/*
 * Copyright (c) 2011, 2012, 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 com.apple.jobjc;

import java.nio.ByteOrder;

import com.apple.jobjc.Coder.PrimitivePointerCoder;

import javax.tools.annotation.GenerateNativeHeader;

/* No native methods here, but the constants are needed in the supporting JNI code */
@GenerateNativeHeader
public final class NativeArgumentBuffer{
    private static final ThreadLocal<NativeArgumentBuffer> threadLocal = new ThreadLocal<NativeArgumentBuffer>();

    static NativeArgumentBuffer getThreadLocalBuffer(final JObjCRuntime runtime) {
        runtime.assertOK();
        final NativeArgumentBuffer alreadyCreated = threadLocal.get();
        if (alreadyCreated != null) return alreadyCreated;

        final NativeArgumentBuffer newThreadLocalState = new NativeArgumentBuffer(runtime);
        threadLocal.set(newThreadLocalState);
        return newThreadLocalState;
    }

    final JObjCRuntime runtime;

    final NativeBuffer buffer;

    long argPtrsPtr;
    long argValuesPtr;
    final long retValPtr;

    private static final int MAX_ARGS = 512;
    private static final int BUF_SIZE = MAX_ARGS * 8 * 2;
    private static final int ARG_VALS_OFFSET = BUF_SIZE/2;

    private NativeArgumentBuffer(final JObjCRuntime runtime) {
        runtime.assertOK();
        this.runtime = runtime;
        this.buffer = new NativeBuffer(BUF_SIZE);
        this.buffer.buffer.order(ByteOrder.nativeOrder());

        reset();
        this.retValPtr = buffer.bufferPtr;
    }


    // Call before each new call
    public void reset() {
        argPtrsPtr = buffer.bufferPtr;
        argValuesPtr = buffer.bufferPtr + ARG_VALS_OFFSET;
        assert buffer.ptrInBounds(argValuesPtr);
    }

    // Push a pointer to a block of memory
    public void doPutArgPtr(long ptr) {
        assert buffer.ptrInBounds(argPtrsPtr);
        PrimitivePointerCoder.INST.push(runtime, argPtrsPtr, ptr);
        argPtrsPtr += JObjCRuntime.PTR_LEN;
    }

    // Call this after having written a value of size `sizeof` to `argValuesPtr`.
    public void didPutArgValue(int sizeof) {
        assert buffer.ptrInBounds(argValuesPtr);
        doPutArgPtr(argValuesPtr);
        argValuesPtr += sizeof;
    }


    @Override public String toString() {
        final StringBuilder builder = new StringBuilder();
        final long bptr = buffer.bufferPtr;

        for(long i = bptr; i < bptr + ARG_VALS_OFFSET; i += JObjCRuntime.PTR_LEN){
            if(argPtrsPtr == i)
                builder.append("*");
            builder.append(PrimitivePointerCoder.INST.popPtr(JObjCRuntime.inst(), i));
            builder.append(" ");
        }

        builder.append("\n");

        for(long i = bptr + ARG_VALS_OFFSET; i < bptr + BUF_SIZE; i += JObjCRuntime.PTR_LEN){
            if(argValuesPtr == i)
                builder.append("*");
            builder.append(PrimitivePointerCoder.INST.popPtr(JObjCRuntime.inst(), i));
            builder.append(" ");
        }

        return builder.toString();
    }
}