#include "tlbmc/pacemaker/pacemaker.h"

#include <cstdint>

#include <cstdio>

#include <cstdlib>

#include <memory>

#include <string>

#include <utility>

#include "absl/functional/any_invocable.h"

#include "absl/log/log.h"

#include "absl/status/status.h"

#include "absl/status/statusor.h"

#include "absl/strings/ascii.h"

#include "absl/strings/match.h"

#include "absl/strings/numbers.h"

#include "absl/strings/str_cat.h"

#include "absl/strings/str_format.h"

#include "absl/synchronization/mutex.h"

#include "absl/time/clock.h"

#include "absl/time/time.h"

#include "g3/macros.h"

#include "time/clock.h"

#include "nlohmann/json.hpp"

namespace milotic_tlbmc {

namespace {

constexpr const int kMaxConsecutiveRestartAttempts = 10;

constexpr const char* kProcessName = "bmcweb";

constexpr const int kExpectedListeningPort = 443;

constexpr const int kMemoryUsageThreshold = 300 * 1024 * 1024;  // 300MB

constexpr const char* kIsActiveCommand = "systemctl is-active %s";

constexpr const char* kActiveStatus = "active";

constexpr const char* kRestartCommand = "systemctl restart %s";

constexpr const char* kIsListeningCommand = "ss -tulpn | grep %d";

constexpr const char* kGetMemoryUsageCommand =

    "cat /proc/%d/status | grep VmRSS | awk '{print $2}'";

constexpr const char* kGetPidCommand =

    "systemctl status %s | grep 'Main PID:' | awk '{print $3}'";

constexpr const char* kGetCpuUsageCommand =

    "top -n1 | grep %s -i | awk '{print int($8)}'";

constexpr const char* kGetActiveEnterTimestampMonotonic =

    "systemctl show --property=ActiveEnterTimestampMonotonic %s | awk -F'=' "

    "'{print $2}'";

constexpr const int kMaxRecentDataPoints = 12;

}  // namespace

nlohmann::json Pacemaker::ErrorInfo::ToJson() const {

  auto error_type_to_string = [](ErrorType type) -> std::string {

    switch (type) {

      case ErrorType::kUnknown:

        return "Unknown";

      case ErrorType::kServiceInactive:

        return "ServiceInactive";

      case ErrorType::kPortNotListening:

        return "PortNotListening";

      case ErrorType::kMemoryUsageAboveThreshold:

        return "MemoryUsageAboveThreshold";

      default:

        return "Unknown";

    }

  };

  nlohmann::json json;

  json["type"] = error_type_to_string(type);

  json["timestamp"] = absl::FormatTime(timestamp);

  return json;

}

nlohmann::json Pacemaker::MonitoredData::ToJson() const {

  nlohmann::json json;

  // Get the last kMaxRecentDataPoints memory usage data points.

  auto it = memory_usage_bytes.rbegin();

  for (int i = 0; i < kMaxRecentDataPoints && it != memory_usage_bytes.rend();

       ++i, ++it) {

    json["MemoryUsageRecentToOldest"].push_back(*it);

  }

  // Get the last kMaxRecentDataPoints error data points.

  auto it_error = restart_log.rbegin();

  for (int i = 0; i < kMaxRecentDataPoints && it_error != restart_log.rend();

       ++i, ++it_error) {

    json["ErrorsRecentToOldest"].push_back(it_error->ToJson());

  }

  json["CpuUsage"] = cpu_usage;

  json["MemoryUsage"] =

      memory_usage_bytes.empty() ? -1 : memory_usage_bytes.back();

  json["LastActiveTimestamp"] = last_active_timestamp;

  json["LastResetTime"] = absl::FormatTime(last_reset_time);

  json["RestartTriggered"] = restart_triggered;

  json["Pid"] = pid;

  json["ConsecutiveRestartAttempts"] = consecutive_restart_attempts;

  return json;

}

absl::StatusOr<std::string> ShellCommandExecutor::Execute(

    const std::string& command) {

  FILE* pipe = popen(command.c_str(), "r");

  if (pipe == nullptr) {

    return absl::InternalError(

        absl::StrCat("Error: Failed to execute command: ", command));

  }

  std::string result;

  char* line = nullptr;

  size_t len = 0;

  ssize_t read;

  while ((read = getline(&line, &len, pipe)) != -1) {

    result.append(line, static_cast<std::string::size_type>(read));

  }

  free(line);

  pclose(pipe);

  return result;

}

absl::StatusOr<bool> Pacemaker::IsServiceActive(

    const std::string& service_name) const {

  LOG(INFO) << "Checking if service " << service_name << " is active.";

  ECCLESIA_ASSIGN_OR_RETURN(

      std::string output, shell_command_executor_->Execute(

                              absl::StrFormat(kIsActiveCommand, service_name)));

  absl::StripAsciiWhitespace(&output);

  // Compare string

  if (!absl::EqualsIgnoreCase(output, "active")) {

    LOG(ERROR) << "Service " << service_name << " is not active."

