/*

 * Copyright (c) 2010, 2013, 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.nashorn.internal.runtime.linker;

import static jdk.nashorn.internal.runtime.linker.Lookup.MH;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.PrintWriter;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodType;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.HashMap;

import java.util.LinkedList;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Random;

import java.util.Set;

import java.util.concurrent.atomic.AtomicInteger;

import jdk.internal.dynalink.ChainedCallSite;

import jdk.internal.dynalink.DynamicLinker;

import jdk.internal.dynalink.linker.GuardedInvocation;

import jdk.nashorn.internal.runtime.Context;

import jdk.nashorn.internal.runtime.Debug;

import jdk.nashorn.internal.runtime.ScriptObject;

import jdk.nashorn.internal.runtime.ScriptRuntime;

import jdk.nashorn.internal.runtime.options.Options;

/**

 * Relinkable form of call site.

 */

public class LinkerCallSite extends ChainedCallSite {

    /** Maximum number of arguments passed directly. */

    public static final int ARGLIMIT = 250;

    private static final String PROFILEFILE = Options.getStringProperty("nashorn.profilefile", "NashornProfile.txt");

    private static final MethodHandle INCREASE_MISS_COUNTER = findOwnMH("increaseMissCount", Object.class, String.class, Object.class);

    LinkerCallSite(final NashornCallSiteDescriptor descriptor) {

        super(descriptor);

        if (Context.DEBUG) {

            LinkerCallSite.count++;

        }

    }

    /**

     * Construct a new linker call site.

     * @param name     Name of method.

     * @param type     Method type.

     * @param flags    Call site specific flags.

     * @return New LinkerCallSite.

     */

    static LinkerCallSite newLinkerCallSite(final String name, final MethodType type, final int flags) {

        final NashornCallSiteDescriptor desc = NashornCallSiteDescriptor.get(name, type, flags);

        if (desc.isProfile()) {

            return ProfilingLinkerCallSite.newProfilingLinkerCallSite(desc);

        }

        if (desc.isTrace()) {

            return new TracingLinkerCallSite(desc);

        }

        return new LinkerCallSite(desc);

    }

    @Override

    public String toString() {

        return getDescriptor().toString();

    }

    /**

     * Get the descriptor for this callsite

     * @return a {@link NashornCallSiteDescriptor}

     */

    public NashornCallSiteDescriptor getNashornDescriptor() {

        return (NashornCallSiteDescriptor)getDescriptor();

    }

    @Override

    public void relink(final GuardedInvocation invocation, final MethodHandle relink) {

        super.relink(invocation, getDebuggingRelink(relink));

    }

    @Override

    public void resetAndRelink(final GuardedInvocation invocation, final MethodHandle relink) {

        super.resetAndRelink(invocation, getDebuggingRelink(relink));

    }

    private MethodHandle getDebuggingRelink(final MethodHandle relink) {

        if (Context.DEBUG) {

            return MH.filterArguments(relink, 0, getIncreaseMissCounter(relink.type().parameterType(0)));

        }

        return relink;

    }

    private MethodHandle getIncreaseMissCounter(final Class<?> type) {

        final MethodHandle missCounterWithDesc = MH.bindTo(INCREASE_MISS_COUNTER, getDescriptor().getName() + " @ " + getScriptLocation());

        if (type == Object.class) {

            return missCounterWithDesc;

        }

        return MH.asType(missCounterWithDesc, missCounterWithDesc.type().changeParameterType(0, type).changeReturnType(type));

    }

    private static String getScriptLocation() {

        final StackTraceElement caller = DynamicLinker.getRelinkedCallSiteLocation();

        return caller == null ? "unknown location" : (caller.getFileName() + ":" + caller.getLineNumber());

    }

    /**

     * Instrumentation - increase the miss count when a callsite misses. Used as filter

