#ifndef SAW_UNIX_XCB
#error "XCB is not supported"
#endif

#include "xcb.h"

namespace saw {
device<backend::linux_xcb>::device(::Display* disp,  int screen, xcb_connection_t *xcb_connection, xcb_screen_t *xcb_screen, own<input_stream>&& an):
	display_{disp}, screen_{screen}, xcb_connection_{xcb_connection}, xcb_screen_{xcb_screen}, async_notifier_{std::move(an)},
	async_conveyor_{async_notifier->read_ready()
						 .then([this]() { handle_events(); })
						 .sink()} {}
{}

device<backend::linux_xcb>::~device(){
	if (display_) {
		xcb_flush(xcb_connection_);
		::XCloseDisplay(display_);
	}
}

void device<backend::linux_xcb>::xcb_window_was_destroyed(xcb_window_t window_id){
	windows_.erase(window_id);
}

void device<backend::linux_xcb>::handle_events(){
	while (xcb_generic_event_t *event = xcb_poll_for_event(xcb_connection)) {
		pending_events.push_back(event);
	}
	for (size_t i = 0; i < pending_events_.size(); ++i) {
		xcb_generic_event_t *event = pending_events_.at(i);
		switch (event->response_type & ~0x80) {
		case XCB_MOTION_NOTIFY: {
			xcb_motion_notify_event_t *motion =
				reinterpret_cast<xcb_motion_notify_event_t *>(event);
			auto find = windows.find(motion->event);
			if (find != windows.end()) {
				assert(find->second);
				find->second->mouse_move_event(motion->event_x,
											   motion->event_y);
			}
		} break;
		case XCB_EXPOSE: {
			xcb_expose_event_t *expose =
				reinterpret_cast<xcb_expose_event_t *>(event);
			auto find = windows.find(expose->window);
			if (find != windows.end()) {
				assert(find->second);
				find->second->resize_event(static_cast<size_t>(expose->x),
										  static_cast<size_t>(expose->y),
										  static_cast<size_t>(expose->width),
										  static_cast<size_t>(expose->height));
			}
		} break;
		case XCB_BUTTON_RELEASE: {
			xcb_button_release_event_t *button =
				reinterpret_cast<xcb_button_release_event_t *>(event);
			auto find = windows.find(button->event);
			if (find != windows.end()) {
				assert(find->second);
				find->second->mouse_event(button->event_x, button->event_y,
										 button->detail, false);
			}
		} break;
		case XCB_BUTTON_PRESS: {
			xcb_button_press_event_t *button =
				reinterpret_cast<xcb_button_press_event_t *>(event);
			auto find = windows.find(button->event);
			if (find != windows.end()) {
				assert(find->second);
				find->second->mouse_event(button->event_x, button->event_y,
										 button->detail, true);
			}
		} break;
		case XCB_KEY_RELEASE: {
			xcb_key_release_event_t *key =
				reinterpret_cast<xcb_key_release_event_t *>(event);

			bool repeat = false;
			/*
			 * Peek into future events
			 */
			for (size_t j = i + 1; j < pending_events.size(); ++j) {
				xcb_generic_event_t *f_ev = pending_events.at(j);

				if ((f_ev->response_type & ~0x80) == XCB_KEY_PRESS) {
					xcb_key_press_event_t *f_key =
						reinterpret_cast<xcb_key_press_event_t *>(f_ev);

					if (key->detail == f_key->detail &&
						key->event == f_key->event) {
						auto iterator = pending_events.begin() + j;
						assert(iterator != pending_events.end());
						free(*iterator);
						pending_events.erase(iterator);
						repeat = true;
						break;
					}
				}
			}

			auto find = windows.find(key->event);
			if (find != windows.end()) {
				assert(find->second);
				find->second->keyboard_event(key->event_x, key->event_y,
											key->detail, repeat, repeat);
			}
		} break;
		case XCB_KEY_PRESS: {
			xcb_key_press_event_t *key =
				reinterpret_cast<xcb_key_press_event_t *>(event);
			auto find = windows.find(key->event);
			if (find != windows.end()) {
				assert(find->second);
				find->second->keyboard_event(key->event_x, key->event_y,
											key->detail, true, false);
			}
		} break;
		default:
			break;
		}
	}

	for (xcb_generic_event_t *event : pending_events_) {
		free(event);
	}
	pending_events_.clear();
}

own<window> device<backend::linux_xcb>::create_window(const video_mode& vid_mode, std::string_view title_view){
	assert(xcb_screen_);
	return create_xcb_window(vid_mode, title_view, xcb_screen_->root_visual);
}

void device<backend::linux_xcb>::flush(){
	assert(xcb_connection_);
	xcb_flush(xcb_connection_);
}

error_or<own<device<backend::linux_xcb>>> create_xcb_device(){
	::Display *display = ::XOpenDisplay(nullptr);
	if (!display) {
		/// @todo log errors
		return make_error<err::critical>();
	}

	int screen = ::XDefaultScreen(display);

	xcb_connection_t *xcb_connection = ::XGetXCBConnection(display);
	if (!xcb_connection) {
		/// @todo log errors
		::XCloseDisplay(display);
		return make_error<err::critical>();
	}

	int fd = xcb_get_file_descriptor(xcb_connection);

	own<input_stream> fd_wrapped = provider.wrap_input_fd(fd);
	if (!fd_wrapped) {
		::XCloseDisplay(display);
		return make_error<err::critical>();
	}

	::XSetEventQueueOwner(display, XCBOwnsEventQueue);

	xcb_screen_iterator_t screen_iter =
		xcb_setup_roots_iterator(xcb_get_setup(xcb_connection));
	for (int screen_i = screen; screen_iter.rem && screen_i > 0;
		 --screen_i, xcb_screen_next(&screen_iter))
		;

	xcb_screen_t *xcb_screen = screen_iter.data;

	return heap<device<backend::linux_xcb>>(display, screen, xcb_connection, xcb_screen, std::move(fd_wrapped));
}

window<backend::linux_xcb>::window(device& dev_, xcb_window_t xcb_win, xcb_colormap_t xcb_colormap_, const video_mode& vid_mode_, std::string_view& title_view):
	device_{&dev_},
	xcb_window_{xcb_win},
	xcb_colormap_{xcb_colormap_},
	video_mode_{vid_mode_},
	window_title_{tile_view_}
{
	// TODO
}

window<backend::linux_xcb>::~window(){
	// TODO
}

void window<backend::linux_xcb>::show(){
	// TODO
}

void window<backend::linux_xcb>::hide(){
	// TODO
}

}