/*
    * Copyright (c) 2006 JMockit developers
    * This file is subject to the terms of the MIT license (see LICENSE.txt).
    */
   package mockit.internal.state;
   
   import static java.lang.reflect.Modifier.isAbstract;
   
   import static mockit.internal.util.GeneratedClasses.getMockedClass;
  import static mockit.internal.util.GeneratedClasses.getMockedClassOrInterfaceType;
  import static mockit.internal.util.GeneratedClasses.isGeneratedImplementationClass;
  import static mockit.internal.util.Utilities.getClassType;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  
  import java.lang.instrument.ClassDefinition;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Type;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.IdentityHashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  
  import mockit.internal.ClassFile;
  import mockit.internal.ClassIdentification;
  import mockit.internal.capturing.CaptureTransformer;
  import mockit.internal.expectations.mocking.CaptureOfNewInstances;
  import mockit.internal.expectations.mocking.InstanceFactory;
  import mockit.internal.startup.Startup;
  import mockit.internal.util.ClassLoad;
  
  /**
   * Holds data about redefined/transformed classes, with methods to add/remove and query such data.
   */
  public final class MockFixture {
      /**
       * Similar to {@link #redefinedClasses}, but for classes modified by a <code>ClassFileTransformer</code> such as the
       * <code>CaptureTransformer</code>, and containing the pre-transform bytecode instead of the modified one.
       *
       * @see #addTransformedClass(ClassIdentification, byte[])
       * @see #getTransformedClasses()
       * @see #restoreTransformedClasses(Set)
       */
      @NonNull
      private final Map<ClassIdentification, byte[]> transformedClasses;
  
      /**
       * Real classes currently redefined in the running JVM and their current (modified) bytecodes.
       * <p>
       * The keys in the map allow each redefined real class to be later restored to a previous definition.
       * <p>
       * The modified bytecode arrays in the map allow a new redefinition to be made on top of the current redefinition
       * (in the case of the Faking API), or to restore the class to a previous definition (provided the map is copied
       * between redefinitions of the same class).
       *
       * @see #addRedefinedClass(ClassDefinition)
       * @see #getRedefinedClasses()
       * @see #getRedefinedClassfile(Class)
       * @see #containsRedefinedClass(Class)
       * @see #restoreRedefinedClasses(Map)
       */
      @NonNull
      private final Map<Class<?>, byte[]> redefinedClasses;
  
      /**
       * Subset of all currently redefined classes which contain one or more native methods.
       * <p/>
       * This is needed because in order to restore such methods it is necessary (for some classes) to re-register them
       * with the JVM.
       *
       * @see #reregisterNativeMethodsForRestoredClass(Class)
       */
      @NonNull
      private final Set<String> redefinedClassesWithNativeMethods;
  
      /**
       * Maps redefined real classes to the internal name of the corresponding fake classes, when it's the case.
       * <p>
       * This allows any global state associated to a fake class to be discarded when the corresponding real class is
       * later restored to its original definition.
       *
       * @see #addRedefinedClass(String, ClassDefinition)
       */
      @NonNull
      private final Map<Class<?>, String> realClassesToFakeClasses;
  
      /**
       * A list of classes that are currently mocked. Said classes are also added to {@link #mockedTypesAndInstances}.
       *
       * @see #registerMockedClass(Class)
      * @see #getMockedClasses()
      * @see #isStillMocked(Object, String)
      * @see #isInstanceOfMockedClass(Object)
      * @see #removeMockedClasses(List)
      */
     @NonNull
     private final List<Class<?>> mockedClasses;
 
     /**
      * A map of mocked types to their corresponding {@linkplain InstanceFactory mocked instance factories}.
      *
      * @see #registerInstanceFactoryForMockedType(Class, InstanceFactory)
      * @see #findInstanceFactory(Type)
      * @see #isStillMocked(Object, String)
      * @see #removeMockedClasses(List)
      */
     @NonNull
     private final Map<Type, InstanceFactory> mockedTypesAndInstances;
 
     /**
      * A list of "capturing" class file transformers, used by both the mocking and faking APIs.
      *
      * @see #addCaptureTransformer(CaptureTransformer)
      * @see #areCapturedClasses(Class, Class)
      * @see #isCaptured(Object)
      * @see #getCaptureTransformerCount()
      * @see #removeCaptureTransformers(int)
      */
     @NonNull
     private final List<CaptureTransformer<?>> captureTransformers;
 
