/*
 *  SPL - The SPL Programming Language
 *  Copyright (C) 2004, 2005  Clifford Wolf <clifford@clifford.at>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  mod_sdl.c: The SPL SDL module
 */

/**
 * A module for doing multimedia using the SDL library.
 *
 * Note: Only one SDL window can be opened by one host program at a time.
 * This is a limitation from SDL.
 */

#include <SDL/SDL.h>
#include <SDL/SDL_image.h>

#include <stdlib.h>

#ifdef ENABLE_PTHREAD_SUPPORT
#include <pthread.h>
#endif

#include "spl.h"
#include "compat.h"

extern void SPL_ABI(spl_mod_sdl_init)(struct spl_vm *vm, struct spl_module *mod, int restore);
extern void SPL_ABI(spl_mod_sdl_done)(struct spl_vm *vm, struct spl_module *mod);

#ifdef ENABLE_PTHREAD_SUPPORT
static pthread_mutex_t spl_sdl_init_lock = PTHREAD_MUTEX_INITIALIZER;
#endif

static int spl_sdl_initialized = 0;
static SDL_Surface *spl_sdl_root = 0;
static Uint32 spl_sdl_last_ticks = 0;
static int spl_sdl_last_ticks_init = 0;

static char *undupable_reason = "VM is active SDL user";

/*** SDL HNODE ***/

struct sdl_hnode_data {
	SDL_Surface *image;
	int revision_counter;
	int reference_counter;
	struct sdl_hnode_data *left, *right;
};

static struct sdl_hnode_data *spl_sdl_hnlist = 0;

static struct sdl_hnode_data *clib_get_hnd(struct spl_task *task, struct spl_node *n)
{
	struct sdl_hnode_data *hnd = n ? n->hnode_data : 0;

	if (!n || (!n->hnode_name && !n->value && !n->subs_counter &&
		   !n->code && !n->ctx && !n->cls)) {
		return 0;
	}

	if (!n->hnode_name || strcmp(n->hnode_name, "sdl") || !hnd || !hnd->image) {
		spl_clib_exception(task, "SdlEx", "description",
				SPL_NEW_PRINTF("Expected SDL image (surface) node"),
				NULL);
		return 0;
	}

	return hnd;
}

static SDL_Surface *clib_get_surface(struct spl_task *task, int isdest)
{
	struct spl_node *n = spl_cleanup(task, spl_clib_get_node(task));
	struct sdl_hnode_data *hnd = n ? n->hnode_data : 0;

	if (!n || (!n->hnode_name && !n->value && !n->subs_counter &&
		   !n->code && !n->ctx && !n->cls)) {
		return spl_sdl_root;
	}

	if (!n->hnode_name || strcmp(n->hnode_name, "sdl") || !hnd || !hnd->image) {
		spl_clib_exception(task, "SdlEx", "description",
				SPL_NEW_PRINTF("Expected SDL image (surface) node"),
				NULL);
		return 0;
	}

	if (isdest)
		hnd->revision_counter++;

	return hnd->image;
}

static struct spl_node *sdl_hnode_new()
{
	struct spl_node *n = SPL_NEW_STRING_DUP("SDL Node");
	struct sdl_hnode_data *hnd = calloc(1, sizeof(struct sdl_hnode_data));

	n->hnode_name = strdup("sdl");
	n->hnode_data = hnd;

	if (spl_sdl_hnlist) {
		hnd->right = spl_sdl_hnlist;
		hnd->right->left = hnd;
	}
	spl_sdl_hnlist = hnd;
	hnd->reference_counter = 1;

	return n;
}

static void sdl_hnode_data_free(struct sdl_hnode_data *hnd)
{
	if (hnd->image) {
		SDL_FreeSurface(hnd->image);
		hnd->image = 0;
	}
}

static void handler_sdl_node(struct spl_task *task UNUSED, struct spl_vm *vm UNUSED,
		struct spl_node *node, struct spl_hnode_args *args, void *data UNUSED)
{
	if (args->action == SPL_HNODE_ACTION_PUT)
	{
		struct sdl_hnode_data *hnd = node->hnode_data;
		if (hnd && --hnd->reference_counter == 0) {
			sdl_hnode_data_free(hnd);
			*(hnd->left ? &hnd->left->right : &spl_sdl_hnlist) = hnd->right;
			if (hnd->right) hnd->right->left = hnd->left;
			free(hnd);
		}
		return;
	}

