#include <bits/time.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <time.h>
#include <math.h>

#include <sys/mman.h>
#include <syscall.h>
#include <unistd.h>
#include <linux/input-event-codes.h>

#include <xdg-shell.h>
#include <viewporter.h>
#include <fractional-scale-v1.h>
#include <wayland-client.h>
#include <xkbcommon/xkbcommon.h>
#include <xkbcommon/xkbcommon-keysyms.h>

#include <tkeyboard.h>
#include <tpointer.h>
#include <config.h>
#include <grid.h>
#include <pattern.h>

struct wl_compositor *compositor;
struct wl_shm *shm;
struct xdg_wm_base *xdg_shell;
struct wl_seat *wl_seat;
struct wl_output *wl_output = NULL;
int output_scale_factor = 1;
int output_width = 0;
int output_height = 0;

struct keyboard_data keyboard_data;
struct pointer_data pointer_data;

int running = 1;
int released = 0;

config_t g_config;
int active_tool = -1; /* -1 none, 0..3 patterns */
int active_rotation = 0;

int logical_width = 400;
int logical_height = 400;
double current_scale = 1.0;
int need_resize = 1;

grid_t grid;
grid_t grid_back;
int sim_paused = 1;
double sim_interval = 0.05; /* 20 tps */
double sim_accumulator = 0.0;
struct timespec sim_last_time;
int sim_time_initialized = 0;
int mouse_left_down = 0;
int mouse_right_down = 0;
double cursor_x = 0, cursor_y = 0;
int click_pending = 0;
double click_x = 0, click_y = 0;
int show_grid_lines = 1;
struct timespec mytime;

struct canvas
{
	int width;   /* physical */
	int height;  /* physical */
	int stride;
	int size;
	struct wl_buffer *buffer;
	unsigned char *data;
	struct wl_shm_pool *pool;
	int fd;
	struct wl_surface *surface;
	struct wl_callback *frame;
} canvas;

struct wp_viewporter *viewporter = NULL;
struct wp_viewport *canvas_viewport = NULL;
struct wp_fractional_scale_manager_v1 *fractional_manager = NULL;
struct wp_fractional_scale_v1 *fractional_scale = NULL;

// output listener
static void output_geometry_handler(void *data, struct wl_output *output, int32_t x, int32_t y, int32_t phys_w, int32_t phys_h, int32_t subpixel, const char *make, const char *model, int32_t transform) { (void)data;(void)output;(void)x;(void)y;(void)phys_w;(void)phys_h;(void)subpixel;(void)make;(void)model;(void)transform; }
static void output_mode_handler(void *data, struct wl_output *output, uint32_t flags, int32_t width, int32_t height, int32_t refresh) {
	(void)data;(void)output;(void)flags;(void)refresh;
	if (width > 0 && height > 0) {
		output_width = width;
		output_height = height;
	}
}
static void output_done_handler(void *data, struct wl_output *output) { (void)data;(void)output; }
static void output_scale_handler(void *data, struct wl_output *output, int32_t factor) {
	(void)data;(void)output;
	output_scale_factor = factor;
	if (!fractional_manager) {
		if (factor > 0) current_scale = factor;
		need_resize = 1;
	}
}
const struct wl_output_listener output_listener = {
	.geometry = output_geometry_handler,
	.mode = output_mode_handler,
	.done = output_done_handler,
	.scale = output_scale_handler,
};

// fractional scale listener
static void fractional_preferred_scale_handler(void *data, struct wp_fractional_scale_v1 *scale_obj, uint32_t scale) {
	(void)data;(void)scale_obj;
	double s = (double)scale / 120.0;
	if (s > 0) current_scale = s;
	need_resize = 1;
}
const struct wp_fractional_scale_v1_listener fractional_scale_listener = {
	.preferred_scale = fractional_preferred_scale_handler,
};

