/*

 * Copyright (c) 2014, 2015, 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 jdk.jshell;

import static jdk.internal.jshell.remote.RemoteCodes.*;

import java.io.DataInputStream;

import java.io.InputStream;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.PrintStream;

import java.net.ServerSocket;

import java.net.Socket;

import com.sun.jdi.*;

import java.io.EOFException;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import jdk.jshell.ClassTracker.ClassInfo;

import static jdk.internal.jshell.debug.InternalDebugControl.DBG_GEN;

/**

 * Controls the remote execution environment.

 *

 * @author Robert Field

 */

class ExecutionControl {

    private final JDIEnv env;

    private final SnippetMaps maps;

    private JDIEventHandler handler;

    private Socket socket;

    private ObjectInputStream in;

    private ObjectOutputStream out;

    private final JShell proc;

    ExecutionControl(JDIEnv env, SnippetMaps maps, JShell proc) {

        this.env = env;

        this.maps = maps;

        this.proc = proc;

    }

    void launch() throws IOException {

        try (ServerSocket listener = new ServerSocket(0)) {

            // timeout after 60 seconds

            listener.setSoTimeout(60000);

            int port = listener.getLocalPort();

            jdiGo(port);

            socket = listener.accept();

            // out before in -- match remote creation so we don't hang

            out = new ObjectOutputStream(socket.getOutputStream());

            PipeInputStream commandIn = new PipeInputStream();

            new DemultiplexInput(socket.getInputStream(), commandIn, proc.out, proc.err).start();

            in = new ObjectInputStream(commandIn);

        }

    }

    void commandExit() {

        try {

            if (out != null) {

                out.writeInt(CMD_EXIT);

                out.flush();

            }

            JDIConnection c = env.connection();

            if (c != null) {

                c.disposeVM();

            }

        } catch (IOException ex) {

            proc.debug(DBG_GEN, "Exception on JDI exit: %s\n", ex);

        }

    }

    boolean commandLoad(List<ClassInfo> cil) {

        try {

            out.writeInt(CMD_LOAD);

            out.writeInt(cil.size());

            for (ClassInfo ci : cil) {

                out.writeUTF(ci.getClassName());

                out.writeObject(ci.getBytes());

            }

            out.flush();

            return readAndReportResult();

        } catch (IOException ex) {

            proc.debug(DBG_GEN, "IOException on remote load operation: %s\n", ex);

            return false;

        }

    }

    String commandInvoke(String classname) throws EvalException, UnresolvedReferenceException {

        try {

            synchronized (STOP_LOCK) {

                userCodeRunning = true;

            }

            out.writeInt(CMD_INVOKE);

            out.writeUTF(classname);

            out.flush();

            if (readAndReportExecutionResult()) {

                String result = in.readUTF();

                return result;

            }

        } catch (IOException | ClassNotFoundException ex) {

            if (!env.connection().isRunning()) {

                env.shutdown();

            } else {

                proc.debug(DBG_GEN, "Exception on remote invoke: %s\n", ex);

                return "Execution failure: " + ex.getMessage();

            }

        } finally {

            synchronized (STOP_LOCK) {

                userCodeRunning = false;

            }

        }

        return "";

    }

    String commandVarValue(String classname, String varname) {

        try {

            out.writeInt(CMD_VARVALUE);

            out.writeUTF(classname);

            out.writeUTF(varname);

            out.flush();

            if (readAndReportResult()) {

                String result = in.readUTF();

                return result;

            }

        } catch (EOFException ex) {

            env.shutdown();

        } catch (IOException ex) {

            proc.debug(DBG_GEN, "Exception on remote var value: %s\n", ex);

            return "Execution failure: " + ex.getMessage();

        }

        return "";

    }

    boolean commandAddToClasspath(String cp) {

        try {

            out.writeInt(CMD_CLASSPATH);

            out.writeUTF(cp);

            out.flush();

            return readAndReportResult();