	if (args->action == SPL_HNODE_ACTION_LOOKUP)
	{
		struct sdl_hnode_data *hnd = node->hnode_data;
		char *mode = spl_hash_decode(args->key);

		if (hnd && hnd->image && !strcmp(mode, "w"))
			args->value = SPL_NEW_INT(hnd->image->w);

		if (hnd && hnd->image && !strcmp(mode, "h"))
			args->value = SPL_NEW_INT(hnd->image->h);

		free(mode);
	}

	return;
}


/*** SDL Functions ***/

/**
 * Initialize SDL and open a window with the specified size.
 *
 * The window is opened in fullscreen when the named parameter 'fullscreen'
 * is passed and has a 'true' (non-zero) value.
 *
 * The window is double-buffered when the named parameter 'doublebf'
 * is passed and has a 'true' (non-zero) value.
 */
// builtin sdl_init(width, height)
static struct spl_node *handler_sdl_init(struct spl_task *task, void *data UNUSED)
{
	struct spl_node *hargs = spl_cleanup(task, spl_clib_get_hargs(task));
	struct spl_node *hnode;

	int width = spl_clib_get_int(task);
	int height = spl_clib_get_int(task);

#ifdef ENABLE_PTHREAD_SUPPORT
	pthread_mutex_lock(&spl_sdl_init_lock);
#endif

	if (spl_sdl_initialized || task->vm->sdl_initialized) {
		spl_clib_exception(task, "SdlEx", "description",
				SPL_NEW_PRINTF("SDL already in use"),
				NULL);
		goto fin;
	}

	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
		spl_clib_exception(task, "SdlEx", "description",
				SPL_NEW_PRINTF("Unable to init SDL: %s", SDL_GetError()),
				NULL);
		goto fin;
	}

	int videoflags = SDL_ANYFORMAT | SDL_HWSURFACE;

	hnode = spl_lookup(task, hargs, "fullscreen", SPL_LOOKUP_TEST);
	if (hnode && spl_get_int(hnode)) videoflags |= SDL_FULLSCREEN;

	hnode = spl_lookup(task, hargs, "doublebuf", SPL_LOOKUP_TEST);
	if (hnode && spl_get_int(hnode)) videoflags |= SDL_DOUBLEBUF;

	spl_sdl_root = SDL_SetVideoMode(width, height, 32, videoflags);
	if (!spl_sdl_root) {
		spl_clib_exception(task, "SdlEx", "description",
				SPL_NEW_PRINTF("Unable to init SDL: %s", SDL_GetError()),
				NULL);
		SDL_Quit();
		goto fin;
	}

	SDL_ShowCursor(0);

	spl_sdl_last_ticks = 0;
	spl_sdl_last_ticks_init = 1;

	spl_sdl_initialized = 1;
	task->vm->sdl_initialized = 1;
	spl_undumpable_inc(task->vm, undupable_reason);

fin:
#ifdef ENABLE_PTHREAD_SUPPORT
	pthread_mutex_unlock(&spl_sdl_init_lock);
#endif
	return 0;
}

#define CHECK_INIT							\
	if (!spl_sdl_initialized || !task->vm->sdl_initialized) {	\
		spl_clib_exception(task, "SdlEx", "description",	\
				SPL_NEW_PRINTF("SDL not initialized"),	\
				NULL);					\
		return 0;						\
	}

/**
 * Terminate the SDL context and close the window.
 */
// builtin sdl_quit()
static struct spl_node *handler_sdl_quit(struct spl_task *task, void *data UNUSED)
{
	// task is a NULL pointer when we
	// are called from SPL_ABI(spl_mod_sdl_done)()
	if (task) {
		CHECK_INIT
	}

	for (struct sdl_hnode_data *i = spl_sdl_hnlist; i; i = i->right)
		sdl_hnode_data_free(i);