     MockFixture() {
         transformedClasses = new HashMap<>(2);
         redefinedClasses = new ConcurrentHashMap<>(8);
         redefinedClassesWithNativeMethods = new HashSet<>();
         realClassesToFakeClasses = new IdentityHashMap<>(8);
         mockedClasses = new ArrayList<>();
         mockedTypesAndInstances = new IdentityHashMap<>();
         captureTransformers = new ArrayList<>();
     }
 
     // Methods to add/remove transformed/redefined classes /////////////////////////////////////////////////////////////
 
     public void addTransformedClass(@NonNull ClassIdentification classId, @NonNull byte[] pretransformClassfile) {
         transformedClasses.put(classId, pretransformClassfile);
     }
 
     // Methods used by both the Mocking and Faking APIs.
 
     public void addRedefinedClass(@NonNull ClassDefinition newClassDefinition) {
         redefinedClasses.put(newClassDefinition.getDefinitionClass(), newClassDefinition.getDefinitionClassFile());
     }
 
     public void registerMockedClass(@NonNull Class<?> mockedType) {
         if (!mockedClasses.contains(mockedType)) {
             mockedType = getMockedClassOrInterfaceType(mockedType);
             mockedClasses.add(mockedType);
         }
     }
 
     // Methods used by the Mocking API.
 
     public void redefineClasses(@NonNull ClassDefinition... definitions) {
         Startup.redefineMethods(definitions);
 
         for (ClassDefinition def : definitions) {
             addRedefinedClass(def);
         }
     }
 
     public void redefineMethods(@NonNull Map<Class<?>, byte[]> modifiedClassfiles) {
         ClassDefinition[] classDefs = new ClassDefinition[modifiedClassfiles.size()];
         int i = 0;
 
         for (Entry<Class<?>, byte[]> classAndBytecode : modifiedClassfiles.entrySet()) {
             Class<?> modifiedClass = classAndBytecode.getKey();
             byte[] modifiedClassfile = classAndBytecode.getValue();
 
             ClassDefinition classDef = new ClassDefinition(modifiedClass, modifiedClassfile);
             classDefs[i] = classDef;
             i++;
 
             addRedefinedClass(classDef);
         }
 
         Startup.redefineMethods(classDefs);
     }
 
     public boolean isStillMocked(@Nullable Object instance, @NonNull String classDesc) {
         Class<?> targetClass;
 
         if (instance == null) {
             targetClass = ClassLoad.loadByInternalName(classDesc);
             return isClassAssignableTo(targetClass);
         }
 
         targetClass = instance.getClass();
         return mockedTypesAndInstances.containsKey(targetClass) || isInstanceOfMockedClass(instance);
     }
 
     private boolean isClassAssignableTo(@NonNull Class<?> toClass) {
         for (Class<?> mockedClass : mockedClasses) {
             if (toClass == mockedClass || toClass.isAssignableFrom(mockedClass)) {
                 return true;
             }
         }
 
         return false;
     }
 
     public boolean isInstanceOfMockedClass(@NonNull Object mockedInstance) {
         Class<?> mockedClass = getMockedClassOrInterfaceType(mockedInstance.getClass());
         Class<?> mockedSuperclass = mockedClass.getSuperclass();
 
         if (mockedSuperclass != null && mockedSuperclass.isEnum()) {
             return mockedClasses.contains(mockedSuperclass);
         }
 
         return mockedClasses.contains(mockedClass) || isCaptured(mockedClass);
     }
 
     public void registerInstanceFactoryForMockedType(@NonNull Class<?> mockedType,
             @NonNull InstanceFactory mockedInstanceFactory) {
         registerMockedClass(mockedType);
         mockedTypesAndInstances.put(mockedType, mockedInstanceFactory);
     }
 
