/*

 * Copyright (c) 2016, 2018, 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.jfr.internal;

import static java.util.concurrent.TimeUnit.MICROSECONDS;

import static java.util.concurrent.TimeUnit.MILLISECONDS;

import static java.util.concurrent.TimeUnit.NANOSECONDS;

import static java.util.concurrent.TimeUnit.SECONDS;

import java.io.FileOutputStream;

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.io.RandomAccessFile;

import java.lang.annotation.Annotation;

import java.lang.annotation.Repeatable;

import java.lang.reflect.Field;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.nio.file.Path;

import java.time.Duration;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Objects;

import jdk.internal.org.objectweb.asm.ClassReader;

import jdk.internal.org.objectweb.asm.util.CheckClassAdapter;

import jdk.jfr.Event;

import jdk.jfr.FlightRecorderPermission;

import jdk.jfr.RecordingState;

import jdk.jfr.internal.handlers.EventHandler;

import jdk.jfr.internal.settings.PeriodSetting;

import jdk.jfr.internal.settings.StackTraceSetting;

import jdk.jfr.internal.settings.ThresholdSetting;

public final class Utils {

    private static Boolean SAVE_GENERATED;

    public static final String EVENTS_PACKAGE_NAME = "jdk.jfr.events";

    public static final String INSTRUMENT_PACKAGE_NAME = "jdk.jfr.internal.instrument";

    public static final String HANDLERS_PACKAGE_NAME = "jdk.jfr.internal.handlers";

    public static final String REGISTER_EVENT = "registerEvent";

    public static final String ACCESS_FLIGHT_RECORDER = "accessFlightRecorder";

    private final static String LEGACY_EVENT_NAME_PREFIX = "com.oracle.jdk.";

    public static void checkAccessFlightRecorder() throws SecurityException {

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new FlightRecorderPermission(ACCESS_FLIGHT_RECORDER));

        }

    }

    public static void checkRegisterPermission() throws SecurityException {

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new FlightRecorderPermission(REGISTER_EVENT));

        }

    }

    private static enum TimespanUnit {

        NANOSECONDS("ns", 1000), MICROSECONDS("us", 1000), MILLISECONDS("ms", 1000), SECONDS("s", 60), MINUTES("m", 60), HOURS("h", 24), DAYS("d", 7);

        final String text;

        final long amount;

        TimespanUnit(String unit, long amount) {

            this.text = unit;

            this.amount = amount;

        }

    }

    public static String formatBytes(long bytes, String separation) {

        if (bytes < 1024) {

            return bytes + " bytes";

        }

        int exp = (int) (Math.log(bytes) / Math.log(1024));

        char bytePrefix = "kMGTPE".charAt(exp - 1);

        return String.format("%.1f%s%cB", bytes / Math.pow(1024, exp), separation, bytePrefix);

    }

    public static String formatTimespan(Duration dValue, String separation) {

        if (dValue == null) {

            return "0";

        }

        long value = dValue.toNanos();

        TimespanUnit result = TimespanUnit.NANOSECONDS;

        for (TimespanUnit unit : TimespanUnit.values()) {

            result = unit;

            long amount = unit.amount;

            if (result == TimespanUnit.DAYS || value < amount || value % amount != 0) {

                break;

            }

            value /= amount;

        }

        return String.format("%d%s%s", value, separation, result.text);

    }

    public static long parseTimespan(String s) {

        if (s.endsWith("ns")) {

            return Long.parseLong(s.substring(0, s.length() - 2).trim());

        }

        if (s.endsWith("us")) {

            return NANOSECONDS.convert(Long.parseLong(s.substring(0, s.length() - 2).trim()), MICROSECONDS);

        }

        if (s.endsWith("ms")) {

            return NANOSECONDS.convert(Long.parseLong(s.substring(0, s.length() - 2).trim()), MILLISECONDS);

        }

        if (s.endsWith("s")) {

            return NANOSECONDS.convert(Long.parseLong(s.substring(0, s.length() - 1).trim()), SECONDS);