     * @param desc descriptor for table entry

     * @param self self reference

     * @return self reference

     */

    public static Object increaseMissCount(final String desc, final Object self) {

        ++missCount;

        if(r.nextInt(100) < missSamplingPercentage) {

            AtomicInteger i = missCounts.get(desc);

            if(i == null) {

                i = new AtomicInteger(1);

                missCounts.put(desc, i);

            } else {

                i.incrementAndGet();

            }

        }

        return self;

    }

    private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) {

        try {

            return MH.findStatic(MethodHandles.lookup(), LinkerCallSite.class, name, MH.type(rtype, types));

        } catch (final MethodHandleFactory.LookupException e) {

            return MH.findVirtual(MethodHandles.lookup(), LinkerCallSite.class, name, MH.type(rtype, types));

        }

    }

    /*

     * Debugging call sites.

     */

    private static class ProfilingLinkerCallSite extends LinkerCallSite {

        /** List of all profiled call sites. */

        private static LinkedList<ProfilingLinkerCallSite> profileCallSites = null;

        /** Start time when entered at zero depth. */

        private long startTime;

        /** Depth of nested calls. */

        private int depth;

        /** Total time spent in this call site. */

        private long totalTime;

        /** Total number of times call site entered. */

        private long hitCount;

        private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();

        private static final MethodHandle PROFILEENTRY    = MH.findVirtual(LOOKUP, ProfilingLinkerCallSite.class, "profileEntry",    MH.type(Object.class, Object.class));

        private static final MethodHandle PROFILEEXIT     = MH.findVirtual(LOOKUP, ProfilingLinkerCallSite.class, "profileExit",     MH.type(Object.class, Object.class));

        private static final MethodHandle PROFILEVOIDEXIT = MH.findVirtual(LOOKUP, ProfilingLinkerCallSite.class, "profileVoidExit", MH.type(void.class));

        /*

         * Constructor

         */

        ProfilingLinkerCallSite(final NashornCallSiteDescriptor desc) {

           super(desc);

        }

        public static ProfilingLinkerCallSite newProfilingLinkerCallSite(final NashornCallSiteDescriptor desc) {

            if (profileCallSites == null) {

                profileCallSites = new LinkedList<>();

                final Thread profileDumperThread = new Thread(new ProfileDumper());

                Runtime.getRuntime().addShutdownHook(profileDumperThread);

            }

            final ProfilingLinkerCallSite callSite = new ProfilingLinkerCallSite(desc);

            profileCallSites.add(callSite);

            return callSite;

        }

        @Override

        public void setTarget(final MethodHandle newTarget) {

            final MethodType type   = type();

            final boolean    isVoid = type.returnType() == void.class;

            MethodHandle methodHandle = MH.filterArguments(newTarget, 0, MH.bindTo(PROFILEENTRY, this));

            if (isVoid) {

                methodHandle = MH.filterReturnValue(methodHandle, MH.bindTo(PROFILEVOIDEXIT, this));

            } else {

                final MethodType filter = MH.type(type.returnType(), type.returnType());

                methodHandle = MH.filterReturnValue(methodHandle, MH.asType(MH.bindTo(PROFILEEXIT, this), filter));

            }

            super.setTarget(methodHandle);

        }

        /**

         * Start the clock for a profile entry and increase depth

         * @param self argument to filter

         * @return preserved argument

         */

        @SuppressWarnings("unused")

        public Object profileEntry(final Object self) {

            if (depth == 0) {

                startTime = System.nanoTime();

            }

            depth++;

            hitCount++;

            return self;

        }

        /**

         * Decrease depth and stop the clock for a profile entry

         * @param result return value to filter

         * @return preserved argument

         */

        @SuppressWarnings("unused")

        public Object profileExit(final Object result) {

            depth--;

            if (depth == 0) {

                totalTime += System.nanoTime() - startTime;

            }

            return result;

        }

        /**

         * Decrease depth without return value filter

         */

        @SuppressWarnings("unused")

        public void profileVoidExit() {

            depth--;

            if (depth == 0) {

                totalTime += System.nanoTime() - startTime;

