/*
 * Various small SDL tools.
 * 
 * Copyright (c) 2002 by the person(s) listed below.  All rights reserved.
 *	Glenn Maynard
 * 
 * Portions from SDL source and documentation.
 */

#include "global.h"

#include "SDL.h"
#include "SDL_utils.h"
#include "SDL_endian.h"

#if defined(WIN32)

/* Pull in all of our SDL libraries here. */
#ifdef DEBUG
#pragma comment(lib, "SDL-1.2.5/lib/SDLd.lib")
#pragma comment(lib, "SDL_image-1.2/SDL_imaged.lib")
#else
#pragma comment(lib, "SDL-1.2.5/lib/SDL.lib")
#pragma comment(lib, "SDL_image-1.2/SDL_image.lib")
#endif


#endif

Uint32 mySDL_Swap24(Uint32 x)
{
	return SDL_Swap32(x) >> 8; // xx223344 -> 443322xx -> 00443322
}

#if SDL_BYTEORDER == SDL_BIG_ENDIAN
#define mySDL_SwapLE24(x) mySDL_Swap24(x)
#else
#define mySDL_SwapLE24(x) (x)
#endif

/* These conditionals in the inner loop are slow.  Templates? */
inline Uint32 decodepixel(const Uint8 *p, int bpp)
{
    switch(bpp) {
    case 1: return *p;
    case 2: return *(Uint16 *)p;
	case 3:
        if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
            return p[0] << 16 | p[1] << 8 | p[2];
        else
            return p[0] | p[1] << 8 | p[2] << 16;

    case 4: return *(Uint32 *)p;
    default: return 0;       /* shouldn't happen, but avoids warnings */
    }
}

void encodepixel(Uint8 *p, int bpp, Uint32 pixel)
{
    switch(bpp) {
    case 1: *p = Uint8(pixel); break;
    case 2: *(Uint16 *)p = Uint16(pixel); break;
    case 3:
        if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {
            p[0] = Uint8((pixel >> 16) & 0xff);
            p[1] = Uint8((pixel >> 8) & 0xff);
            p[2] = Uint8(pixel & 0xff);
        } else {
            p[0] = Uint8(pixel & 0xff);
            p[1] = Uint8((pixel >> 8) & 0xff);
            p[2] = Uint8((pixel >> 16) & 0xff);
        }
        break;
    case 4: *(Uint32 *)p = pixel; break;
    }
}

/* Get and set colors without scaling them to 0..255.  Get them into
 * an array, which is much easier to work with.  We need the surface
 * to get at flags, or we won't know if colorkey is valid.  (Why isn't
 * format self-contained?) Use mySDL_GetBitsPerChannel() to get the
 * number of bits per channel. */
void mySDL_GetRawRGBAV(Uint32 pixel, const SDL_Surface *src, Uint8 *v)
{
	const SDL_PixelFormat *fmt = src->format;
	if(src->format->BytesPerPixel == 1) {
		v[0] = fmt->palette->colors[pixel].r;
		v[1] = fmt->palette->colors[pixel].g;
		v[2] = fmt->palette->colors[pixel].b;
		v[3] = 0xFF;
	} else {
		v[0] = Uint8((pixel & fmt->Rmask) >> fmt->Rshift);
		v[1] = Uint8((pixel & fmt->Gmask) >> fmt->Gshift);
		v[2] = Uint8((pixel & fmt->Bmask) >> fmt->Bshift);
		v[3] = Uint8((pixel & fmt->Amask) >> fmt->Ashift);
	}

	if(src->flags & SDL_SRCCOLORKEY) {
		if((fmt->colorkey & ~fmt->Amask) == (pixel & ~fmt->Amask))
			v[3] = 0;
	}
}

void mySDL_GetRawRGBAV(const Uint8 *p, const SDL_Surface *src, Uint8 *v)
{
	Uint32 pixel = decodepixel(p, src->format->BytesPerPixel);
	mySDL_GetRawRGBAV(pixel, src, v);	
}

void mySDL_GetRGBAV(Uint32 pixel, const SDL_Surface *src, Uint8 *v)
{
	mySDL_GetRawRGBAV(pixel, src, v);
	const SDL_PixelFormat *fmt = src->format;
	v[0] = v[0] << fmt->Rloss;
	v[1] = v[1] << fmt->Gloss;
	v[2] = v[2] << fmt->Bloss;
	// Correct for surfaces that don't have an alpha channel.
	if( fmt->Aloss == 8)
		v[3] = 255;
	else
		v[3] = v[3] << fmt->Aloss;
}

void mySDL_GetRGBAV(const Uint8 *p, const SDL_Surface *src, Uint8 *v)
{
	Uint32 pixel = decodepixel(p, src->format->BytesPerPixel);
	mySDL_GetRGBAV(pixel, src, v);	
}


