#define _POSIX_C_SOURCE 200809L
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <wayland-server.h>
#include <wlr/types/wlr_input_device.h>
#include <wlr/util/log.h>
#include "types/wlr_seat.h"
#include "util/signal.h"

static void default_pointer_enter(struct wlr_seat_pointer_grab *grab,
		struct wlr_surface *surface, double sx, double sy) {
	wlr_seat_pointer_enter(grab->seat, surface, sx, sy);
}

static void default_pointer_motion(struct wlr_seat_pointer_grab *grab,
		uint32_t time, double sx, double sy) {
	wlr_seat_pointer_send_motion(grab->seat, time, sx, sy);
}

static uint32_t default_pointer_button(struct wlr_seat_pointer_grab *grab,
		uint32_t time, uint32_t button, uint32_t state) {
	return wlr_seat_pointer_send_button(grab->seat, time, button, state);
}

static void default_pointer_axis(struct wlr_seat_pointer_grab *grab,
		uint32_t time, enum wlr_axis_orientation orientation, double value,
		int32_t value_discrete, enum wlr_axis_source source) {
	wlr_seat_pointer_send_axis(grab->seat, time, orientation, value,
		value_discrete, source);
}

static void default_pointer_cancel(struct wlr_seat_pointer_grab *grab) {
	// cannot be cancelled
}

const struct wlr_pointer_grab_interface default_pointer_grab_impl = {
	.enter = default_pointer_enter,
	.motion = default_pointer_motion,
	.button = default_pointer_button,
	.axis = default_pointer_axis,
	.cancel = default_pointer_cancel,
};


static void pointer_send_frame(struct wl_resource *resource) {
	if (wl_resource_get_version(resource) >=
			WL_POINTER_FRAME_SINCE_VERSION) {
		wl_pointer_send_frame(resource);
	}
}

static const struct wl_pointer_interface pointer_impl;

static struct wlr_seat_client *seat_client_from_pointer_resource(
		struct wl_resource *resource) {
	assert(wl_resource_instance_of(resource, &wl_pointer_interface,
		&pointer_impl));
	return wl_resource_get_user_data(resource);
}

static const struct wlr_surface_role pointer_cursor_surface_role = {
	.name = "wl_pointer-cursor",
};

static void pointer_set_cursor(struct wl_client *client,
		struct wl_resource *pointer_resource, uint32_t serial,
		struct wl_resource *surface_resource,
		int32_t hotspot_x, int32_t hotspot_y) {
	struct wlr_seat_client *seat_client =
		seat_client_from_pointer_resource(pointer_resource);
	if (seat_client == NULL) {
		return;
	}

	struct wlr_surface *surface = NULL;
	if (surface_resource != NULL) {
		surface = wlr_surface_from_resource(surface_resource);
		if (!wlr_surface_set_role(surface, &pointer_cursor_surface_role, NULL,
				surface_resource, WL_POINTER_ERROR_ROLE)) {
			return;
		}
	}

	struct wlr_seat_pointer_request_set_cursor_event event = {
		.seat_client = seat_client,
		.surface = surface,
		.serial = serial,
		.hotspot_x = hotspot_x,
		.hotspot_y = hotspot_y,
	};
	wlr_signal_emit_safe(&seat_client->seat->events.request_set_cursor, &event);
}

static void pointer_release(struct wl_client *client,
		struct wl_resource *resource) {
	wl_resource_destroy(resource);
}

static const struct wl_pointer_interface pointer_impl = {
	.set_cursor = pointer_set_cursor,
	.release = pointer_release,
};

static void pointer_handle_resource_destroy(struct wl_resource *resource) {
	wl_list_remove(wl_resource_get_link(resource));
	seat_client_destroy_pointer(resource);
}


bool wlr_seat_pointer_surface_has_focus(struct wlr_seat *wlr_seat,
		struct wlr_surface *surface) {
	return surface == wlr_seat->pointer_state.focused_surface;
}

static void seat_pointer_handle_surface_destroy(struct wl_listener *listener,
		void *data) {
	struct wlr_seat_pointer_state *state =
		wl_container_of(listener, state, surface_destroy);
	wl_list_remove(&state->surface_destroy.link);
	wl_list_init(&state->surface_destroy.link);
	wlr_seat_pointer_clear_focus(state->seat);
}

void wlr_seat_pointer_enter(struct wlr_seat *wlr_seat,
		struct wlr_surface *surface, double sx, double sy) {
	if (wlr_seat->pointer_state.focused_surface == surface) {
		// this surface already got an enter notify
		return;
	}

	struct wlr_seat_client *client = NULL;
	if (surface) {
		struct wl_client *wl_client = wl_resource_get_client(surface->resource);
		client = wlr_seat_client_for_wl_client(wlr_seat, wl_client);
	}

	struct wlr_seat_client *focused_client =
		wlr_seat->pointer_state.focused_client;
	struct wlr_surface *focused_surface =
		wlr_seat->pointer_state.focused_surface;

