#pragma once

#include <algorithm>
#include <csignal>
#include <cstdint>
#include <optional>
#include <random>
#include <vector>

#include "boost/asio/ip/address.hpp"  // NOLINT
#include "utility.hpp"
#include <nlohmann/json.hpp>

namespace persistent_data {

// entropy: 20 characters, 62 possibilities.  log2(62^20) = 119 bits of
// entropy.  OWASP recommends at least 64
// https://cheatsheetseries.owasp.org/cheatsheets/Session_Management_Cheat_Sheet.html#session-id-entropy
constexpr std::size_t sessionTokenSize = 20;

enum class PersistenceType : std::uint8_t {
  TIMEOUT,        // User session times out after a predetermined amount of time
  SINGLE_REQUEST  // User times out once this request is completed.
};

struct UserSession {
  std::string uniqueId;
  std::string sessionToken;
  std::string username;
  std::string csrfToken;
  std::optional<std::string> clientId;
  std::string clientIp;
  std::chrono::time_point<std::chrono::steady_clock> lastUpdated;
  PersistenceType persistence{PersistenceType::TIMEOUT};
  bool cookieAuth = false;
  bool isConfigureSelfOnly = false;

  // There are two sources of truth for isConfigureSelfOnly:
  //  1. When pamAuthenticateUser() returns PAM_NEW_AUTHTOK_REQD.
  //  2. D-Bus User.Manager.GetUserInfo property UserPasswordExpired.
  // These should be in sync, but the underlying condition can change at any
  // time.  For example, a password can expire or be changed outside of
  // bmcweb.  The value stored here is updated at the start of each
  // operation and used as the truth within bmcweb.

  /**
   * @brief Fills object with data from UserSession's JSON representation
   *
   * This replaces nlohmann's from_json to ensure no-throw approach
   *
   * @param[in] j   JSON object from which data should be loaded
   *
   * @return a shared pointer if data has been loaded properly, nullptr
   * otherwise
   */
  static std::shared_ptr<UserSession> fromJson(const nlohmann::json& j);
};

struct AuthConfigMethods {
#ifdef BMCWEB_ENABLE_BASIC_AUTHENTICATION
  bool basic = true;
#else
  bool basic = false;
#endif

#ifdef BMCWEB_ENABLE_SESSION_AUTHENTICATION
  bool sessionToken = true;
#else
  bool sessionToken = false;
#endif

#ifdef BMCWEB_ENABLE_XTOKEN_AUTHENTICATION
  bool xtoken = true;
#else
  bool xtoken = false;
#endif

#ifdef BMCWEB_ENABLE_COOKIE_AUTHENTICATION
  bool cookie = true;
#else
  bool cookie = false;
#endif

#ifdef BMCWEB_ENABLE_MUTUAL_TLS_AUTHENTICATION
  bool tls = true;
#else
  bool tls = false;
#endif

  void fromJson(const nlohmann::json& j);
};

class SessionStore {
 public:
  std::shared_ptr<UserSession> generateUserSession(
      std::string_view username, const boost::asio::ip::address& clientIp,
      const std::optional<std::string>& clientId,
      PersistenceType persistence = PersistenceType::TIMEOUT,
      bool isConfigureSelfOnly = false);

  std::shared_ptr<UserSession> loginSessionByToken(std::string_view token);

  std::shared_ptr<UserSession> getSessionByUid(std::string_view uid);

  void removeSession(const std::shared_ptr<UserSession>& session);

  std::vector<const std::string*> getUniqueIds(
      bool getAll = true,
      const PersistenceType& type = PersistenceType::SINGLE_REQUEST);

  void removeSessionsByUsername(std::string_view username);

  void updateAuthMethodsConfig(const AuthConfigMethods& config);

  AuthConfigMethods& getAuthMethodsConfig() { return authMethodsConfig; }

  bool needsWrite() const { return needWrite; }
  int64_t getTimeoutInSeconds() const {
    return std::chrono::seconds(timeoutInSeconds).count();
  }

  void updateSessionTimeout(std::chrono::seconds newTimeoutInSeconds) {
    timeoutInSeconds = newTimeoutInSeconds;
    needWrite = true;
  }

  static SessionStore& getInstance() {
    static SessionStore sessionStore;
    return sessionStore;
  }

  void applySessionTimeouts();

  SessionStore(const SessionStore&) = delete;
  SessionStore& operator=(const SessionStore&) = delete;
  SessionStore(SessionStore&&) = delete;
  SessionStore& operator=(const SessionStore&&) = delete;
  ~SessionStore() = default;

  std::unordered_map<std::string, std::shared_ptr<UserSession>,
                     std::hash<std::string>, crow::utility::ConstantTimeCompare>
      authTokens;

  std::chrono::time_point<std::chrono::steady_clock> lastTimeoutUpdate;
  bool needWrite{false};
  std::chrono::seconds timeoutInSeconds;
  AuthConfigMethods authMethodsConfig;

 private:
  SessionStore() : timeoutInSeconds(1800) {}
};

}  // namespace persistent_data