/*
 * 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
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package jdk.nashorn.internal.runtime;

import static jdk.nashorn.internal.codegen.CompilerConstants.SOURCE;
import static jdk.nashorn.internal.runtime.UnwarrantedOptimismException.INVALID_PROGRAM_POINT;

import java.lang.invoke.MethodHandle;
import java.lang.reflect.Field;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;
import jdk.nashorn.internal.scripts.JS;

This class provides support for external debuggers.  Its primary purpose is
is to simplify the debugger tasks and provide better performance.
Even though the methods are not public, there are still part of the
external debugger interface.
/**
 * This class provides support for external debuggers.  Its primary purpose is
 * is to simplify the debugger tasks and provide better performance.
 * Even though the methods are not public, there are still part of the
 * external debugger interface.
 */
final class DebuggerSupport {
    
Hook to force the loading of the DebuggerSupport class so that it is
available to external debuggers.
/**
     * Hook to force the loading of the DebuggerSupport class so that it is
     * available to external debuggers.
     */
    static boolean FORCELOAD = true;

    static {
        /**
         * Hook to force the loading of the DebuggerValueDesc class so that it is
         * available to external debuggers.
         */
        @SuppressWarnings("unused")
        final
        DebuggerValueDesc forceLoad = new DebuggerValueDesc(null, false, null, null);

        // Hook to force the loading of the SourceInfo class
        @SuppressWarnings("unused")
        final
        SourceInfo srcInfo = new SourceInfo(null, 0, null, null);
    }

    
This class is used to send a bulk description of a value. /** This class is used to send a bulk description of a value. */
    static class DebuggerValueDesc {
        
Property key (or index) or field name. /** Property key (or index) or field name. */
        final String key;

        
If the value is expandable. /** If the value is expandable. */
        final boolean expandable;

        
Property or field value as object. /** Property or field value as object. */
        final Object valueAsObject;

        
Property or field value as string. /** Property or field value as string. */
        final String valueAsString;

        DebuggerValueDesc(final String key, final boolean expandable, final Object valueAsObject, final String valueAsString) {
            this.key           = key;
            this.expandable    = expandable;
            this.valueAsObject = valueAsObject;
            this.valueAsString = valueAsString;
        }
    }

    static class SourceInfo {
        final String name;
        final URL    url;
        final int    hash;
        final char[] content;

        SourceInfo(final String name, final int hash, final URL url, final char[] content) {
            this.name    = name;
            this.hash    = hash;
            this.url     = url;
            this.content = content;
        }
    }

    
Hook that is called just before invoking method handle
from ScriptFunctionData via invoke, constructor method calls.
Params:
mh – script class method about to be invoked./**
     * Hook that is called just before invoking method handle
     * from ScriptFunctionData via invoke, constructor method calls.
     *
     * @param mh script class method about to be invoked.
     */
    static void notifyInvoke(final MethodHandle mh) {
        // Do nothing here. This is placeholder method on which a
        // debugger can place a breakpoint so that it can access the
        // (script class) method handle that is about to be invoked.
        // See ScriptFunctionData.invoke and ScriptFunctionData.construct.
    }

    
Return the script source info for the given script class.
Params:
clazz – compiled script class
Returns:
SourceInfo/**
     * Return the script source info for the given script class.
     *
     * @param clazz compiled script class
     * @return SourceInfo
     */
    static SourceInfo getSourceInfo(final Class<?> clazz) {
        if (JS.class.isAssignableFrom(clazz)) {
            try {
                final Field sourceField = clazz.getDeclaredField(SOURCE.symbolName());
                sourceField.setAccessible(true);
                final Source src = (Source) sourceField.get(null);
                return src.getSourceInfo();
            } catch (final IllegalAccessException | NoSuchFieldException ignored) {
                return null;
            }
        }

        return null;
    }

    
Return the current context global.
Returns:
context global./**
     * Return the current context global.
     * @return context global.
     */
    static Object getGlobal() {
        return Context.getGlobal();
    }

