#include "DatabaseManager.h"
#include "Logger.h"
#include <boost/asio/bind_executor.hpp>
#include <boost/asio/post.hpp>
#include <boost/asio/use_awaitable.hpp>

DatabaseManager::PooledConnection::PooledConnection(
    DatabaseManager &manager,
    std::unique_ptr<boost::mysql::tcp_ssl_connection> conn)
    : manager_(manager), conn_(std::move(conn)) {}

DatabaseManager::PooledConnection::~PooledConnection() {
  if (conn_)
    manager_.ReturnConnection(std::move(conn_));
}

boost::mysql::tcp_ssl_connection &DatabaseManager::PooledConnection::Get() {
  return *conn_;
}

boost::mysql::tcp_ssl_connection *
DatabaseManager::PooledConnection::operator->() {
  return conn_.get();
}

DatabaseManager &DatabaseManager::GetInstance() {
  static DatabaseManager instance;
  return instance;
}

bool DatabaseManager::Init(boost::asio::io_context &io_context,
                           const std::string &host, uint16_t port,
                           const std::string &user, const std::string &password,
                           const std::string &db) {
  host_ = host;
  port_ = port;
  user_ = user;
  password_ = password;
  db_ = db;

  strand_ = std::make_unique<
      boost::asio::strand<boost::asio::io_context::executor_type>>(
      io_context.get_executor());

  Logger::Log("DatabaseManager Init 성공 (Connection Pool 준비됨): ", host, ":",
              port);
  return true;
}

boost::asio::awaitable<std::unique_ptr<DatabaseManager::PooledConnection>>
DatabaseManager::GetConnection() {
  auto executor = co_await boost::asio::this_coro::executor;

  co_await boost::asio::post(
      boost::asio::bind_executor(*strand_, boost::asio::use_awaitable));

  std::unique_ptr<boost::mysql::tcp_ssl_connection> conn;

  if (!available_conns_.empty()) {
    // 가져오기
    conn = std::move(available_conns_.back());
    available_conns_.pop_back();
  } else if (current_total_conns_ < max_pool_size_) {
    // 생성
    current_total_conns_++;
    try {
      static boost::asio::ssl::context ssl_ctx(
          boost::asio::ssl::context::tlsv12_client);
      conn =
          std::make_unique<boost::mysql::tcp_ssl_connection>(executor, ssl_ctx);

      boost::asio::ip::tcp::resolver resolver(executor);
      auto endpoints = resolver.resolve(host_, std::to_string(port_));
      boost::mysql::handshake_params params(user_, password_, db_);

      co_await conn->async_connect(*endpoints.begin(), params,
                                   boost::asio::use_awaitable);
      Logger::Log("새로운 DB 커넥션 생성됨. 현재 총 개수: ",
                  current_total_conns_);
    } catch (const std::exception &e) {
      current_total_conns_--;
      Logger::Log("커넥션 생성 실패: ", e.what());
      throw;
    }
  } else {
    // 대기
    auto timer = std::make_shared<boost::asio::steady_timer>(
        executor, std::chrono::steady_clock::time_point::max());
    waiting_queue_.push(timer);

    try {
      co_await timer->async_wait(boost::asio::use_awaitable);
    } catch (...) {
    }

    co_return co_await GetConnection();
  }

  co_return std::make_unique<PooledConnection>(*this, std::move(conn));
}

void DatabaseManager::ReturnConnection(
    std::unique_ptr<boost::mysql::tcp_ssl_connection> conn) {
  boost::asio::dispatch(*strand_, [this, conn = std::move(conn)]() mutable {
    if (!waiting_queue_.empty()) {
      // 대기 중이면 넣어주기
      available_conns_.push_back(std::move(conn));
      auto next = waiting_queue_.front();
      waiting_queue_.pop();
      next->cancel();
    } else {
      // 없으면 보관
      available_conns_.push_back(std::move(conn));
    }
  });
}

boost::asio::awaitable<DatabaseManager::UserData>
DatabaseManager::LoadUser(std::string nickname) {
  try {
    auto conn_ptr = co_await GetConnection();
    auto &conn = conn_ptr->Get();

