/*

 * Copyright (c) 2015, 2018, 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.

 */

import java.nio.ByteBuffer;

import java.util.Arrays;

public class SettingsFrame extends Http2Frame {

    private final int[] parameters;

    public static final int TYPE = 0x4;

    // Flags

    public static final int ACK = 0x1;

    @Override

    public String flagAsString(int flag) {

        switch (flag) {

        case ACK:

            return "ACK";

        }

        return super.flagAsString(flag);

    }

    @Override

    public String toString() {

        StringBuilder sb = new StringBuilder();

        sb.append(super.toString())

          .append(" Settings: ");

        for (int i = 0; i < MAX_PARAM; i++) {

            if (parameters[i] != -1) {

                sb.append(name(i))

                  .append("=")

                  .append(Integer.toString(parameters[i]))

                  .append(' ');

            }

        }

        return sb.toString();

    }

    // Parameters

    public static final int HEADER_TABLE_SIZE = 0x1;

    public static final int ENABLE_PUSH = 0x2;

    public static final int MAX_CONCURRENT_STREAMS = 0x3;

    public static final int INITIAL_WINDOW_SIZE = 0x4;

    public static final int MAX_FRAME_SIZE = 0x5;

    public static final int MAX_HEADER_LIST_SIZE = 0x6;

    private String name(int i) {

        switch (i+1) {

        case HEADER_TABLE_SIZE:

            return "HEADER_TABLE_SIZE";

        case ENABLE_PUSH:

            return "ENABLE_PUSH";

        case MAX_CONCURRENT_STREAMS:

            return "MAX_CONCURRENT_STREAMS";

        case INITIAL_WINDOW_SIZE:

            return "INITIAL_WINDOW_SIZE";

        case MAX_FRAME_SIZE:

            return "MAX_FRAME_SIZE";

        case MAX_HEADER_LIST_SIZE:

            return "MAX_HEADER_LIST_SIZE";

        }

        return "unknown parameter";

    }

    public static final int MAX_PARAM = 0x6;

    public SettingsFrame(int flags) {

        super(0, flags);

        parameters = new int [MAX_PARAM];

        Arrays.fill(parameters, -1);

    }

    public SettingsFrame() {

        this(0);

    }

    public SettingsFrame(SettingsFrame other) {

        super(0, other.flags);

        parameters = Arrays.copyOf(other.parameters, MAX_PARAM);

    }

    @Override

    public int type() {

        return TYPE;

    }

    public int getParameter(int paramID) {

        if (paramID > MAX_PARAM) {

            throw new IllegalArgumentException("illegal parameter");

        }

        return parameters[paramID-1];

    }

    public SettingsFrame setParameter(int paramID, int value) {

        if (paramID > MAX_PARAM) {

            throw new IllegalArgumentException("illegal parameter");

        }

        parameters[paramID-1] = value;

        return this;

    }

    int length() {

        int len = 0;

        for (int i : parameters) {

            if (i != -1) {

                len  += 6;

            }

        }

        return len;

    }

    void toByteBuffer(ByteBuffer buf) {

        for (int i = 0; i < MAX_PARAM; i++) {

            if (parameters[i] != -1) {

                buf.putShort((short) (i + 1));

                buf.putInt(parameters[i]);

            }

        }

    }

    public byte[] toByteArray() {

        byte[] bytes = new byte[length()];

        ByteBuffer buf = ByteBuffer.wrap(bytes);

        toByteBuffer(buf);

        return bytes;

    }

    private static final int K = 1024;

    public static SettingsFrame getDefaultSettings() {

        SettingsFrame f = new SettingsFrame();

        // TODO: check these values

        f.setParameter(ENABLE_PUSH, 1);

        f.setParameter(HEADER_TABLE_SIZE, 4 * K);

        f.setParameter(MAX_CONCURRENT_STREAMS, 35);

        f.setParameter(INITIAL_WINDOW_SIZE, 64 * K - 1);

        f.setParameter(MAX_FRAME_SIZE, 16 * K);

        return f;

    }

}