/* Inverse of mySDL_GetRawRGBAV. */
Uint32 mySDL_SetRawRGBAV(const SDL_PixelFormat *fmt, const Uint8 *v)
{
	return 	v[0] << fmt->Rshift |
			v[1] << fmt->Gshift |
			v[2] << fmt->Bshift |
			v[3] << fmt->Ashift;
}

void mySDL_SetRawRGBAV(Uint8 *p, const SDL_Surface *src, const Uint8 *v)
{
	Uint32 pixel = mySDL_SetRawRGBAV(src->format, v);
	encodepixel(p, src->format->BytesPerPixel, pixel);
}

/* Inverse of mySDL_GetRGBAV. */
Uint32 mySDL_SetRGBAV(const SDL_PixelFormat *fmt, const Uint8 *v)
{
	return 	(v[0] >> fmt->Rloss) << fmt->Rshift |
			(v[1] >> fmt->Gloss) << fmt->Gshift |
			(v[2] >> fmt->Bloss) << fmt->Bshift |
			(v[3] >> fmt->Aloss) << fmt->Ashift;
}

void mySDL_SetRGBAV(Uint8 *p, const SDL_Surface *src, const Uint8 *v)
{
	Uint32 pixel = mySDL_SetRGBAV(src->format, v);
	encodepixel(p, src->format->BytesPerPixel, pixel);
}


/* Get the number of bits representing each color channel in fmt. */
void mySDL_GetBitsPerChannel(const SDL_PixelFormat *fmt, Uint32 bits[4])
{
	if(fmt->BytesPerPixel == 1) {
		/* If we're paletted, the palette is 8888. For some reason, the 
		 * *loss values are all 8 on paletted surfaces; they should be
		 * 0, to represent the palette.  Since they're not, we have to
		 * special case this. */
		bits[0] = bits[1] = bits[2] = bits[3] = 8;
		return;
	}

	/* The actual bits stored in each color is 8-loss.  */
	bits[0] = 8 - fmt->Rloss;
	bits[1] = 8 - fmt->Gloss;
	bits[2] = 8 - fmt->Bloss;
	bits[3] = 8 - fmt->Aloss;
}

void ConvertSDLSurface(SDL_Surface *&image,
		int width, int height, int bpp,
		Uint32 R, Uint32 G, Uint32 B, Uint32 A)
{
    SDL_Surface *ret_image = SDL_CreateRGBSurfaceSane(
            SDL_SWSURFACE, width, height, bpp, R, G, B, A);
	ASSERT(ret_image != NULL);

	/* If the formats are the same, no conversion is needed. */
	if(width == image->w && height == image->h && bpp == image->format->BitsPerPixel &&
	   image->format->Rmask == ret_image->format->Rmask &&
	   image->format->Gmask == ret_image->format->Gmask &&
	   image->format->Bmask == ret_image->format->Bmask &&
	   image->format->Amask == ret_image->format->Amask)
	{
		/* One exception: if we have a color key and we're not paletted (8-bit). 
		 * In this case, we need to do the blit to get rid of the color key. */
		if(!( image->flags & SDL_SRCCOLORKEY && image->format->BitsPerPixel != 8) )
		{
			SDL_FreeSurface(ret_image);
			return;
		}
	}

	/* We don't want to actually blend the alpha channel over the destination converted
	 * surface; we want to simply blit it, so make sure SDL_SRCALPHA is not on. */
	SDL_SetAlpha( image, 0, SDL_ALPHA_OPAQUE );

	/* Copy the palette, if we have one. */
	if(image->format->palette)
		SDL_SetPalette(ret_image, SDL_LOGPAL, image->format->palette->colors,
			0, image->format->palette->ncolors);

	if(image->format->BitsPerPixel == 8 && ret_image->format->BitsPerPixel == 8 &&
	   image->flags & SDL_SRCCOLORKEY)
	{
		/* The source and dest are both paletted, and we have a color key. 
		 * First, make sure that the image we're blitting to has a default
		 * color of the color key, so any places we don't blit to will
		 * be transparent.  (The default color in the image is 0, so we're
		 * all set if the color key is 0.) */
		if(image->format->colorkey != 0)
			SDL_FillRect(ret_image, NULL, image->format->colorkey);