     @Nullable
     public InstanceFactory findInstanceFactory(@NonNull Type mockedType) {
         InstanceFactory instanceFactory = mockedTypesAndInstances.get(mockedType);
 
         if (instanceFactory != null) {
             return instanceFactory;
         }
 
         Class<?> mockedClass = getClassType(mockedType);
         // noinspection ReuseOfLocalVariable
         instanceFactory = mockedTypesAndInstances.get(mockedClass);
 
         if (instanceFactory != null) {
             return instanceFactory;
         }
 
         boolean abstractType = mockedClass.isInterface() || isAbstract(mockedClass.getModifiers());
 
         for (Entry<Type, InstanceFactory> entry : mockedTypesAndInstances.entrySet()) {
             Type registeredMockedType = entry.getKey();
             Class<?> registeredMockedClass = getClassType(registeredMockedType);
 
             if (abstractType) {
                 registeredMockedClass = getMockedClassOrInterfaceType(registeredMockedClass);
             }
 
             if (mockedClass.isAssignableFrom(registeredMockedClass)) {
                 instanceFactory = entry.getValue();
                 break;
             }
         }
 
         return instanceFactory;
     }
 
     // Methods used by the Faking API.
 
     public void addRedefinedClass(@NonNull String fakeClassInternalName, @NonNull ClassDefinition classDef) {
         @NonNull
         Class<?> redefinedClass = classDef.getDefinitionClass();
         String previousNames = realClassesToFakeClasses.put(redefinedClass, fakeClassInternalName);
 
         if (previousNames != null) {
             realClassesToFakeClasses.put(redefinedClass, previousNames + ' ' + fakeClassInternalName);
         }
 
         addRedefinedClass(classDef);
     }
 
     // Methods used by test save-points ////////////////////////////////////////////////////////////////////////////////
 
     void restoreTransformedClasses(@NonNull Set<ClassIdentification> previousTransformedClasses) {
         if (!transformedClasses.isEmpty()) {
             Set<ClassIdentification> classesToRestore;
 
             if (previousTransformedClasses.isEmpty()) {
                 classesToRestore = transformedClasses.keySet();
             } else {
                 classesToRestore = getTransformedClasses();
                 classesToRestore.removeAll(previousTransformedClasses);
             }
 
             if (!classesToRestore.isEmpty()) {
                 restoreAndRemoveTransformedClasses(classesToRestore);
             }
         }
     }
 
     @NonNull
     Set<ClassIdentification> getTransformedClasses() {
         return transformedClasses.isEmpty() ? Collections.emptySet() : new HashSet<>(transformedClasses.keySet());
     }
 
     @NonNull
     Map<Class<?>, byte[]> getRedefinedClasses() {
         return redefinedClasses.isEmpty() ? Collections.emptyMap() : new HashMap<>(redefinedClasses);
     }
 
     private void restoreAndRemoveTransformedClasses(@NonNull Set<ClassIdentification> classesToRestore) {
         for (ClassIdentification transformedClassId : classesToRestore) {
             byte[] definitionToRestore = transformedClasses.get(transformedClassId);
             Startup.redefineMethods(transformedClassId, definitionToRestore);
         }
 
         transformedClasses.keySet().removeAll(classesToRestore);
     }
 
     void restoreRedefinedClasses(@NonNull Map<?, byte[]> previousDefinitions) {
         if (redefinedClasses.isEmpty()) {
             return;
         }
 
         Iterator<Entry<Class<?>, byte[]>> itr = redefinedClasses.entrySet().iterator();
 
         while (itr.hasNext()) {
             Entry<Class<?>, byte[]> entry = itr.next();
             Class<?> redefinedClass = entry.getKey();
             byte[] currentDefinition = entry.getValue();
             byte[] previousDefinition = previousDefinitions.get(redefinedClass);
 
             if (previousDefinition == null) {
                 restoreDefinition(redefinedClass);
                 itr.remove();
             } else if (currentDefinition != previousDefinition) {
                 Startup.redefineMethods(redefinedClass, previousDefinition);
                 entry.setValue(previousDefinition);
             }
         }
     }
 
     private void restoreDefinition(@NonNull Class<?> redefinedClass) {
         if (!isGeneratedImplementationClass(redefinedClass)) {
             byte[] previousDefinition = ClassFile.getClassFile(redefinedClass);
             Startup.redefineMethods(redefinedClass, previousDefinition);
         }
         if (redefinedClassesWithNativeMethods.contains(redefinedClass.getName())) {
             reregisterNativeMethodsForRestoredClass(redefinedClass);
         }
 
         removeMockedClass(redefinedClass);
         discardStateForCorrespondingFakeClassIfAny(redefinedClass);
     }
 
     private void removeMockedClass(@NonNull Class<?> mockedClass) {
         mockedTypesAndInstances.remove(mockedClass);
         mockedClasses.remove(mockedClass);
     }
 
