// Copyright 2021, 2022 Benjamin Barenblat
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

// X events.

#ifndef GLPLANET_SRC_X_EVENT_H_
#define GLPLANET_SRC_X_EVENT_H_

#include <string.h>
#include <xcb/xcb.h>

#include <array>

#include "src/x/types.h"
#include "third_party/abseil/absl/types/variant.h"

namespace x_internal {

template <typename From, typename To>
void XcbDowncast(const From& from, To& to) noexcept {
  static_assert(sizeof(From) >= sizeof(To));
  memcpy(&to, &from, sizeof(To));
}

}  // namespace x_internal

namespace x {

class ExposeEvent final {
 public:
  explicit ExposeEvent(const xcb_expose_event_t& event) noexcept
      : event_(event) {}
  explicit ExposeEvent(const xcb_generic_event_t& event) noexcept {
    x_internal::XcbDowncast(event, event_);
  }

  ExposeEvent(const ExposeEvent&) noexcept = default;
  ExposeEvent& operator=(const ExposeEvent&) noexcept = default;
  ExposeEvent(ExposeEvent&&) noexcept = default;
  ExposeEvent& operator=(ExposeEvent&&) noexcept = default;

  xcb_expose_event_t& AsXcbEvent() noexcept { return event_; }
  const xcb_expose_event_t& AsXcbEvent() const noexcept { return event_; }

 private:
  xcb_expose_event_t event_;
};

class ConfigureNotifyEvent final {
 public:
  explicit ConfigureNotifyEvent(
      const xcb_configure_notify_event_t& event) noexcept
      : event_(event) {}
  explicit ConfigureNotifyEvent(const xcb_generic_event_t& event) noexcept {
    x_internal::XcbDowncast(event, event_);
  }

  ConfigureNotifyEvent(const ConfigureNotifyEvent&) noexcept = default;
  ConfigureNotifyEvent& operator=(const ConfigureNotifyEvent&) noexcept =
      default;
  ConfigureNotifyEvent(ConfigureNotifyEvent&&) noexcept = default;
  ConfigureNotifyEvent& operator=(ConfigureNotifyEvent&&) noexcept = default;

  int width() const noexcept { return event_.width; }
  int height() const noexcept { return event_.height; }

  xcb_configure_notify_event_t& AsXcbEvent() noexcept { return event_; }
  const xcb_configure_notify_event_t& AsXcbEvent() const noexcept {
    return event_;
  }

 private:
  xcb_configure_notify_event_t event_;
};

class ClientMessageEvent final {
 public:
  explicit ClientMessageEvent(const xcb_client_message_event_t& event) noexcept
      : event_(event) {}
  explicit ClientMessageEvent(const xcb_generic_event_t& event) noexcept {
    x_internal::XcbDowncast(event, event_);
  }

  ClientMessageEvent(const ClientMessageEvent&) noexcept = default;
  ClientMessageEvent& operator=(const ClientMessageEvent&) noexcept = default;
  ClientMessageEvent(ClientMessageEvent&&) noexcept = default;
  ClientMessageEvent& operator=(ClientMessageEvent&&) noexcept = default;

  Id type() const noexcept { return event_.type; }

  xcb_client_message_event_t& AsXcbEvent() noexcept { return event_; }
  const xcb_client_message_event_t& AsXcbEvent() const noexcept {
    return event_;
  }

 private:
  xcb_client_message_event_t event_;
};

// An X event that doesn't fit into any of the previous classes.
class UnknownEvent final {
 public:
  explicit UnknownEvent(const xcb_generic_event_t& event) : event_(event) {}

  UnknownEvent(const UnknownEvent&) noexcept = default;
  UnknownEvent& operator=(const UnknownEvent&) noexcept = default;
  UnknownEvent(UnknownEvent&&) noexcept = default;
  UnknownEvent& operator=(UnknownEvent&&) noexcept = default;

  xcb_generic_event_t& AsXcbEvent() noexcept { return event_; }
  const xcb_generic_event_t& AsXcbEvent() const noexcept { return event_; }

 private:
  xcb_generic_event_t event_;
};

using Event = absl::variant<UnknownEvent, ExposeEvent, ConfigureNotifyEvent,
                            ClientMessageEvent>;

Event FromXcbGenericEvent(const xcb_generic_event_t&) noexcept;

std::array<char, 32> SerializeEvent(const Event&) noexcept;

}  // namespace x

#endif  // GLPLANET_SRC_X_EVENT_H_