/*
 * nghttp2 - HTTP/2.0 C Library
 *
 * Copyright (c) 2012 Tatsuhiro Tsujikawa
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#ifndef NGHTTP2_SESSION_H
#define NGHTTP2_SESSION_H

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif /* HAVE_CONFIG_H */

#include <nghttp2/nghttp2.h>
#include "nghttp2_pq.h"
#include "nghttp2_map.h"
#include "nghttp2_frame.h"
#include "nghttp2_hd.h"
#include "nghttp2_stream.h"
#include "nghttp2_buffer.h"
#include "nghttp2_outbound_item.h"

/*
 * Option flags.
 */
typedef enum {
  NGHTTP2_OPTMASK_NO_AUTO_STREAM_WINDOW_UPDATE = 1 << 0,
  NGHTTP2_OPTMASK_NO_AUTO_CONNECTION_WINDOW_UPDATE = 1 << 1
} nghttp2_optmask;

typedef struct {
  nghttp2_outbound_item *item;
  /* Buffer for outbound frames. Used to pack one frame. The memory
     pointed by framebuf is initially allocated by
     nghttp2_session_{client,server}_new() and deallocated by
     nghttp2_session_del() */
  uint8_t *framebuf;
  /* The capacity of framebuf in bytes */
  size_t framebufmax;
  /* The length of the frame stored in framebuf */
  size_t framebuflen;
  /* The number of bytes has been sent */
  size_t framebufoff;
} nghttp2_active_outbound_item;

/* Buffer length for inbound raw byte stream. */
#define NGHTTP2_INBOUND_BUFFER_LENGTH 16384

#define NGHTTP2_INITIAL_OUTBOUND_FRAMEBUF_LENGTH (NGHTTP2_DATA_PAYLOAD_LENGTH+8)
#define NGHTTP2_INITIAL_INBOUND_FRAMEBUF_LENGTH \
  NGHTTP2_INITIAL_OUTBOUND_FRAMEBUF_LENGTH
#define NGHTTP2_INITIAL_NV_BUFFER_LENGTH 4096

/* Internal state when receiving incoming frame */
typedef enum {
  /* Receiving frame header */
  NGHTTP2_RECV_HEAD,
  /* Receiving frame payload (comes after length field) */
  NGHTTP2_RECV_PAYLOAD,
  /* Receiving frame payload, but the received bytes are discarded. */
  NGHTTP2_RECV_PAYLOAD_IGN
} nghttp2_inbound_state;

typedef struct {
  nghttp2_frame frame;
  nghttp2_inbound_state state;
  uint8_t headbuf[NGHTTP2_FRAME_HEAD_LENGTH];
  /* How many bytes are filled in headbuf */
  size_t headbufoff;
  /* Payload for non-DATA frames. */
  uint8_t *buf;
  /* Capacity of buf */
  size_t bufmax;
  /* For frames without name/value header block, this is how many
     bytes are going to filled in buf. For frames with the block, buf
     only contains bytes that come before ther block, but this value
     includes the length of the block. buflen <= bufmax must be
     fulfilled. */
  size_t buflen;
  /* length in Length field */
  size_t payloadlen;
  /* How many bytes are received for this frame. off <= payloadlen
     must be fulfilled. */
  size_t off;
  /* Error code */
  int error_code;
} nghttp2_inbound_frame;

typedef enum {
  NGHTTP2_GOAWAY_NONE = 0,
  /* Flag means GOAWAY frame is sent to the remote peer. */
  NGHTTP2_GOAWAY_SEND = 0x1,
  /* Flag means GOAWAY frame is received from the remote peer. */
  NGHTTP2_GOAWAY_RECV = 0x2,
  /* Flag means connection should be dropped after sending GOAWAY. */
  NGHTTP2_GOAWAY_FAIL_ON_SEND = 0x4
} nghttp2_goaway_flag;

struct nghttp2_session {
  uint8_t server;
  /* Next Stream ID. Made unsigned int to detect >= (1 << 31). */
  uint32_t next_stream_id;
  /* The largest stream ID received so far */
  int32_t last_recv_stream_id;
  /* The largest stream ID which has been processed in some way. This
     value will be used as last-stream-id when sending GOAWAY
     frame. */
  int32_t last_proc_stream_id;
  /* Counter of unique ID of PING. Wraps when it exceeds
     NGHTTP2_MAX_UNIQUE_ID */
  uint32_t next_unique_id;

