//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2020 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    as published by the Free Software Foundation.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.

// This file describes the basic set of OpenVPN client events, including the
// normal events leading up to a connection as well as error events.

#ifndef OPENVPN_CLIENT_CLIEVENT_H
#define OPENVPN_CLIENT_CLIEVENT_H

#include <sstream>
#include <deque>
#include <utility>

#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/rc.hpp>
#include <openvpn/transport/protocol.hpp>

namespace openvpn {
  namespace ClientEvent {
    enum Type {
      // normal events including disconnected, connected, and other transitional events
      DISCONNECTED=0,
      CONNECTED,
      RECONNECTING,
      AUTH_PENDING,
      RESOLVE,
      WAIT,
      WAIT_PROXY,
      CONNECTING,
      GET_CONFIG,
      ASSIGN_IP,
      ADD_ROUTES,
      ECHO_OPT,
      INFO,
      WARN,
      PAUSE,
      RESUME,
      RELAY,
      COMPRESSION_ENABLED,
      UNSUPPORTED_FEATURE,

      // start of nonfatal errors, must be marked by NONFATAL_ERROR_START below
      TRANSPORT_ERROR,
      TUN_ERROR,
      CLIENT_RESTART,

      // start of errors, must be marked by FATAL_ERROR_START below
      AUTH_FAILED,
      CERT_VERIFY_FAIL,
      TLS_VERSION_MIN,
      CLIENT_HALT,
      CLIENT_SETUP,
      TUN_HALT,
      CONNECTION_TIMEOUT,
      INACTIVE_TIMEOUT,
      DYNAMIC_CHALLENGE,
      PROXY_NEED_CREDS,
      PROXY_ERROR,
      TUN_SETUP_FAILED,
      TUN_IFACE_CREATE,
      TUN_IFACE_DISABLED,
      EPKI_ERROR,          // EPKI refers to External PKI errors, i.e. errors in accessing external
      EPKI_INVALID_ALIAS,  //    certificates or keys.
      RELAY_ERROR,

      N_TYPES
    };

    enum {
      NONFATAL_ERROR_START = TRANSPORT_ERROR, // start of nonfatal errors that automatically reconnect
      FATAL_ERROR_START    = AUTH_FAILED,     // start of fatal errors
    };

    inline const char *event_name(const Type type)
    {
      static const char *names[] = {
	"DISCONNECTED",
	"CONNECTED",
	"RECONNECTING",
	"AUTH_PENDING",
	"RESOLVE",
	"WAIT",
	"WAIT_PROXY",
	"CONNECTING",
	"GET_CONFIG",
	"ASSIGN_IP",
	"ADD_ROUTES",
	"ECHO",
	"INFO",
	"WARN",
	"PAUSE",
	"RESUME",
	"RELAY",
	"COMPRESSION_ENABLED",
	"UNSUPPORTED_FEATURE",

	// nonfatal errors
	"TRANSPORT_ERROR",
	"TUN_ERROR",
	"CLIENT_RESTART",

	// fatal errors
	"AUTH_FAILED",
	"CERT_VERIFY_FAIL",
	"TLS_VERSION_MIN",
	"CLIENT_HALT",
	"CLIENT_SETUP",
	"TUN_HALT",
	"CONNECTION_TIMEOUT",
	"INACTIVE_TIMEOUT",
	"DYNAMIC_CHALLENGE",
	"PROXY_NEED_CREDS",
	"PROXY_ERROR",
	"TUN_SETUP_FAILED",
	"TUN_IFACE_CREATE",
	"TUN_IFACE_DISABLED",
	"EPKI_ERROR",
	"EPKI_INVALID_ALIAS",
	"RELAY_ERROR",
      };

      static_assert(N_TYPES == array_size(names), "event names array inconsistency");
      if (type < N_TYPES)
	return names[type];
      else
	return "UNKNOWN_EVENT_TYPE";
    }

    struct Connected;

    // The base class for all events.
    class Base : public RC<thread_safe_refcount>
    {
    public:
      typedef RCPtr<Base> Ptr;
      Base(Type id) : id_(id) {}

