/*
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  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.

  This program is designed to work with certain software (including
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  permission to link the program and your derivative works with the
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  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

/**
 * @file
 * @brief Component Tests to test Router shutdown
 */

#include <chrono>
#include <csignal>
#include <thread>

#include <gmock/gmock.h>

#ifdef RAPIDJSON_NO_SIZETYPEDEFINE
#include "my_rapidjson_size_t.h"
#endif
#include <rapidjson/document.h>

#include "mock_server_rest_client.h"
#include "mock_server_testutils.h"
#include "mysqlrouter/rest_client.h"
#include "rest_api_testutils.h"
#include "router_component_test.h"

using ::testing::Eq;
using namespace std::chrono_literals;

class ShutdownTest : public RouterComponentTest {
 protected:
  void SetUp() override {
    RouterComponentTest::SetUp();

    // Valgrind needs way more time
    if (getenv("WITH_VALGRIND")) {
      wait_for_cache_ready_timeout_ = 5000;
    }
  }

  auto &launch_router(const std::string &temp_test_dir,
                      const std::string &other_sections) {
    auto default_section = get_DEFAULT_defaults();
    init_keyring(default_section, temp_test_dir);

    // create tmp conf dir (note that it will be RAII-deleted before router
    // shuts down, but that's ok)
    const std::string conf_file =
        create_config_file(temp_test_dir, other_sections, &default_section);

    // launch the router
    auto &router = ProcessManager::launch_router(
        {"-c", conf_file}, EXIT_SUCCESS, true, false, -1s);

    return router;
  }

  void delay_sending_handshake(
      const JsonValue &existing_globals,
      const std::vector<uint16_t> cluster_node_http_ports) {
    const std::string kRestGlobalsUri = "/api/v1/mock_server/globals/";
    const std::string kHostname = "127.0.0.1";
    const int kHandshakeSendDelayMs = 10000;

    JsonValue globals;
    JsonAllocator allocator;
    globals.CopyFrom(existing_globals, allocator);
    globals.AddMember("connect_exec_time", kHandshakeSendDelayMs, allocator);
    const auto json_str = json_to_string(globals);

    // tell all the server mocks to delay sending handshake by 10 seconds
    for (auto http_port : cluster_node_http_ports) {
      EXPECT_NO_THROW(MockServerRestClient(http_port).set_globals(json_str));
    }
  }

  int get_delayed_handshakes_count(const uint16_t http_port) {
    const std::string kRestGlobalsUri = "/api/v1/mock_server/globals/";
    const std::string kHostname = "127.0.0.1";
    constexpr char kDelayedHandshakes[] = "delayed_handshakes";

    // GET request

    EXPECT_TRUE(wait_for_rest_endpoint_ready(kRestGlobalsUri, http_port))
        << "wait_for_rest_endpoint_ready() timed out";

    IOContext io_ctx;
    RestClient rest_client(io_ctx, kHostname, http_port);
    HttpRequest req =
        rest_client.request_sync(HttpMethod::Get, kRestGlobalsUri);

    EXPECT_TRUE(req) << "HTTP Request to " << kHostname << ":"
                     << std::to_string(http_port)
                     << " failed (early): " << req.error_msg() << std::endl;
    EXPECT_GT(req.get_response_code(), 0u)
        << "HTTP Request to " << kHostname << ":" << std::to_string(http_port)
        << " failed: " << req.error_msg() << std::endl;
    EXPECT_EQ(req.get_response_code(), 200u);

    auto resp_body = req.get_input_buffer();
    auto resp_body_content = resp_body.pop_front(resp_body.length());

    // parse JSON

    std::string json_payload(resp_body_content.begin(),
                             resp_body_content.end());

    using JsonDocument =
        rapidjson::GenericDocument<rapidjson::UTF8<>, rapidjson::CrtAllocator>;

    JsonDocument json_doc;
    json_doc.Parse(json_payload.c_str());

    EXPECT_TRUE(!json_doc.HasParseError());

    const auto &v = json_doc.GetObject();
    if (v.HasMember(kDelayedHandshakes)) {
      if (!v[kDelayedHandshakes].IsInt())
        throw std::logic_error("field 'delayed_handshakes' is not an integer!");
      return v[kDelayedHandshakes].GetInt();
    } else {
      return 0;
    }
  }

  unsigned wait_for_cache_ready_timeout_ = 1000;
};

/** @test
 * Verify that Router shutdown is quick when connectivity to cluster is flaky
 *
 * NOTE: If one day Router shutdown is quicker than at the time of writing,
 *       kAcceptableShutdownWait could be reduced
 *
 * At the time of writing, the bottleneck is Metadata Cache's refresh thread.
 * After the shutdown signal has been received and shutdown flag raised, all
 * other threads quickly exit while Refresh thread lingers on
 * mysql_real_connect(), trying to connect to a metadata server. Unfortunately
 * there's no simple way to interrupt this call, so the best we can hope for is
 * that the Router shuts down immediately after that call times out. This is
 * the expectation of this test.
 *
 * To simulate flaky connection, we send a special HTTP request to server mocks
 * that will cause them to reply very slowly during MySQL handshake for all new
 * connections. This is enough to cause mysql_real_connect() to block, just
 * like it would on a flaky TCP connection.
 */
TEST_F(ShutdownTest, flaky_connection_to_cluster) {
  // MdC's refresh thread can block up to this many seconds on
  // mysql_real_connect(<metadata server>)
  constexpr std::chrono::milliseconds kConnectTimeout = 2000ms;