    boost::mysql::results result;
    boost::mysql::statement stmt = co_await conn.async_prepare_statement(
        "SELECT username, gold, sword_level, max_sword_level FROM users WHERE "
        "username = ?",
        boost::asio::use_awaitable);
    co_await conn.async_execute(stmt.bind(nickname), result,
                                boost::asio::use_awaitable);

    if (result.rows().empty()) {
      boost::mysql::statement ins_stmt = co_await conn.async_prepare_statement(
          "INSERT INTO users (username, gold, sword_level) VALUES (?, 10000, "
          "0)",
          boost::asio::use_awaitable);
      co_await conn.async_execute(ins_stmt.bind(nickname), result,
                                  boost::asio::use_awaitable);
      Logger::Log("새로운 유저 탄생 (DB): ", nickname);
      co_return UserData{nickname, 10000, 0, 0};
    } else {
      auto row = result.rows().at(0);
      UserData data;
      data.nickname = row.at(0).as_string();
      data.gold = row.at(1).as_uint64();
      data.swordLevel = (uint32_t)row.at(2).as_int64();
      data.maxSwordLevel = (uint32_t)row.at(3).as_int64();
      co_return data;
    }
  } catch (const std::exception &e) {
    Logger::Log("LoadUser 에러: ", e.what());
    co_return UserData{nickname, 10000, 0, 0};
  }
}

boost::asio::awaitable<void> DatabaseManager::SaveUser(std::string nickname,
                                                       uint64_t gold,
                                                       uint32_t swordLevel) {
  try {
    auto conn_ptr = co_await GetConnection();
    auto &conn = conn_ptr->Get();

    boost::mysql::results result;
    boost::mysql::statement stmt = co_await conn.async_prepare_statement(
        "UPDATE users SET gold = ?, sword_level = ?, max_sword_level = "
        "GREATEST(max_sword_level, ?) WHERE username = ?",
        boost::asio::use_awaitable);
    co_await conn.async_execute(
        stmt.bind(gold, (int64_t)swordLevel, (int64_t)swordLevel, nickname),
        result, boost::asio::use_awaitable);
  } catch (const std::exception &e) {
    Logger::Log("SaveUser 에러: ", e.what());
  }
  co_return;
}

boost::asio::awaitable<DatabaseManager::RankingResult>
DatabaseManager::GetRanking(int type, std::string nickname) {
  RankingResult res;
  res.myRank = -1;
  res.myValue = 0;

  try {
    auto conn_ptr = co_await GetConnection();
    auto &conn = conn_ptr->Get();

    std::string columnName = (type == 0) ? "max_sword_level" : "gold";

    boost::mysql::results topResult;
    std::string topQuery = "SELECT username, " + columnName +
                           " FROM users ORDER BY " + columnName +
                           " DESC LIMIT 10";
    co_await conn.async_execute(topQuery, topResult,
                                boost::asio::use_awaitable);

    uint32_t rank = 1;
    for (auto row : topResult.rows()) {
      RankingResult::Entry entry;
      entry.rank = rank++;
      entry.nickname = row.at(0).as_string();
      if (type == 0) {
        entry.value = (uint64_t)row.at(1).as_int64();
      } else {
        entry.value = row.at(1).as_uint64();
      }
      res.topEntries.push_back(entry);
    }

    boost::mysql::results myResult;
    std::string myQuery =
        "SELECT " + columnName + ", (SELECT COUNT(*) + 1 FROM users WHERE " +
        columnName + " > u." + columnName + ") FROM users u WHERE username = ?";

    boost::mysql::statement stmt = co_await conn.async_prepare_statement(
        myQuery, boost::asio::use_awaitable);
    co_await conn.async_execute(stmt.bind(nickname), myResult,
                                boost::asio::use_awaitable);

    if (!myResult.rows().empty()) {
      auto row = myResult.rows().at(0);
      if (type == 0) {
        res.myValue = (uint64_t)row.at(0).as_int64();
      } else {
        res.myValue = row.at(0).as_uint64();
      }
      res.myRank = (int32_t)row.at(1).as_int64();
    }
  } catch (const std::exception &e) {
    Logger::Log("GetRanking 에러: ", e.what());
  }

  co_return res;
}