//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once

#include "td/telegram/Global.h"
#include "td/telegram/Version.h"

#include "td/utils/buffer.h"
#include "td/utils/format.h"
#include "td/utils/logging.h"
#include "td/utils/Slice.h"
#include "td/utils/Status.h"
#include "td/utils/Storer.h"
#include "td/utils/StringBuilder.h"
#include "td/utils/tl_helpers.h"
#include "td/utils/tl_parsers.h"
#include "td/utils/tl_storers.h"

#include <type_traits>

namespace td {
namespace logevent {

template <class ParentT>
class WithVersion : public ParentT {
 public:
  using ParentT::ParentT;
  void set_version(int32 version) {
    version_ = version;
  }
  int32 version() const {
    return version_;
  }

 private:
  int32 version_;
};

template <class ParentT, class ContextT>
class WithContext : public ParentT {
 public:
  using ParentT::ParentT;
  void set_context(ContextT context) {
    context_ = context;
  }
  ContextT context() const {
    return context_;
  }

 private:
  ContextT context_;
};

class LogEvent {
 public:
  LogEvent() = default;
  LogEvent(const LogEvent &) = delete;
  LogEvent &operator=(const LogEvent &) = delete;
  virtual ~LogEvent() = default;
  enum HandlerType : uint32 {
    SecretChats = 1,
    Users = 2,
    Chats = 3,
    Channels = 4,
    SecretChatInfos = 5,
    WebPages = 0x10,
    SendMessage = 0x100,
    DeleteMessage = 0x101,
    DeleteMessagesFromServer = 0x102,
    ReadHistoryOnServer = 0x103,
    ForwardMessages = 0x104,
    ReadMessageContentsOnServer = 0x105,
    SendBotStartMessage = 0x106,
    SendScreenshotTakenNotificationMessage = 0x107,
    SendInlineQueryResultMessage = 0x108,
    DeleteDialogHistoryFromServer = 0x109,
    ReadAllDialogMentionsOnServer = 0x10a,
    DeleteAllChannelMessagesFromUserOnServer = 0x10b,
    ToggleDialogIsPinnedOnServer = 0x10c,
    ReorderPinnedDialogsOnServer = 0x10d,
    SaveDialogDraftMessageOnServer = 0x10e,
    GetChannelDifference = 0x140,
    ConfigPmcMagic = 0x1f18,
    BinlogPmcMagic = 0x4327
  };

  using Id = uint64;

  Id logevent_id() const {
    return logevent_id_;
  }
  void set_logevent_id(Id logevent_id) {
    logevent_id_ = logevent_id;
  }

  virtual StringBuilder &print(StringBuilder &sb) const {
    return sb << "[Logevent " << tag("id", logevent_id()) << "]";
  }

 private:
  Id logevent_id_;
};
inline StringBuilder &operator<<(StringBuilder &sb, const LogEvent &log_event) {
  return log_event.print(sb);
}

namespace detail {

template <class EventT>
int32 magic(EventT &event) {
  return static_cast<int32>(event.get_type());
}

template <class EventT, class StorerT>
void store(const EventT &event, StorerT &storer) {
  EventT::downcast_call(event.get_type(),
                        [&](auto *ptr) { static_cast<const std::decay_t<decltype(*ptr)> &>(event).store(storer); });
}

template <class DestT, class T>
Result<std::unique_ptr<DestT>> from_parser(T &&parser) {
  auto version = parser.fetch_int();
  parser.set_version(version);
  parser.set_context(G());
  auto magic = static_cast<typename DestT::Type>(parser.fetch_int());

  std::unique_ptr<DestT> event;
  DestT::downcast_call(magic, [&](auto *ptr) {
    auto tmp = make_unique<std::decay_t<decltype(*ptr)>>();
    tmp->parse(parser);
    event = std::move(tmp);
  });
  parser.fetch_end();
  TRY_STATUS(parser.get_status());
  if (event) {
    return std::move(event);
  }
  return Status::Error(PSLICE() << "Unknown SecretChatEvent type: " << format::as_hex(magic));
}

template <class DestT>
Result<std::unique_ptr<DestT>> from_buffer_slice(BufferSlice slice) {
  return from_parser<DestT>(WithVersion<WithContext<TlBufferParser, Global *>>{&slice});
}