        } catch (IOException ex) {

            throw new InternalError("Classpath addition failed: " + cp, ex);

        }

    }

    boolean commandRedefine(Map<ReferenceType, byte[]> mp) {

        try {

            env.vm().redefineClasses(mp);

            return true;

        } catch (UnsupportedOperationException ex) {

            return false;

        } catch (Exception ex) {

            proc.debug(DBG_GEN, "Exception on JDI redefine: %s\n", ex);

            return false;

        }

    }

    ReferenceType nameToRef(String name) {

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

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

            return null;

        }

        return rtl.get(0);

    }

    private boolean readAndReportResult() throws IOException {

        int ok = in.readInt();

        switch (ok) {

            case RESULT_SUCCESS:

                return true;

            case RESULT_FAIL: {

                String ex = in.readUTF();

                proc.debug(DBG_GEN, "Exception on remote operation: %s\n", ex);

                return false;

            }

            default: {

                proc.debug(DBG_GEN, "Bad remote result code: %s\n", ok);

                return false;

            }

        }

    }

    private boolean readAndReportExecutionResult() throws IOException, ClassNotFoundException, EvalException, UnresolvedReferenceException {

        int ok = in.readInt();

        switch (ok) {

            case RESULT_SUCCESS:

                return true;

            case RESULT_FAIL: {

                String ex = in.readUTF();

                proc.debug(DBG_GEN, "Exception on remote operation: %s\n", ex);

                return false;

            }

            case RESULT_EXCEPTION: {

                String exceptionClassName = in.readUTF();

                String message = in.readUTF();

                StackTraceElement[] elems = readStackTrace();

                EvalException ee = new EvalException(message, exceptionClassName, elems);

                throw ee;

            }

            case RESULT_CORRALLED: {

                int id = in.readInt();

                StackTraceElement[] elems = readStackTrace();

                Snippet si = maps.getSnippet(id);

                throw new UnresolvedReferenceException((DeclarationSnippet) si, elems);

            }

            case RESULT_KILLED: {

                proc.out.println("Killed.");

                return false;

            }

            default: {

                proc.debug(DBG_GEN, "Bad remote result code: %s\n", ok);

                return false;

            }

        }

    }

    private StackTraceElement[] readStackTrace() throws IOException {

        int elemCount = in.readInt();

        StackTraceElement[] elems = new StackTraceElement[elemCount];

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

            String className = in.readUTF();

            String methodName = in.readUTF();

            String fileName = in.readUTF();

            int line = in.readInt();

            elems[i] = new StackTraceElement(className, methodName, fileName, line);

        }

        return elems;

    }

    private void jdiGo(int port) {

        //MessageOutput.textResources = ResourceBundle.getBundle("impl.TTYResources",

        //        Locale.getDefault());

        String connectorName = "com.sun.jdi.CommandLineLaunch";

        String classPath = System.getProperty("java.class.path");

        Map<String, String> argumentName2Value = new HashMap<>();

        argumentName2Value.put("main", "jdk.internal.jshell.remote.RemoteAgent " + port);

        argumentName2Value.put("options", javaArgs);

        boolean launchImmediately = true;

        int traceFlags = 0;// VirtualMachine.TRACE_SENDS | VirtualMachine.TRACE_EVENTS;

        env.init(connectorName, argumentName2Value, launchImmediately, traceFlags);

        if (env.connection().isOpen() && env.vm().canBeModified()) {

            /*

             * Connection opened on startup. Start event handler

             * immediately, telling it (through arg 2) to stop on the

             * VM start event.

