/*

 * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.jdi;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import com.sun.jdi.ClassNotLoadedException;

import com.sun.jdi.ClassType;

import com.sun.jdi.Field;

import com.sun.jdi.IncompatibleThreadStateException;

import com.sun.jdi.InterfaceType;

import com.sun.jdi.InternalException;

import com.sun.jdi.InvalidTypeException;

import com.sun.jdi.InvocationException;

import com.sun.jdi.Method;

import com.sun.jdi.ObjectReference;

import com.sun.jdi.ReferenceType;

import com.sun.jdi.ThreadReference;

import com.sun.jdi.Type;

import com.sun.jdi.Value;

import com.sun.jdi.VirtualMachine;

public class ObjectReferenceImpl extends ValueImpl

             implements ObjectReference, VMListener

{

    protected long ref;

    private ReferenceType type = null;

    private int gcDisableCount = 0;

    boolean addedListener = false;

    // This is cached only while the VM is suspended

    protected static class Cache {

        JDWP.ObjectReference.MonitorInfo monitorInfo = null;

    }

    private static final Cache noInitCache = new Cache();

    private static final Cache markerCache = new Cache();

    private Cache cache = noInitCache;

    private void disableCache() {

        synchronized (vm.state()) {

            cache = null;

        }

    }

    private void enableCache() {

        synchronized (vm.state()) {

            cache = markerCache;

        }

    }

    // Override in subclasses

    protected Cache newCache() {

        return new Cache();

    }

    protected Cache getCache() {

        synchronized (vm.state()) {

            if (cache == noInitCache) {

                if (vm.state().isSuspended()) {

                    // Set cache now, otherwise newly created objects are

                    // not cached until resuspend

                    enableCache();

                } else {

                    disableCache();

                }

            }

            if (cache == markerCache) {

                cache = newCache();

            }

            return cache;

        }

    }

    // Return the ClassTypeImpl upon which to invoke a method.

    // By default it is our very own referenceType() but subclasses

    // can override.

    protected ClassTypeImpl invokableReferenceType(Method method) {

        return (ClassTypeImpl)referenceType();

    }

    ObjectReferenceImpl(VirtualMachine aVm,long aRef) {

        super(aVm);

        ref = aRef;

    }

    protected String description() {

        return "ObjectReference " + uniqueID();

    }

    /*

     * VMListener implementation

     */

    public boolean vmSuspended(VMAction action) {

        enableCache();

        return true;

    }

    public boolean vmNotSuspended(VMAction action) {

        // make sure that cache and listener management are synchronized

        synchronized (vm.state()) {

            if (cache != null && (vm.traceFlags & VirtualMachine.TRACE_OBJREFS) != 0) {

                vm.printTrace("Clearing temporary cache for " + description());

            }

            disableCache();

            if (addedListener) {

                /*

                 * If a listener was added (i.e. this is not a

                 * ObjectReference that adds a listener on startup),

                 * remove it here.

                 */

                addedListener = false;

                return false;  // false says remove

            } else {

                return true;

            }

        }

    }

    public boolean equals(Object obj) {

        if ((obj != null) && (obj instanceof ObjectReferenceImpl)) {

            ObjectReferenceImpl other = (ObjectReferenceImpl)obj;

            return (ref() == other.ref()) &&

                   super.equals(obj);

        } else {

            return false;

        }

    }

    public int hashCode() {

        return(int)ref();

    }

    public Type type() {

        return referenceType();

    }

    public ReferenceType referenceType() {

        if (type == null) {

            try {

                JDWP.ObjectReference.ReferenceType rtinfo =

                    JDWP.ObjectReference.ReferenceType.process(vm, this);

                type = vm.referenceType(rtinfo.typeID,

                                        rtinfo.refTypeTag);

            } catch (JDWPException exc) {

                throw exc.toJDIException();

            }

        }

        return type;

    }

    public Value getValue(Field sig) {

        List<Field> list = new ArrayList<>(1);

        list.add(sig);

        Map<Field, Value> map = getValues(list);

        return map.get(sig);

    }

    public Map<Field,Value> getValues(List<? extends Field> theFields) {

        validateMirrors(theFields);

        List<Field> staticFields = new ArrayList<>(0);

        int size = theFields.size();

        List<Field> instanceFields = new ArrayList<>(size);

        for (int i = 0; i < size; i++) {

            Field field = theFields.get(i);

            // Make sure the field is valid

            ((ReferenceTypeImpl)referenceType()).validateFieldAccess(field);

            // FIX ME! We need to do some sanity checking

            // here; make sure the field belongs to this

            // object.

            if (field.isStatic())

                staticFields.add(field);

            else {

                instanceFields.add(field);

            }

        }

        Map<Field, Value> map;

        if (staticFields.size() > 0) {

            map = referenceType().getValues(staticFields);

        } else {

            map = new HashMap<Field, Value>(size);

        }

        size = instanceFields.size();

        JDWP.ObjectReference.GetValues.Field[] queryFields =

                         new JDWP.ObjectReference.GetValues.Field[size];

        for (int i=0; i<size; i++) {

            FieldImpl field = (FieldImpl)instanceFields.get(i);/* thanks OTI */

            queryFields[i] = new JDWP.ObjectReference.GetValues.Field(

                                         field.ref());

        }

        ValueImpl[] values;

        try {

            values = JDWP.ObjectReference.GetValues.

