/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *

 *   - Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 *

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodType;

import java.util.ArrayList;

import java.util.List;

import java.util.regex.Pattern;

import java.util.regex.Matcher;

import jdk.dynalink.CallSiteDescriptor;

import jdk.dynalink.CompositeOperation;

import jdk.dynalink.NamedOperation;

import jdk.dynalink.Operation;

import jdk.dynalink.CompositeOperation;

import jdk.dynalink.StandardOperation;

import jdk.dynalink.linker.GuardingDynamicLinker;

import jdk.dynalink.linker.GuardingDynamicLinkerExporter;

import jdk.dynalink.linker.GuardedInvocation;

import jdk.dynalink.linker.LinkRequest;

import jdk.dynalink.linker.LinkerServices;

import jdk.dynalink.linker.support.SimpleLinkRequest;

/**

 * This is a dynalink pluggable linker (see http://openjdk.java.net/jeps/276).

 * This linker translater underscore_separated method names to CamelCase names

 * used in Java APIs.

 */

public final class UnderscoreNameLinkerExporter extends GuardingDynamicLinkerExporter {

    static {

        System.out.println("pluggable dynalink underscore name linker loaded");

    }

    private static final Pattern UNDERSCORE_NAME = Pattern.compile("_(.)");

    // translate underscore_separated name as a CamelCase name

    private static String translateToCamelCase(String name) {

        Matcher m = UNDERSCORE_NAME.matcher(name);

        StringBuilder buf = new StringBuilder();

        while (m.find()) {

            m.appendReplacement(buf, m.group(1).toUpperCase());

        }

        m.appendTail(buf);

        return buf.toString();

    }

    // locate the first standard operation from the call descriptor

    private static StandardOperation getFirstStandardOperation(final CallSiteDescriptor desc) {

        final Operation base = NamedOperation.getBaseOperation(desc.getOperation());

        if (base instanceof StandardOperation) {

            return (StandardOperation)base;

        } else if (base instanceof CompositeOperation) {

            final CompositeOperation cop = (CompositeOperation)base;

            for(int i = 0; i < cop.getOperationCount(); ++i) {

                final Operation op = cop.getOperation(i);

                if (op instanceof StandardOperation) {

                    return (StandardOperation)op;

                }

            }

        }

        return null;

    }

    @Override

    public List<GuardingDynamicLinker> get() {

        final ArrayList<GuardingDynamicLinker> linkers = new ArrayList<>();

        linkers.add(new GuardingDynamicLinker() {

            @Override

            public GuardedInvocation getGuardedInvocation(LinkRequest request,

                LinkerServices linkerServices) throws Exception {

                final Object self = request.getReceiver();

                CallSiteDescriptor desc = request.getCallSiteDescriptor();

                Operation op = desc.getOperation();

                Object name = NamedOperation.getName(op);

                // is this a named GET_METHOD?

                boolean isGetMethod = getFirstStandardOperation(desc) == StandardOperation.GET_METHOD;

                if (isGetMethod && name instanceof String) {

                    String str = (String)name;

                    if (str.indexOf('_') == -1) {

                        return null;

                    }

                    String nameStr = translateToCamelCase(str);

                    // create a new call descriptor to use translated name

                    CallSiteDescriptor newDesc = new CallSiteDescriptor(

                        desc.getLookup(),

                        new NamedOperation(NamedOperation.getBaseOperation(op), nameStr),

                        desc.getMethodType());

                    // create a new Link request to link the call site with translated name

                    LinkRequest newRequest = new SimpleLinkRequest(newDesc,

                        request.isCallSiteUnstable(), request.getArguments());

                    // return guarded invocation linking the translated request

                    return linkerServices.getGuardedInvocation(newRequest);

                }

                return null;

            }

        });

        return linkers;

    }

}