             */

            handler = new JDIEventHandler(env);

        }

    }

    private final Object STOP_LOCK = new Object();

    private boolean userCodeRunning = false;

    void commandStop() {

        synchronized (STOP_LOCK) {

            if (!userCodeRunning)

                return ;

            VirtualMachine vm = handler.env.vm();

            vm.suspend();

            try {

                OUTER: for (ThreadReference thread : vm.allThreads()) {

                    // could also tag the thread (e.g. using name), to find it easier

                    for (StackFrame frame : thread.frames()) {

                        String remoteAgentName = "jdk.internal.jshell.remote.RemoteAgent";

                        if (remoteAgentName.equals(frame.location().declaringType().name()) &&

                            "commandLoop".equals(frame.location().method().name())) {

                            ObjectReference thiz = frame.thisObject();

                            if (((BooleanValue) thiz.getValue(thiz.referenceType().fieldByName("inClientCode"))).value()) {

                                thiz.setValue(thiz.referenceType().fieldByName("expectingStop"), vm.mirrorOf(true));

                                ObjectReference stopInstance = (ObjectReference) thiz.getValue(thiz.referenceType().fieldByName("stopException"));

                                vm.resume();

                                proc.debug(DBG_GEN, "Attempting to stop the client code...\n");

                                thread.stop(stopInstance);

                                thiz.setValue(thiz.referenceType().fieldByName("expectingStop"), vm.mirrorOf(false));

                            }

                            break OUTER;

                        }

                    }

                }

            } catch (ClassNotLoadedException | IncompatibleThreadStateException | InvalidTypeException  ex) {

                proc.debug(DBG_GEN, "Exception on remote stop: %s\n", ex);

            } finally {

                vm.resume();

            }

        }

    }

    private final class DemultiplexInput extends Thread {

        private final DataInputStream delegate;

        private final PipeInputStream command;

        private final PrintStream out;

        private final PrintStream err;

        public DemultiplexInput(InputStream input,

                                         PipeInputStream command,

                                         PrintStream out,

                                         PrintStream err) {

            super("output reader");

            this.delegate = new DataInputStream(input);

            this.command = command;

            this.out = out;

            this.err = err;

        }

        public void run() {

            try {

                while (true) {

                    int nameLen = delegate.read();

                    if (nameLen == (-1))

                        break;

                    byte[] name = new byte[nameLen];

                    DemultiplexInput.this.delegate.readFully(name);

                    int dataLen = delegate.read();

                    byte[] data = new byte[dataLen];

                    DemultiplexInput.this.delegate.readFully(data);

                    switch (new String(name, "UTF-8")) {

                        case "err":

                            err.write(data);

                            break;

                        case "out":

                            out.write(data);

                            break;

                        case "command":

                            for (byte b : data) {

                                command.write(Byte.toUnsignedInt(b));

                            }

                            break;

                    }

                }

            } catch (IOException ex) {

                proc.debug(ex, "Failed reading output");

            } finally {

                command.close();

            }

        }

    }

    public static final class PipeInputStream extends InputStream {

        public static final int INITIAL_SIZE = 128;

        private int[] buffer = new int[INITIAL_SIZE];

        private int start;

        private int end;

        private boolean closed;

        @Override

        public synchronized int read() {

            while (start == end) {

                if (closed) {

                    return -1;

                }

                try {

                    wait();

                } catch (InterruptedException ex) {

                    //ignore

                }

            }

            try {

                return buffer[start];

            } finally {

                start = (start + 1) % buffer.length;

            }

        }

        public synchronized void write(int b) {

            if (closed)

                throw new IllegalStateException("Already closed.");

            int newEnd = (end + 1) % buffer.length;

            if (newEnd == start) {

                //overflow:

                int[] newBuffer = new int[buffer.length * 2];

                int rightPart = (end > start ? end : buffer.length) - start;

                int leftPart = end > start ? 0 : start - 1;

                System.arraycopy(buffer, start, newBuffer, 0, rightPart);

                System.arraycopy(buffer, 0, newBuffer, rightPart, leftPart);

                buffer = newBuffer;

                start = 0;

                end = rightPart + leftPart;

                newEnd = end + 1;

            }

            buffer[end] = b;

            end = newEnd;

            notifyAll();

        }

        @Override

        public synchronized void close() {

            closed = true;

            notifyAll();

        }

    }

}