	SDL_Quit();
	spl_sdl_root = 0;
	spl_sdl_last_ticks = 0;
	spl_sdl_initialized = 0;

	if (task) {
		task->vm->sdl_initialized = 0;
		spl_undumpable_inc(task->vm, undupable_reason);
	}

	return 0;
}

/**
 * Set the window and icon name.
 */
// builtin sdl_title(title, icon)
static struct spl_node *handler_sdl_title(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	const char *title = spl_clib_get_string(task);
	const char *icon = spl_clib_get_string(task);
	SDL_WM_SetCaption(title, icon);
	return 0;
}

/**
 * Delay program execution for the specified number of milliseconds.
 *
 * Note that the given number of ms is relative to the end of the last call
 * to [[sdl_delay()]]. The return code is the effective number of ms the
 * program execution has been delayed.
 *
 * A zero or negative return code means that the function did not sleep and
 * you are likely to have a timing/performance problem in your application.
 */
// builtin sdl_delay(ms)
static struct spl_node *handler_sdl_delay(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	int delay = spl_clib_get_int(task);
	int ticks = SDL_GetTicks();

	if (spl_sdl_last_ticks_init) {
		spl_sdl_last_ticks = ticks;
		spl_sdl_last_ticks_init = 0;
	}

	int returncode = (spl_sdl_last_ticks + delay) - ticks;

	if (returncode > 0)
		SDL_Delay(returncode);

	spl_sdl_last_ticks = SDL_GetTicks();
	return SPL_NEW_INT(returncode);
}

/**
 * Update the window (switch backend framebuffers if the window is created
 * in doublebuffering mode).
 */
// builtin sdl_flip()
static struct spl_node *handler_sdl_flip(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT
	SDL_Flip(spl_sdl_root);
	return 0;
}

/**
 * Update the specified area of the window.
 */
// builtin sdl_update(x, y, w, h)
static struct spl_node *handler_sdl_update(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	int x = spl_clib_get_int(task);
	int y = spl_clib_get_int(task);
	int w = spl_clib_get_int(task);
	int h = spl_clib_get_int(task);

	SDL_UpdateRect(spl_sdl_root, x, y, w, h);
	return 0;
}

/**
 * Load the image from the specified filename and return the image handler.
 */
// builtin sdl_image_load(filename)
static struct spl_node *handler_sdl_image_load(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	const char *filename = spl_clib_get_string(task);

	struct spl_node *n = sdl_hnode_new();
	struct sdl_hnode_data *hnd = n->hnode_data;

	SDL_Surface *imgbuffer = IMG_Load(filename);
	if (!imgbuffer) {
		spl_clib_exception(task, "SdlEx", "description",
				SPL_NEW_PRINTF("Can't load image '%s': %s",
					filename, IMG_GetError()),
				NULL);
		spl_put(task->vm, n);
		return 0;
	}

	hnd->image = SDL_DisplayFormatAlpha(imgbuffer);
	SDL_FreeSurface(imgbuffer);

	return n;
}

/**
 * Create an empty image with the specified size.
 */
// builtin sdl_image_create(w, h)
static struct spl_node *handler_sdl_image_create(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	int w = spl_clib_get_int(task);
	int h = spl_clib_get_int(task);

	struct spl_node *n = sdl_hnode_new();
	struct sdl_hnode_data *hnd = n->hnode_data;

	Uint32 rmask, gmask, bmask, amask;

#if SDL_BYTEORDER == SDL_BIG_ENDIAN
	rmask = 0xff000000;
	gmask = 0x00ff0000;
	bmask = 0x0000ff00;
	amask = 0x000000ff;
#else
	rmask = 0x000000ff;
	gmask = 0x0000ff00;
	bmask = 0x00ff0000;
	amask = 0xff000000;
#endif