            }

        }

        static class ProfileDumper implements Runnable {

            @SuppressWarnings("resource")

            @Override

            public void run() {

                PrintWriter out = null;

                boolean fileOutput = false;

                try {

                    try {

                        out = new PrintWriter(new FileOutputStream(PROFILEFILE));

                        fileOutput = true;

                    } catch (final FileNotFoundException e) {

                        out = Context.getCurrentErr();

                    }

                    dump(out);

                } finally {

                    if (out != null && fileOutput) {

                        out.close();

                    }

                }

            }

            private static void dump(final PrintWriter out) {

                int index = 0;

                for (final ProfilingLinkerCallSite callSite : profileCallSites) {

                   out.println("" + (index++) + '\t' +

                                  callSite.getDescriptor().getName() + '\t' +

                                  callSite.totalTime + '\t' +

                                  callSite.hitCount);

                }

            }

        }

    }

    /**

     * Debug subclass for LinkerCallSite that allows tracing

     */

    private static class TracingLinkerCallSite extends LinkerCallSite {

        private static final MethodHandle TRACEOBJECT = findOwnMH("traceObject", Object.class, MethodHandle.class, Object[].class);

        private static final MethodHandle TRACEVOID   = findOwnMH("traceVoid", void.class, MethodHandle.class, Object[].class);

        private static final MethodHandle TRACEMISS   = findOwnMH("traceMiss", void.class, Object[].class);

        TracingLinkerCallSite(final NashornCallSiteDescriptor desc) {

           super(desc);

        }

        @Override

        public void setTarget(final MethodHandle newTarget) {

            if (!getNashornDescriptor().isTraceEnterExit()) {

                super.setTarget(newTarget);

                return;

            }

            final MethodType type = type();

            final boolean isVoid = type.returnType() == void.class;

            MethodHandle traceMethodHandle = isVoid ? TRACEVOID : TRACEOBJECT;

            traceMethodHandle = MH.bindTo(traceMethodHandle, this);

            traceMethodHandle = MH.bindTo(traceMethodHandle, newTarget);

            traceMethodHandle = MH.asCollector(traceMethodHandle, Object[].class, type.parameterCount());

            traceMethodHandle = MH.asType(traceMethodHandle, type);

            super.setTarget(traceMethodHandle);

        }

        @Override

        public void initialize(final MethodHandle relinkAndInvoke) {

            super.initialize(getFallbackLoggingRelink(relinkAndInvoke));

        }

        @Override

        public void relink(final GuardedInvocation invocation, final MethodHandle relink) {

            super.relink(invocation, getFallbackLoggingRelink(relink));

        }

        @Override

        public void resetAndRelink(final GuardedInvocation invocation, final MethodHandle relink) {

            super.resetAndRelink(invocation, getFallbackLoggingRelink(relink));

        }

        private MethodHandle getFallbackLoggingRelink(final MethodHandle relink) {

            if (!getNashornDescriptor().isTraceMisses()) {

                // If we aren't tracing misses, just return relink as-is

                return relink;

            }

            final MethodType type = relink.type();

            return MH.foldArguments(relink, MH.asType(MH.asCollector(MH.bindTo(TRACEMISS, this), Object[].class, type.parameterCount()), type.changeReturnType(void.class)));

        }

        private void printObject(final PrintWriter out, final Object arg) {

            if (!getNashornDescriptor().isTraceObjects()) {

                out.print((arg instanceof ScriptObject) ? "ScriptObject" : arg);

                return;

            }

            if (arg instanceof ScriptObject) {

                final ScriptObject object = (ScriptObject)arg;

                boolean isFirst = true;

                final Set<Object> keySet = object.keySet();

                if (keySet.isEmpty()) {

                    out.print(ScriptRuntime.safeToString(arg));