// registry
void registry_global_handler(
	void *data, struct wl_registry *registry,
	uint32_t name, const char *interface,
	uint32_t version)
{
	//  printf(" -> %s\n", interface);
	if (strcmp(interface, wl_compositor_interface.name) == 0)
	{
		compositor = wl_registry_bind(registry, name, &wl_compositor_interface, wl_compositor_interface.version);
		printf("Got wl_compositor %d\n", version);
	}
	else if (strcmp(interface, wl_shm_interface.name) == 0)
	{
		shm = wl_registry_bind(registry, name, &wl_shm_interface, wl_shm_interface.version);
		printf("Got wl_shm %d\n", version);
	}
	else if (strcmp(interface, xdg_wm_base_interface.name) == 0)
	{
		xdg_shell = wl_registry_bind(registry, name, &xdg_wm_base_interface, 4);
		printf("Got xdg_wm_base %d\n", version);
	}
	else if (strcmp(interface, wl_seat_interface.name) == 0)
	{
		wl_seat = wl_registry_bind(registry, name, &wl_seat_interface, 5);
		printf("Got wl_seat (%d)\n", version);
	}
	else if (strcmp(interface, wl_output_interface.name) == 0)
	{
		if (!wl_output)
		{
			wl_output = wl_registry_bind(registry, name, &wl_output_interface, 2);
			wl_output_add_listener(wl_output, &output_listener, NULL);
			printf("Got wl_output (%d)\n", version);
		}
	}
	else if (strcmp(interface, wp_viewporter_interface.name) == 0)
	{
		viewporter = wl_registry_bind(registry, name, &wp_viewporter_interface, 1);
		printf("Got wp_viewporter (%d)\n", version);
	}
	else if (strcmp(interface, wp_fractional_scale_manager_v1_interface.name) == 0)
	{
		fractional_manager = wl_registry_bind(registry, name, &wp_fractional_scale_manager_v1_interface, 1);
		printf("Got fractional_scale_manager (%d)\n", version);
	}
}

void registry_global_remove_handler(
	void *data, struct wl_registry *registry,
	uint32_t name)
{
	// nothing
}

const struct wl_registry_listener registry_listener = {
	.global = registry_global_handler,
	.global_remove = registry_global_remove_handler};

// xdg_toplevel
void xdg_toplevel_configure_handler(
	void *data,
	struct xdg_toplevel *xdg_toplevel,
	int32_t width, int32_t height,
	struct wl_array *states)
{
	printf("xdg_toplevel_configure: %dx%d\n", width, height);
	if (width > 0) logical_width = width;
	if (height > 0) logical_height = height;
	need_resize = 1;
}

void xdg_toplevel_close_handler(void *data, struct xdg_toplevel *xdg_toplevel)
{
	printf("xdg_toplevel_close\n");
	running = 0;
}

void xdg_toplevel_configure_bounds_handler(
	void *data,
	struct xdg_toplevel *xdg_toplevel,
	int32_t width,
	int32_t height)
{
	// nothing
}

const struct xdg_toplevel_listener xdg_toplevel_listener = {
	.configure = xdg_toplevel_configure_handler,
	.close = xdg_toplevel_close_handler,
	.configure_bounds = xdg_toplevel_configure_bounds_handler};

// xdg_surface
void xdg_surface_configure_handler(void *data, struct xdg_surface *xdg_surface,
								   uint32_t serial)
{
	printf("xdg_surface_configure\n");
	xdg_surface_ack_configure(xdg_surface, serial);
}

const struct xdg_surface_listener xdg_surface_listener = {
	.configure = xdg_surface_configure_handler};

// xdg_shell
void xdg_wm_base_ping_handler(void *data, struct xdg_wm_base *xdg_shell,
							  uint32_t serial)
{
	xdg_wm_base_pong(xdg_shell, serial);
	// printf("wm_base ping-pong\n");
}

const struct xdg_wm_base_listener xdg_shell_listener = {
	.ping = xdg_wm_base_ping_handler};

void wl_buffer_release_handler(void *data, struct wl_buffer *wl_buffer)
{
	// printf("wl_buffer_release\n");
	released = 1;
}

const struct wl_buffer_listener wl_buffer_listener = {
	.release = wl_buffer_release_handler};

void redraw(); // forward declaration

static void simulation_tick(void);

static void handle_key(uint32_t key, uint32_t state, xkb_keysym_t sym, uint32_t mods, void *user_data)
{
	(void)key;
	(void)user_data;

	if (state != WL_KEYBOARD_KEY_STATE_PRESSED) return;

	action_t a = config_lookup(&g_config, mods, sym);
	printf("action=%d\n", a);