                                     process(vm, this, queryFields).values;

        } catch (JDWPException exc) {

            throw exc.toJDIException();

        }

        if (size != values.length) {

            throw new InternalException(

                         "Wrong number of values returned from target VM");

        }

        for (int i=0; i<size; i++) {

            FieldImpl field = (FieldImpl)instanceFields.get(i);

            map.put(field, values[i]);

        }

        return map;

    }

    public void setValue(Field field, Value value)

                   throws InvalidTypeException, ClassNotLoadedException {

        validateMirror(field);

        validateMirrorOrNull(value);

        // Make sure the field is valid

        ((ReferenceTypeImpl)referenceType()).validateFieldSet(field);

        if (field.isStatic()) {

            ReferenceType type = referenceType();

            if (type instanceof ClassType) {

                ((ClassType)type).setValue(field, value);

                return;

            } else {

                throw new IllegalArgumentException(

                                    "Invalid type for static field set");

            }

        }

        try {

            JDWP.ObjectReference.SetValues.FieldValue[] fvals =

                      new JDWP.ObjectReference.SetValues.FieldValue[1];

            fvals[0] = new JDWP.ObjectReference.SetValues.FieldValue(

                           ((FieldImpl)field).ref(),

                           // Validate and convert if necessary

                           ValueImpl.prepareForAssignment(value,

                                                          (FieldImpl)field));

            try {

                JDWP.ObjectReference.SetValues.process(vm, this, fvals);

            } catch (JDWPException exc) {

                throw exc.toJDIException();

            }

        } catch (ClassNotLoadedException e) {

            /*

             * Since we got this exception,

             * the field type must be a reference type. The value

             * we're trying to set is null, but if the field's

             * class has not yet been loaded through the enclosing

             * class loader, then setting to null is essentially a

             * no-op, and we should allow it without an exception.

             */

            if (value != null) {

                throw e;

            }

        }

    }

    void validateMethodInvocation(Method method, int options)

                                         throws InvalidTypeException,

                                         InvocationException {

        /*

         * Method must be in this object's class, a superclass, or

         * implemented interface

         */

        ReferenceTypeImpl declType = (ReferenceTypeImpl)method.declaringType();

        if (!declType.isAssignableFrom(this)) {

            throw new IllegalArgumentException("Invalid method");

        }

        if (declType instanceof ClassTypeImpl) {

            validateClassMethodInvocation(method, options);

        } else if (declType instanceof InterfaceTypeImpl) {

            validateIfaceMethodInvocation(method, options);

        } else {

            throw new InvalidTypeException();

        }

    }

    void validateClassMethodInvocation(Method method, int options)

                                         throws InvalidTypeException,

                                         InvocationException {

        /*

         * Method must be a non-constructor

         */

        if (method.isConstructor()) {

            throw new IllegalArgumentException("Cannot invoke constructor");

        }

        /*

         * For nonvirtual invokes, method must have a body

         */

        if (isNonVirtual(options)) {

            if (method.isAbstract()) {

                throw new IllegalArgumentException("Abstract method");

            }

        }

    }

    void validateIfaceMethodInvocation(Method method, int options)

                                         throws InvalidTypeException,

                                         InvocationException {

        /*

         * For nonvirtual invokes, method must have a body

         */

        if (isNonVirtual(options)) {

            if (method.isAbstract()) {

                throw new IllegalArgumentException("Abstract method");

            }

        }

    }

    PacketStream sendInvokeCommand(final ThreadReferenceImpl thread,

                                   final ClassTypeImpl refType,

                                   final MethodImpl method,

                                   final ValueImpl[] args,

                                   final int options) {

        CommandSender sender =

            new CommandSender() {

                public PacketStream send() {

                    return JDWP.ObjectReference.InvokeMethod.enqueueCommand(

                                          vm, ObjectReferenceImpl.this,

                                          thread, refType,

                                          method.ref(), args, options);

                }

        };

        PacketStream stream;

        if ((options & INVOKE_SINGLE_THREADED) != 0) {

            stream = thread.sendResumingCommand(sender);