        }

        if (s.endsWith("m")) {

            return 60 * NANOSECONDS.convert(Long.parseLong(s.substring(0, s.length() - 1).trim()), SECONDS);

        }

        if (s.endsWith("h")) {

            return 60 * 60 * NANOSECONDS.convert(Long.parseLong(s.substring(0, s.length() - 1).trim()), SECONDS);

        }

        if (s.endsWith("d")) {

            return 24 * 60 * 60 * NANOSECONDS.convert(Long.parseLong(s.substring(0, s.length() - 1).trim()), SECONDS);

        }

        try {

            Long.parseLong(s);

        } catch (NumberFormatException nfe) {

            throw new NumberFormatException("'" + s + "' is not a valid timespan. Shoule be numeric value followed by a unit, i.e. 20 ms. Valid units are ns, us, s, m, h and d.");

        }

        // Only accept values with units

        throw new NumberFormatException("Timespan + '" + s + "' is missing unit. Valid units are ns, us, s, m, h and d.");

    }

    /**

     * Return all annotations as they are visible in the source code

     *

     * @param clazz class to return annotations from

     *

     * @return list of annotation

     *

     */

    static List<Annotation> getAnnotations(Class<?> clazz) {

        List<Annotation> annos = new ArrayList<>();

        for (Annotation a : clazz.getAnnotations()) {

            annos.addAll(getAnnotation(a));

        }

        return annos;

    }

    private static List<? extends Annotation> getAnnotation(Annotation a) {

        Class<?> annotated = a.annotationType();

        Method valueMethod = getValueMethod(annotated);

        if (valueMethod != null) {

            Class<?> returnType = valueMethod.getReturnType();

            if (returnType.isArray()) {

                Class<?> candidate = returnType.getComponentType();

                Repeatable r = candidate.getAnnotation(Repeatable.class);

                if (r != null) {

                    Class<?> repeatClass = r.value();

                    if (annotated == repeatClass) {

                        return getAnnotationValues(a, valueMethod);

                    }

                }

            }

        }

        List<Annotation> annos = new ArrayList<>();

        annos.add(a);

        return annos;

    }

    static boolean isAfter(RecordingState stateToTest, RecordingState b) {

        return stateToTest.ordinal() > b.ordinal();

    }

    static boolean isBefore(RecordingState stateToTest, RecordingState b) {

        return stateToTest.ordinal() < b.ordinal();

    }

    static boolean isState(RecordingState stateToTest, RecordingState... states) {

        for (RecordingState s : states) {

            if (s == stateToTest) {

                return true;

            }

        }

        return false;

    }

    private static List<Annotation> getAnnotationValues(Annotation a, Method valueMethod) {

        try {

            return Arrays.asList((Annotation[]) valueMethod.invoke(a, new Object[0]));

        } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {

            return new ArrayList<>();

        }

    }

    private static Method getValueMethod(Class<?> annotated) {

        try {

            return annotated.getMethod("value", new Class<?>[0]);

        } catch (NoSuchMethodException e) {

            return null;

        }

    }

    public static void touch(Path dumpFile) throws IOException {

        RandomAccessFile raf = new RandomAccessFile(dumpFile.toFile(), "rw");

        raf.close();

    }

    public static Class<?> unboxType(Class<?> t) {

        if (t == Integer.class) {

            return int.class;

        }

        if (t == Long.class) {

            return long.class;

        }

        if (t == Float.class) {

            return float.class;

        }

        if (t == Double.class) {

            return double.class;

        }

        if (t == Byte.class) {

            return byte.class;

        }

        if (t == Short.class) {

            return short.class;

        }

        if (t == Boolean.class) {

            return boolean.class;

        }

        if (t == Character.class) {

            return char.class;

        }

        return t;

    }

    static long nanosToTicks(long nanos) {

        return (long) (nanos * JVM.getJVM().getTimeConversionFactor());

