/*
    * Copyright 2002-2013 the original author or authors.
    *
    * Licensed 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.springframework.aop.aspectj;
  
  import java.lang.reflect.Field;
  
  import org.aspectj.weaver.ReferenceType;
  import org.aspectj.weaver.ReferenceTypeDelegate;
  import org.aspectj.weaver.ResolvedType;
  import org.aspectj.weaver.ast.And;
  import org.aspectj.weaver.ast.Call;
  import org.aspectj.weaver.ast.FieldGetCall;
  import org.aspectj.weaver.ast.HasAnnotation;
  import org.aspectj.weaver.ast.ITestVisitor;
  import org.aspectj.weaver.ast.Instanceof;
  import org.aspectj.weaver.ast.Literal;
  import org.aspectj.weaver.ast.Not;
  import org.aspectj.weaver.ast.Or;
  import org.aspectj.weaver.ast.Test;
  import org.aspectj.weaver.internal.tools.MatchingContextBasedTest;
  import org.aspectj.weaver.reflect.ReflectionBasedReferenceTypeDelegate;
  import org.aspectj.weaver.reflect.ReflectionVar;
  import org.aspectj.weaver.reflect.ShadowMatchImpl;
  import org.aspectj.weaver.tools.ShadowMatch;
  
  import org.springframework.util.ClassUtils;
  import org.springframework.util.ReflectionUtils;
  
  /**
   * This class encapsulates some AspectJ internal knowledge that should be
   * pushed back into the AspectJ project in a future release.
   *
   * <p>It relies on implementation specific knowledge in AspectJ to break
   * encapsulation and do something AspectJ was not designed to do: query
   * the types of runtime tests that will be performed. The code here should
   * migrate to {@code ShadowMatch.getVariablesInvolvedInRuntimeTest()}
   * or some similar operation.
   *
   * <p>See <a href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=151593"/>Bug 151593</a>
   *
   * @author Adrian Colyer
   * @author Ramnivas Laddad
   * @since 2.0
   */
  class RuntimeTestWalker {
  
  	private static final Field residualTestField;
  
  	private static final Field varTypeField;
  
  	private static final Field myClassField;
  
  
  	static {
  		try {
  			residualTestField = ShadowMatchImpl.class.getDeclaredField("residualTest");
  			varTypeField = ReflectionVar.class.getDeclaredField("varType");
  			myClassField = ReflectionBasedReferenceTypeDelegate.class.getDeclaredField("myClass");
  		}
  		catch (NoSuchFieldException ex) {
  			throw new IllegalStateException("The version of aspectjtools.jar / aspectjweaver.jar " +
  					"on the classpath is incompatible with this version of Spring: " + ex);
  		}
  	}
  
  
  	private final Test runtimeTest;
  
  
  	public RuntimeTestWalker(ShadowMatch shadowMatch) {
  		try {
  			ReflectionUtils.makeAccessible(residualTestField);
  			this.runtimeTest = (Test) residualTestField.get(shadowMatch);
  		}
  		catch (IllegalAccessException ex) {
  			throw new IllegalStateException(ex);
  		}
  	}
  
  
  	/**
  	 * If the test uses any of the this, target, at_this, at_target, and at_annotation vars,
  	 * then it tests subtype sensitive vars.
  	 */
  	public boolean testsSubtypeSensitiveVars() {
 		return (this.runtimeTest != null &&
 				new SubtypeSensitiveVarTypeTestVisitor().testsSubtypeSensitiveVars(this.runtimeTest));
 	}
 
 	public boolean testThisInstanceOfResidue(Class<?> thisClass) {
 		return (this.runtimeTest != null &&
 				new ThisInstanceOfResidueTestVisitor(thisClass).thisInstanceOfMatches(this.runtimeTest));
 	}
 
 	public boolean testTargetInstanceOfResidue(Class<?> targetClass) {
 		return (this.runtimeTest != null &&
 				new TargetInstanceOfResidueTestVisitor(targetClass).targetInstanceOfMatches(this.runtimeTest));
 	}
 
 
 	private static class TestVisitorAdapter implements ITestVisitor {
 
 		protected static final int THIS_VAR = 0;
 		protected static final int TARGET_VAR = 1;
 		protected static final int AT_THIS_VAR = 3;
 		protected static final int AT_TARGET_VAR = 4;
 		protected static final int AT_ANNOTATION_VAR = 8;
 
 		@Override
 		public void visit(And e) {
 			e.getLeft().accept(this);
 			e.getRight().accept(this);
 		}
 
 		@Override
 		public void visit(Or e) {
 			e.getLeft().accept(this);
 			e.getRight().accept(this);
 		}
 
