/* ====================================================================
 *    Licensed to the Apache Software Foundation (ASF) under one
 *    or more contributor license agreements.  See the NOTICE file
 *    distributed with this work for additional information
 *    regarding copyright ownership.  The ASF licenses this file
 *    to you under the Apache License, Version 2.0 (the
 *    "License"); you may not use this file except in compliance
 *    with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing,
 *    software distributed under the License is distributed on an
 *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *    KIND, either express or implied.  See the License for the
 *    specific language governing permissions and limitations
 *    under the License.
 * ====================================================================
 */

#ifndef SERF_PROTOCOL_HTTP2_PRIVATE_H
#define SERF_PROTOCOL_HTTP2_PRIVATE_H

#include "serf.h"
#include "serf_private.h"

#ifdef _DEBUG
#include <assert.h>
#define SERF_H2_assert(x) assert(x)
#else
#define SERF_H2_assert(x) ((void)0)
#endif

#define SERF_LOGHTTP2 \
    SERF_LOGCOMP_PROTOCOL, (__FILE__ ":" APR_STRINGIFY(__LINE__))

#ifdef __cplusplus
extern "C" {
#endif

/* ********** HTTP2 Frame types ********** */

/* The standard maximum framesize. Always supported */
#define HTTP2_DEFAULT_MAX_FRAMESIZE     16384
/* The default stream and connection window size before updates */
#define HTTP2_DEFAULT_WINDOW_SIZE       65535
#define HTTP2_DEFAULT_MAX_CONCURRENT    0xFFFFFFFF
#define HTTP2_DEFAULT_HPACK_TABLE_SIZE  4096

#define HTTP2_PRIORITY_DATA_SIZE        5
#define HTTP2_RST_DATA_SIZE             4
#define HTTP2_PROMISE_DATA_SIZE         4
#define HTTP2_PING_DATA_SIZE            8
#define HTTP2_GOWAWAY_DATA_SIZE         8
#define HTTP2_WINDOW_UPDATE_DATA_SIZE   4

#define HTTP2_SETTING_SIZE              6

#define HTTP2_WINDOW_MAX_ALLOWED        0x7FFFFFFF

/* Frame type is an 8 bit unsigned integer */

/* http://tools.ietf.org/html/rfc7540#section-11.2 */
#define HTTP2_FRAME_TYPE_DATA           0x00
#define HTTP2_FRAME_TYPE_HEADERS        0x01
#define HTTP2_FRAME_TYPE_PRIORITY       0x02
#define HTTP2_FRAME_TYPE_RST_STREAM     0x03
#define HTTP2_FRAME_TYPE_SETTINGS       0x04
#define HTTP2_FRAME_TYPE_PUSH_PROMISE   0x05
#define HTTP2_FRAME_TYPE_PING           0x06
#define HTTP2_FRAME_TYPE_GOAWAY         0x07
#define HTTP2_FRAME_TYPE_WINDOW_UPDATE  0x08
#define HTTP2_FRAME_TYPE_CONTINUATION   0x09
/* https://httpwg.github.io/http-extensions/alt-svc.html
   documents that frame 0x0A will most likely be assigned
   to ALT-SVC */

/* ********** HTTP2 Flags ********** */


/* Defined on SETTINGS and PING */
#define HTTP2_FLAG_ACK            0x01
/* Defined on DATA and HEADERS */
#define HTTP2_FLAG_END_STREAM     0x01
/* Defined on HEADERS and CONTINUATION */
#define HTTP2_FLAG_END_HEADERS    0x04
/* Defined on DATA and HEADERS */
#define HTTP2_FLAG_PADDED         0x08
/* Defined on HEADERS */
#define HTTP2_FLAG_PRIORITY       0x20


/* ********** HTTP2 Settings ********** */

/* Settings are 16 bit unsigned integers*/
#define HTTP2_SETTING_HEADER_TABLE_SIZE       0x0001  /* default: 4096 */
#define HTTP2_SETTING_ENABLE_PUSH             0x0002  /* default: 1 */
#define HTTP2_SETTING_MAX_CONCURRENT_STREAMS  0x0003  /* default: (infinite) */
#define HTTP2_SETTING_INITIAL_WINDOW_SIZE     0x0004  /* default: 65535 */
#define HTTP2_SETTING_MAX_FRAME_SIZE          0x0005  /* default: 16384 */
#define HTTP2_SETTING_MAX_HEADER_LIST_SIZE    0x0006  /* default: (infinite) */

/* https://tools.ietf.org/html/rfc7540#section-3.5 */
#define HTTP2_CONNECTION_PREFIX "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"


/* Maximum size for a headerline in HPACK */
#define HTTP2_MAX_HEADER_ENTRYSIZE          0x20000 /* 128 KByte */


/* ------------------------------------- */
typedef struct serf_http2_protocol_t serf_http2_protocol_t;
typedef struct serf_http2_stream_data_t serf_http2_stream_data_t;

typedef struct serf_http2_stream_t
{
  struct serf_http2_protocol_t *h2;
  serf_bucket_alloc_t *alloc;