  /* Sequence number of outbound frame to maintain the order of
     enqueue if priority is equal. */
  int64_t next_seq;

  nghttp2_map /* <nghttp2_stream*> */ streams;
  /* The number of outgoing streams. This will be capped by
     remote_settings[NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS]. */
  size_t num_outgoing_streams;
  /* The number of incoming streams. This will be capped by
     local_settings[NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS]. */
  size_t num_incoming_streams;

  /* Queue for outbound frames other than stream-creating HEADERS */
  nghttp2_pq /* <nghttp2_outbound_item*> */ ob_pq;
  /* Queue for outbound stream-creating HEADERS frame */
  nghttp2_pq /* <nghttp2_outbound_item*> */ ob_ss_pq;

  nghttp2_active_outbound_item aob;

  nghttp2_inbound_frame iframe;

  /* Buffer used to store inflated name/value pairs in wire format
     temporarily on pack/unpack. */
  uint8_t *nvbuf;
  /* The number of bytes allocated for nvbuf */
  size_t nvbuflen;

  nghttp2_hd_context hd_deflater;
  nghttp2_hd_context hd_inflater;

  /* Flags indicating GOAWAY is sent and/or recieved. The flags are
     composed by bitwise OR-ing nghttp2_goaway_flag. */
  uint8_t goaway_flags;
  /* This is the value in GOAWAY frame received from remote endpoint. */
  int32_t last_stream_id;

  /* Non-zero indicates connection-level flow control on remote side
     is in effect. This will be disabled when WINDOW_UPDATE with
     END_FLOW_CONTROL bit set is received. */
  uint8_t remote_flow_control;
  /* Non-zero indicates connection-level flow control on local side is
     in effect. This will be disabled when WINDOW_UPDATE with
     END_FLOW_CONTROL bit set is sent. */
  uint8_t local_flow_control;
  /* Current sender window size. This value is computed against the
     current initial window size of remote endpoint. */
  int32_t remote_window_size;
  /* Keep track of the number of bytes received without
     WINDOW_UPDATE. This could be negative after submitting negative
     value to WINDOW_UPDATE. */
  int32_t recv_window_size;
  /* The amount of recv_window_size cut using submitting negative
     value to WINDOW_UPDATE */
  int32_t recv_reduction;
  /* window size for local flow control. It is initially set to
     NGHTTP2_INITIAL_CONNECTION_WINDOW_SIZE and could be
     increased/decreased by submitting WINDOW_UPDATE. See
     nghttp2_submit_window_update(). */
  int32_t local_window_size;

  /* Settings value received from the remote endpoint. We just use ID
     as index. The index = 0 is unused. */
  uint32_t remote_settings[NGHTTP2_SETTINGS_MAX+1];
  /* Settings value of the local endpoint. */
  uint32_t local_settings[NGHTTP2_SETTINGS_MAX+1];

  /* In-flight SETTINGS values. NULL does not necessarily mean there
     is no in-flight SETTINGS. */
  nghttp2_settings_entry *inflight_iv;
  /* The number of entries in |inflight_iv|. -1 if there is no
     in-flight SETTINGS. */
  ssize_t inflight_niv;

  /* Option flags. This is bitwise-OR of 0 or more of nghttp2_optmask. */
  uint32_t opt_flags;

  nghttp2_session_callbacks callbacks;
  void *user_data;
};

/* Struct used when updating initial window size of each active
   stream. */
typedef struct {
  nghttp2_session *session;
  int32_t new_window_size, old_window_size;
} nghttp2_update_window_size_arg;

/* TODO stream timeout etc */

/*
 * Returns nonzero value if |stream_id| is initiated by local
 * endpoint.
 */
int nghttp2_session_is_my_stream_id(nghttp2_session *session,
                                    int32_t stream_id);

/*
 * Adds frame |frame| to the outbound queue in |session|. The
 * |frame_cat| must be either NGHTTP2_CTRL or NGHTTP2_DATA. If the
 * |frame_cat| is NGHTTP2_CTRL, the |frame| must be a pointer to
 * nghttp2_frame. If the |frame_cat| is NGHTTP2_DATA, it must be a
 * pointer to nghttp2_data. |aux_data| is a pointer to the arbitrary
 * data. Its interpretation is defined per the type of the frame. When
 * this function succeeds, it takes ownership of |frame| and
 * |aux_data|, so caller must not free them on success.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_add_frame(nghttp2_session *session,
                              nghttp2_frame_category frame_cat,
                              void *abs_frame, void *aux_data);

/*
 * Adds RST_STREAM frame for the stream |stream_id| with the error
 * code |error_code|. This is a convenient function built on top of
 * nghttp2_session_add_frame() to add RST_STREAM easily.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_add_rst_stream(nghttp2_session *session,
                                   int32_t stream_id,
                                   nghttp2_error_code error_code);