 		@Override
 		public void visit(Not e) {
 			e.getBody().accept(this);
 		}
 
 		@Override
 		public void visit(Instanceof i) {
 		}
 
 		@Override
 		public void visit(Literal literal) {
 		}
 
 		@Override
 		public void visit(Call call) {
 		}
 
 		@Override
 		public void visit(FieldGetCall fieldGetCall) {
 		}
 
 		@Override
 		public void visit(HasAnnotation hasAnnotation) {
 		}
 
 		@Override
 		public void visit(MatchingContextBasedTest matchingContextTest) {
 		}
 
 		protected int getVarType(ReflectionVar v) {
 			try {
 				ReflectionUtils.makeAccessible(varTypeField);
 				return (Integer) varTypeField.get(v);
 			}
 			catch (IllegalAccessException ex) {
 				throw new IllegalStateException(ex);
 			}
 		}
 	}
 
 
 	private static abstract class InstanceOfResidueTestVisitor extends TestVisitorAdapter {
 
 		private final Class<?> matchClass;
 
 		private boolean matches;
 
 		private final int matchVarType;
 
 		public InstanceOfResidueTestVisitor(Class<?> matchClass, boolean defaultMatches, int matchVarType) {
 			this.matchClass = matchClass;
 			this.matches = defaultMatches;
 			this.matchVarType = matchVarType;
 		}
 
 		public boolean instanceOfMatches(Test test) {
 			test.accept(this);
 			return this.matches;
 		}
 
 		@Override
 		public void visit(Instanceof i) {
 			int varType = getVarType((ReflectionVar) i.getVar());
 			if (varType != this.matchVarType) {
 				return;
 			}
 			Class<?> typeClass = null;
 			ResolvedType type = (ResolvedType) i.getType();
 			if (type instanceof ReferenceType) {
 				ReferenceTypeDelegate delegate = ((ReferenceType) type).getDelegate();
 				if (delegate instanceof ReflectionBasedReferenceTypeDelegate) {
 					try {
 						ReflectionUtils.makeAccessible(myClassField);
 						typeClass = (Class<?>) myClassField.get(delegate);
 					}
 					catch (IllegalAccessException ex) {
 						throw new IllegalStateException(ex);
 					}
 				}
 			}
 			try {
 				// Don't use ResolvedType.isAssignableFrom() as it won't be aware of (Spring) mixins
 				if (typeClass == null) {
 					typeClass = ClassUtils.forName(type.getName(), this.matchClass.getClassLoader());
 				}
 				this.matches = typeClass.isAssignableFrom(this.matchClass);
 			}
 			catch (ClassNotFoundException ex) {
 				this.matches = false;
 			}
 		}
 	}
 
 
 	/**
 	 * Check if residue of target(TYPE) kind. See SPR-3783 for more details.
 	 */
 	private static class TargetInstanceOfResidueTestVisitor extends InstanceOfResidueTestVisitor {
 
 		public TargetInstanceOfResidueTestVisitor(Class<?> targetClass) {
 			super(targetClass, false, TARGET_VAR);
 		}
 
 		public boolean targetInstanceOfMatches(Test test) {
 			return instanceOfMatches(test);
 		}
 	}
 
 
 	/**
 	 * Check if residue of this(TYPE) kind. See SPR-2979 for more details.
 	 */
 	private static class ThisInstanceOfResidueTestVisitor extends InstanceOfResidueTestVisitor {
 
 		public ThisInstanceOfResidueTestVisitor(Class<?> thisClass) {
 			super(thisClass, true, THIS_VAR);
 		}
 
 		// TODO: Optimization: Process only if this() specifies a type and not an identifier.
 		public boolean thisInstanceOfMatches(Test test) {
 			return instanceOfMatches(test);
 		}
 	}
 
 
 	private static class SubtypeSensitiveVarTypeTestVisitor extends TestVisitorAdapter {
 
 		private final Object thisObj = new Object();
 
 		private final Object targetObj = new Object();
 
 		private final Object[] argsObjs = new Object[0];
 
 		private boolean testsSubtypeSensitiveVars = false;
 
 		public boolean testsSubtypeSensitiveVars(Test aTest) {
 			aTest.accept(this);
 			return this.testsSubtypeSensitiveVars;
 		}
 
 		@Override
 		public void visit(Instanceof i) {
 			ReflectionVar v = (ReflectionVar) i.getVar();
 			Object varUnderTest = v.getBindingAtJoinPoint(this.thisObj, this.targetObj, this.argsObjs);
 			if (varUnderTest == this.thisObj || varUnderTest == this.targetObj) {
 				this.testsSubtypeSensitiveVars = true;
 			}
 		}
 
 		@Override
 		public void visit(HasAnnotation hasAnn) {
 			// If you thought things were bad before, now we sink to new levels of horror...
 			ReflectionVar v = (ReflectionVar) hasAnn.getVar();
 			int varType = getVarType(v);
 			if (varType == AT_THIS_VAR || varType == AT_TARGET_VAR || varType == AT_ANNOTATION_VAR) {
 				this.testsSubtypeSensitiveVars = true;
 			}
 		}
 	}
 
 }