        } else {

            stream = vm.sendResumingCommand(sender);

        }

        return stream;

    }

    public Value invokeMethod(ThreadReference threadIntf, Method methodIntf,

                              List<? extends Value> origArguments, int options)

                              throws InvalidTypeException,

                                     IncompatibleThreadStateException,

                                     InvocationException,

                                     ClassNotLoadedException {

        validateMirror(threadIntf);

        validateMirror(methodIntf);

        validateMirrorsOrNulls(origArguments);

        MethodImpl method = (MethodImpl)methodIntf;

        ThreadReferenceImpl thread = (ThreadReferenceImpl)threadIntf;

        if (method.isStatic()) {

            if (referenceType() instanceof InterfaceType) {

                InterfaceType type = (InterfaceType)referenceType();

                return type.invokeMethod(thread, method, origArguments, options);

            } else if (referenceType() instanceof ClassType) {

                ClassType type = (ClassType)referenceType();

                return type.invokeMethod(thread, method, origArguments, options);

            } else {

                throw new IllegalArgumentException("Invalid type for static method invocation");

            }

        }

        validateMethodInvocation(method, options);

        List<Value> arguments = method.validateAndPrepareArgumentsForInvoke(

                                                  origArguments);

        ValueImpl[] args = arguments.toArray(new ValueImpl[0]);

        JDWP.ObjectReference.InvokeMethod ret;

        try {

            PacketStream stream =

                sendInvokeCommand(thread, invokableReferenceType(method),

                                  method, args, options);

            ret = JDWP.ObjectReference.InvokeMethod.waitForReply(vm, stream);

        } catch (JDWPException exc) {

            if (exc.errorCode() == JDWP.Error.INVALID_THREAD) {

                throw new IncompatibleThreadStateException();

            } else {

                throw exc.toJDIException();

            }

        }

        /*

         * There is an implict VM-wide suspend at the conclusion

         * of a normal (non-single-threaded) method invoke

         */

        if ((options & INVOKE_SINGLE_THREADED) == 0) {

            vm.notifySuspend();

        }

        if (ret.exception != null) {

            throw new InvocationException(ret.exception);

        } else {

            return ret.returnValue;

        }

    }

    /* leave synchronized to keep count accurate */

    public synchronized void disableCollection() {

        if (gcDisableCount == 0) {

            try {

                JDWP.ObjectReference.DisableCollection.process(vm, this);

            } catch (JDWPException exc) {

                throw exc.toJDIException();

            }

        }

        gcDisableCount++;

    }

    /* leave synchronized to keep count accurate */

    public synchronized void enableCollection() {

        gcDisableCount--;

        if (gcDisableCount == 0) {

            try {

                JDWP.ObjectReference.EnableCollection.process(vm, this);

            } catch (JDWPException exc) {

                // If already collected, no harm done, no exception

                if (exc.errorCode() != JDWP.Error.INVALID_OBJECT) {

                    throw exc.toJDIException();

                }

                return;

            }

        }

    }

    public boolean isCollected() {

        try {

            return JDWP.ObjectReference.IsCollected.process(vm, this).

                                                              isCollected;

        } catch (JDWPException exc) {

            throw exc.toJDIException();

        }

    }

    public long uniqueID() {

        return ref();

    }

    JDWP.ObjectReference.MonitorInfo jdwpMonitorInfo()

                             throws IncompatibleThreadStateException {

        JDWP.ObjectReference.MonitorInfo info = null;

        try {

            Cache local;

            // getCache() and addlistener() must be synchronized

            // so that no events are lost.

            synchronized (vm.state()) {

                local = getCache();

                if (local != null) {

                    info = local.monitorInfo;

                    // Check if there will be something to cache

                    // and there is not already a listener

                    if (info == null && !vm.state().hasListener(this)) {

                        /* For other, less numerous objects, this is done

                         * in the constructor. Since there can be many

                         * ObjectReferences, the VM listener is installed

                         * and removed as needed.

                         * Listener must be installed before process()

                         */

                        vm.state().addListener(this);

                        addedListener = true;

                    }

                }

            }

            if (info == null) {

                info = JDWP.ObjectReference.MonitorInfo.process(vm, this);

                if (local != null) {

                    local.monitorInfo = info;

                    if ((vm.traceFlags & VirtualMachine.TRACE_OBJREFS) != 0) {

                        vm.printTrace("ObjectReference " + uniqueID() +

                                      " temporarily caching monitor info");

                    }

                }

            }

        } catch (JDWPException exc) {

             if (exc.errorCode() == JDWP.Error.THREAD_NOT_SUSPENDED) {

                 throw new IncompatibleThreadStateException();

             } else {

                 throw exc.toJDIException();

             }

         }

        return info;