  // This is our expectation - the test will pass if Router shuts down within
  // these many seconds. The value should should allow for up do
  // kConnectTimeout to pass, plus maybe some additional time to account for
  // additional CPU cycles needed. But it should not be at 2 * kConnectTimeout
  // or higher, because we want to make sure no more than one metadata server
  // is blocking the shutdown.
  constexpr std::chrono::milliseconds kAcceptableShutdownWait =
      kConnectTimeout +
      kConnectTimeout / 2;  // should be between 1 and 2 * kConnectTimeout

  TempDirectory temp_test_dir;

  const std::vector<uint16_t> cluster_node_ports{
      port_pool_.get_next_available(),
      port_pool_.get_next_available(),
      port_pool_.get_next_available(),
      port_pool_.get_next_available(),
  };
  const std::vector<uint16_t> cluster_node_http_ports{
      port_pool_.get_next_available(),
      port_pool_.get_next_available(),
      port_pool_.get_next_available(),
      port_pool_.get_next_available(),
  };
  const uint16_t router_port = port_pool_.get_next_available();

  const std::string json_primary_node =
      get_data_dir().join("test_shutdown.js").str();

  // launch cluster
  // NOTE: We reuse the primary's JSON file for all the secondaries just for
  //       convenience. Only the primary is expected to receive queries,
  //       therefore any arbitrary JSON will do for the secondaries.
  std::vector<ProcessWrapper *> cluster_nodes;
  for (size_t i = 0; i < cluster_node_ports.size(); i++) {
    const auto http_port = cluster_node_http_ports[i];
    auto &node =
        launch_mysql_server_mock(json_primary_node, cluster_node_ports[i],
                                 EXIT_SUCCESS, false /*debug_mode*/, http_port);
    cluster_nodes.emplace_back(&node);
    set_mock_metadata(http_port, "gr-id",
                      classic_ports_to_gr_nodes(cluster_node_ports), i,
                      classic_ports_to_cluster_nodes(cluster_node_ports));
  }

  // write Router config
  std::string servers;
  for (unsigned port : cluster_node_ports)
    servers += "mysql://127.0.0.1:" + std::to_string(port) + ",";
  servers.resize(servers.size() - 1);  // trim last ","
  const std::string config =
      /*[DEFAULT]*/
      "connect_timeout = " + std::to_string(kConnectTimeout.count() / 1000) +
      "\n"
      "\n"
      "[metadata_cache:test]\n"
      "router_id=1\n"
      "bootstrap_server_addresses=" +
      servers +
      "\n"
      "user=mysql_router1_user\n"
      "metadata_cluster=test\n"
      "ttl=0.1\n"
      "\n"
      "[routing:test_default]\n"
      "bind_port=" +
      std::to_string(router_port) +
      "\n"
      "destinations=metadata-cache://test/default?role=PRIMARY\n"
      "protocol=classic\n"
      "routing_strategy=round-robin\n"
      "\n";

  // launch the Router
  auto &router = launch_router(temp_test_dir.name(), config);
  ASSERT_NO_FATAL_FAILURE(check_port_ready(router, router_port));

  // give the Router a chance to initialise metadata-cache module
  // there is currently no easy way to check that
  std::this_thread::sleep_for(
      std::chrono::milliseconds(wait_for_cache_ready_timeout_));

  // now let's tell server nodes to delay sending MySQL Protocol handshake on
  // new connections (to simulate them being unreachable)
  auto current_globals = mock_GR_metadata_as_json(
      "gr-id", classic_ports_to_gr_nodes(cluster_node_ports), 0,
      classic_ports_to_cluster_nodes(cluster_node_ports));
  ASSERT_NO_FATAL_FAILURE(
      { delay_sending_handshake(current_globals, cluster_node_http_ports); });

  // wait for a new (slow) Refresh cycle to commence
  auto deadline = std::chrono::steady_clock::now() + std::chrono::seconds(5);
  while (std::chrono::steady_clock::now() < deadline &&
         !get_delayed_handshakes_count(cluster_node_http_ports.front())) {
    std::this_thread::sleep_for(std::chrono::milliseconds(10));
  }

  // and tell Router to shutdown and expect it to finish it within
  // kAcceptableShutdownWait seconds
  EXPECT_FALSE(router.send_clean_shutdown_event());
  check_exit_code(router, EXIT_SUCCESS, kAcceptableShutdownWait);
}

int main(int argc, char *argv[]) {
  init_windows_sockets();
  ProcessManager::set_origin(Path(argv[0]).dirname());
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}