//
//  ========================================================================
//  Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.websocket.common.test;

import java.nio.ByteBuffer;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.is;

public class RawFrameBuilder
{
    public static void putOpFin(ByteBuffer buf, byte opcode, boolean fin)
    {
        byte b = 0x00;
        if (fin)
        {
            b |= 0x80;
        }
        b |= opcode & 0x0F;
        buf.put(b);
    }

    public static void putLengthAndMask(ByteBuffer buf, int length, byte[] mask)
    {
        if (mask != null)
        {
            assertThat("Mask.length", mask.length, is(4));
            putLength(buf, length, (mask != null));
            buf.put(mask);
        }
        else
        {
            putLength(buf, length, false);
        }
    }

    public static byte[] mask(final byte[] data, final byte[] mask)
    {
        assertThat("Mask.length", mask.length, is(4));
        int len = data.length;
        byte[] ret = new byte[len];
        System.arraycopy(data, 0, ret, 0, len);
        for (int i = 0; i < len; i++)
        {
            ret[i] ^= mask[i % 4];
        }
        return ret;
    }

    public static void putLength(ByteBuffer buf, int length, boolean masked)
    {
        if (length < 0)
        {
            throw new IllegalArgumentException("Length cannot be negative");
        }
        byte b = (masked ? (byte)0x80 : 0x00);

        // write the uncompressed length
        if (length > 0xFF_FF)
        {
            buf.put((byte)(b | 0x7F));
            buf.put((byte)0x00);
            buf.put((byte)0x00);
            buf.put((byte)0x00);
            buf.put((byte)0x00);
            buf.put((byte)((length >> 24) & 0xFF));
            buf.put((byte)((length >> 16) & 0xFF));
            buf.put((byte)((length >> 8) & 0xFF));
            buf.put((byte)(length & 0xFF));
        }
        else if (length >= 0x7E)
        {
            buf.put((byte)(b | 0x7E));
            buf.put((byte)(length >> 8));
            buf.put((byte)(length & 0xFF));
        }
        else
        {
            buf.put((byte)(b | length));
        }
    }

    public static void putMask(ByteBuffer buf, byte[] mask)
    {
        assertThat("Mask.length", mask.length, is(4));
        buf.put(mask);
    }

    public static void putPayloadLength(ByteBuffer buf, int length)
    {
        putLength(buf, length, true);
    }
}