		/* Copy over the color key mode, and then turn off color keying in the
		 * source so the color key index gets copied like any other color. */
		SDL_SetColorKey( ret_image, SDL_SRCCOLORKEY, image->format->colorkey);
		SDL_SetColorKey( image, 0, 0 );
	}

	SDL_Rect area;
	area.x = area.y = 0;
	area.w = short(image->w);
	area.h = short(image->h);

	SDL_BlitSurface(image, &area, ret_image, &area);
	SDL_FreeSurface(image);
	image = ret_image;
}

/* With d3d, textures are stored little endian (local endian for x86).
 *
 * I'm not sure if we should store textures in big endian, little endian
 * or local endian with OpenGL.  It doesn't really impact anything except
 * the actual code that loads the texture itself, and OpenGL does have
 * byte order toggles, so maybe we can get rid of this. */
SDL_Surface *SDL_CreateRGBSurfaceSane
			(Uint32 flags, int width, int height, int depth, 
			Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
{
	/* This is untested on big-endian machines. */
	if(depth == 16) {
		Rmask = SDL_SwapLE16((Uint16)Rmask);
		Gmask = SDL_SwapLE16((Uint16)Gmask);
		Bmask = SDL_SwapLE16((Uint16)Bmask);
		Amask = SDL_SwapLE16((Uint16)Amask);
	} else if(depth == 24) {  // completely untested
		Rmask = mySDL_SwapLE24(Rmask);
		Gmask = mySDL_SwapLE24(Gmask);
		Bmask = mySDL_SwapLE24(Bmask);
		Amask = mySDL_SwapLE24(Amask);
	} else if(depth == 32) {
		Rmask = SDL_SwapLE32(Rmask);
		Gmask = SDL_SwapLE32(Gmask);
		Bmask = SDL_SwapLE32(Bmask);
		Amask = SDL_SwapLE32(Amask);
	}

	return SDL_CreateRGBSurface(flags, width, height, depth,
		Rmask, Gmask, Bmask, Amask);
}

static void FindAlphaRGB(const SDL_Surface *img, Uint8 &r, Uint8 &g, Uint8 &b, bool reverse)
{
	/* If we have no alpha or no color key, there's no alpha color. */
	if(img->format->BitsPerPixel == 8 && !(img->flags & SDL_SRCCOLORKEY))
		return;
	if(img->format->BitsPerPixel > 8 && !img->format->Amask)
		return;

	/* Eww.  Sorry.  Iterate front-to-back or in reverse. */
	for(int y = reverse? img->h-1:0;
		reverse? (y >=0):(y < img->h); reverse? (--y):(++y))
	{
		Uint8 *row = (Uint8 *)img->pixels + img->pitch*y;
		if(reverse)
			row += img->format->BytesPerPixel * (img->w-1);

		for(int x = 0; x < img->w; ++x)
		{
			Uint32 val = decodepixel(row, img->format->BytesPerPixel);
			if((img->format->BitsPerPixel == 8 && val != img->format->colorkey) ||
			   (img->format->BitsPerPixel != 8 && val & img->format->Amask))
			{
				/* This color isn't fully transparent, so grab it. */
				SDL_GetRGB(val, img->format, &r, &g, &b);
				return;
			}

			if(reverse)
				row -= img->format->BytesPerPixel;
			else
				row += img->format->BytesPerPixel;
		}
	}

	/* Huh?  The image is completely transparent. */
	r = g = b = 0;
}

/* Set the underlying RGB values of all pixels in 'img' that are
 * completely transparent. */
static void SetAlphaRGB(const SDL_Surface *img, Uint8 r, Uint8 g, Uint8 b)
{
	/* If it's a paletted surface, all we have to do is change the
	 * colorkey, if any. */
	if(img->format->BitsPerPixel == 8)
	{
		if(img->flags & SDL_SRCCOLORKEY)
		{
			img->format->palette->colors[img->format->colorkey].r = r;
			img->format->palette->colors[img->format->colorkey].g = g;
			img->format->palette->colors[img->format->colorkey].b = b;
		}

		return;
	}

	/* It's RGBA.  If there's no alpha channel, we have nothing to do. */
	if(!img->format->Amask)
		return;