	switch (a) {
	case ACTION_QUIT:
		running = 0;
		break;
	case ACTION_CANCEL:
		active_tool = -1;
		printf("tool cancelled\n");
		break;
	case ACTION_ROTATE:
		if (active_tool >= 0) {
			active_rotation = (active_rotation + 1) % 4;
			printf("rotation=%d\n", active_rotation);
		}
		break;
	case ACTION_SELECT_GLIDER:
		active_tool = 0; active_rotation = 0; printf("selected glider\n"); break;
	case ACTION_SELECT_BLINKER:
		active_tool = 1; active_rotation = 0; printf("selected blinker\n"); break;
	case ACTION_SELECT_BLOCK:
		active_tool = 2; active_rotation = 0; printf("selected block\n"); break;
	case ACTION_SELECT_TOAD:
		active_tool = 3; active_rotation = 0; printf("selected toad\n"); break;
	case ACTION_SELECT_BEACON:
		active_tool = 4; active_rotation = 0; printf("selected beacon\n"); break;
	case ACTION_SELECT_BOAT:
		active_tool = 5; active_rotation = 0; printf("selected boat\n"); break;
	case ACTION_SELECT_TUB:
		active_tool = 6; active_rotation = 0; printf("selected tub\n"); break;
	case ACTION_SELECT_BEEHIVE:
		active_tool = 7; active_rotation = 0; printf("selected beehive\n"); break;
	case ACTION_SELECT_RPENTOMINO:
		active_tool = 8; active_rotation = 0; printf("selected rpentomino\n"); break;
	case ACTION_SELECT_ACORN:
		active_tool = 9; active_rotation = 0; printf("selected acorn\n"); break;
	case ACTION_CLEAR:
		printf("clear requested\n");
		break;
	case ACTION_PAUSE:
		sim_paused = !sim_paused;
		sim_accumulator = 0;
		printf("paused=%d\n", sim_paused);
		break;
	case ACTION_STEP:
		if (sim_paused) {
			simulation_tick();
			printf("stepped\n");
		}
		break;
	case ACTION_SPEED_UP:
		sim_interval /= 2.0;
		if (sim_interval < 0.025) sim_interval = 0.025;
		printf("interval=%g\n", sim_interval);
		break;
	case ACTION_SPEED_DOWN:
		sim_interval *= 2.0;
		if (sim_interval > 1.0) sim_interval = 1.0;
		printf("interval=%g\n", sim_interval);
		break;
	case ACTION_TOGGLE_GRID:
		show_grid_lines = !show_grid_lines;
		break;
	default:
		break;
	}
}

static void handle_button(uint32_t button, uint32_t state, double x, double y, void *user_data)
{
	(void)user_data;
	if (button == BTN_LEFT) {
		if (state == WL_POINTER_BUTTON_STATE_PRESSED) {
			mouse_left_down = 1;
			click_x = x;
			click_y = y;
			click_pending = 1;
		} else {
			mouse_left_down = 0;
		}
	}
	if (button == BTN_RIGHT) {
		if (state == WL_POINTER_BUTTON_STATE_PRESSED) {
			mouse_right_down = 1;
		} else {
			mouse_right_down = 0;
		}
	}
	printf("button %u state %u at %.1f %.1f\n", button, state, x, y);
}

void wl_callack_done(void *data, struct wl_callback *callback, uint32_t time)
{
	if (canvas.frame)
	{
		wl_callback_destroy(canvas.frame);
		canvas.frame = NULL;
	}
	if (released)
	{
		redraw();
		released = 0;
	}
}

const struct wl_callback_listener wl_surface_frame_listener = {
	.done = wl_callack_done};

static void canvas_resize(int log_w, int log_h, double scale) {
	if (log_w < 1) log_w = 1;
	if (log_h < 1) log_h = 1;
	if (scale <= 0) scale = 1.0;
	int phys_w = (int)ceil((double)log_w * scale);
	int phys_h = (int)ceil((double)log_h * scale);
	if (phys_w < 1) phys_w = 1;
	if (phys_h < 1) phys_h = 1;