	// It seems like there is no API for allocating a
	// surface in DisplayFormatAlpha format directly
	SDL_Surface *imgbuffer = SDL_CreateRGBSurface(0, w, h, 32,
			spl_sdl_root->format->Rmask,
			spl_sdl_root->format->Gmask,
			spl_sdl_root->format->Bmask,
			spl_sdl_root->format->Amask);

	hnd->image = SDL_DisplayFormatAlpha(imgbuffer);
	SDL_FreeSurface(imgbuffer);

	return n;
}

/**
 * Blit the source image to the specified coordinates in the destination
 * image. If 'undef' is passed as destination image, the image is blitted to
 * the window and will be displayed after the next call to [[sdl_flip()]].
 */
// builtin sdl_blit(dstimg, srcimg, x, y)
static struct spl_node *handler_sdl_blit(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	SDL_Surface *dst = clib_get_surface(task, 1);
	SDL_Surface *src = clib_get_surface(task, 0);

	if (dst && src) {
		SDL_Rect srcrect;
		SDL_Rect dstrect;

		srcrect.x = 0;
		srcrect.y = 0;
		srcrect.w = src->w;
		srcrect.h = src->h;

		dstrect.x = spl_clib_get_int(task);
		dstrect.y = spl_clib_get_int(task);
		dstrect.w = srcrect.w;
		dstrect.h = srcrect.h;

		SDL_BlitSurface(src, &srcrect, dst, &dstrect);
	}

	return 0;
}

/**
 * Like [[sdl_blit()]], but only blit the specified rectangle.
 */
// builtin sdl_blitrect(dstimg, srcimg, dest_x, dest_y, src_x, src_y, w, h)
static struct spl_node *handler_sdl_blitrect(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	SDL_Surface *dst = clib_get_surface(task, 1);
	SDL_Surface *src = clib_get_surface(task, 0);

	if (dst && src) {
		SDL_Rect srcrect;
		SDL_Rect dstrect;

		dstrect.x = spl_clib_get_int(task);
		dstrect.y = spl_clib_get_int(task);
		srcrect.x = spl_clib_get_int(task);
		srcrect.y = spl_clib_get_int(task);
		dstrect.w = srcrect.w = spl_clib_get_int(task);
		dstrect.h = srcrect.h = spl_clib_get_int(task);

		SDL_BlitSurface(src, &srcrect, dst, &dstrect);
	}

	return 0;
}

/**
 * Copy the the specified rectangle to a new image. The new image is returned.
 */
// builtin sdl_copy(srcimg, x, y, w, h)
static struct spl_node *handler_sdl_copy(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	SDL_Surface *src = clib_get_surface(task, 0);
	int x = spl_clib_get_int(task);
	int y = spl_clib_get_int(task);
	int w = spl_clib_get_int(task);
	int h = spl_clib_get_int(task);

	if (src) {
		struct spl_node *n = sdl_hnode_new();
		struct sdl_hnode_data *hnd = n->hnode_data;

		Uint32 rmask, gmask, bmask, amask;

#if SDL_BYTEORDER == SDL_BIG_ENDIAN
		rmask = 0xff000000;
		gmask = 0x00ff0000;
		bmask = 0x0000ff00;
		amask = 0x000000ff;
#else
		rmask = 0x000000ff;
		gmask = 0x0000ff00;
		bmask = 0x00ff0000;
		amask = 0xff000000;
#endif

		// It seems like there is no API for allocating a
		// surface in DisplayFormatAlpha format directly
		SDL_Surface *imgbuffer = SDL_CreateRGBSurface(0, w, h, 32,
				spl_sdl_root->format->Rmask,
				spl_sdl_root->format->Gmask,
				spl_sdl_root->format->Bmask,
				spl_sdl_root->format->Amask);

		hnd->image = SDL_DisplayFormatAlpha(imgbuffer);
		SDL_FreeSurface(imgbuffer);

		SDL_Rect srcrect;
		SDL_Rect dstrect;

		srcrect.x = x;
		srcrect.y = y;
		srcrect.w = w;
		srcrect.h = h;

		dstrect.x = 0;
		dstrect.y = 0;
		dstrect.w = w;
		dstrect.h = h;

		SDL_BlitSurface(src, &srcrect, hnd->image, &dstrect);

		return n;
	}

	return 0;
}

/**
 * Fill the specified rectangle in the destination image with the specified
 * RGBA values. (The RGBA values are in the range from 0 to 255.)
 */
// builtin sdl_fill(dstimg, x, y, w, h, r, g, b, a)
static struct spl_node *handler_sdl_fill(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	SDL_Surface *dst = clib_get_surface(task, 1);

	if (dst) {
		SDL_Rect dstrect;

		dstrect.x = spl_clib_get_int(task);
		dstrect.y = spl_clib_get_int(task);
		dstrect.w = spl_clib_get_int(task);
		dstrect.h = spl_clib_get_int(task);

		int r = spl_clib_get_int(task);
		int g = spl_clib_get_int(task);
		int b = spl_clib_get_int(task);
		int a = spl_clib_get_int(task);

