/*

 * 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.objects;

import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;

import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;

import java.lang.reflect.Array;

import java.util.Collection;

import jdk.internal.dynalink.beans.StaticClass;

import jdk.internal.dynalink.support.TypeUtilities;

import jdk.nashorn.internal.objects.annotations.Attribute;

import jdk.nashorn.internal.objects.annotations.Function;

import jdk.nashorn.internal.objects.annotations.ScriptClass;

import jdk.nashorn.internal.objects.annotations.Where;

import jdk.nashorn.internal.runtime.JSType;

import jdk.nashorn.internal.runtime.ScriptObject;

import jdk.nashorn.internal.runtime.linker.JavaAdapterFactory;

/**

 * This class is the implementation for the {@code Java} global object exposed to programs running under Nashorn. This

 * object acts as the API entry point to Java platform specific functionality, dealing with creating new instances of

 * Java classes, subclassing Java classes, implementing Java interfaces, converting between Java arrays and ECMAScript

 * arrays, and so forth.

 */

@ScriptClass("Java")

public final class NativeJava {

    private NativeJava() {

    }

    /**

     * Returns true if the specified object is a Java type object, that is an instance of {@link StaticClass}.

     * @param self not used

     * @param type the object that is checked if it is a type object or not

     * @return tells whether given object is a Java type object or not.

     * @see #type(Object, Object)

     */

    @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)

    public static Object isType(final Object self, final Object type) {

        return type instanceof StaticClass;

    }

    /**

     * <p>

     * Given a name of a Java type, returns an object representing that type in Nashorn. The Java class of the objects

     * used to represent Java types in Nashorn is not {@link java.lang.Class} but rather {@link StaticClass}. They are

     * the objects that you can use with the {@code new} operator to create new instances of the class as well as to

     * access static members of the class. In Nashorn, {@code Class} objects are just regular Java objects that aren't

     * treated specially. Instead of them, {@link StaticClass} instances - which we sometimes refer to as "Java type

     * objects" are used as constructors with the {@code new} operator, and they expose static fields, properties, and

     * methods. While this might seem confusing at first, it actually closely matches the Java language: you use a

     * different expression (e.g. {@code java.io.File}) as an argument in "new" and to address statics, and it is

     * distinct from the {@code Class} object (e.g. {@code java.io.File.class}). Below we cover in details the

     * properties of the type objects.

     * </p>

     * <p><b>Constructing Java objects</b></p>

     * Examples:

     * <pre>

     * var arrayListType = Java.type("java.util.ArrayList")

     * var intType = Java.type("int")

     * var stringArrayType = Java.type("java.lang.String[]")

     * var int2DArrayType = Java.type("int[][]")

     * </pre>

     * Note that the name of the type is always a string for a fully qualified name. You can use any of these types to

     * create new instances, e.g.:

     * <pre>

     * var anArrayList = new Java.type("java.util.ArrayList")

     * </pre>

     * or

     * <pre>

     * var ArrayList = Java.type("java.util.ArrayList")

     * var anArrayList = new ArrayList

     * var anArrayListWithSize = new ArrayList(16)

     * </pre>

     * In the special case of inner classes, you need to use the JVM fully qualified name, meaning using {@code $} sign

     * in the class name:

     * <pre>

     * var ftype = Java.type("java.awt.geom.Arc2D$Float")

     * </pre>

     * However, once you retrieved the outer class, you can access the inner class as a property on it:

     * <pre>

     * var arctype = Java.type("java.awt.geom.Arc2D")

     * var ftype = arctype.Float

     * </pre>

     * <p>

     * You can access both static and non-static inner classes. If you want to create an instance of a non-static

     * inner class, remember to pass an instance of its outer class as the first argument to the constructor.