	if (canvas.buffer) { wl_buffer_destroy(canvas.buffer); canvas.buffer = NULL; }
	if (canvas.pool) { wl_shm_pool_destroy(canvas.pool); canvas.pool = NULL; }
	if (canvas.data && canvas.size > 0) { munmap(canvas.data, canvas.size); canvas.data = NULL; }
	if (canvas.fd >= 0) { close(canvas.fd); canvas.fd = -1; }

	canvas.width = phys_w;
	canvas.height = phys_h;
	canvas.stride = phys_w * 4;
	canvas.size = canvas.stride * phys_h;

	canvas.fd = syscall(SYS_memfd_create, "buffer", 0);
	ftruncate(canvas.fd, canvas.size);
	canvas.data = mmap(NULL, canvas.size, PROT_READ | PROT_WRITE, MAP_SHARED, canvas.fd, 0);
	canvas.pool = wl_shm_create_pool(shm, canvas.fd, canvas.size);
	close(canvas.fd);
	canvas.fd = -1;

	canvas.buffer = wl_shm_pool_create_buffer(canvas.pool, 0, phys_w, phys_h, canvas.stride, WL_SHM_FORMAT_ARGB8888);
	wl_buffer_add_listener(canvas.buffer, &wl_buffer_listener, NULL);

	if (canvas_viewport) {
		wp_viewport_set_destination(canvas_viewport, log_w, log_h);
	}

	grid_resize(&grid, log_w / 8, log_h / 8);
	grid_resize(&grid_back, grid.cols, grid.rows);
	need_resize = 0;
	printf("canvas resized logical=%dx%d phys=%dx%d scale=%g grid=%dx%d\n", log_w, log_h, phys_w, phys_h, scale, grid.cols, grid.rows);
}

int main(void)
{
	clock_gettime(CLOCK_MONOTONIC, &mytime);

	struct wl_display *display = wl_display_connect(NULL);
	struct wl_registry *registry = wl_display_get_registry(display);
	wl_registry_add_listener(registry, &registry_listener, NULL);

	// wait for the "initial" set of globals to appear
	wl_display_roundtrip(display);

	xdg_wm_base_add_listener(xdg_shell, &xdg_shell_listener, NULL);

	canvas.surface = wl_compositor_create_surface(compositor);

	if (viewporter) {
		canvas_viewport = wp_viewporter_get_viewport(viewporter, canvas.surface);
	}
	if (fractional_manager) {
		fractional_scale = wp_fractional_scale_manager_v1_get_fractional_scale(fractional_manager, canvas.surface);
		wp_fractional_scale_v1_add_listener(fractional_scale, &fractional_scale_listener, NULL);
	}

	struct xdg_surface *xdg_surface = xdg_wm_base_get_xdg_surface(xdg_shell, canvas.surface);
	struct xdg_toplevel *xdg_toplevel = xdg_surface_get_toplevel(xdg_surface);

	xdg_surface_add_listener(xdg_surface, &xdg_surface_listener, NULL);
	xdg_toplevel_add_listener(xdg_toplevel, &xdg_toplevel_listener, NULL);

	xdg_toplevel_set_app_id(xdg_toplevel, "eu.ar76.wlgol");
	xdg_toplevel_set_title(xdg_toplevel, "Game Of Life.");

	// signal that the surface is ready to be configured
	wl_surface_commit(canvas.surface);

	keyboard_data.keyboard = wl_seat_get_keyboard(wl_seat);
	keyboard_set_handler(&keyboard_data, handle_key, NULL);
	wl_keyboard_add_listener(keyboard_data.keyboard, &keyboard_listener, &keyboard_data);

	pointer_init_cursor(&pointer_data, compositor, shm);
	pointer_set_button_handler(&pointer_data, handle_button, NULL);
	pointer_data.pointer = wl_seat_get_pointer(wl_seat);
	wl_pointer_add_listener(pointer_data.pointer, &pointer_listener, &pointer_data);

	canvas.fd = -1;
	logical_width = 1024;
	logical_height = 576;
	grid_init(&grid, logical_width / 8, logical_height / 8);
	grid.show_lines = 1;

	// wait for the surface to be configured
	wl_display_roundtrip(display);

	if (output_width > 0 && output_height > 0 && current_scale > 0) {
		logical_width = (int)(output_width * 0.8 / current_scale);
		logical_height = (int)(output_height * 0.8 / current_scale);
	}
	if (logical_width < 8) logical_width = 8;
	if (logical_height < 8) logical_height = 8;

