#include "tlbmc/hal/shared_mem/segment_manager.h"

#include <cstddef>
#include <filesystem>  // NOLINT
#include <fstream>
#include <memory>
#include <new>
#include <string>
#include <string_view>
#include <utility>

#include "absl/log/log.h"
#include "absl/memory/memory.h"
#include "boost/interprocess/exceptions.hpp"  // NOLINT
#include "boost/interprocess/managed_shared_memory.hpp"  // NOLINT
#include "tlbmc/hal/shared_mem/metrics.h"
#include "tlbmc/hal/shared_mem/sensors.h"

namespace milotic_tlbmc {

constexpr const char* kSharedMemoryName = "TlbmcSharedMemory";
constexpr const char* kMetricsObjectName = "TlbmcMetrics";
constexpr int kMaximumSensorCount = 1024;

std::unique_ptr<SegmentManager> SegmentManager::Create(
    std::string_view initialized_file_path) {
  if (std::filesystem::exists(initialized_file_path)) {
    try {
      boost::interprocess::managed_shared_memory sensors_memory(
          boost::interprocess::open_only, kSharedMemoryName);
      return absl::WrapUnique(new SegmentManager(std::move(sensors_memory)));
    } catch (const boost::interprocess::interprocess_exception& e) {
      LOG(ERROR) << "Failed to open shared memory: " << e.what();
      return nullptr;
    }
  }
  std::filesystem::path path(initialized_file_path);
  std::filesystem::path directory = path.parent_path();
  if (!std::filesystem::exists(directory) &&
      !std::filesystem::create_directories(directory)) {
    LOG(ERROR) << "Failed to create directory: " << directory;
    return nullptr;
  }
  LOG(WARNING)
      << "Creating shared memory; this should only happen once per boot.";
  try {
    // Times 2 for accounting for overhead.
    constexpr std::size_t kSharedMemorySize =
        (kMaximumSensorCount * sizeof(IpcSensor) + sizeof(TlbmcMetrics)) * 2;
    // Creates the segment.
    boost::interprocess::managed_shared_memory memory(
        boost::interprocess::create_only, kSharedMemoryName, kSharedMemorySize);
    std::ofstream file(std::string{initialized_file_path});
    if (!file.is_open()) {
      LOG(ERROR) << "Failed to open file: " << initialized_file_path;
      return nullptr;
    }
    file << 1;
    file.flush();
    return absl::WrapUnique(new SegmentManager(std::move(memory)));
  } catch (const boost::interprocess::interprocess_exception& e) {
    LOG(ERROR) << "Failed to create shared memory: " << e.what();
    return nullptr;
  }
  return nullptr;
}

std::unique_ptr<SegmentManager> SegmentManager::Get(
    std::string_view initialized_file_path) {
  if (!std::filesystem::exists(initialized_file_path)) {
    DLOG(WARNING) << "File " << initialized_file_path
                  << " not found. Shared memory is not initialized yet.";
    return nullptr;
  }
  try {
    boost::interprocess::managed_shared_memory memory(
        boost::interprocess::open_only, kSharedMemoryName);
    return absl::WrapUnique(new SegmentManager(std::move(memory)));
  } catch (const boost::interprocess::interprocess_exception& e) {
    DLOG(ERROR) << "Failed to open shared memory: " << e.what();
    return nullptr;
  }
}

IpcSensor* SegmentManager::GetOrCreateSensor(const char* sensor_name) {
  return memory_.find_or_construct<IpcSensor>(sensor_name, std::nothrow)();
}

TlbmcMetrics* SegmentManager::GetOrCreateMetrics() {
  return memory_.find_or_construct<TlbmcMetrics>(kMetricsObjectName,
                                                 std::nothrow)();
}

}  // namespace milotic_tlbmc