    
Call eval on the current global.
Params:
scope –           Scope to use.
self –            Receiver to use.
string –          String to evaluate.
returnException – true if exceptions are to be returned.
Returns:
Result of eval, or, an exception or null depending on returnException./**
     * Call eval on the current global.
     * @param scope           Scope to use.
     * @param self            Receiver to use.
     * @param string          String to evaluate.
     * @param returnException true if exceptions are to be returned.
     * @return Result of eval, or, an exception or null depending on returnException.
     */
    static Object eval(final ScriptObject scope, final Object self, final String string, final boolean returnException) {
        final ScriptObject global = Context.getGlobal();
        final ScriptObject initialScope = scope != null ? scope : global;
        final Object callThis = self != null ? self : global;
        final Context context = global.getContext();

        try {
            return context.eval(initialScope, string, callThis, ScriptRuntime.UNDEFINED);
        } catch (final Throwable ex) {
            return returnException ? ex : null;
        }
    }

    
This method returns a bulk description of an object's properties.
Params:
object – Script object to be displayed by the debugger.
all –    true if to include non-enumerable values.
Returns:
An array of DebuggerValueDesc./**
     * This method returns a bulk description of an object's properties.
     * @param object Script object to be displayed by the debugger.
     * @param all    true if to include non-enumerable values.
     * @return An array of DebuggerValueDesc.
     */
    static DebuggerValueDesc[] valueInfos(final Object object, final boolean all) {
        assert object instanceof ScriptObject;
        return getDebuggerValueDescs((ScriptObject)object, all, new HashSet<>());
    }

    
This method returns a debugger description of the value.
Params:
name –  Name of value (property name).
value – Data value.
all –   true if to include non-enumerable values.
Returns:
A DebuggerValueDesc./**
     * This method returns a debugger description of the value.
     * @param name  Name of value (property name).
     * @param value Data value.
     * @param all   true if to include non-enumerable values.
     * @return A DebuggerValueDesc.
     */
    static DebuggerValueDesc valueInfo(final String name, final Object value, final boolean all) {
        return valueInfo(name, value, all, new HashSet<>());
    }

   
This method returns a debugger description of the value.
Params:
name –       Name of value (property name).
value –      Data value.
all –        true if to include non-enumerable values.
duplicates – Duplication set to avoid cycles.
Returns:
A DebuggerValueDesc./**
     * This method returns a debugger description of the value.
     * @param name       Name of value (property name).
     * @param value      Data value.
     * @param all        true if to include non-enumerable values.
     * @param duplicates Duplication set to avoid cycles.
     * @return A DebuggerValueDesc.
     */
    private static DebuggerValueDesc valueInfo(final String name, final Object value, final boolean all, final Set<Object> duplicates) {
        if (value instanceof ScriptObject && !(value instanceof ScriptFunction)) {
            final ScriptObject object = (ScriptObject)value;
            return new DebuggerValueDesc(name, !object.isEmpty(), value, objectAsString(object, all, duplicates));
        }
        return new DebuggerValueDesc(name, false, value, valueAsString(value));
    }

    
Generate the descriptions for an object's properties.
Params:
object –     Object to introspect.
all –        true if to include non-enumerable values.
duplicates – Duplication set to avoid cycles.
Returns:
An array of DebuggerValueDesc./**
     * Generate the descriptions for an object's properties.
     * @param object     Object to introspect.
     * @param all        true if to include non-enumerable values.
     * @param duplicates Duplication set to avoid cycles.
     * @return An array of DebuggerValueDesc.
     */
    private static DebuggerValueDesc[] getDebuggerValueDescs(final ScriptObject object, final boolean all, final Set<Object> duplicates) {
        if (duplicates.contains(object)) {
            return null;
        }

        duplicates.add(object);

        final String[] keys = object.getOwnKeys(all);
        final DebuggerValueDesc[] descs = new DebuggerValueDesc[keys.length];

        for (int i = 0; i < keys.length; i++) {
            final String key = keys[i];
            descs[i] = valueInfo(key, object.get(key), all, duplicates);
        }

        duplicates.remove(object);