	// leave the previously entered surface
	if (focused_client != NULL && focused_surface != NULL) {
		uint32_t serial = wl_display_next_serial(wlr_seat->display);
		struct wl_resource *resource;
		wl_resource_for_each(resource, &focused_client->pointers) {
			if (seat_client_from_pointer_resource(resource) == NULL) {
				continue;
			}

			wl_pointer_send_leave(resource, serial, focused_surface->resource);
			pointer_send_frame(resource);
		}
	}

	// enter the current surface
	if (client != NULL && surface != NULL) {
		uint32_t serial = wl_display_next_serial(wlr_seat->display);
		struct wl_resource *resource;
		wl_resource_for_each(resource, &client->pointers) {
			if (seat_client_from_pointer_resource(resource) == NULL) {
				continue;
			}

			wl_pointer_send_enter(resource, serial, surface->resource,
				wl_fixed_from_double(sx), wl_fixed_from_double(sy));
			pointer_send_frame(resource);
		}
	}

	// reinitialize the focus destroy events
	wl_list_remove(&wlr_seat->pointer_state.surface_destroy.link);
	wl_list_init(&wlr_seat->pointer_state.surface_destroy.link);
	if (surface != NULL) {
		wl_signal_add(&surface->events.destroy,
			&wlr_seat->pointer_state.surface_destroy);
		wlr_seat->pointer_state.surface_destroy.notify =
			seat_pointer_handle_surface_destroy;
	}

	wlr_seat->pointer_state.focused_client = client;
	wlr_seat->pointer_state.focused_surface = surface;

	// TODO: send focus change event
}

void wlr_seat_pointer_clear_focus(struct wlr_seat *wlr_seat) {
	wlr_seat_pointer_enter(wlr_seat, NULL, 0, 0);
}

void wlr_seat_pointer_send_motion(struct wlr_seat *wlr_seat, uint32_t time,
		double sx, double sy) {
	struct wlr_seat_client *client = wlr_seat->pointer_state.focused_client;
	if (client == NULL) {
		return;
	}

	struct wl_resource *resource;
	wl_resource_for_each(resource, &client->pointers) {
		if (seat_client_from_pointer_resource(resource) == NULL) {
			continue;
		}

		wl_pointer_send_motion(resource, time, wl_fixed_from_double(sx),
			wl_fixed_from_double(sy));
		pointer_send_frame(resource);
	}
}

uint32_t wlr_seat_pointer_send_button(struct wlr_seat *wlr_seat, uint32_t time,
		uint32_t button, uint32_t state) {
	struct wlr_seat_client *client = wlr_seat->pointer_state.focused_client;
	if (client == NULL) {
		return 0;
	}

	uint32_t serial = wl_display_next_serial(wlr_seat->display);
	struct wl_resource *resource;
	wl_resource_for_each(resource, &client->pointers) {
		if (seat_client_from_pointer_resource(resource) == NULL) {
			continue;
		}

		wl_pointer_send_button(resource, serial, time, button, state);
		pointer_send_frame(resource);
	}
	return serial;
}

void wlr_seat_pointer_send_axis(struct wlr_seat *wlr_seat, uint32_t time,
		enum wlr_axis_orientation orientation, double value,
		int32_t value_discrete, enum wlr_axis_source source) {
	struct wlr_seat_client *client = wlr_seat->pointer_state.focused_client;
	if (client == NULL) {
		return;
	}

	struct wl_resource *resource;
	wl_resource_for_each(resource, &client->pointers) {
		if (seat_client_from_pointer_resource(resource) == NULL) {
			continue;
		}

		uint32_t version = wl_resource_get_version(resource);

		if (version >= WL_POINTER_AXIS_SOURCE_SINCE_VERSION) {
			wl_pointer_send_axis_source(resource, source);
		}
		if (value) {
			if (value_discrete &&
					version >= WL_POINTER_AXIS_DISCRETE_SINCE_VERSION) {
				wl_pointer_send_axis_discrete(resource, orientation,
					value_discrete);
			}