		Uint32 color = SDL_MapRGBA(dst->format, r, g, b, a);

		SDL_FillRect(dst, &dstrect, color);
	}

	return 0;
}

/**
 * Fill the specified rectangle in the destination image with a
 * pattern.
 */
// builtin sdl_fill_pattern(dstimg, x, y, w, h, patternimg)
static struct spl_node *handler_sdl_fill_pattern(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	SDL_Surface *dst = clib_get_surface(task, 1);

	if (dst) {
		int dx = spl_clib_get_int(task);
		int dy = spl_clib_get_int(task);
		int dw = spl_clib_get_int(task);
		int dh = spl_clib_get_int(task);

		SDL_Surface *src = clib_get_surface(task, 0);

		SDL_Rect srcrect;

		srcrect.x = 0;
		srcrect.y = 0;
		srcrect.w = src->w;
		srcrect.h = src->h;

		for (int x=0; x<dw; x+=src->w)
		for (int y=0; y<dh; y+=src->h)
		{
			SDL_Rect dstrect;

			dstrect.x = dx + x;
			dstrect.y = dy + y;
			dstrect.w = src->w;
			dstrect.h = src->h;

			if (dstrect.x + dstrect.w > dx + dw)
				dstrect.w = dx + dw - dstrect.x;
			if (dstrect.y + dstrect.h > dy + dh)
				dstrect.h = dy + dh - dstrect.y;

			SDL_BlitSurface(src, &srcrect, dst, &dstrect);
		}
	}

	return 0;
}

/**
 * Return '1' if the specified key is pressed and '0' if it isn't. The keynames
 * are listed at:
 *
 *	http://www.libsdl.org/cgi/docwiki.cgi/SDLKey
 *
 * (lowercase versions of the SDLK_* strings without the SDLK_ prefix and with
 * blanks instead of underscores)
 */
// builtin sdl_keystat(keyname)
static struct spl_node *handler_sdl_keystate(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	const char *keyname = spl_clib_get_string(task);

	SDL_PumpEvents();

	int numkeys;
	Uint8 *keystates = SDL_GetKeyState(&numkeys);

	for (int i=0; i<numkeys; i++) {
		if (!strcmp(SDL_GetKeyName(i), keyname))
			return SPL_NEW_INT(keystates[i]);
	}

	spl_clib_exception(task, "SdlEx", "description",
			SPL_NEW_PRINTF("Unknown SDL keyname: %s", keyname),
			NULL);
	return 0;
}


/*** SDL Sprite HNODE ***/

struct sdl_sprite_hnode_data {
	struct sdl_hnode_data *image;
	int ox, oy, ow, oh, orev, oactive;
	int x, y, z, idx, updated;
	int schedule_destroy;
};

static struct sdl_sprite_hnode_data **sprite_list;
static int sprite_list_resort;
static int sprite_list_nextfree;
static int sprite_list_roof;

static void destroy_sprite_data(int idx)
{
	struct sdl_sprite_hnode_data *hnd = sprite_list[idx];
	struct sdl_hnode_data *ihnd = hnd->image;

	if (ihnd && --ihnd->reference_counter == 0) {
		sdl_hnode_data_free(ihnd);
		*(ihnd->left ? &ihnd->left->right : &spl_sdl_hnlist) = ihnd->right;
		if (ihnd->right) ihnd->right->left = ihnd->left;
		free(ihnd);
	}

	sprite_list[idx] = 0;
	sprite_list_resort = 1;
	free(hnd);
}

static void handler_sdl_sprite_node(struct spl_task *task, struct spl_vm *vm UNUSED,
		struct spl_node *node, struct spl_hnode_args *args, void *data UNUSED)
{
	if (args->action == SPL_HNODE_ACTION_PUT)
	{
		struct sdl_sprite_hnode_data *hnd = node->hnode_data;