        return descs;
    }

    
Generate a string representation of a Script object.
Params:
object –     Script object to represent.
all –        true if to include non-enumerable values.
duplicates – Duplication set to avoid cycles.
Returns:
String representation./**
     * Generate a string representation of a Script object.
     * @param object     Script object to represent.
     * @param all        true if to include non-enumerable values.
     * @param duplicates Duplication set to avoid cycles.
     * @return String representation.
     */
    private static String objectAsString(final ScriptObject object, final boolean all, final Set<Object> duplicates) {
        final StringBuilder sb = new StringBuilder();

        if (ScriptObject.isArray(object)) {
            sb.append('[');
            final long length = (long) object.getDouble("length", INVALID_PROGRAM_POINT);

            for (long i = 0; i < length; i++) {
                if (object.has(i)) {
                    final Object valueAsObject = object.get(i);
                    final boolean isUndefined = valueAsObject == ScriptRuntime.UNDEFINED;

                    if (isUndefined) {
                        if (i != 0) {
                            sb.append(",");
                        }
                    } else {
                        if (i != 0) {
                            sb.append(", ");
                        }

                        if (valueAsObject instanceof ScriptObject && !(valueAsObject instanceof ScriptFunction)) {
                            final String objectString = objectAsString((ScriptObject)valueAsObject, all, duplicates);
                            sb.append(objectString != null ? objectString : "{...}");
                        } else {
                            sb.append(valueAsString(valueAsObject));
                        }
                    }
                } else {
                    if (i != 0) {
                        sb.append(',');
                    }
                }
            }

            sb.append(']');
        } else {
            sb.append('{');
            final DebuggerValueDesc[] descs = getDebuggerValueDescs(object, all, duplicates);

            if (descs != null) {
                for (int i = 0; i < descs.length; i++) {
                    if (i != 0) {
                        sb.append(", ");
                    }

                    final String valueAsString = descs[i].valueAsString;
                    sb.append(descs[i].key);
                    sb.append(": ");
                    sb.append(valueAsString);
                }
            }

            sb.append('}');
        }

        return sb.toString();
    }

    
This method returns a string representation of a value.
Params:
value – Arbitrary value to be displayed by the debugger.
Returns:
A string representation of the value or an array of DebuggerValueDesc./**
     * This method returns a string representation of a value.
     * @param value Arbitrary value to be displayed by the debugger.
     * @return A string representation of the value or an array of DebuggerValueDesc.
     */
    static String valueAsString(final Object value) {
        final JSType type = JSType.of(value);

        switch (type) {
        case BOOLEAN:
            return value.toString();

        case STRING:
            return escape(value.toString());

        case NUMBER:
            return JSType.toString(((Number)value).doubleValue());

        case NULL:
            return "null";

        case UNDEFINED:
            return "undefined";

        case OBJECT:
            return ScriptRuntime.safeToString(value);

        case FUNCTION:
            if (value instanceof ScriptFunction) {
                return ((ScriptFunction)value).toSource();
            }
            return value.toString();

        default:
            return value.toString();
        }
    }

    
Escape a string into a form that can be parsed by JavaScript.
Params:
value – String to be escaped.
Returns:
Escaped string./**
     * Escape a string into a form that can be parsed by JavaScript.
     * @param value String to be escaped.
     * @return Escaped string.
     */
    private static String escape(final String value) {
        final StringBuilder sb = new StringBuilder();

        sb.append("\"");

        for (final char ch : value.toCharArray()) {
            switch (ch) {
            case '\\':
                sb.append("\\\\");
                break;
            case '"':
                sb.append("\\\"");
                break;
            case '\'':
                sb.append("\\\'");
                break;
            case '\b':
                sb.append("\\b");
                break;
            case '\f':
                sb.append("\\f");
                break;
            case '\n':
                sb.append("\\n");
                break;
            case '\r':
                sb.append("\\r");
                break;
            case '\t':
                sb.append("\\t");
                break;
            default:
                if (ch < ' ' || ch >= 0xFF) {
                    sb.append("\\u");

                    final String hex = Integer.toHexString(ch);
                    for (int i = hex.length(); i < 4; i++) {
                        sb.append('0');
                    }
                    sb.append(hex);
                } else {
                    sb.append(ch);
                }

                break;
            }
        }

        sb.append("\"");

        return sb.toString();
    }
}