/*

 * Copyright (c) 2015, 2016, 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

 */

package java.net.http;

import java.io.IOException;

import java.nio.ByteBuffer;

/**

 * When sending a frame, the length field must be set in sub-class

 * by calling computeLength()

 */

abstract class Http2Frame {

    int length = -1;

    int type;

    int streamid;

    int flags;

    // called when reading in only

    void initCommon(int length, int type, int streamid, int flags) {

        this.length = length;

        this.type = type;

        this.streamid = streamid;

        this.flags = flags;

    }

    public int length() {

        return length;

    }

    public int type() {

        return type;

    }

    public int streamid() {

        return streamid;

    }

    public void setFlag(int flag) {

        flags |= flag;

    }

    public void setFlags(int flags) {

        this.flags = flags;

    }

    public int getFlags() {

        return flags;

    }

    public boolean getFlag(int flag) {

        return (flags & flag) != 0;

    }

    public void clearFlag(int flag) {

        flags &= 0xffffffff ^ flag;

    }

    public void streamid(int streamid) {

        this.streamid = streamid;

    }

    abstract void readIncomingImpl(ByteBufferConsumer bc) throws IOException;

    /**

     * assume given array contains at least one complete frame.

     */

    static Http2Frame readIncoming(ByteBufferConsumer bc) throws IOException {

        int x = bc.getInt();

        int length = x >> 8;

        int type = x & 0xff;

        int flags = bc.getByte();

        int streamid = bc.getInt();

        Http2Frame f = null;

        switch (type) {

          case DataFrame.TYPE:

            f = new DataFrame();

            break;

          case HeadersFrame.TYPE:

            f = new HeadersFrame();

            break;

          case ContinuationFrame.TYPE:

            f = new ContinuationFrame();

            break;

          case ResetFrame.TYPE:

            f = new ResetFrame();

            break;

          case PriorityFrame.TYPE:

            f = new PriorityFrame();

            break;

          case SettingsFrame.TYPE:

            f = new SettingsFrame();

            break;

          case GoAwayFrame.TYPE:

            f = new GoAwayFrame();

            break;

          case PingFrame.TYPE:

            f = new PingFrame();

            break;

          case PushPromiseFrame.TYPE:

            f = new PushPromiseFrame();

            break;

          case WindowUpdateFrame.TYPE:

            f = new WindowUpdateFrame();

            break;

          default:

            String msg = Integer.toString(type);

            throw new IOException("unknown frame type " + msg);

        }

        f.initCommon(length, type, streamid, flags);

        f.readIncomingImpl(bc);

        return f;

    }

    public String typeAsString() {

        return asString(this.type);

    }

    public static String asString(int type) {

        switch (type) {

          case DataFrame.TYPE:

            return "DATA";

          case HeadersFrame.TYPE:

            return "HEADERS";

          case ContinuationFrame.TYPE:

            return "CONTINUATION";

          case ResetFrame.TYPE:

            return "RESET";

          case PriorityFrame.TYPE:

            return "PRIORITY";

          case SettingsFrame.TYPE:

            return "SETTINGS";

          case GoAwayFrame.TYPE:

            return "GOAWAY";

          case PingFrame.TYPE:

            return "PING";

          case PushPromiseFrame.TYPE:

            return "PUSH_PROMISE";

          case WindowUpdateFrame.TYPE:

            return "WINDOW_UPDATE";

          default:

            return "UNKNOWN";

        }

    }

    @Override

    public String toString() {

        StringBuilder sb = new StringBuilder();

        sb.append(typeAsString())

                .append(": length=")

                .append(Integer.toString(length))

                .append(", streamid=")

                .append(streamid)

                .append(", flags=");

        int f = flags;

        int i = 0;

        if (f == 0) {

            sb.append("0 ");

        } else {

            while (f != 0) {

                if ((f & 1) == 1) {

                    sb.append(flagAsString(1 << i))

                      .append(' ');

                }

                f = f >> 1;

                i++;

            }

        }

        return sb.toString();

    }

    // Override

    String flagAsString(int f) {

        return "unknown";

    }

    abstract void computeLength();

    void writeOutgoing(ByteBufferGenerator bg) {

        if (length == -1) {

            throw new InternalError("Length not set on outgoing frame");

        }

        ByteBuffer buf = bg.getBuffer(9);

        int x = (length << 8) + type;

        buf.putInt(x);

        buf.put((byte)flags);

        buf.putInt(streamid);

    }

}