		if (!hnd)
			return;

		if (hnd->oactive)
			hnd->schedule_destroy = 1;
		else
			destroy_sprite_data(hnd->idx);

		node->hnode_data = 0;
		return;
	}

	if (args->action == SPL_HNODE_ACTION_LOOKUP ||
	    args->action == SPL_HNODE_ACTION_CREATE)
	{
		struct sdl_sprite_hnode_data *hnd = node->hnode_data;
		char *mode = spl_hash_decode(args->key);

		if (!strcmp(mode, "x") || !strcmp(mode, "y") || !strcmp(mode, "z"))
		{
			int *value = 0;

			switch (*mode)
			{
			case 'x':
				value = &hnd->x;
				break;
			case 'y':
				value = &hnd->y;
				break;
			case 'z':
				value = &hnd->z;
				break;
			}

			if (args->action == SPL_HNODE_ACTION_LOOKUP)
				args->value = SPL_NEW_INT(*value);

			if (args->action == SPL_HNODE_ACTION_CREATE) {
				int new_value = spl_get_int(args->value);
				if (new_value != *value) {
					*value = spl_get_int(args->value);
					if (*mode == 'z')
						sprite_list_resort = 1;
					hnd->updated = 1;
				}
			}
		}

		if (!strcmp(mode, "image") && args->action == SPL_HNODE_ACTION_CREATE)
		{
			if (hnd->image) {
				struct sdl_hnode_data *ihnd = hnd->image;
				if (ihnd && --ihnd->reference_counter == 0) {
					sdl_hnode_data_free(ihnd);
					*(ihnd->left ? &ihnd->left->right : &spl_sdl_hnlist) = ihnd->right;
					if (ihnd->right) ihnd->right->left = ihnd->left;
					free(ihnd);
				}
				hnd->image = 0;
			}

			struct sdl_hnode_data *ihnd = clib_get_hnd(task, args->value);
			hnd->image = ihnd;
			if (hnd->image) {
				hnd->image->reference_counter++;
				hnd->orev = hnd->image->revision_counter;
			}
			hnd->updated = 1;
		}

		free(mode);
	}
}


static int sort_sprite_list_compar(const void *va, const void *vb)
{
	struct sdl_sprite_hnode_data **pa = (void*)va;
	struct sdl_sprite_hnode_data **pb = (void*)vb;
	struct sdl_sprite_hnode_data *a = *pa;
	struct sdl_sprite_hnode_data *b = *pb;

	if (!a && !b)
		return 0;

	if (!a) return +1;
	if (!b) return -1;

	if (a->z < b->z) return -1;
	if (a->z > b->z) return +1;

	return 0;
}

static void sort_sprite_list()
{
	if (!sprite_list_resort)
		return;

	qsort(sprite_list, sprite_list_nextfree,
		sizeof(struct sdl_sprite_hnode_data *),
		sort_sprite_list_compar);

	int i;
	for (i = 0; sprite_list[i] && i < sprite_list_nextfree; i++)
		sprite_list[i]->idx = i;
	sprite_list_nextfree = i;

	sprite_list_resort = 0;
}


/*** SDL Sprite Functions ***/

/**
 * Usually, when doing SDL programming in C, everyone is creating his own SDL
 * sprite library. This is possible when doing SDL programming with SDL to. But
 * for performance reasons I recommend to use the built-in sprites of this
 * module.
 *
 * This function returns a new sprite object. Such a sprite object has the
 * following attributes:
 *
 *	.x
 *		x-coordinate of the sprite (upper left corner)
 *	.y
 *		y-coordinate of the sprite (upper left corner)
 *
 *	.z
 *		z-coordinate of the sprite.
 *		sprites with higher values overlap sprites with lower values
 *
 *	.image
 *		the image data for the sprite.
 *		this must be set to one of SDL Image the object such as
 *		returned by [[sdl_image_create()]].
 */
// builtin sdl_sprite_create()
static struct spl_node *handler_sdl_sprite_create(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	struct sdl_sprite_hnode_data *hnd = calloc(1, sizeof(struct sdl_sprite_hnode_data));