     * </p>

     * <p>

     * If the type is abstract, you can instantiate an anonymous subclass of it using an argument list that is

     * applicable to any of its public or protected constructors, but inserting a JavaScript object with functions

     * properties that provide JavaScript implementations of the abstract methods. If method names are overloaded, the

     * JavaScript function will provide implementation for all overloads. E.g.:

     * </p>

     * <pre>

     * var TimerTask =  Java.type("java.util.TimerTask")

     * var task = new TimerTask({ run: function() { print("Hello World!") } })

     * </pre>

     * <p>

     * Nashorn supports a syntactic extension where a "new" expression followed by an argument is identical to

     * invoking the constructor and passing the argument to it, so you can write the above example also as:

     * </p>

     * <pre>

     * var task = new TimerTask {

     *     run: function() {

     *       print("Hello World!")

     *     }

     * }

     * </pre>

     * <p>

     * which is very similar to Java anonymous inner class definition. On the other hand, if the type is an abstract

     * type with a single abstract method (commonly referred to as a "SAM type") or all abstract methods it has share

     * the same overloaded name), then instead of an object, you can just pass a function, so the above example can

     * become even more simplified to:

     * </p>

     * <pre>

     * var task = new TimerTask(function() { print("Hello World!") })

     * </pre>

     * <p>

     * Note that in every one of these cases if you are trying to instantiate an abstract class that has constructors

     * that take some arguments, you can invoke those simply by specifying the arguments after the initial

     * implementation object or function.

     * </p>

     * <p>The use of functions can be taken even further; if you are invoking a Java method that takes a SAM type,

     * you can just pass in a function object, and Nashorn will know what you meant:

     * </p>

     * <pre>

     * var timer = new Java.type("java.util.Timer")

     * timer.schedule(function() { print("Hello World!") })

     * </pre>

     * <p>

     * Here, {@code Timer.schedule()} expects a {@code TimerTask} as its argument, so Nashorn creates an instance of a

     * {@code TimerTask} subclass and uses the passed function to implement its only abstract method, {@code run()}. In

     * this usage though, you can't use non-default constructors; the type must be either an interface, or must have a

     * protected or public no-arg constructor.

     * </p>

     * <p>

     * You can also subclass non-abstract classes; for that you will need to use the {@link #extend(Object, Object...)}

     * method.

     * </p>

     * <p><b>Accessing static members</b></p>

     * Examples:

     * <pre>

     * var File = Java.type("java.io.File")

     * var pathSep = File.pathSeparator

     * var tmpFile1 = File.createTempFile("abcdefg", ".tmp")

     * var tmpFile2 = File.createTempFile("abcdefg", ".tmp", new File("/tmp"))

     * </pre>

     * Actually, you can even assign static methods to variables, so the above example can be rewritten as:

     * <pre>

     * var File = Java.type("java.io.File")

     * var createTempFile = File.createTempFile

     * var tmpFile1 = createTempFile("abcdefg", ".tmp")

     * var tmpFile2 = createTempFile("abcdefg", ".tmp", new File("/tmp"))

     * </pre>

     * If you need to access the actual {@code java.lang.Class} object for the type, you can use the {@code class}

     * property on the object representing the type:

     * <pre>

     * var File = Java.type("java.io.File")

     * var someFile = new File("blah")

     * print(File.class === someFile.getClass()) // prints true

     * </pre>

     * Of course, you can also use the {@code getClass()} method or its equivalent {@code class} property on any

     * instance of the class. Other way round, you can use the synthetic {@code static} property on any

     * {@code java.lang.Class} object to retrieve its type-representing object:

     * <pre>

     * var File = Java.type("java.io.File")

     * print(File.class.static === File) // prints true

     * </pre>

     * <p><b>{@code instanceof} operator</b></p>

     * The standard ECMAScript {@code instanceof} operator is extended to recognize Java objects and their type objects:

     * <pre>

     * var File = Java.type("java.io.File")

     * var aFile = new File("foo")

     * print(aFile instanceof File) // prints true

     * print(aFile instanceof File.class) // prints false - Class objects aren't type objects.

     * </pre>

     * @param self not used

     * @param objTypeName the object whose JS string value represents the type name. You can use names of primitive Java

     * types to obtain representations of them, and you can use trailing square brackets to represent Java array types.