      Type id() const { return id_; }

      const char *name() const
      {
	return event_name(id_);
      }

      bool is_error() const
      {
	return int(id_) >= NONFATAL_ERROR_START;
      }

      bool is_fatal() const
      {
	return int(id_) >= FATAL_ERROR_START;
      }

      virtual std::string render() const
      {
	return "";
      }

      const Connected* connected_cast() const
      {
	if (id_ == CONNECTED)
	  return (const Connected*)this;
	else
	  return nullptr;
      }

    private:
      Type id_;
    };

    // Specific client events.  Some events have no additional data attached to them,
    // while other events (such as Connected) have many additional data fields.

    struct Resolve : public Base
    {
      Resolve() : Base(RESOLVE) {}
    };

    struct Wait : public Base
    {
      Wait() : Base(WAIT) {}
    };

    struct WaitProxy : public Base
    {
      WaitProxy() : Base(WAIT_PROXY) {}
    };

    struct Connecting : public Base
    {
      Connecting() : Base(CONNECTING) {}
    };

    struct Reconnecting : public Base
    {
      Reconnecting() : Base(RECONNECTING) {}
    };

    struct GetConfig : public Base
    {
      GetConfig() : Base(GET_CONFIG) {}
    };

    struct AssignIP : public Base
    {
      AssignIP() : Base(ASSIGN_IP) {}
    };

    struct AddRoutes : public Base
    {
      AddRoutes() : Base(ADD_ROUTES) {}
    };

    struct Resume : public Base
    {
      Resume() : Base(RESUME) {}
    };

    struct Relay : public Base
    {
      Relay() : Base(RELAY) {}
    };

    struct Disconnected : public Base
    {
      Disconnected() : Base(DISCONNECTED) {}
    };

    struct ConnectionTimeout : public Base
    {
      ConnectionTimeout() : Base(CONNECTION_TIMEOUT) {}
    };

    struct InactiveTimeout : public Base
    {
      InactiveTimeout() : Base(INACTIVE_TIMEOUT) {}
    };

    struct TLSVersionMinFail : public Base
    {
      TLSVersionMinFail() : Base(TLS_VERSION_MIN) {}
    };

    struct UnsupportedFeature : public Base
    {
      typedef RCPtr<UnsupportedFeature> Ptr;

      UnsupportedFeature(const std::string& name_arg, const std::string& reason_arg, bool critical_arg)
	: Base(UNSUPPORTED_FEATURE),
	  name(name_arg),
	  reason(reason_arg),
	  critical(critical_arg) {}

      std::string name;
      std::string reason;
      bool critical;

      virtual std::string render() const
      {
	std::ostringstream out;
	out << "name: " << name << ", reason: " << reason << ", critical: " << critical;
	return out.str();
      }
    };

    struct Connected : public Base
    {
      typedef RCPtr<Connected> Ptr;

      Connected() : Base(CONNECTED) {}

      std::string user;
      std::string server_host;
      std::string server_port;
      std::string server_proto;
      std::string server_ip;
      std::string vpn_ip4;
      std::string vpn_ip6;
      std::string vpn_gw4;
      std::string vpn_gw6;
      std::string client_ip;
      std::string tun_name;

      virtual std::string render() const
      {
	std::ostringstream out;
	// eg. "godot@foo.bar.gov:443 (1.2.3.4) via TCPv4 on tun0/5.5.1.1"
	if (!user.empty())
	  out << user << '@';
	if (server_host.find_first_of(':') == std::string::npos)
	  out << server_host;
	else
	  out << '[' << server_host << ']';
	out << ':' << server_port
	    << " (" << server_ip << ") via " << client_ip << '/' << server_proto
	    << " on " << tun_name << '/' << vpn_ip4 << '/' << vpn_ip6
	    << " gw=[" << vpn_gw4 << '/' << vpn_gw6 << ']';
	return out.str();
      }
    };

    struct ReasonBase : public Base {
      ReasonBase(const Type id, const std::string& reason_arg)
	: Base(id),
	  reason(reason_arg)
      {
      }