	/* initial scale may arrive via fractional/output after roundtrip */
	if (fractional_manager && !fractional_scale) {
		/* already created above */
	}
	canvas_resize(logical_width, logical_height, current_scale);

	const char *home = getenv("HOME");
	char config_path[1024];
	if (home) snprintf(config_path, sizeof(config_path), "%s/.config/wlgol/keys.conf", home);
	else snprintf(config_path, sizeof(config_path), ".config/wlgol/keys.conf");
	g_config = config_load(config_path);

	redraw();

	while (wl_display_dispatch(display) != -1 && running)
	{
		// nothing inside
	}

	xdg_toplevel_destroy(xdg_toplevel);
	xdg_surface_destroy(xdg_surface);
	wl_surface_destroy(canvas.surface);
	if (canvas.pool) wl_shm_pool_destroy(canvas.pool);
	if (canvas.buffer) wl_buffer_destroy(canvas.buffer);
	wl_keyboard_destroy(keyboard_data.keyboard);
	if (keyboard_data.xkb_state != NULL)
	{
		xkb_state_unref(keyboard_data.xkb_state);
	}
	if (keyboard_data.xkb_keymap != NULL)
	{
		xkb_keymap_unref(keyboard_data.xkb_keymap);
	}
	if (keyboard_data.xkb_context != NULL)
	{
		xkb_context_unref(keyboard_data.xkb_context);
	}
	wl_registry_destroy(registry);
	wl_display_disconnect(display);
}

unsigned char mycolour = 0;
char direction = 1;
int framecounter = 0;

static void fill_rect(int x0, int y0, int w, int h, unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
	if (w <= 0 || h <= 0) return;
	for (int y = y0; y < y0 + h && y < canvas.height; y++) {
		if (y < 0) continue;
		for (int x = x0; x < x0 + w && x < canvas.width; x++) {
			if (x < 0) continue;
			struct pixel {
				unsigned char blue;
				unsigned char green;
				unsigned char red;
				unsigned char alpha;
			} *px = (struct pixel *)(canvas.data + y * canvas.stride + x * 4);
			px->red = r;
			px->green = g;
			px->blue = b;
			px->alpha = a;
		}
	}
}

static int count_neighbors(int c, int r) {
    int n = 0;
    for (int dr = -1; dr <= 1; dr++) {
        for (int dc = -1; dc <= 1; dc++) {
            if (dr == 0 && dc == 0) continue;
            n += grid_get(&grid, c + dc, r + dr);
        }
    }
    return n;
}

static void simulation_tick(void) {
    if (grid_back.cols != grid.cols || grid_back.rows != grid.rows) {
        grid_free(&grid_back);
        grid_init(&grid_back, grid.cols, grid.rows);
    }
    grid_clear(&grid_back);
    for (int r = 0; r < grid.rows; r++) {
        for (int c = 0; c < grid.cols; c++) {
            int alive = grid_get(&grid, c, r);
            int nb = count_neighbors(c, r);
            int next = 0;
            if (alive && (nb == 2 || nb == 3)) next = 1;
            if (!alive && nb == 3) next = 1;
            grid_set(&grid_back, c, r, next);
        }
    }
    /* swap cell buffers */
    unsigned char *tmp = grid.cells;
    grid.cells = grid_back.cells;
    grid_back.cells = tmp;
}

void redraw()
{
	if (need_resize) {
		canvas_resize(logical_width, logical_height, current_scale);
	}

	clock_t start = clock();

	/* update cursor from pointer */
	cursor_x = pointer_data.x;
	cursor_y = pointer_data.y;

	/* tick timing */
	struct timespec now;
	clock_gettime(CLOCK_MONOTONIC, &now);
	if (!sim_time_initialized) {
		sim_last_time = now;
		sim_time_initialized = 1;
	}
	double dt = (now.tv_sec - sim_last_time.tv_sec) + (now.tv_nsec - sim_last_time.tv_nsec) / 1e9;
	sim_last_time = now;
	if (!sim_paused) {
		sim_accumulator += dt;
		while (sim_accumulator >= sim_interval) {
			simulation_tick();
			sim_accumulator -= sim_interval;
		}
	}

