/*
    * 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
    *
    *      https://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.internal.introspection;
  
  import java.util.Iterator;
  import java.util.List;
  import java.util.Objects;
  
  import org.apache.commons.jexl3.JexlArithmetic;
  import org.apache.commons.jexl3.JexlOperator;
  import org.apache.commons.jexl3.introspection.JexlMethod;
  import org.apache.commons.jexl3.introspection.JexlPropertyGet;
  import org.apache.commons.jexl3.introspection.JexlPropertySet;
  import org.apache.commons.jexl3.introspection.JexlSandbox;
  import org.apache.commons.jexl3.introspection.JexlUberspect;
  
  /**
   * An uberspect that controls usage of properties, methods and constructors through a sandbox.
   *
   * @since 3.0
   */
  public final class SandboxUberspect implements JexlUberspect {
  
      /**
       * Identity equality.
       * <p>Spotbugs just <em>hates</em> string identity...</p>
       *
       * @param lhs left hand side
       * @param rhs right hand side
       * @return true if left is identical to right
       */
      private static boolean eq(final Object lhs, final Object rhs) {
          return lhs == rhs;
      }
  
      /** The base uberspect. */
      private final JexlUberspect uberspect;
  
      /**  The sandbox. */
      private final JexlSandbox sandbox;
  
      /**
       * A constructor for JexlSandbox uberspect.
       *
       * @param theUberspect The JexlUberspect to sandbox
       * @param theSandbox The sandbox which is copied to avoid changes at runtime
       */
      public SandboxUberspect(final JexlUberspect theUberspect, final JexlSandbox theSandbox) {
          Objects.requireNonNull(theSandbox, "theSandbox");
          Objects.requireNonNull(theUberspect, "theUberspect");
          this.uberspect = theUberspect;
          this.sandbox = theSandbox.copy();
      }
  
      @Override
      public JexlArithmetic.Uberspect getArithmetic(final JexlArithmetic arithmetic) {
          return uberspect.getArithmetic(arithmetic);
      }
  
      @Override
      public Class<?> getClassByName(final String className) {
          return uberspect.getClassByName(className);
      }
  
      @Override
      public ClassLoader getClassLoader() {
          return uberspect.getClassLoader();
      }
  
      @Override
      public JexlMethod getConstructor(final Object ctorHandle, final Object... args) {
          final String className;
          if (ctorHandle instanceof Class<?>) {
              className = sandbox.execute((Class<?>) ctorHandle, "");
          } else if (ctorHandle != null) {
              className = sandbox.execute(ctorHandle.toString(), "");
          } else {
              className = null;
          }
          return className != null && className != JexlSandbox.NULL ? uberspect.getConstructor(className, args) : null;
      }
  
      @Override
      public Iterator<?> getIterator(final Object obj) {
          if (obj != null) {
             // route iteration through the sandbox: consult the "iterator" method permission for the
             // object's class so an explicitly restricted class cannot be iterated over (f006).
             final Class<?> clazz = obj instanceof Class<?> ? (Class<?>) obj : obj.getClass();
             final String actual = sandbox.execute(clazz, "iterator");
             if (actual != null && actual != JexlSandbox.NULL) {
                 return uberspect.getIterator(obj);
             }
         }
         return null;
     }
 
     @Override
     public JexlMethod getMethod(final Object obj, final String method, final Object... args) {
         if (obj != null && method != null) {
             final Class<?> clazz = obj instanceof Class ? (Class<?>) obj : obj.getClass();
             final String actual = sandbox.execute(clazz, method);
             if (actual != null && actual != JexlSandbox.NULL) {
                 return uberspect.getMethod(obj, actual, args);
             }
         }
         return null;
     }
 
     @Override
     public JexlPropertyGet getPropertyGet(final List<PropertyResolver> resolvers,
                                           final Object obj,
                                           final Object identifier) {
         if (obj != null) {
             final Class<?> clazz = obj instanceof Class<?>? (Class<?>) obj : obj.getClass();
             if (identifier != null) {
                 final String property = identifier.toString();
                 final String actual = sandbox.read(clazz, property);
                 if (actual != null) {
                     // no transformation, strict equality: use identifier before string conversion
                     final Object pty = eq(actual, property) ? identifier : actual;
                     return uberspect.getPropertyGet(resolvers, obj, pty);
                 }
             } else {
                 final String actual = sandbox.read(clazz, null);
                 if (actual != JexlSandbox.NULL) {
                      return uberspect.getPropertyGet(resolvers, obj, null);
                 }
             }
         }
         return null;
     }
 
     @Override
     public JexlPropertyGet getPropertyGet(final Object obj, final Object identifier) {
         return getPropertyGet(null, obj, identifier);
     }
 
     @Override
     public JexlPropertySet getPropertySet(final List<PropertyResolver> resolvers,
                                           final Object obj,
                                           final Object identifier,
                                           final Object arg) {
         if (obj != null) {
             final Class<?> clazz = obj instanceof Class<?>? (Class<?>) obj : obj.getClass();
             if (identifier != null) {
                 final String property = identifier.toString();
                 final String actual = sandbox.write(clazz, property);
                 if (actual != null) {
                     // no transformation, strict equality: use identifier before string conversion
                     final Object pty = eq(actual, property) ? identifier : actual;
                     return uberspect.getPropertySet(resolvers, obj, pty, arg);
                 }
             } else {
                 final String actual = sandbox.write(clazz, null);
                 if (actual != JexlSandbox.NULL) {
                     return uberspect.getPropertySet(resolvers, obj, null, arg);
                 }
             }
         }
         return null;
     }
 
     @Override
     public JexlPropertySet getPropertySet(final Object obj,final Object identifier,final Object arg) {
         return getPropertySet(null, obj, identifier, arg);
     }
 
     @Override
     public List<PropertyResolver> getResolvers(final JexlOperator op, final Object obj) {
         return uberspect.getResolvers(op, obj);
     }
 
     @Override
     public int getVersion() {
         return uberspect.getVersion();
     }
 
     @Override
     public void setClassLoader(final ClassLoader loader) {
         uberspect.setClassLoader(loader);
     }
 }