			wl_pointer_send_axis(resource, time, orientation,
				wl_fixed_from_double(value));
		} else if (version >= WL_POINTER_AXIS_STOP_SINCE_VERSION) {
			wl_pointer_send_axis_stop(resource, time, orientation);
		}
		pointer_send_frame(resource);
	}
}

void wlr_seat_pointer_start_grab(struct wlr_seat *wlr_seat,
		struct wlr_seat_pointer_grab *grab) {
	assert(wlr_seat);
	grab->seat = wlr_seat;
	wlr_seat->pointer_state.grab = grab;

	wlr_signal_emit_safe(&wlr_seat->events.pointer_grab_begin, grab);
}

void wlr_seat_pointer_end_grab(struct wlr_seat *wlr_seat) {
	struct wlr_seat_pointer_grab *grab = wlr_seat->pointer_state.grab;
	if (grab != wlr_seat->pointer_state.default_grab) {
		wlr_seat->pointer_state.grab = wlr_seat->pointer_state.default_grab;
		wlr_signal_emit_safe(&wlr_seat->events.pointer_grab_end, grab);
		if (grab->interface->cancel) {
			grab->interface->cancel(grab);
		}
	}
}

void wlr_seat_pointer_notify_enter(struct wlr_seat *wlr_seat,
		struct wlr_surface *surface, double sx, double sy) {
	struct wlr_seat_pointer_grab *grab = wlr_seat->pointer_state.grab;
	grab->interface->enter(grab, surface, sx, sy);
}

void wlr_seat_pointer_notify_motion(struct wlr_seat *wlr_seat, uint32_t time,
		double sx, double sy) {
	clock_gettime(CLOCK_MONOTONIC, &wlr_seat->last_event);
	struct wlr_seat_pointer_grab *grab = wlr_seat->pointer_state.grab;
	grab->interface->motion(grab, time, sx, sy);
}

uint32_t wlr_seat_pointer_notify_button(struct wlr_seat *wlr_seat,
		uint32_t time, uint32_t button, uint32_t state) {
	clock_gettime(CLOCK_MONOTONIC, &wlr_seat->last_event);
	if (state == WL_POINTER_BUTTON_STATE_PRESSED) {
		if (wlr_seat->pointer_state.button_count == 0) {
			wlr_seat->pointer_state.grab_button = button;
			wlr_seat->pointer_state.grab_time = time;
		}
		wlr_seat->pointer_state.button_count++;
	} else {
		wlr_seat->pointer_state.button_count--;
	}

	struct wlr_seat_pointer_grab *grab = wlr_seat->pointer_state.grab;
	uint32_t serial = grab->interface->button(grab, time, button, state);

	if (serial && wlr_seat->pointer_state.button_count == 1) {
		wlr_seat->pointer_state.grab_serial = serial;
	}

	return serial;
}

void wlr_seat_pointer_notify_axis(struct wlr_seat *wlr_seat, uint32_t time,
		enum wlr_axis_orientation orientation, double value,
		int32_t value_discrete, enum wlr_axis_source source) {
	clock_gettime(CLOCK_MONOTONIC, &wlr_seat->last_event);
	struct wlr_seat_pointer_grab *grab = wlr_seat->pointer_state.grab;
	grab->interface->axis(grab, time, orientation, value, value_discrete,
		source);
}

bool wlr_seat_pointer_has_grab(struct wlr_seat *seat) {
	return seat->pointer_state.grab->interface != &default_pointer_grab_impl;
}


void seat_client_create_pointer(struct wlr_seat_client *seat_client,
		uint32_t version, uint32_t id) {
	struct wl_resource *resource = wl_resource_create(seat_client->client,
		&wl_pointer_interface, version, id);
	if (resource == NULL) {
		wl_client_post_no_memory(seat_client->client);
		return;
	}
	wl_resource_set_implementation(resource, &pointer_impl, seat_client,
		&pointer_handle_resource_destroy);
	wl_list_insert(&seat_client->pointers, wl_resource_get_link(resource));
}

void seat_client_destroy_pointer(struct wl_resource *resource) {
	struct wlr_seat_client *seat_client =
		seat_client_from_pointer_resource(resource);
	if (seat_client == NULL) {
		return;
	}
	wl_resource_set_user_data(resource, NULL);
}