	/* paused-only editing */
	if (sim_paused && active_tool < 0) {
		if (mouse_left_down || mouse_right_down) {
			int cx = (int)(cursor_x / 8.0);
			int cy = (int)(cursor_y / 8.0);
			if (cx >= 0 && cy >= 0 && cx < grid.cols && cy < grid.rows) {
				if (mouse_left_down) grid_set(&grid, cx, cy, 1);
				if (mouse_right_down) grid_set(&grid, cx, cy, 0);
			}
		}
	}

	/* handle pending click placement */
	if (click_pending) {
		click_pending = 0;
		if (active_tool >= 0) {
			int cx = (int)(click_x / 8.0);
			int cy = (int)(click_y / 8.0);
			int dx[16], dy[16];
			int n = pattern_rotated_offsets(active_tool, active_rotation, dx, dy);
			int ok = 1;
			for (int i = 0; i < n; i++) {
				int c = cx + dx[i];
				int r = cy + dy[i];
				if (c < 0 || r < 0 || c >= grid.cols || r >= grid.rows) { ok = 0; break; }
			}
			if (ok) {
				for (int i = 0; i < n; i++) {
					grid_set(&grid, cx + dx[i], cy + dy[i], 1);
				}
			}
		}
	}

	int cell_px = (grid.cols > 0) ? (canvas.width / grid.cols) : 8;
	if (cell_px < 1) cell_px = 1;

	/* clear background */
	fill_rect(0, 0, canvas.width, canvas.height, 20, 20, 24, 255);

	/* grid lines */
	if (show_grid_lines && grid.show_lines) {
		for (int c = 0; c <= grid.cols; c++) {
			int x = c * cell_px;
			fill_rect(x, 0, 1, canvas.height, 40, 40, 48, 255);
		}
		for (int r = 0; r <= grid.rows; r++) {
			int y = r * cell_px;
			fill_rect(0, y, canvas.width, 1, 40, 40, 48, 255);
		}
	}

	/* alive cells */
	for (int r = 0; r < grid.rows; r++) {
		for (int c = 0; c < grid.cols; c++) {
			if (grid_get(&grid, c, r)) {
				fill_rect(c * cell_px + 1, r * cell_px + 1, cell_px - 2, cell_px - 2, 80, 200, 120, 255);
			}
		}
	}

	/* preview */
	if (active_tool >= 0) {
		int cx = (int)(cursor_x / 8.0);
		int cy = (int)(cursor_y / 8.0);
		int dx[16], dy[16];
		int n = pattern_rotated_offsets(active_tool, active_rotation, dx, dy);
		int ok = 1;
		for (int i = 0; i < n; i++) {
			int c = cx + dx[i];
			int r = cy + dy[i];
			if (c < 0 || r < 0 || c >= grid.cols || r >= grid.rows) { ok = 0; break; }
		}
		unsigned char pr = ok ? 220 : 220;
		unsigned char pg = ok ? 200 : 80;
		unsigned char pb = ok ? 80 : 80;
		for (int i = 0; i < n; i++) {
			int c = cx + dx[i];
			int r = cy + dy[i];
			fill_rect(c * cell_px + 2, r * cell_px + 2, cell_px - 4, cell_px - 4, pr, pg, pb, 160);
		}
	}

	// callback
	canvas.frame = wl_surface_frame(canvas.surface);
	wl_callback_add_listener(canvas.frame, &wl_surface_frame_listener, NULL);
	wl_surface_attach(canvas.surface, canvas.buffer, 0, 0);
	wl_surface_damage(canvas.surface, 0, 0, canvas.width, canvas.height);
	wl_surface_commit(canvas.surface);

	framecounter++;

	struct timespec ntime;
	clock_gettime(CLOCK_MONOTONIC, &ntime);
	double elapsed_time = (ntime.tv_sec - mytime.tv_sec) + (ntime.tv_nsec - mytime.tv_nsec) / 1e9;

	if (elapsed_time > 1.0)
	{
		clock_t end = clock();
		double dur = ((double)end - start) / CLOCKS_PER_SEC;
		printf("FPS: %d  in %g sec\n", framecounter, dur);
		mytime = ntime;
		framecounter = 0;
	}
}