/*

 * Copyright (c) 2016, 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 java.lang.invoke;

import java.util.Map;

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

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

import java.util.ArrayList;

import java.util.HashSet;

/**

 * Helper class to assist the GenerateJLIClassesPlugin to get access to

 * generate classes ahead of time.

 */

class GenerateJLIClassesHelper {

    static byte[] generateDirectMethodHandleHolderClassBytes(String className,

            MethodType[] methodTypes, int[] types) {

        LambdaForm[] forms = new LambdaForm[methodTypes.length];

        String[] names = new String[methodTypes.length];

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

            forms[i] = DirectMethodHandle.makePreparedLambdaForm(methodTypes[i],

                                                                 types[i]);

            names[i] = forms[i].kind.defaultLambdaName;

        }

        return generateCodeBytesForLFs(className, names, forms);

    }

    static byte[] generateDelegatingMethodHandleHolderClassBytes(String className,

            MethodType[] methodTypes) {

        HashSet<MethodType> dedupSet = new HashSet<>();

        ArrayList<LambdaForm> forms = new ArrayList<>();

        ArrayList<String> names = new ArrayList<>();

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

            // generate methods representing the DelegatingMethodHandle

            if (dedupSet.add(methodTypes[i])) {

                // reinvokers are variant with the associated SpeciesData

                // and shape of the target LF, but we can easily pregenerate

                // the basic reinvokers associated with Species_L. Ultimately we

                // may want to consider pregenerating more of these, which will

                // require an even more complex naming scheme

                LambdaForm reinvoker = makeReinvokerFor(methodTypes[i]);

                forms.add(reinvoker);

                String speciesSig = BoundMethodHandle

                        .speciesData(reinvoker).fieldSignature();

                assert(speciesSig.equals("L"));

                names.add(reinvoker.kind.defaultLambdaName + "_" + speciesSig);

                LambdaForm delegate = makeDelegateFor(methodTypes[i]);

                forms.add(delegate);

                names.add(delegate.kind.defaultLambdaName);

            }

        }

        return generateCodeBytesForLFs(className,

                names.toArray(new String[0]),

                forms.toArray(new LambdaForm[0]));

    }

    /*

     * Generate customized code for a set of LambdaForms of specified types into

     * a class with a specified name.

     */

    private static byte[] generateCodeBytesForLFs(String className,

            String[] names, LambdaForm[] forms) {

        ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);

        cw.visit(Opcodes.V1_8, Opcodes.ACC_PRIVATE + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER,

                className, null, InvokerBytecodeGenerator.INVOKER_SUPER_NAME, null);

        cw.visitSource(className.substring(className.lastIndexOf('/') + 1), null);

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

            addMethod(className, names[i], forms[i],

                    forms[i].methodType(), cw);

        }

        return cw.toByteArray();

    }

    private static void addMethod(String className, String methodName, LambdaForm form,

            MethodType type, ClassWriter cw) {

        InvokerBytecodeGenerator g

                = new InvokerBytecodeGenerator(className, methodName, form, type);

        g.setClassWriter(cw);

        g.addMethod();

    }

    private static LambdaForm makeReinvokerFor(MethodType type) {

        MethodHandle emptyHandle = MethodHandles.empty(type);

        return DelegatingMethodHandle.makeReinvokerForm(emptyHandle,

                MethodTypeForm.LF_REBIND,

                BoundMethodHandle.speciesData_L(),

                BoundMethodHandle.speciesData_L().getterFunction(0));

    }

    private static LambdaForm makeDelegateFor(MethodType type) {

        MethodHandle handle = MethodHandles.empty(type);

        return DelegatingMethodHandle.makeReinvokerForm(

                handle,

                MethodTypeForm.LF_DELEGATE,

                DelegatingMethodHandle.class,

                DelegatingMethodHandle.NF_getTarget);

    }

    static Map.Entry<String, byte[]> generateConcreteBMHClassBytes(

            final String types) {

        for (char c : types.toCharArray()) {

            if ("LIJFD".indexOf(c) < 0) {

                throw new IllegalArgumentException("All characters must "

                        + "correspond to a basic field type: LIJFD");

            }

        }

        String shortTypes = LambdaForm.shortenSignature(types);

        final String className =

                BoundMethodHandle.Factory.speciesInternalClassName(shortTypes);

        return Map.entry(className,

                         BoundMethodHandle.Factory.generateConcreteBMHClassBytes(

                                 shortTypes, types, className));

    }

}