     private void discardStateForCorrespondingFakeClassIfAny(@NonNull Class<?> redefinedClass) {
         String mockClassesInternalNames = realClassesToFakeClasses.remove(redefinedClass);
         TestRun.getFakeStates().removeClassState(redefinedClass, mockClassesInternalNames);
     }
 
     void removeMockedClasses(@NonNull List<Class<?>> previousMockedClasses) {
         int currentMockedClassCount = mockedClasses.size();
 
         if (currentMockedClassCount > 0) {
             int previousMockedClassCount = previousMockedClasses.size();
 
             if (previousMockedClassCount == 0) {
                 mockedClasses.clear();
                 mockedTypesAndInstances.clear();
             } else if (previousMockedClassCount < currentMockedClassCount) {
                 mockedClasses.retainAll(previousMockedClasses);
                 mockedTypesAndInstances.keySet().retainAll(previousMockedClasses);
             }
         }
     }
 
     // Getter methods for the maps and collections of transformed/redefined/mocked classes /////////////////////////////
 
     @Nullable
     public byte[] getRedefinedClassfile(@NonNull Class<?> redefinedClass) {
         return redefinedClasses.get(redefinedClass);
     }
 
     public boolean containsRedefinedClass(@NonNull Class<?> redefinedClass) {
         return redefinedClasses.containsKey(redefinedClass);
     }
 
     @NonNull
     public List<Class<?>> getMockedClasses() {
         return mockedClasses.isEmpty() ? Collections.emptyList() : new ArrayList<>(mockedClasses);
     }
 
     // Methods dealing with capture transformers ///////////////////////////////////////////////////////////////////////
 
     public void addCaptureTransformer(@NonNull CaptureTransformer<?> transformer) {
         captureTransformers.add(transformer);
     }
 
     // The following methods are used by test save-points to discard currently active capture transformers.
 
     int getCaptureTransformerCount() {
         return captureTransformers.size();
     }
 
     void removeCaptureTransformers(int previousTransformerCount) {
         int currentTransformerCount = captureTransformers.size();
 
         for (int i = currentTransformerCount - 1; i >= previousTransformerCount; i--) {
             CaptureTransformer<?> transformer = captureTransformers.get(i);
             transformer.deactivate();
             Startup.instrumentation().removeTransformer(transformer);
             captureTransformers.remove(i);
         }
     }
 
     // The following methods are only used by the Mocking API.
 
     public boolean isCaptured(@NonNull Object mockedInstance) {
         if (!captureTransformers.isEmpty()) {
             Class<?> mockedClass = getMockedClass(mockedInstance);
             return isCaptured(mockedClass);
         }
 
         return false;
     }
 
     private boolean isCaptured(@NonNull Class<?> mockedClass) {
         for (CaptureTransformer<?> captureTransformer : captureTransformers) {
             CaptureOfNewInstances capture = captureTransformer.getCaptureOfImplementationsIfApplicable(mockedClass);
 
             if (capture != null) {
                 return true;
             }
         }
 
         return false;
     }
 
     public boolean areCapturedClasses(@NonNull Class<?> mockedClass1, @NonNull Class<?> mockedClass2) {
         for (CaptureTransformer<?> captureTransformer : captureTransformers) {
             if (captureTransformer.areCapturedClasses(mockedClass1, mockedClass2)) {
                 return true;
             }
         }
 
         return false;
     }
 
     private static void reregisterNativeMethodsForRestoredClass(@NonNull Class<?> realClass) {
         Method registerNatives = null;
 
         try {
             registerNatives = realClass.getDeclaredMethod("registerNatives");
         } catch (NoSuchMethodException ignore) {
             try {
                 registerNatives = realClass.getDeclaredMethod("initIDs");
             } catch (NoSuchMethodException ignored) {
             } // OK
         }
 
         if (registerNatives != null) {
             try {
                 registerNatives.setAccessible(true);
                 registerNatives.invoke(null);
             } catch (IllegalAccessException ignore) {
             } // won't happen
             catch (InvocationTargetException ignore) {
             } // shouldn't happen either
         }
 
         // OK, although another solution will be required for this particular class if it requires
         // natives to be explicitly registered again (not all do, such as java.lang.Float).
     }
 
     public void addRedefinedClassWithNativeMethods(@NonNull String redefinedClassInternalName) {
         redefinedClassesWithNativeMethods.add(redefinedClassInternalName.replace('/', '.'));
     }
 }