  /* Opaque implementation details */
  serf_http2_stream_data_t *data;

  /* Linked list of currently existing streams */
  struct serf_http2_stream_t *next;
  struct serf_http2_stream_t *prev;

  apr_uint32_t lr_window; /* local->remote */
  apr_uint32_t rl_window; /* remote->local */

  apr_uint32_t rl_window_upd_below;
  apr_uint32_t rl_window_upd_to;

  /* -1 until allocated. Odd is client side initiated, even server side */
  apr_int32_t streamid;

  enum
  {
    H2S_INIT = 0,
    H2S_IDLE,
    H2S_RESERVED_REMOTE,
    H2S_RESERVED_LOCAL,
    H2S_OPEN,
    H2S_HALFCLOSED_REMOTE,
    H2S_HALFCLOSED_LOCAL,
    H2S_CLOSED
  } status;

  /* Used while receiving a promise stream */
  struct serf_http2_stream_t *new_reserved_stream;

  /* TODO: Priority, etc. */
  struct serf_http2_stream_t *next_writable, *prev_writable;
} serf_http2_stream_t;

typedef apr_status_t (* serf_http2_processor_t)(void *baton,
                                                serf_http2_protocol_t *h2,
                                                serf_bucket_t *body);

/* Enques an http2 frame for output */
apr_status_t
serf_http2__enqueue_frame(serf_http2_protocol_t *h2,
                          serf_bucket_t *frame,
                          bool flush);

/* Creates a new stream */
serf_http2_stream_t *
serf_http2__stream_create(serf_http2_protocol_t *h2,
                          apr_int32_t streamid,
                          apr_uint32_t lr_window,
                          apr_uint32_t rl_window,
                          serf_bucket_alloc_t *alloc);


apr_status_t
serf_http2__enqueue_stream_reset(serf_http2_protocol_t *h2,
                                 apr_int32_t streamid,
                                 apr_status_t reason);

/* Allocates a new stream id for a stream.
   BATON is a serf_http2_stream_t * instance.

   Passed to serf__bucket_http2_frame_create when writing for
   a stream.
*/
void
serf_http2__allocate_stream_id(void *baton,
                               apr_int32_t *streamid);

void
serf_http2__stream_cleanup(serf_http2_stream_t *stream);

void
serf_http2__stream_pre_cleanup(serf_http2_stream_t *stream);


serf_http2_stream_t *
serf_http2__stream_get(serf_http2_protocol_t *h2,
                       apr_int32_t streamid,
                       bool create_for_remote,
                       bool move_first);

/* Sets up STREAM to handle the next request from CONN */
apr_status_t
serf_http2__stream_setup_next_request(serf_http2_stream_t *stream,
                                      serf_connection_t *conn,
                                      apr_size_t max_payload_size,
                                      serf_hpack_table_t *hpack_tbl);

apr_status_t
serf_http2__setup_incoming_request(serf_incoming_request_t **in_request,
                                   serf_incoming_request_setup_t *req_setup,
                                   void **req_setup_baton,
                                   serf_http2_protocol_t *h2);

/* Gets current l->r max payload size */
apr_size_t
serf_http2__max_payload_size(serf_http2_protocol_t *h2);

apr_size_t serf_http2__alloc_window(serf_http2_protocol_t *h2,
                                    serf_http2_stream_t *stream,
                                    apr_size_t requested);

void serf_http2__return_window(serf_http2_protocol_t *h2,
                               serf_http2_stream_t *stream,
                               apr_size_t returned);

void serf_http2__ensure_writable(serf_http2_stream_t *stream);

apr_status_t
serf_http2__stream_reset(serf_http2_stream_t *stream,
                         apr_status_t reason,
                         bool local_reset);

void serf_http2__stream_cancel_request(serf_http2_stream_t *stream,
                                       serf_request_t *rq,
                                       apr_status_t reason);

void serf_http2__stream_prioritize_request(serf_http2_stream_t *stream,
                                           serf_request_t *rq, bool exclusive);

serf_bucket_t *
serf_http2__stream_handle_hpack(serf_http2_stream_t *stream,
                                serf_bucket_t *bucket,
                                unsigned char frametype,
                                bool end_stream,
                                apr_size_t max_entry_size,
                                serf_hpack_table_t *hpack_tbl,
                                serf_config_t *config,
                                serf_bucket_alloc_t *allocator);

serf_bucket_t *
serf_http2__stream_handle_data(serf_http2_stream_t *stream,
                               serf_bucket_t *bucket,
                               unsigned char frametype,
                               bool end_stream,
                               serf_config_t *config,
                               serf_bucket_alloc_t *allocator);

apr_status_t
serf_http2__stream_processor(void *baton,
                             serf_http2_protocol_t *h2,
                             serf_bucket_t *bucket);

apr_status_t
serf_http2__stream_write_data(serf_http2_stream_t *stream);

#ifdef __cplusplus
}
#endif

#endif