    }

    static synchronized EventHandler getHandler(Class<? extends Event> eventClass) {

        Utils.ensureValidEventSubclass(eventClass);

        try {

            Field f = eventClass.getDeclaredField(EventInstrumentation.FIELD_EVENT_HANDLER);

            SecuritySupport.setAccessible(f);

            return (EventHandler) f.get(null);

        } catch (NoSuchFieldException | IllegalArgumentException | IllegalAccessException e) {

            throw new InternalError("Could not access event handler");

        }

    }

    static synchronized void setHandler(Class<? extends Event> eventClass, EventHandler handler) {

        Utils.ensureValidEventSubclass(eventClass);

        try {

            Field field = eventClass.getDeclaredField(EventInstrumentation.FIELD_EVENT_HANDLER);

            SecuritySupport.setAccessible(field);

            field.set(null, handler);

        } catch (NoSuchFieldException | IllegalArgumentException | IllegalAccessException e) {

            throw new InternalError("Could not access event handler");

        }

    }

    public static Map<String, String> sanitizeNullFreeStringMap(Map<String, String> settings) {

        HashMap<String, String> map = new HashMap<>(settings.size());

        for (Map.Entry<String, String> e : settings.entrySet()) {

            String key = e.getKey();

            if (key == null) {

                throw new NullPointerException("Null key is not allowed in map");

            }

            String value = e.getValue();

            if (value == null) {

                throw new NullPointerException("Null value is not allowed in map");

            }

            map.put(key, value);

        }

        return map;

    }

    public static <T> List<T> sanitizeNullFreeList(List<T> elements, Class<T> clazz) {

        List<T> sanitized = new ArrayList<>(elements.size());

        for (T element : elements) {

            if (element == null) {

                throw new NullPointerException("Null is not an allowed element in list");

            }

            if (element.getClass() != clazz) {

                throw new ClassCastException();

            }

            sanitized.add(element);

        }

        return sanitized;

    }

    static List<Field> getVisibleEventFields(Class<?> clazz) {

        Utils.ensureValidEventSubclass(clazz);

        List<Field> fields = new ArrayList<>();

        for (Class<?> c = clazz; c != Event.class; c = c.getSuperclass()) {

            for (Field field : c.getDeclaredFields()) {

                // skip private field in base classes

                if (c == clazz || !Modifier.isPrivate(field.getModifiers())) {

                    fields.add(field);

                }

            }

        }

        return fields;

    }

    public static void ensureValidEventSubclass(Class<?> eventClass) {

        if (Event.class.isAssignableFrom(eventClass) && Modifier.isAbstract(eventClass.getModifiers())) {

            throw new IllegalArgumentException("Abstract event classes are not allowed");

        }

        if (eventClass == Event.class || !Event.class.isAssignableFrom(eventClass)) {

            throw new IllegalArgumentException("Must be a subclass to " + Event.class.getName());

        }

    }

    public static void writeGeneratedASM(String className, byte[] bytes) {

        if (SAVE_GENERATED == null) {

            // We can't calculate value statically because it will force

            // initialization of SecuritySupport, which cause

            // UnsatisfiedLinkedError on JDK 8 or non-Oracle JDKs

            SAVE_GENERATED = SecuritySupport.getBooleanProperty("jfr.save.generated.asm");

        }

        if (SAVE_GENERATED) {

            try {

                try (FileOutputStream fos = new FileOutputStream(className + ".class")) {

                    fos.write(bytes);

                }

                try (FileWriter fw = new FileWriter(className + ".asm"); PrintWriter pw = new PrintWriter(fw)) {

                    ClassReader cr = new ClassReader(bytes);

                    CheckClassAdapter.verify(cr, true, pw);

                }

                Logger.log(LogTag.JFR_SYSTEM_BYTECODE, LogLevel.INFO, "Instrumented code saved to " + className + ".class and .asm");

            } catch (IOException e) {

                Logger.log(LogTag.JFR_SYSTEM_BYTECODE, LogLevel.INFO, "Could not save instrumented code, for " + className + ".class and .asm");