/*
 * Adds PING frame. This is a convenient functin built on top of
 * nghttp2_session_add_frame() to add PING easily.
 *
 * If the |opaque_data| is not NULL, it must point to 8 bytes memory
 * region of data. The data pointed by |opaque_data| is copied. It can
 * be NULL. In this case, 8 bytes NULL is used.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_add_ping(nghttp2_session *session, uint8_t flags,
                             uint8_t *opaque_data);

/*
 * Adds GOAWAY frame with the last-stream-ID |last_stream_id| and the
 * error code |error_code|. This is a convenient function built on top
 * of nghttp2_session_add_frame() to add GOAWAY easily.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_add_goaway(nghttp2_session *session,
                               int32_t last_stream_id,
                               nghttp2_error_code error_code,
                               uint8_t *opaque_data, size_t opaque_data_len);

/*
 * Adds WINDOW_UPDATE frame with stream ID |stream_id| and
 * window-size-increment |window_size_increment|. This is a convenient
 * function built on top of nghttp2_session_add_frame() to add
 * WINDOW_UPDATE easily.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_add_window_update(nghttp2_session *session, uint8_t flags,
                                      int32_t stream_id,
                                      int32_t window_size_increment);

/*
 * Adds SETTINGS frame.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_add_settings(nghttp2_session *session, uint8_t flags,
                                 const nghttp2_settings_entry *iv, size_t niv);

/*
 * Creates new stream in |session| with stream ID |stream_id|,
 * priority |pri| and flags |flags|. NGHTTP2_FLAG_END_STREAM flag is
 * set in |flags|, the sender of HEADERS will not send any further
 * data in this stream. Since this function is called when initial
 * HEADERS is sent or received, these flags are taken from it.  The
 * state of stream is set to |initial_state|. The |stream_user_data|
 * is a pointer to the arbitrary user supplied data to be associated
 * to this stream.
 *
 * This function returns a pointer to created new stream object, or
 * NULL.
 */
nghttp2_stream* nghttp2_session_open_stream(nghttp2_session *session,
                                            int32_t stream_id,
                                            uint8_t flags, int32_t pri,
                                            nghttp2_stream_state initial_state,
                                            void *stream_user_data);

/*
 * Closes stream whose stream ID is |stream_id|. The reason of closure
 * is indicated by the |error_code|. When closing the stream,
 * on_stream_close_callback will be called.
 *
 * This function returns 0 if it succeeds, or one the following
 * negative error codes:
 *
 * NGHTTP2_ERR_INVALID_ARGUMENT
 *     The specified stream does not exist.
 */
int nghttp2_session_close_stream(nghttp2_session *session, int32_t stream_id,
                                 nghttp2_error_code error_code);

/*
 * If further receptions and transmissions over the stream |stream_id|
 * are disallowed, close the stream with error code NGHTTP2_NO_ERROR.
 *
 * This function returns 0 if it
 * succeeds, or one of the following negative error codes:
 *
 * NGHTTP2_ERR_INVALID_ARGUMENT
 *     The specified stream does not exist.
 */
int nghttp2_session_close_stream_if_shut_rdwr(nghttp2_session *session,
                                              nghttp2_stream *stream);


int nghttp2_session_on_request_headers_received(nghttp2_session *session,
                                                nghttp2_frame *frame);

int nghttp2_session_on_response_headers_received(nghttp2_session *session,
                                                 nghttp2_frame *frame,
                                                 nghttp2_stream *stream);

int nghttp2_session_on_push_response_headers_received(nghttp2_session *session,
                                                      nghttp2_frame *frame,
                                                      nghttp2_stream *stream);

/*
 * Called when HEADERS is received, assuming |frame| is properly
 * initialized.  This function does first validate received frame and
 * then open stream and call callback functions.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_on_headers_received(nghttp2_session *session,
                                        nghttp2_frame *frame,
                                        nghttp2_stream *stream);


/*
 * Called when PRIORITY is received, assuming |frame| is properly
 * initialized.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_on_priority_received(nghttp2_session *session,
                                         nghttp2_frame *frame);

/*
 * Called when RST_STREAM is received, assuming |frame| is properly
 * initialized.
 *
 * This function returns 0 if it succeeds, or one the following
 * negative error codes:
 *
 * TBD
 */
int nghttp2_session_on_rst_stream_received(nghttp2_session *session,
                                           nghttp2_frame *frame);