     * @return the object representing the named type

     * @throws ClassNotFoundException if the class is not found

     */

    @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)

    public static Object type(final Object self, final Object objTypeName) throws ClassNotFoundException {

        return type(objTypeName);

    }

    private static StaticClass type(final Object objTypeName) throws ClassNotFoundException {

        return StaticClass.forClass(type(JSType.toString(objTypeName)));

    }

    private static Class<?> type(final String typeName) throws ClassNotFoundException {

        if (typeName.endsWith("[]")) {

            return arrayType(typeName);

        }

        return simpleType(typeName);

    }

    /**

     * Given a JavaScript array and a Java type, returns a Java array with the same initial contents, and with the

     * specified component type. Example:

     * <pre>

     * var anArray = [1, "13", false]

     * var javaIntArray = Java.toJavaArray(anArray, "int")

     * print(javaIntArray[0]) // prints 1

     * print(javaIntArray[1]) // prints 13, as string "13" was converted to number 13 as per ECMAScript ToNumber conversion

     * print(javaIntArray[2]) // prints 0, as boolean false was converted to number 0 as per ECMAScript ToNumber conversion

     * </pre>

     * @param self not used

     * @param objArray the JavaScript array. Can be null.

     * @param objType either a {@link #type(Object, Object) type object} or a String describing the component type of

     * the Java array to create. Can not be null. If undefined, Object is assumed (allowing the argument to be omitted).

     * @return a Java array with the copy of JavaScript array's contents, converted to the appropriate Java component

     * type. Returns null if objArray is null.

     * @throws ClassNotFoundException if the class described by objType is not found

     */

    @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)

    public static Object toJavaArray(final Object self, final Object objArray, final Object objType) throws ClassNotFoundException {

        final StaticClass componentType =

            objType instanceof StaticClass ?

                (StaticClass)objType :

                objType == UNDEFINED ?

                    StaticClass.forClass(Object.class) :

                    type(objType);

        if (objArray == null) {

            return null;

        }

        Global.checkObject(objArray);

        return ((ScriptObject)objArray).getArray().asArrayOfType(componentType.getRepresentedClass());

    }

    /**

     * Given a Java array or {@link Collection}, returns a JavaScript array with a shallow copy of its contents. Note

     * that in most cases, you can use Java arrays and lists natively in Nashorn; in cases where for some reason you

     * need to have an actual JavaScript native array (e.g. to work with the array comprehensions functions), you will

     * want to use this method. Example:

     * <pre>

     * var File = Java.type("java.io.File")

     * var listHomeDir = new File("~").listFiles()

     * var jsListHome = Java.toJavaScriptArray(listHomeDir)

     * var jpegModifiedDates = jsListHome

     *     .filter(function(val) { return val.getName().endsWith(".jpg") })

     *     .map(function(val) { return val.lastModified() })

     * </pre>

     * @param self not used

     * @param objArray the java array or collection. Can be null.

     * @return a JavaScript array with the copy of Java array's or collection's contents. Returns null if objArray is

     * null.

     */

    @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)

    public static Object toJavaScriptArray(final Object self, final Object objArray) {

        if (objArray == null) {

            return null;

        } else if (objArray instanceof Collection) {

            return new NativeArray(((Collection<?>)objArray).toArray());

        } else if (objArray instanceof Object[]) {

            return new NativeArray(((Object[])objArray).clone());

        } else if (objArray instanceof int[]) {

            return new NativeArray(((int[])objArray).clone());

        } else if (objArray instanceof double[]) {

            return new NativeArray(((double[])objArray).clone());

        } else if (objArray instanceof long[]) {

            return new NativeArray(((long[])objArray).clone());

        } else if (objArray instanceof byte[]) {

            return new NativeArray(copyArray((byte[])objArray));

        } else if (objArray instanceof short[]) {

            return new NativeArray(copyArray((short[])objArray));

        } else if (objArray instanceof char[]) {

            return new NativeArray(copyArray((char[])objArray));

        } else if (objArray instanceof float[]) {

            return new NativeArray(copyArray((float[])objArray));

        } else if (objArray instanceof boolean[]) {

            return new NativeArray(copyArray((boolean[])objArray));

        }

        throw typeError("cant.convert.to.javascript.array", objArray.getClass().getName());

