//
//  ========================================================================
//  Copyright (c) 1995-2022 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.message;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.StandardCharsets;

import org.eclipse.jetty.util.BufferUtil;
import org.eclipse.jetty.util.Utf8Appendable;

/**
 * A CharBuffer wrapped with the Utf8Appendable logic.
 */
public class Utf8CharBuffer extends Utf8Appendable
{
    // TODO this class does not correctly implement the Appendable contract.
    // The length is currently the capacity, but it should be the number of characters
    // appended!  It also violates the jetty standard of leaving buffers in flush mode.

    /**
     * Convenience method to wrap a ByteBuffer with a {@link Utf8CharBuffer}
     *
     * @param buffer the buffer to wrap
     * @return the Utf8ByteBuffer for the provided ByteBuffer
     */
    public static Utf8CharBuffer wrap(ByteBuffer buffer)
    {
        return new Utf8CharBuffer(buffer.asCharBuffer());
    }

    private final CharBuffer buffer;

    private Utf8CharBuffer(CharBuffer buffer)
    {
        super(buffer);
        this.buffer = buffer;
    }

    public void append(char[] cbuf, int offset, int size)
    {
        append(BufferUtil.toDirectBuffer(new String(cbuf, offset, size), StandardCharsets.UTF_8));
    }

    public void append(int c)
    {
        buffer.append((char)c);
    }

    @Override
    public void reset()
    {
        clear();
        super.reset();
    }

    public void clear()
    {
        buffer.position(0);
        buffer.limit(buffer.capacity());
    }

    public ByteBuffer getByteBuffer()
    {
        // remember settings
        int limit = buffer.limit();
        int position = buffer.position();

        // flip to flush
        buffer.limit(buffer.position());
        buffer.position(0);

        // get byte buffer
        ByteBuffer bb = StandardCharsets.UTF_8.encode(buffer);

        // restor settings
        buffer.limit(limit);
        buffer.position(position);

        return bb;
    }

    @Override
    public int length()
    {
        return buffer.capacity();
    }

    public int remaining()
    {
        return buffer.remaining();
    }

    @Override
    public String getPartialString()
    {
        return buffer.toString();
    }

    @Override
    public String toString()
    {
        StringBuilder str = new StringBuilder();
        str.append("Utf8CharBuffer@").append(hashCode());
        str.append("[p=").append(buffer.position());
        str.append(",l=").append(buffer.limit());
        str.append(",c=").append(buffer.capacity());
        str.append(",r=").append(buffer.remaining());
        str.append("]");
        return str.toString();
    }
}