            }

        }

    }

    public static void ensureInitialized(Class<? extends Event> eventClass) {

        SecuritySupport.ensureClassIsInitialized(eventClass);

    }

    public static Object makePrimitiveArray(String typeName, List<Object> values) {

        int length = values.size();

        switch (typeName) {

        case "int":

            int[] ints = new int[length];

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

                ints[i] = (int) values.get(i);

            }

            return ints;

        case "long":

            long[] longs = new long[length];

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

                longs[i] = (long) values.get(i);

            }

            return longs;

        case "float":

            float[] floats = new float[length];

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

                floats[i] = (float) values.get(i);

            }

            return floats;

        case "double":

            double[] doubles = new double[length];

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

                doubles[i] = (double) values.get(i);

            }

            return doubles;

        case "short":

            short[] shorts = new short[length];

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

                shorts[i] = (short) values.get(i);

            }

            return shorts;

        case "char":

            char[] chars = new char[length];

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

                chars[i] = (char) values.get(i);

            }

            return chars;

        case "byte":

            byte[] bytes = new byte[length];

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

                bytes[i] = (byte) values.get(i);

            }

            return bytes;

        case "boolean":

            boolean[] booleans = new boolean[length];

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

                booleans[i] = (boolean) values.get(i);

            }

            return booleans;

        case "java.lang.String":

            String[] strings = new String[length];

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

                strings[i] = (String) values.get(i);

            }

            return strings;

        }

        return null;

    }

    public static boolean isSettingVisible(Control c, boolean hasEventHook) {

        if (c instanceof ThresholdSetting) {

            return !hasEventHook;

        }

        if (c instanceof PeriodSetting) {

            return hasEventHook;

        }

        if (c instanceof StackTraceSetting) {

            return !hasEventHook;

        }

        return true;

    }

    public static boolean isSettingVisible(long typeId, boolean hasEventHook) {

        if (ThresholdSetting.isType(typeId)) {

            return !hasEventHook;

        }

        if (PeriodSetting.isType(typeId)) {

            return hasEventHook;

        }

        if (StackTraceSetting.isType(typeId)) {

            return !hasEventHook;

        }

        return true;

    }

    public static Type getValidType(Class<?> type, String name) {

        Objects.requireNonNull(type, "Null is not a valid type for value descriptor " + name);

        if (type.isArray()) {

            type = type.getComponentType();

            if (type != String.class && !type.isPrimitive()) {

                throw new IllegalArgumentException("Only arrays of primitives and Strings are allowed");

            }

        }

        Type knownType = Type.getKnownType(type);

        if (knownType == null || knownType == Type.STACK_TRACE) {

            throw new IllegalArgumentException("Only primitive types, java.lang.Thread, java.lang.String and java.lang.Class are allowed for value descriptors. " + type.getName());

        }

        return knownType;

    }

    public static <T> List<T> smallUnmodifiable(List<T> list) {

        if (list.isEmpty()) {

            return Collections.emptyList();

        }

        if (list.size() == 1) {

            return Collections.singletonList(list.get(0));

        }

        return Collections.unmodifiableList(list);

    }

    public static void updateSettingPathToGcRoots(Map<String, String> settings, Boolean pathToGcRoots) {

        if (pathToGcRoots != null) {

            settings.put(Type.EVENT_NAME_PREFIX + "OldObjectSample#cutoff", pathToGcRoots ? "infinity" : "0 ns" );

        }

    }

    public static String upgradeLegacyJDKEvent(String eventName) {

        if (eventName.length() <= LEGACY_EVENT_NAME_PREFIX.length()) {

            return eventName;

        }

        if (eventName.startsWith(LEGACY_EVENT_NAME_PREFIX)) {

            int index = eventName.lastIndexOf(".");

            if (index == LEGACY_EVENT_NAME_PREFIX.length() - 1) {

                return Type.EVENT_NAME_PREFIX + eventName.substring(index + 1);

            }

        }

        return eventName;

    }

}