	if (sprite_list_nextfree >= sprite_list_roof) {
		if (sprite_list_roof < 32)
			sprite_list_roof = 64;
		else
			sprite_list_roof = sprite_list_roof * 2;
		sprite_list = realloc(sprite_list, sprite_list_roof * sizeof(struct sdl_sprite_hnode_data*));
	}

	hnd->idx = sprite_list_nextfree++;
	sprite_list[hnd->idx] = hnd;
	sprite_list_resort = 1;

	struct spl_node *n = SPL_NEW_STRING_DUP("SDL Sprite");
	n->hnode_name = strdup("sdl_sprite");
	n->hnode_data = hnd;

	return n;
}

static void sprite_update_backend(int x, int y, int w, int h, int usexywh)
{
	for (int i = 0; i < sprite_list_nextfree; i++)
	{
		if (!usexywh) {
			if (sprite_list[i]->schedule_destroy) {
				destroy_sprite_data(i);
				continue;
			}
			if (sprite_list[i]->image)
				sprite_list[i]->orev = sprite_list[i]->image->revision_counter;
			sprite_list[i]->updated = 0;
		}

		if (!sprite_list[i] || !sprite_list[i]->image || !sprite_list[i]->image->image)
			continue;

		struct sdl_sprite_hnode_data *hnd = sprite_list[i];
		SDL_Surface *src = hnd->image->image;

		if (usexywh) {
			if (hnd->x + src->w < x) continue;
			if (hnd->y + src->h < y) continue;
			if (hnd->x > x + w) continue;
			if (hnd->y > y + h) continue;
		}

		SDL_Rect srcrect;
		SDL_Rect dstrect;

		if (usexywh) {
			if (hnd->x < x) {
				srcrect.x = x - hnd->x;
				dstrect.x = x;
			} else {
				srcrect.x = 0;
				dstrect.x = hnd->x;
			}

			if (hnd->y < y) {
				srcrect.y = y - hnd->y;
				dstrect.y = y;
			} else {
				srcrect.y = 0;
				dstrect.y = hnd->y;
			}

			srcrect.w = w;
			srcrect.h = h;
			dstrect.w = w;
			dstrect.h = h;
		} else {
			srcrect.x = 0;
			srcrect.y = 0;
			srcrect.w = src->w;
			srcrect.h = src->h;

			dstrect.x = sprite_list[i]->x;
			dstrect.y = sprite_list[i]->y;
			dstrect.w = srcrect.w;
			dstrect.h = srcrect.h;
		}

		SDL_BlitSurface(src, &srcrect, spl_sdl_root, &dstrect);
	}

	if (usexywh) {
		if (x < 0) x = 0;
		if (y < 0) y = 0;
		if (x + w > spl_sdl_root->w) w = spl_sdl_root->w - x;
		if (y + h > spl_sdl_root->h) h = spl_sdl_root->h - y;

		if (w > 0 && h > 0)
			SDL_UpdateRect(spl_sdl_root, x, y, w, h);
	}
}

/**
 * This redraws all sprites, also those which haven't been updated.
 *
 * This function is only needed if you are mixing sprites with direct blitting
 * to the window. Usually [[sdl_sprite_update()]] is used instead.
 *
 * In some corner cases (when many sprites have been updated) this function
 * might be faster than [[sdl_sprite_update()]]. But this is a very seldom
 * case.
 */
// builtin sdl_sprite_redraw()
static struct spl_node *handler_sdl_sprite_redraw(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	sort_sprite_list();
	sprite_update_backend(0, 0, 0, 0, 0);
	SDL_UpdateRect(spl_sdl_root, 0, 0, 0, 0);

	return 0;
}

/**
 * This redraws all the updated sprites.
 */
// builtin sdl_sprite_update()
static struct spl_node *handler_sdl_sprite_update(struct spl_task *task, void *data UNUSED)
{
	CHECK_INIT

	sort_sprite_list();

	for (int i = 0; i < sprite_list_nextfree; i++)
	{
		struct sdl_sprite_hnode_data *hnd = sprite_list[i];

		if (hnd->image && hnd->orev != hnd->image->revision_counter) {
			hnd->orev = hnd->image->revision_counter;
			hnd->updated = 1;
		}