               << " status is " << output << " instead of " << kActiveStatus;

    return false;

  }

  return true;

}

absl::StatusOr<bool> Pacemaker::IsPortListening(int port) const {

  LOG(INFO) << "Checking if port " << port << " is listening.";

  ECCLESIA_ASSIGN_OR_RETURN(std::string output,

                            shell_command_executor_->Execute(

                                absl::StrFormat(kIsListeningCommand, port)));

  return !output.empty();

}

absl::StatusOr<int> Pacemaker::GetMemoryUsage(int pid) const {

  LOG(INFO) << "Getting memory usage for pid " << pid;

  ECCLESIA_ASSIGN_OR_RETURN(std::string output,

                            shell_command_executor_->Execute(

                                absl::StrFormat(kGetMemoryUsageCommand, pid)));

  int memory_usage;

  if (!absl::SimpleAtoi(output, &memory_usage)) {

    return absl::InternalError(

        absl::StrCat("Error: Failed to parse memory usage: ", output));

  }

  return memory_usage;

}

absl::StatusOr<int> Pacemaker::GetCpuUsage(

    const std::string& process_name) const {

  LOG(INFO) << "Getting CPU usage for process " << process_name;

  ECCLESIA_ASSIGN_OR_RETURN(std::string output,

                            shell_command_executor_->Execute(absl::StrFormat(

                                kGetCpuUsageCommand, process_name)));

  int cpu_usage = -1;

  if (output.empty()) {

    return cpu_usage;

  }

  if (!absl::SimpleAtoi(output, &cpu_usage)) {

    return absl::InternalError(

        absl::StrCat("Error: Failed to parse CPU usage: ", output));

  }

  return cpu_usage;

}

absl::StatusOr<int64_t> Pacemaker::GetLastActiveTimestamp(

    const std::string& process_name) const {

  LOG(INFO) << "Getting last active timestamp for process " << process_name;

  ECCLESIA_ASSIGN_OR_RETURN(

      std::string output,

      shell_command_executor_->Execute(

          absl::StrFormat(kGetActiveEnterTimestampMonotonic, process_name)));

  int64_t last_active_timestamp;

  if (!absl::SimpleAtoi(output, &last_active_timestamp)) {

    return absl::InternalError(

        absl::StrCat("Error: Failed to parse last reset time: ", output));

  }

  return last_active_timestamp;

}

absl::Status Pacemaker::RestartService(const std::string& service_name) {

  LOG(ERROR) << "Restarting service " << service_name;

  {

    absl::MutexLock lock(&mutex_);

    if (monitored_data_.restart_triggered) {

      if (monitored_data_.consecutive_restart_attempts >=

          kMaxConsecutiveRestartAttempts) {

        LOG(ERROR) << "Restart attempts exceeded the limit of "

                   << kMaxConsecutiveRestartAttempts;

        return absl::InternalError(

            absl::StrCat("Error: Restart attempts exceeded the limit of ",

                         kMaxConsecutiveRestartAttempts));

      }

      ++monitored_data_.consecutive_restart_attempts;

    }

    monitored_data_.restart_triggered = true;

    monitored_data_.last_reset_time = absl::Now();

  }

  ECCLESIA_ASSIGN_OR_RETURN(

      std::string output, shell_command_executor_->Execute(

                              absl::StrFormat(kRestartCommand, service_name)));

  return absl::OkStatus();

}

// Get PID of the process.

absl::StatusOr<int> Pacemaker::GetPid(const std::string& process_name) const {

  LOG(INFO) << "Getting PID for process " << process_name;

  ECCLESIA_ASSIGN_OR_RETURN(std::string output,

                            shell_command_executor_->Execute(

                                absl::StrFormat(kGetPidCommand, process_name)));

  int pid = -1;

  if (output.empty()) {

    return absl::InternalError(

        absl::StrCat("Error: Main PID not found for service: ", process_name));

  }

  // Trim leading and trailing whitespace, including newlines.

  output = std::string(absl::StripAsciiWhitespace(output));

  if (absl::SimpleAtoi(output, &pid)) {

    return pid;

  }

  return absl::InternalError(

      absl::StrCat("Error: Invalid PID found in systemctl output: ", output,

                   " for service: ", process_name));

}

void Pacemaker::RecordError(ErrorType type) {

  absl::MutexLock lock(&mutex_);

  // If the error type is unknown, we can't determine the timestamp.

