#include "utils/snowflake.h"

#include <thread>

namespace utils {

static struct EpochInitializer {
  EpochInitializer() { EPOCH = std::chrono::system_clock::now(); }
  std::chrono::system_clock::time_point EPOCH;
} epochInitializer;

Snowflake GenerateID() {
  static std::mutex snowflakeGenerateMutex_;

  std::lock_guard<std::mutex> lock(snowflakeGenerateMutex_);

  std::size_t tid =
      std::hash<std::thread::id>{}(std::this_thread::get_id());

  thread_local static int sequence = 0;
  Snowflake id = {};

  auto timestamp = std::chrono::duration_cast<std::chrono::milliseconds>(
      std::chrono::system_clock::now() - epochInitializer.EPOCH);
  id.timestamp = timestamp.count();
  id.instance = tid;
  id.sequence = sequence++;

  return id;
}

};  // namespace Chattr