      ReasonBase(const Type id, std::string&& reason_arg)
	: Base(id),
	  reason(std::move(reason_arg))
      {
      }

      virtual std::string render() const
      {
	return reason;
      }

      std::string reason;
    };

    struct AuthFailed : public ReasonBase
    {
      AuthFailed(std::string reason) : ReasonBase(AUTH_FAILED, std::move(reason)) {}
    };

    struct CertVerifyFail : public ReasonBase
    {
      CertVerifyFail(std::string reason) : ReasonBase(CERT_VERIFY_FAIL, std::move(reason)) {}
    };

    struct ClientHalt : public ReasonBase
    {
      ClientHalt(std::string reason) : ReasonBase(CLIENT_HALT, std::move(reason)) {}
    };

    struct ClientRestart : public ReasonBase
    {
      ClientRestart(std::string reason) : ReasonBase(CLIENT_RESTART, std::move(reason)) {}
    };

    struct TunHalt : public ReasonBase
    {
      TunHalt(std::string reason) : ReasonBase(TUN_HALT, std::move(reason)) {}
    };

    struct RelayError : public ReasonBase
    {
      RelayError(std::string reason) : ReasonBase(RELAY_ERROR, std::move(reason)) {}
    };

    struct DynamicChallenge : public ReasonBase
    {
      DynamicChallenge(std::string reason) : ReasonBase(DYNAMIC_CHALLENGE, std::move(reason)) {}
    };

    struct Pause : public ReasonBase
    {
      Pause(std::string reason) : ReasonBase(PAUSE, std::move(reason)) {}
    };

    struct ProxyError : public ReasonBase
    {
      ProxyError(std::string reason) : ReasonBase(PROXY_ERROR, std::move(reason)) {}
    };

    struct ProxyNeedCreds : public ReasonBase
    {
      ProxyNeedCreds(std::string reason) : ReasonBase(PROXY_NEED_CREDS, std::move(reason)) {}
    };

    struct TransportError : public ReasonBase
    {
      TransportError(std::string reason) : ReasonBase(TRANSPORT_ERROR, std::move(reason)) {}
    };

    struct TunSetupFailed : public ReasonBase
    {
      TunSetupFailed(std::string reason) : ReasonBase(TUN_SETUP_FAILED, std::move(reason)) {}
    };

    struct TunIfaceCreate : public ReasonBase
    {
      TunIfaceCreate(std::string reason) : ReasonBase(TUN_IFACE_CREATE, std::move(reason)) {}
    };

    struct TunIfaceDisabled : public ReasonBase
    {
      TunIfaceDisabled(std::string reason) : ReasonBase(TUN_IFACE_DISABLED, std::move(reason)) {}
    };

    struct TunError : public ReasonBase
    {
      TunError(std::string reason) : ReasonBase(TUN_ERROR, std::move(reason)) {}
    };

    struct EpkiError : public ReasonBase
    {
      EpkiError(std::string reason) : ReasonBase(EPKI_ERROR, std::move(reason)) {}
    };

    struct EpkiInvalidAlias : public ReasonBase
    {
      EpkiInvalidAlias(std::string reason) : ReasonBase(EPKI_INVALID_ALIAS, std::move(reason)) {}
    };

    struct Echo : public ReasonBase
    {
      Echo(std::string value) : ReasonBase(ECHO_OPT, std::move(value)) {}
    };

    struct Info : public ReasonBase
    {
      Info(std::string value) : ReasonBase(INFO, std::move(value)) {}
    };

    struct AuthPending : public ReasonBase
    {
      int timeout;
      AuthPending(int timeout, std::string value): ReasonBase(AUTH_PENDING, std::move(value)), timeout(timeout) {}
    };

    struct Warn : public ReasonBase
    {
      Warn(std::string value) : ReasonBase(WARN, std::move(value)) {}
    };

    class ClientSetup : public ReasonBase
    {
    public:
      ClientSetup(const std::string& status, const std::string& message)
	: ReasonBase(CLIENT_SETUP, make(status, message))
      {
      }

    private:
      static std::string make(const std::string& status, const std::string& message)
      {
	std::string ret;
	ret += status;
	if (!status.empty() && !message.empty())
	  ret += ": ";
	ret += message;
	return ret;
      }
    };

    struct CompressionEnabled : public ReasonBase
    {
       CompressionEnabled(std::string msg)
         : ReasonBase(COMPRESSION_ENABLED, std::move(msg))
       {
       }
    };

    class Queue : public RC<thread_unsafe_refcount>
    {
    public:
      typedef RCPtr<Queue> Ptr;

      virtual void add_event(Base::Ptr event) = 0;
    };
  }
}

#endif // OPENVPN_CLIENT_CLIEVENT_H