    }

    private static int[] copyArray(final byte[] in) {

        final int[] out = new int[in.length];

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

            out[i] = in[i];

        }

        return out;

    }

    private static int[] copyArray(final short[] in) {

        final int[] out = new int[in.length];

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

            out[i] = in[i];

        }

        return out;

    }

    private static int[] copyArray(final char[] in) {

        final int[] out = new int[in.length];

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

            out[i] = in[i];

        }

        return out;

    }

    private static double[] copyArray(final float[] in) {

        final double[] out = new double[in.length];

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

            out[i] = in[i];

        }

        return out;

    }

    private static Object[] copyArray(final boolean[] in) {

        final Object[] out = new Object[in.length];

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

            out[i] = in[i];

        }

        return out;

    }

    private static Class<?> simpleType(final String typeName) throws ClassNotFoundException {

        final Class<?> primClass = TypeUtilities.getPrimitiveTypeByName(typeName);

        return primClass != null ? primClass : Global.getThisContext().findClass(typeName);

    }

    private static Class<?> arrayType(final String typeName) throws ClassNotFoundException {

        return Array.newInstance(type(typeName.substring(0, typeName.length() - 2)), 0).getClass();

    }

    /**

     * Returns a type object for a subclass of the specified Java class (or implementation of the specified interface)

     * that acts as a script-to-Java adapter for it. See {@link #type(Object, Object)} for a discussion of type objects,

     * and see {@link JavaAdapterFactory} for details on script-to-Java adapters. Note that you can also implement

     * interfaces and subclass abstract classes using {@code new} operator on a type object for an interface or abstract

     * class. However, to extend a non-abstract class, you will have to use this method. Example:

     * <pre>

     * var ArrayList = Java.type("java.util.ArrayList")

     * var ArrayListExtender = Java.extend(ArrayList)

     * var printSizeInvokedArrayList = new ArrayListExtender() {

     *     size: function() { print("size invoked!"); }

     * }

     * var printAddInvokedArrayList = new ArrayListExtender() {

     *     add: function(x, y) {

     *       if(typeof(y) === "undefined") {

     *           print("add(e) invoked!");

     *       } else {

     *           print("add(i, e) invoked!");

     *       }

     * }

     * </pre>

     * We can see several important concepts in the above example:

     * <ul>

     * <li>Every Java class will have exactly one extender subclass in Nashorn - repeated invocations of {@code extend}

     * for the same type will yield the same extender type. It's a generic adapter that delegates to whatever JavaScript

     * functions its implementation object has on a per-instance basis.</li>

     * <li>If the Java method is overloaded (as in the above example {@code List.add()}), then your JavaScript adapter

     * must be prepared to deal with all overloads.</li>

     * <li>You can't invoke {@code super.*()} from adapters for now.</li>

     * </ul>

     * @param self not used

     * @param types the original types. The caller must pass at least one Java type object of class {@link StaticClass}

     * representing either a public interface or a non-final public class with at least one public or protected

     * constructor. If more than one type is specified, at most one can be a class and the rest have to be interfaces.

     * Invoking the method twice with exactly the same types in the same order will return the same adapter

     * class, any reordering of types or even addition or removal of redundant types (i.e. interfaces that other types

     * in the list already implement/extend, or {@code java.lang.Object} in a list of types consisting purely of

     * interfaces) will result in a different adapter class, even though those adapter classes are functionally

     * identical; we deliberately don't want to incur the additional processing cost of canonicalizing type lists.

     * @return a new {@link StaticClass} that represents the adapter for the original types.

     */

    @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)

    public static Object extend(final Object self, final Object... types) {

        if(types == null || types.length == 0) {

            throw typeError("extend.expects.at.least.one.argument");

        }

        final Class<?>[] stypes = new Class<?>[types.length];

        try {

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

                stypes[i] = ((StaticClass)types[i]).getRepresentedClass();

            }

        } catch(final ClassCastException e) {

            throw typeError("extend.expects.java.types");

        }

        return JavaAdapterFactory.getAdapterClassFor(stypes);

    }

}