
     private int lc = -1;
 
     public JexlNode(final int id) {
         super(id);
     }
 
     /**
      * Constructs a new instance.
      *
      * @param p not used.
      * @param id the node type identifier
      * @deprecated Use {@link #JexlNode(int)}.
      */
     @Deprecated
     public JexlNode(final Parser p, final int id) {
         super(p, id);
     }
 
     /**
      * Clears any cached value of type JexlProperty{G,S}et or JexlMethod.
      * <p>
      * This is called when the engine detects the evaluation of a script occurs with a class loader
      * different that the one that created it.</p>
      */
     public void clearCache() {
         final Object value = jjtGetValue();
         if (value instanceof JexlPropertyGet
             || value instanceof JexlPropertySet
             || value instanceof JexlMethod
             || value instanceof Funcall
             || value instanceof Class
             || value instanceof NamespaceFunctor) {
             jjtSetValue(null);
         }
         for (int n = 0; n < jjtGetNumChildren(); ++n) {
             jjtGetChild(n).clearCache();
         }
     }
 
     public int getColumn() {
         return this.lc & 0xfff;
     }
 
     public int getLine() {
         return this.lc >>> 0xc;
     }
 
     /**
      * Tests whether this node is a constant node.
      * <p>Its value cannot change after the first evaluation and can be cached
      * indefinitely.</p>
      *
      * @return true if constant, false otherwise
      */
     public boolean isConstant() {
         return isConstant(this instanceof JexlNode.Constant<?>);
     }
 
     protected boolean isConstant(final boolean literal) {
         if (literal) {
             for (int n = 0; n < jjtGetNumChildren(); ++n) {
                 final JexlNode child = jjtGetChild(n);
                 if (child instanceof ASTReference || child instanceof ASTMapEntry) {
                     final boolean is = child.isConstant(true);
                     if (!is) {
                         return false;
                     }
                 } else if (!child.isConstant()) {
                     return false;
                 }
             }
             return true;
         }
         return false;
     }
 
     /**
      * @return true if this node looks like a global var
      */
     public boolean isGlobalVar() {
         if (this instanceof ASTVar) {
             return false;
         }
         if (this instanceof ASTIdentifier) {
             return ((ASTIdentifier) this).getSymbol() < 0;
         }
         final int nc = jjtGetNumChildren() - 1;
         if (nc >= 0) {
             final JexlNode first = jjtGetChild(0);
             return first.isGlobalVar();
         }
         if (jjtGetParent() instanceof ASTReference) {
             return true;
         }
         return false;
     }
 
     /**
      * Tests whether this node is a left value.
      * @return true if node is assignable, false otherwise
      */
     public boolean isLeftValue() {
         JexlNode walk = this;
         do {
             if (walk instanceof ASTIdentifier
                 || walk instanceof ASTIdentifierAccess
                 || walk instanceof ASTArrayAccess) {
                 return true;
             }
             final int nc = walk.jjtGetNumChildren() - 1;
             if (nc < 0) {
                 return walk.jjtGetParent() instanceof ASTReference;
             }
             walk = walk.jjtGetChild(nc);
         } while (walk != null);
         return false;
     }
 
     /**
      * Tests whether this node is the left-hand side of a safe access identifier as in.
      * For instance, in 'x?.y' , 'x' is safe.
      * @param safe whether the engine is in safe-navigation mode
      * @return true if safe lhs, false otherwise
      */
     public boolean isSafeLhs(final boolean safe) {
         if (this instanceof ASTReference) {
             return jjtGetChild(0).isSafeLhs(safe);
         }
         if (this instanceof ASTMethodNode) {
             if (jjtGetNumChildren() > 1
                     && jjtGetChild(0) instanceof ASTIdentifierAccess
                     && (((ASTIdentifierAccess) jjtGetChild(0)).isSafe() || safe)) {
                 return true;
             }
         }
         final JexlNode parent = jjtGetParent();
         if (parent == null) {
             return false;
         }
         // find this node in its parent
         final int nsiblings = parent.jjtGetNumChildren();
         int rhs = -1;
         for(int s = 0; s < nsiblings; ++s) {
             final JexlNode sibling = parent.jjtGetChild(s);
             if (sibling == this) {
                 // the next chid offset of this nodes parent
                 rhs = s + 1;
                 break;
             }
         }
         // seek next child in parent
         if (rhs >= 0 && rhs < nsiblings) {
             JexlNode rsibling = parent.jjtGetChild(rhs);
             if (rsibling instanceof ASTMethodNode || rsibling instanceof ASTFunctionNode) {
                 rsibling = rsibling.jjtGetChild(0);
             }
             if (rsibling instanceof ASTIdentifierAccess
                 && (((ASTIdentifierAccess) rsibling).isSafe() || safe)) {
                 return true;
             }
             if (rsibling instanceof ASTArrayAccess) {
                 return safe;
             }
         }
         return false;
     }
 
     /**
      * Checks whether this node is an operator that accepts a null argument
      * even when arithmetic is in strict mode.
      * The default cases are equals and not equals.
      *
      * @param arithmetic the node to test
      * @return true if node accepts null arguments, false otherwise
      */
     public boolean isStrictOperator(final JexlArithmetic arithmetic) {
         return OperatorController.INSTANCE.isStrict(arithmetic, this);
     }
 
     /**
      * Gets the associated JexlInfo instance.
      *
      * @return the info
      */
     public JexlInfo jexlInfo() {
         return jexlInfo(null);
     }
 
     /**
      * Gets the associated JexlInfo instance.
      *
      * @param name the source name
      * @return the info
      */
     public JexlInfo jexlInfo(String name) {
         JexlInfo info = null;
         JexlNode node = this;
         while (node != null) {
             if (node.jjtGetValue() instanceof JexlInfo) {
                 info = (JexlInfo) node.jjtGetValue();
                 break;
             }
             node = node.jjtGetParent();
         }
         if (lc >= 0) {
             final int c = lc & 0xfff;
             final int l = lc >> 0xc;
             // at least an info with line/column number
             return info != null ? info.at(info.getLine() + l - 1, c) : new JexlInfo(name, l, c);
         }
         // weird though; no jjSetFirstToken(...) ever called?
         return info;
     }
 
     public void jjtSetFirstToken(final Token t) {
         // 0xc = 12, 12 bits -> 4096
         // 0xfff, 12 bits mask
         this.lc = t.beginLine << 0xc | 0xfff & t.beginColumn;
     }
 
     public void jjtSetLastToken(final Token t) {
         // nothing
     }
 
 }