/*
 * Called when SETTINGS is received, assuming |frame| is properly
 * initialized. If |noack| is non-zero, SETTINGS with ACK will not be
 * submitted. If |frame| has NGHTTP2_FLAG_ACK flag set, no SETTINGS
 * with ACK will not be submitted regardless of |noack|.
 *
 * This function returns 0 if it succeeds, or one the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory
 * NGHTTP2_ERR_PAUSE
 *     Callback function returns NGHTTP2_ERR_PAUSE
 * NGHTTP2_ERR_CALLBACK_FAILURE
 *     The read_callback failed
 */
int nghttp2_session_on_settings_received(nghttp2_session *session,
                                         nghttp2_frame *frame,
                                         int noack);

/*
 * Called when PUSH_PROMISE is received, assuming |frame| is properly
 * initialized.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_on_push_promise_received(nghttp2_session *session,
                                             nghttp2_frame *frame);

/*
 * Called when PING is received, assuming |frame| is properly
 * initialized.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_on_ping_received(nghttp2_session *session,
                                     nghttp2_frame *frame);

/*
 * Called when GOAWAY is received, assuming |frame| is properly
 * initialized.
 *
 * This function returns 0 and never fail.
 */
int nghttp2_session_on_goaway_received(nghttp2_session *session,
                                       nghttp2_frame *frame);

/*
 * Called when WINDOW_UPDATE is recieved, assuming |frame| is properly
 * initialized.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_on_window_update_received(nghttp2_session *session,
                                              nghttp2_frame *frame);

/*
 * Called when DATA is received.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 */
int nghttp2_session_on_data_received(nghttp2_session *session,
                                     uint16_t length, uint8_t flags,
                                     int32_t stream_id);

/*
 * Returns nghttp2_stream* object whose stream ID is |stream_id|.  It
 * could be NULL if such stream does not exist.
 */
nghttp2_stream* nghttp2_session_get_stream(nghttp2_session *session,
                                           int32_t stream_id);

/*
 * Packs DATA frame |frame| in wire frame format and stores it in
 * |*buf_ptr|.  The capacity of |*buf_ptr| is |*buflen_ptr|
 * length. This function expands |*buf_ptr| as necessary to store
 * given |frame|. It packs header in first 8 bytes. Remaining bytes
 * are the DATA apyload and are filled using |frame->data_prd|. The
 * length of payload is at most |datamax| bytes.
 *
 * This function returns the size of packed frame if it succeeds, or
 * one of the following negative error codes:
 *
 * NGHTTP2_ERR_DEFERRED
 *     The DATA frame is postponed.
 * NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE
 *     The read_callback failed (stream error).
 * NGHTTP2_ERR_NOMEM
 *     Out of memory.
 * NGHTTP2_ERR_CALLBACK_FAILURE
 *     The read_callback failed (session error).
 */
ssize_t nghttp2_session_pack_data(nghttp2_session *session,
                                  uint8_t **buf_ptr, size_t *buflen_ptr,
                                  size_t datamax,
                                  nghttp2_data *frame);

/*
 * Returns top of outbound frame queue. This function returns NULL if
 * queue is empty.
 */
nghttp2_outbound_item* nghttp2_session_get_ob_pq_top(nghttp2_session *session);

/*
 * Pops and returns next item to send. If there is no such item,
 * returns NULL.  This function takes into account max concurrent
 * streams. That means if session->ob_pq is empty but
 * session->ob_ss_pq has item and max concurrent streams is reached,
 * then this function returns NULL.
 */
nghttp2_outbound_item* nghttp2_session_pop_next_ob_item
(nghttp2_session *session);

/*
 * Returns next item to send. If there is no such item, this function
 * returns NULL.  This function takes into account max concurrent
 * streams. That means if session->ob_pq is empty but
 * session->ob_ss_pq has item and max concurrent streams is reached,
 * then this function returns NULL.
 */
nghttp2_outbound_item* nghttp2_session_get_next_ob_item
(nghttp2_session *session);

/*
 * Updates local settings with the |iv|. The number of elements in the
 * array pointed by the |iv| is given by the |niv|.  This function
 * assumes that the all settings_id member in |iv| are in range 1 to
 * NGHTTP2_SETTINGS_MAX, inclusive.
 *
 * While updating individual stream's local window size, if the window
 * size becomes strictly larger than NGHTTP2_MAX_WINDOW_SIZE,
 * RST_STREAM is issued against such a stream.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *     Out of memory
 */
int nghttp2_session_update_local_settings(nghttp2_session *session,
                                          nghttp2_settings_entry *iv,
                                          size_t niv);

/*
 * Re-prioritize |stream|. The new priority is |pri|.
 */
void nghttp2_session_reprioritize_stream
(nghttp2_session *session, nghttp2_stream *stream, int32_t pri);

#endif /* NGHTTP2_SESSION_H */