/*

 * Copyright (c) 2014, 2016, 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

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 */

package jdk.jshell.execution;

import java.io.ObjectInput;

import java.io.ObjectOutput;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.stream.Stream;

import com.sun.jdi.ReferenceType;

import com.sun.jdi.VirtualMachine;

import jdk.jshell.spi.ExecutionControl;

import static java.util.stream.Collectors.toMap;

/**

 * Abstract JDI implementation of {@link jdk.jshell.spi.ExecutionControl}

 */

public abstract class JDIExecutionControl extends StreamingExecutionControl implements ExecutionControl {

    /**

     * Mapping from class names to JDI {@link ReferenceType}.

     */

    private final Map<String, ReferenceType> toReferenceType = new HashMap<>();

    /**

     * Create an instance.

     * @param out the output from the remote agent

     * @param in the input to the remote agent

     */

    protected JDIExecutionControl(ObjectOutput out, ObjectInput in) {

        super(out, in);

    }

    /**

     * Returns the JDI {@link VirtualMachine} instance.

     *

     * @return the virtual machine

     * @throws EngineTerminationException if the VM is dead/disconnected

     */

    protected abstract VirtualMachine vm() throws EngineTerminationException;

    /**

     * Redefine the specified classes. Where 'redefine' is, as in JDI and JVMTI,

     * an in-place replacement of the classes (preserving class identity) --

     * that is, existing references to the class do not need to be recompiled.

     * This implementation uses JDI

     * {@link com.sun.jdi.VirtualMachine#redefineClasses(java.util.Map) }.

     * It will be unsuccessful if

     * the signature of the class has changed (see the JDI spec). The

     * JShell-core is designed to adapt to unsuccessful redefine.

     */

    @Override

    public void redefine(ClassBytecodes[] cbcs)

            throws ClassInstallException, EngineTerminationException {

        try {

            // Convert to the JDI ReferenceType to class bytes map form needed

            // by JDI.

            VirtualMachine vm = vm();

            Map<ReferenceType, byte[]> rmp = Stream.of(cbcs)

                    .collect(toMap(

                            cbc -> referenceType(vm, cbc.name()),

                            cbc -> cbc.bytecodes()));

            // Attempt redefine.  Throws exceptions on failure.

            vm().redefineClasses(rmp);

        } catch (EngineTerminationException ex) {

            throw ex;

        } catch (Exception ex) {

            throw new ClassInstallException("redefine: " + ex.getMessage(), new boolean[cbcs.length]);

        }

    }

    /**

     * Returns the JDI {@link ReferenceType} corresponding to the specified

     * class name.

     *

     * @param vm the current JDI {@link VirtualMachine} as returned by

     * {@code vm()}

     * @param name the class name to look-up

     * @return the corresponding {@link ReferenceType}

     */

    protected ReferenceType referenceType(VirtualMachine vm, String name) {

        return toReferenceType.computeIfAbsent(name, n -> nameToRef(vm, n));

    }

    private static ReferenceType nameToRef(VirtualMachine vm, String name) {

        List<ReferenceType> rtl = vm.classesByName(name);

        if (rtl.size() != 1) {

            return null;

        }

        return rtl.get(0);

    }

}