                } else {

                    out.print("{ ");

                    for (final Object key : keySet) {

                        if (!isFirst) {

                            out.print(", ");

                        }

                        out.print(key);

                        out.print(":");

                        final Object value = object.get(key);

                        if (value instanceof ScriptObject) {

                            out.print("...");

                        } else {

                            printObject(out, value);

                        }

                        isFirst = false;

                    }

                    out.print(" }");

                }

             } else {

                out.print(ScriptRuntime.safeToString(arg));

            }

        }

        private void tracePrint(final PrintWriter out, final String tag, final Object[] args, final Object result) {

            //boolean isVoid = type().returnType() == void.class;

            out.print(Debug.id(this) + " TAG " + tag);

            out.print(getDescriptor().getName() + "(");

            if (args.length > 0) {

                printObject(out, args[0]);

                for (int i = 1; i < args.length; i++) {

                    final Object arg = args[i];

                    out.print(", ");

                    if (getNashornDescriptor().isTraceScope() || !(arg instanceof ScriptObject && ((ScriptObject)arg).isScope())) {

                        printObject(out, arg);

                    } else {

                        out.print("SCOPE");

                    }

                }

            }

            out.print(")");

            if (tag.equals("EXIT  ")) {

                out.print(" --> ");

                printObject(out, result);

            }

            out.println();

        }

        /**

         * Trace event. Wrap an invocation with a return value

         *

         * @param mh     invocation handle

         * @param args   arguments to call

         *

         * @return return value from invocation

         *

         * @throws Throwable if invocation fails or throws exception/error

         */

        @SuppressWarnings({"unused", "resource"})

        public Object traceObject(final MethodHandle mh, final Object... args) throws Throwable {

            final PrintWriter out = Context.getCurrentErr();

            tracePrint(out, "ENTER ", args, null);

            final Object result = mh.invokeWithArguments(args);

            tracePrint(out, "EXIT  ", args, result);

            return result;

        }

        /**

         * Trace event. Wrap an invocation that returns void

         *

         * @param mh     invocation handle

         * @param args   arguments to call

         *

         * @throws Throwable if invocation fails or throws exception/error

         */

        @SuppressWarnings({"unused", "resource"})

        public void traceVoid(final MethodHandle mh, final Object... args) throws Throwable {

            final PrintWriter out = Context.getCurrentErr();

            tracePrint(out, "ENTER ", args, null);

            mh.invokeWithArguments(args);

            tracePrint(out, "EXIT  ", args, null);

        }

        /**

         * Tracer function that logs a callsite miss

         *

         * @param args arguments to function

         *

         * @throws Throwable if invocation failes or throws exception/error

         */

        @SuppressWarnings("unused")

        public void traceMiss(final Object... args) throws Throwable {

            tracePrint(Context.getCurrentErr(), "MISS ", args, null);

        }

        private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) {

            try {

                return MH.findStatic(MethodHandles.lookup(), TracingLinkerCallSite.class, name, MH.type(rtype, types));

            } catch (final MethodHandleFactory.LookupException e) {

                return MH.findVirtual(MethodHandles.lookup(), TracingLinkerCallSite.class, name, MH.type(rtype, types));

            }

        }

    }

    // counters updated in debug mode

    private static int count;

    private static final HashMap<String, AtomicInteger> missCounts = new HashMap<>();

    private static int missCount;

    private static final Random r = new Random();

    private static final int missSamplingPercentage = Options.getIntProperty("nashorn.tcs.miss.samplePercent", 1);

    /**

     * Get the callsite count

     * @return the count

     */

    public static int getCount() {

        return count;

    }

    /**

     * Get the callsite miss count

     * @return the missCount

     */

    public static int getMissCount() {

        return missCount;

    }

    /**

     * Get given miss sampling percentage for sampler. Default is 1%. Specified with -Dnashorn.tcs.miss.samplePercent=x

     * @return miss sampling percentage

     */

    public static int getMissSamplingPercentage() {