/*
 *
 * Copyright 2015 gRPC authors.
 *
 * Licensed 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.
 *
 */

#include "test/core/util/reconnect_server.h"

#include <string.h>

#include "absl/strings/string_view.h"

#include <grpc/grpc.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/time.h>

#include "src/core/lib/iomgr/endpoint.h"
#include "src/core/lib/iomgr/error.h"
#include "src/core/lib/iomgr/iomgr_fwd.h"
#include "src/core/lib/iomgr/tcp_server.h"
#include "test/core/util/test_tcp_server.h"

static void pretty_print_backoffs(reconnect_server* server) {
  gpr_timespec diff;
  int i = 1;
  double expected_backoff = 1000.0, backoff;
  timestamp_list* head = server->head;
  gpr_log(GPR_INFO, "reconnect server: new connection");
  for (head = server->head; head && head->next; head = head->next, i++) {
    diff = gpr_time_sub(head->next->timestamp, head->timestamp);
    backoff = gpr_time_to_millis(diff);
    gpr_log(GPR_INFO,
            "retry %2d:backoff %6.2fs,expected backoff %6.2fs, jitter %4.2f%%",
            i, backoff / 1000.0, expected_backoff / 1000.0,
            (backoff - expected_backoff) * 100.0 / expected_backoff);
    expected_backoff *= 1.6;
    int max_reconnect_backoff_ms = 120 * 1000;
    if (server->max_reconnect_backoff_ms > 0) {
      max_reconnect_backoff_ms = server->max_reconnect_backoff_ms;
    }
    if (expected_backoff > max_reconnect_backoff_ms) {
      expected_backoff = max_reconnect_backoff_ms;
    }
  }
}

static void on_connect(void* arg, grpc_endpoint* tcp,
                       grpc_pollset* /*accepting_pollset*/,
                       grpc_tcp_server_acceptor* acceptor) {
  gpr_free(acceptor);
  absl::string_view peer;
  absl::string_view::size_type last_colon;
  reconnect_server* server = static_cast<reconnect_server*>(arg);
  gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
  timestamp_list* new_tail;
  peer = grpc_endpoint_get_peer(tcp);
  grpc_endpoint_shutdown(tcp,
                         GRPC_ERROR_CREATE_FROM_STATIC_STRING("Connected"));
  grpc_endpoint_destroy(tcp);
  last_colon = peer.rfind(':');
  if (server->peer == nullptr) {
    server->peer = new std::string(peer);
  } else {
    if (last_colon == std::string::npos) {
      gpr_log(GPR_ERROR, "peer does not contain a ':'");
    } else if (peer.compare(0, static_cast<size_t>(last_colon),
                            *server->peer) != 0) {
      gpr_log(GPR_ERROR, "mismatched peer! %s vs %s", server->peer->c_str(),
              std::string(peer).c_str());
    }
  }
  new_tail = static_cast<timestamp_list*>(gpr_malloc(sizeof(timestamp_list)));
  new_tail->timestamp = now;
  new_tail->next = nullptr;
  if (server->tail == nullptr) {
    server->head = new_tail;
    server->tail = new_tail;
  } else {
    server->tail->next = new_tail;
    server->tail = new_tail;
  }
  pretty_print_backoffs(server);
}

void reconnect_server_init(reconnect_server* server) {
  test_tcp_server_init(&server->tcp_server, on_connect, server);
  server->head = nullptr;
  server->tail = nullptr;
  server->peer = nullptr;
  server->max_reconnect_backoff_ms = 0;
}

void reconnect_server_start(reconnect_server* server, int port) {
  test_tcp_server_start(&server->tcp_server, port);
}

void reconnect_server_poll(reconnect_server* server, int seconds) {
  test_tcp_server_poll(&server->tcp_server, 1000 * seconds);
}

void reconnect_server_clear_timestamps(reconnect_server* server) {
  timestamp_list* new_head = server->head;
  while (server->head) {
    new_head = server->head->next;
    gpr_free(server->head);
    server->head = new_head;
  }
  server->tail = nullptr;
  delete server->peer;
  server->peer = nullptr;
}

void reconnect_server_destroy(reconnect_server* server) {
  reconnect_server_clear_timestamps(server);
  test_tcp_server_destroy(&server->tcp_server);
}