  // So we just record the error and continue.

  if (type == ErrorType::kUnknown) {

    monitored_data_.restart_log.push_back({type, absl::InfinitePast()});

    return;

  }

  ErrorInfo error_info = {type, absl::Now()};

  LOG(ERROR) << "Restart required due to Error:\n"

             << error_info.ToJson().dump(2);

  monitored_data_.restart_log.push_back(error_info);

}

absl::Status Pacemaker::PerformChecks() {

  bool unknown_restart_detected = false;

  ECCLESIA_ASSIGN_OR_RETURN(bool is_active, IsServiceActive(kProcessName));

  int pid = -1;

  int cpu_usage = -1;

  int memory_usage = -1;

  bool is_listening = false;

  if (is_active) {

    ECCLESIA_ASSIGN_OR_RETURN(is_listening,

                              IsPortListening(kExpectedListeningPort));

    ECCLESIA_ASSIGN_OR_RETURN(pid, GetPid(kProcessName));

    ECCLESIA_ASSIGN_OR_RETURN(cpu_usage, GetCpuUsage(kProcessName));

    if (pid > 0) {

      ECCLESIA_ASSIGN_OR_RETURN(memory_usage, GetMemoryUsage(pid));

    }

  }

  absl::StatusOr<int64_t> last_active_timestamp =

      GetLastActiveTimestamp(kProcessName);

  if (!last_active_timestamp.ok()) {

    LOG(ERROR) << "Failed to get last active timestamp: "

               << last_active_timestamp.status();

  }

  // Update monitored data.

  {

    absl::MutexLock lock(&mutex_);

    monitored_data_.memory_usage_bytes.push_back(memory_usage);

    monitored_data_.cpu_usage = cpu_usage;

    monitored_data_.pid = pid;

    // Check if the process was restarted outside of pacemaker.

    if (last_active_timestamp.ok()) {

      // We check if the `last_active_timestamp` we got from systemctl

      // is different from the one we got from the previous run and if the

      // process was not restarted by pacemaker.

      // If the timestamps are different, it means the process was restarted

      // outside of pacemaker and we should record it as an unknown error.

      if (monitored_data_.last_active_timestamp != -1 &&

          *last_active_timestamp != monitored_data_.last_active_timestamp &&

          !monitored_data_.restart_triggered) {

        LOG(INFO) << "Process " << kProcessName

                  << " was restarted outside of pacemaker.";

        unknown_restart_detected = true;

      }

      monitored_data_.last_active_timestamp = *last_active_timestamp;

    }

  }

  if (unknown_restart_detected) {

    RecordError(ErrorType::kUnknown);

  }

  if (!is_active) {

    RecordError(ErrorType::kServiceInactive);

    ECCLESIA_RETURN_IF_ERROR(RestartService(kProcessName));

    return absl::OkStatus();

  }

  if (!is_listening) {

    LOG(ERROR) << "Process " << kProcessName << " is not listening on port "

               << kExpectedListeningPort;

    RecordError(ErrorType::kPortNotListening);

    ECCLESIA_RETURN_IF_ERROR(RestartService(kProcessName));

    return absl::OkStatus();

  }

  if (memory_usage > kMemoryUsageThreshold) {

    LOG(ERROR) << "Process " << kProcessName << " memory usage is "

               << memory_usage << " bytes which is more than the threshold of "

               << kMemoryUsageThreshold;

    RecordError(ErrorType::kMemoryUsageAboveThreshold);

    ECCLESIA_RETURN_IF_ERROR(RestartService(kProcessName));

    return absl::OkStatus();

  }

  // If we reach here, it means all checks passed.

  // Reset the restart triggered and consecutive restart attempts counters.

  absl::MutexLock lock(&mutex_);

  monitored_data_.restart_triggered = false;

  monitored_data_.consecutive_restart_attempts = 0;

  return absl::OkStatus();

}

nlohmann::json Pacemaker::GetMonitoringData() const {

  nlohmann::json json;

  {

    absl::MutexLock lock(&mutex_);

    json = monitored_data_.ToJson();

  }

  json["PacemakerSchedulerStats"] = scheduler_.ToJson();

  return json;

}

Pacemaker::Pacemaker(

    absl::Duration interval,

    std::unique_ptr<ShellCommandExecutor> shell_command_executor,

    ecclesia::Clock* clock)

    : shell_command_executor_(std::move(shell_command_executor)),

      scheduler_(clock) {

  scheduler_.ScheduleAsync(

      [this](absl::AnyInvocable<void()> OnDone) {

        if (absl::Status status = PerformChecks(); !status.ok()) {

          LOG(ERROR) << "Failed to perform checks: " << status;

        } else {

          // Dump the monitoring data to the syslog periodically.

          LOG(WARNING) << "tlBMC Health stats:\n"

                       << GetMonitoringData().dump(2);

        }

        OnDone();

      },

      interval);

}

}  // namespace milotic_tlbmc