/*
 * nghttp2 - HTTP/2 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 SHRPX_HTTP2_SESSION_H
#define SHRPX_HTTP2_SESSION_H

#include "shrpx.h"

#include <set>
#include <memory>

#include <openssl/ssl.h>

#include <ev.h>

#include <nghttp2/nghttp2.h>

#include "http-parser/http_parser.h"

#include "ringbuf.h"

using namespace nghttp2;

namespace shrpx {

class Http2DownstreamConnection;

struct StreamData {
  Http2DownstreamConnection *dconn;
};

class Http2Session {
public:
  Http2Session(struct ev_loop *loop, SSL_CTX *ssl_ctx);
  ~Http2Session();

  int check_cert();

  // If hard is true, all pending requests are abandoned and
  // associated ClientHandlers will be deleted.
  int disconnect(bool hard = false);
  int initiate_connection();

  void add_downstream_connection(Http2DownstreamConnection *dconn);
  void remove_downstream_connection(Http2DownstreamConnection *dconn);

  void remove_stream_data(StreamData *sd);

  int submit_request(Http2DownstreamConnection *dconn, int32_t pri,
                     const nghttp2_nv *nva, size_t nvlen,
                     const nghttp2_data_provider *data_prd);

  int submit_rst_stream(int32_t stream_id, uint32_t error_code);

  int submit_priority(Http2DownstreamConnection *dconn, int32_t pri);

  int terminate_session(uint32_t error_code);

  nghttp2_session *get_session() const;

  bool get_flow_control() const;

  int resume_data(Http2DownstreamConnection *dconn);

  int on_connect();

  int do_read();
  int do_write();

  int on_read();
  int on_write();

  int connected();
  int read_clear();
  int write_clear();
  int tls_handshake();
  int read_tls();
  int write_tls();

  int downstream_read_proxy();
  int downstream_connect_proxy();

  int downstream_read();
  int downstream_write();

  int noop();

  void signal_write();
  void clear_write_request();
  bool write_requested() const;

  struct ev_loop *get_loop() const;

  ev_io *get_wev();

  int get_state() const;
  void set_state(int state);

  void start_settings_timer();
  void stop_settings_timer();

  SSL *get_ssl() const;

  int consume(int32_t stream_id, size_t len);

  // Returns true if request can be issued on downstream connection.
  bool can_push_request() const;
  // Initiates the connection checking if downstream connection has
  // been established and connection checking is required.
  void start_checking_connection();
  // Resets connection check timer.  After timeout, we require
  // connection checking.
  void reset_connection_check_timer();
  // Signals that connection is alive.  Internally
  // reset_connection_check_timer() is called.
  void connection_alive();
  // Change connection check state.
  void set_connection_check_state(int state);

  bool should_hard_fail() const;

  enum {
    // Disconnected
    DISCONNECTED,
    // Connecting proxy and making CONNECT request
    PROXY_CONNECTING,
    // Tunnel is established with proxy
    PROXY_CONNECTED,
    // Establishing tunnel is failed
    PROXY_FAILED,
    // Connecting to downstream and/or performing SSL/TLS handshake
    CONNECTING,
    // Connected to downstream
    CONNECTED,
    // Connection is started to fail
    CONNECT_FAILING,
  };

  static const size_t OUTBUF_MAX_THRES = 64 * 1024;

  enum {
    // Connection checking is not required
    CONNECTION_CHECK_NONE,
    // Connection checking is required
    CONNECTION_CHECK_REQUIRED,
    // Connection checking has been started
    CONNECTION_CHECK_STARTED
  };

  using ReadBuf = RingBuf<8192>;
  using WriteBuf = RingBuf<65536>;

private:
  ev_io wev_;
  ev_io rev_;
  ev_timer wt_;
  ev_timer rt_;
  ev_timer settings_timer_;
  ev_timer connchk_timer_;
  ev_prepare wrsched_prep_;
  std::set<Http2DownstreamConnection *> dconns_;
  std::set<StreamData *> streams_;
  std::function<int(Http2Session &)> read_, write_;
  std::function<int(Http2Session &)> on_read_, on_write_;
  // Used to parse the response from HTTP proxy
  std::unique_ptr<http_parser> proxy_htp_;
  struct ev_loop *loop_;
  // NULL if no TLS is configured
  SSL_CTX *ssl_ctx_;
  SSL *ssl_;
  nghttp2_session *session_;
  const uint8_t *data_pending_;
  size_t data_pendinglen_;
  // fd_ is used for proxy connection and no TLS connection. For
  // direct or TLS connection, it may be -1 even after connection is
  // established. Use bufferevent_getfd(bev_) to get file descriptor
  // in these cases.
  int fd_;
  int state_;
  int connection_check_state_;
  bool flow_control_;
  bool write_requested_;
  WriteBuf wb_;
  ReadBuf rb_;
};

} // namespace shrpx

#endif // SHRPX_HTTP2_SESSION_H