/*
 * nghttp2 - HTTP/2 C Library
 *
 * Copyright (c) 2014 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.
 */
#include "h2load_spdy_session.h"

#include <cassert>
#include <cerrno>

#include "h2load.h"
#include "util.h"

using namespace nghttp2;

namespace h2load {

SpdySession::SpdySession(Client *client, uint16_t spdy_version)
    : client_(client), session_(nullptr), spdy_version_(spdy_version) {}

SpdySession::~SpdySession() { spdylay_session_del(session_); }

namespace {
void before_ctrl_send_callback(spdylay_session *session,
                               spdylay_frame_type type, spdylay_frame *frame,
                               void *user_data) {
  auto client = static_cast<Client *>(user_data);
  if (type != SPDYLAY_SYN_STREAM) {
    return;
  }
  client->on_request(frame->syn_stream.stream_id);
  auto req_stat =
      static_cast<RequestStat *>(spdylay_session_get_stream_user_data(
          session, frame->syn_stream.stream_id));
  client->record_request_time(req_stat);
}
} // namespace

namespace {
void on_ctrl_recv_callback(spdylay_session *session, spdylay_frame_type type,
                           spdylay_frame *frame, void *user_data) {
  auto client = static_cast<Client *>(user_data);
  if (type != SPDYLAY_SYN_REPLY) {
    return;
  }
  for (auto p = frame->syn_reply.nv; *p; p += 2) {
    auto name = *p;
    auto value = *(p + 1);
    auto namelen = strlen(name);
    auto valuelen = strlen(value);
    client->on_header(frame->syn_reply.stream_id,
                      reinterpret_cast<const uint8_t *>(name), namelen,
                      reinterpret_cast<const uint8_t *>(value), valuelen);
    client->worker->stats.bytes_head_decomp += namelen + valuelen;
  }

  // Strictly speaking, we have to subtract 2 (unused field) if SPDY
  // version is 2.  But it is already deprecated, and we don't do
  // extra work for it.
  client->worker->stats.bytes_head += frame->syn_reply.hd.length - 4;

  if (frame->syn_stream.hd.flags & SPDYLAY_CTRL_FLAG_FIN) {
    client->record_ttfb();
  }
}
} // namespace

namespace {
void on_data_chunk_recv_callback(spdylay_session *session, uint8_t flags,
                                 int32_t stream_id, const uint8_t *data,
                                 size_t len, void *user_data) {
  auto client = static_cast<Client *>(user_data);

  client->record_ttfb();
  client->worker->stats.bytes_body += len;

  auto spdy_session = static_cast<SpdySession *>(client->session.get());

  spdy_session->handle_window_update(stream_id, len);
}
} // namespace

namespace {
void on_stream_close_callback(spdylay_session *session, int32_t stream_id,
                              spdylay_status_code status_code,
                              void *user_data) {
  auto client = static_cast<Client *>(user_data);
  auto req_stat = static_cast<RequestStat *>(
      spdylay_session_get_stream_user_data(session, stream_id));
  client->on_stream_close(stream_id, status_code == SPDYLAY_OK, req_stat);
}
} // namespace

namespace {
ssize_t send_callback(spdylay_session *session, const uint8_t *data,
                      size_t length, int flags, void *user_data) {
  auto client = static_cast<Client *>(user_data);
  auto &wb = client->wb;

  if (wb.wleft() == 0) {
    return SPDYLAY_ERR_DEFERRED;
  }

  return wb.write(data, length);
}
} // namespace

namespace {
ssize_t file_read_callback(spdylay_session *session, int32_t stream_id,
                           uint8_t *buf, size_t length, int *eof,
                           spdylay_data_source *source, void *user_data) {
  auto client = static_cast<Client *>(user_data);
  auto config = client->worker->config;
  auto req_stat = static_cast<RequestStat *>(
      spdylay_session_get_stream_user_data(session, stream_id));

  ssize_t nread;
  while ((nread = pread(config->data_fd, buf, length, req_stat->data_offset)) ==
             -1 &&
         errno == EINTR)
    ;

  if (nread == -1) {
    return SPDYLAY_ERR_TEMPORAL_CALLBACK_FAILURE;
  }

  req_stat->data_offset += nread;