template <class T>
class StorerImpl : public Storer {
 public:
  explicit StorerImpl(const T &event) : event_(event) {
  }

  size_t size() const override {
    WithContext<TlStorerCalcLength, Global *> storer;
    storer.set_context(G());

    storer.store_int(T::version());
    td::store(magic(event_), storer);
    td::store(event_, storer);
    return storer.get_length();
  }
  size_t store(uint8 *ptr_x) const override {
    char *ptr = reinterpret_cast<char *>(ptr_x);
    WithContext<TlStorerUnsafe, Global *> storer(ptr);
    storer.set_context(G());

    storer.store_int(T::version());
    td::store(magic(event_), storer);
    td::store(event_, storer);
    return storer.get_buf() - ptr;
  }

 private:
  const T &event_;
};
}  // namespace detail

template <class ChildT>
class LogEventBase : public LogEvent {
 public:
  template <class StorerT>
  void store(StorerT &storer) const {
    detail::store(static_cast<const ChildT &>(*this), storer);
  }
  static Result<std::unique_ptr<ChildT>> from_buffer_slice(BufferSlice slice) {
    return detail::from_buffer_slice<ChildT>(std::move(slice));
  }
};

template <class ChildT, class ParentT>
class LogEventHelper : public ParentT {
 public:
  typename ParentT::Type get_type() const override {
    return ChildT::type;
  }

  constexpr int32 magic() const {
    return static_cast<int32>(get_type());
  }
};

class LogEventParser : public WithVersion<WithContext<TlParser, Global *>> {
 public:
  explicit LogEventParser(Slice data) : WithVersion<WithContext<TlParser, Global *>>(data) {
    set_version(fetch_int());
    CHECK(version() < static_cast<int32>(Version::Next)) << "Wrong version " << version();
    set_context(G());
  }
};

class LogEventStorerCalcLength : public WithContext<TlStorerCalcLength, Global *> {
 public:
  LogEventStorerCalcLength() : WithContext<TlStorerCalcLength, Global *>() {
    store_int(static_cast<int32>(Version::Next) - 1);
    set_context(G());
  }
};

class LogEventStorerUnsafe : public WithContext<TlStorerUnsafe, Global *> {
 public:
  explicit LogEventStorerUnsafe(char *buf) : WithContext<TlStorerUnsafe, Global *>(buf) {
    store_int(static_cast<int32>(Version::Next) - 1);
    set_context(G());
  }
};

}  // namespace logevent

using LogEvent = logevent::LogEvent;
using LogEventParser = logevent::LogEventParser;
using LogEventStorerCalcLength = logevent::LogEventStorerCalcLength;
using LogEventStorerUnsafe = logevent::LogEventStorerUnsafe;

template <class T>
Status log_event_parse(T &data, Slice slice) TD_WARN_UNUSED_RESULT;

template <class T>
Status log_event_parse(T &data, Slice slice) {
  LogEventParser parser(slice);
  parse(data, parser);
  parser.fetch_end();
  return parser.get_status();
}

template <class T>
class LogEventStorerImpl : public Storer {
 public:
  explicit LogEventStorerImpl(const T &event) : event_(event) {
  }

  size_t size() const override {
    LogEventStorerCalcLength storer;
    td::store(event_, storer);
    return storer.get_length();
  }
  size_t store(uint8 *ptr_x) const override {
    char *ptr = reinterpret_cast<char *>(ptr_x);
    LogEventStorerUnsafe storer(ptr);
    td::store(event_, storer);
#ifdef TD_DEBUG
    T check_result;
    log_event_parse(check_result, Slice(ptr, storer.get_buf())).ensure();
#endif
    return storer.get_buf() - ptr;
  }

 private:
  const T &event_;
};

template <class T>
BufferSlice log_event_store(const T &data) {
  LogEventStorerCalcLength storer_calc_length;
  store(data, storer_calc_length);

  BufferSlice value_buffer{storer_calc_length.get_length()};

  LogEventStorerUnsafe storer_unsafe(value_buffer.as_slice().begin());
  store(data, storer_unsafe);

#ifdef TD_DEBUG
  T check_result;
  log_event_parse(check_result, value_buffer.as_slice()).ensure();
#endif
  return value_buffer;
}

}  // namespace td