		if (!hnd->updated)
			continue;

		if (hnd->oactive && (hnd->x != hnd->ox || hnd->y != hnd->oy ||
		                     !hnd->image || !hnd->image->image ||
		                     hnd->image->image->w != hnd->ow ||
		                     hnd->image->image->h != hnd->oh)) {
			sprite_update_backend(hnd->ox, hnd->oy, hnd->ow, hnd->oh, 1);
		}

		if (hnd->schedule_destroy) {
			destroy_sprite_data(hnd->idx);
			continue;
		}

		if (!hnd->image || !hnd->image->image) {
			hnd->updated = 0;
			hnd->oactive = 0;
			continue;
		}

		sprite_update_backend(hnd->x, hnd->y,
				hnd->image->image->w, hnd->image->image->h, 1);

		hnd->ox = hnd->x;
		hnd->oy = hnd->y;
		hnd->ow = hnd->image->image->w;
		hnd->oh = hnd->image->image->h;

		hnd->updated = 0;
		hnd->oactive = 1;
	}

	return 0;
}


/*** Initializations ***/

/**
 * An instance of this object is thrown on SDL errors.
 */
//object SdlEx

/**
 * A description text describing the error.
 */
// var description;

void SPL_ABI(spl_mod_sdl_init)(struct spl_vm *vm, struct spl_module *mod, int restore)
{
	if (!restore)
		spl_eval(vm, 0, strdup(mod->name), "object SdlEx { }");

	spl_hnode_reg(vm, "sdl", handler_sdl_node, 0);
	spl_hnode_reg(vm, "sdl_sprite", handler_sdl_sprite_node, 0);

	spl_clib_reg(vm, "sdl_init", handler_sdl_init, 0);
	spl_clib_reg(vm, "sdl_quit", handler_sdl_quit, 0);

	spl_clib_reg(vm, "sdl_title", handler_sdl_title, 0);
	spl_clib_reg(vm, "sdl_delay", handler_sdl_delay, 0);
	spl_clib_reg(vm, "sdl_flip", handler_sdl_flip, 0);
	spl_clib_reg(vm, "sdl_update", handler_sdl_update, 0);

	spl_clib_reg(vm, "sdl_image_load", handler_sdl_image_load, 0);
	spl_clib_reg(vm, "sdl_image_create", handler_sdl_image_create, 0);

	spl_clib_reg(vm, "sdl_blit", handler_sdl_blit, 0);
	spl_clib_reg(vm, "sdl_blitrect", handler_sdl_blitrect, 0);
	spl_clib_reg(vm, "sdl_copy", handler_sdl_copy, 0);

	spl_clib_reg(vm, "sdl_fill", handler_sdl_fill, 0);
	spl_clib_reg(vm, "sdl_fill_pattern", handler_sdl_fill_pattern, 0);

	spl_clib_reg(vm, "sdl_keystate", handler_sdl_keystate, 0);

	spl_clib_reg(vm, "sdl_sprite_create", handler_sdl_sprite_create, 0);
	spl_clib_reg(vm, "sdl_sprite_redraw", handler_sdl_sprite_redraw, 0);
	spl_clib_reg(vm, "sdl_sprite_update", handler_sdl_sprite_update, 0);
}

void SPL_ABI(spl_mod_sdl_done)(struct spl_vm *vm, struct spl_module *mod UNUSED)
{
	if (vm->sdl_initialized) {
		spl_report(SPL_REPORT_HOST, vm, "Missing call to sdl_quit()!\n");
		handler_sdl_quit(0, 0);
		vm->sdl_initialized = 0;
	}

	for (int i = 0; i < sprite_list_nextfree; i++) {
		if (sprite_list[i]) {
			if (sprite_list[i]->schedule_destroy) {
				destroy_sprite_data(i);
			} else {
				spl_report(SPL_REPORT_HOST, vm, "Found active non-null entry in SDL sprite list on module unload!\n");
				goto skip_free_sprite_list;
			}
		}
	}

	free(sprite_list);
	sprite_list_resort = 0;
	sprite_list_nextfree = 0;
	sprite_list_roof = 0;

skip_free_sprite_list:
	return;
}