  if (nread == 0 || req_stat->data_offset == config->data_length) {
    *eof = 1;
  }

  return nread;
}
} // namespace

void SpdySession::on_connect() {
  spdylay_session_callbacks callbacks = {0};
  callbacks.send_callback = send_callback;
  callbacks.before_ctrl_send_callback = before_ctrl_send_callback;
  callbacks.on_data_chunk_recv_callback = on_data_chunk_recv_callback;
  callbacks.on_stream_close_callback = on_stream_close_callback;
  callbacks.on_ctrl_recv_callback = on_ctrl_recv_callback;

  spdylay_session_client_new(&session_, spdy_version_, &callbacks, client_);

  int val = 1;
  spdylay_session_set_option(session_, SPDYLAY_OPT_NO_AUTO_WINDOW_UPDATE, &val,
                             sizeof(val));

  spdylay_settings_entry iv;
  iv.settings_id = SPDYLAY_SETTINGS_INITIAL_WINDOW_SIZE;
  iv.flags = SPDYLAY_ID_FLAG_SETTINGS_NONE;
  iv.value = (1 << client_->worker->config->window_bits);
  spdylay_submit_settings(session_, SPDYLAY_FLAG_SETTINGS_NONE, &iv, 1);

  auto config = client_->worker->config;

  if (spdy_version_ >= SPDYLAY_PROTO_SPDY3_1 &&
      config->connection_window_bits > 16) {
    auto delta =
        (1 << config->connection_window_bits) - SPDYLAY_INITIAL_WINDOW_SIZE;
    spdylay_submit_window_update(session_, 0, delta);
  }

  client_->signal_write();
}

int SpdySession::submit_request(RequestStat *req_stat) {
  int rv;
  auto config = client_->worker->config;
  auto &nv = config->nv[client_->reqidx++];

  if (client_->reqidx == config->nv.size()) {
    client_->reqidx = 0;
  }

  spdylay_data_provider prd{{0}, file_read_callback};

  rv = spdylay_submit_request(session_, 0, nv.data(),
                              config->data_fd == -1 ? nullptr : &prd, req_stat);

  if (rv != 0) {
    return -1;
  }

  return 0;
}

int SpdySession::on_read(const uint8_t *data, size_t len) {
  auto rv = spdylay_session_mem_recv(session_, data, len);
  if (rv < 0) {
    return -1;
  }

  assert(static_cast<size_t>(rv) == len);

  if (spdylay_session_want_read(session_) == 0 &&
      spdylay_session_want_write(session_) == 0 && client_->wb.rleft() == 0) {
    return -1;
  }

  client_->signal_write();

  return 0;
}

int SpdySession::on_write() {
  auto rv = spdylay_session_send(session_);
  if (rv != 0) {
    return -1;
  }

  if (spdylay_session_want_read(session_) == 0 &&
      spdylay_session_want_write(session_) == 0 && client_->wb.rleft() == 0) {
    return -1;
  }
  return 0;
}

void SpdySession::terminate() {
  spdylay_session_fail_session(session_, SPDYLAY_OK);
}

namespace {
int32_t determine_window_update_transmission(spdylay_session *session,
                                             int32_t stream_id,
                                             size_t window_bits) {
  int32_t recv_length;

  if (stream_id == 0) {
    recv_length = spdylay_session_get_recv_data_length(session);
  } else {
    recv_length =
        spdylay_session_get_stream_recv_data_length(session, stream_id);
  }

  auto window_size = 1 << window_bits;

  if (recv_length != -1 && recv_length >= window_size / 2) {
    return recv_length;
  }

  return -1;
}
} // namespace

void SpdySession::handle_window_update(int32_t stream_id, size_t recvlen) {
  auto config = client_->worker->config;
  size_t connection_window_bits;

  if (config->connection_window_bits > 16) {
    connection_window_bits = config->connection_window_bits;
  } else {
    connection_window_bits = 16;
  }

  auto delta =
      determine_window_update_transmission(session_, 0, connection_window_bits);
  if (delta > 0) {
    spdylay_submit_window_update(session_, 0, delta);
  }

  delta = determine_window_update_transmission(session_, stream_id,
                                               config->window_bits);
  if (delta > 0) {
    spdylay_submit_window_update(session_, stream_id, delta);
  }
}

} // namespace h2load