	Uint32 trans = SDL_MapRGBA(img->format, r, g, b, 0);
	for(int y = 0; y < img->h; ++y)
	{
		Uint8 *row = (Uint8 *)img->pixels + img->pitch*y;

		for(int x = 0; x < img->w; ++x)
		{
			Uint32 val = decodepixel(row, img->format->BytesPerPixel);
			if(val != trans && !(val&img->format->Amask))
			{
				encodepixel(row, img->format->BytesPerPixel, trans);
			}

			row += img->format->BytesPerPixel;
		}
	}
}

/* When we scale up images (which we always do in high res), pixels
 * that are completely transparent can be blended with opaque pixels,
 * causing their RGB elements to show.  This is visible in many textures
 * as a pixel-wide border in the wrong color.  This is tricky to fix.
 * We need to set the RGB components of completely transparent pixels
 * to a reasonable color.
 *
 * Most images have a single border color.  For these, the transparent
 * color is easy: search through the image top-bottom-left-right,
 * find the first non-transparent pixel, and pull out its RGB.
 *
 * A few images don't.  We can only make a guess here.  What we'll do
 * is, after the above search, do the same in reverse (bottom-top-right-
 * left).  If the color we find is different, we'll just set the border
 * color to black.  
 */
void FixHiddenAlpha(SDL_Surface *img)
{
	Uint8 r, g, b;
	FindAlphaRGB(img, r, g, b, false);

	Uint8 cr, cg, cb; /* compare */
	FindAlphaRGB(img, cr, cg, cb, true);

	if(cr != r || cg != g || cb != b)
		r = g = b = 0;

	SetAlphaRGB(img, r, g, b);
}

/* XXX: currently only TRAIT_NO_TRANSPARENCY and TRAIT_BOOL_TRANSPARENCY work. */
/* Find various traits of a surface.  Do these all at once, so we only have to
 * iterate the surface once. */

/* We could theoretically do a test to see if an image fits in GL_ALPHA4,
 * by looking at the least significant bits of each alpha value.  This is
 * not likely to ever find a match, though, so don't bother; only use 8alphaonly
 * if it's explicitly enabled. 
 *
 * XXX: We could do the FindAlphaRGB search here, too, but we need that information
 * in a different place. */
// #define TRAIT_CONSISTENT_TRANSPARENT_COLOR	0x0008

int FindSurfaceTraits(const SDL_Surface *img)
//							  Uint8 AlphaColor[3])
{
//	bool HaveAlphaValue = false; /* whether ar, ag, ab is valid */
//	bool HaveConsistentAlphaValue = true;
	const int NEEDS_NO_ALPHA=0, NEEDS_BOOL_ALPHA=1, NEEDS_FULL_ALPHA=2;
	int alpha_type = NEEDS_NO_ALPHA;
//	bool HaveTransparency = false;
//	bool HaveTranslucensy = false;
//	bool WhiteOnly = true;

	for(int y = 0; y < img->h; ++y)
	{
		Uint8 *row = (Uint8 *)img->pixels + img->pitch*y;
//		bool FirstVisible = true;

		for(int x = 0; x < img->w; ++x)
		{
			Uint32 val = decodepixel(row, img->format->BytesPerPixel);

			if( img->format->BitsPerPixel == 8 ) {
				if(img->flags & SDL_SRCCOLORKEY && val == img->format->colorkey )
					alpha_type = max( alpha_type, NEEDS_BOOL_ALPHA );
			} else if(img->format->Amask) {
				Uint32 masked_alpha = val & img->format->Amask;
				if(masked_alpha == 0) 
					alpha_type = max( alpha_type, NEEDS_BOOL_ALPHA );
				else if(masked_alpha != img->format->Amask)
					alpha_type = max( alpha_type, NEEDS_FULL_ALPHA );
			}

#if 0
			/* Hmm.  This doesn't quite work.  For example, the ScreenCompany
			 * shadow is actually black; we load it as 8alphaonly, which discards
			 * the black completely (making it a white shadow), and then we make
			 * it black again by setting the diffuse color to black.  This is hard
			 * to generalize.  I guess we could just make the shadow white, but
			 * that's a little ugly to edit.
			 *
			 * Also, for some reason, the font borders are actually a combination
			 * of a shade of gray and some alpha value.  Those need to be simplified
			 * to white and some alpha value (multiply the luma by alpha), but
			 * that's another special case.
			 *
			 * So, this doesn't actually help anything right now, and we still
			 * need 8alphaonly. */
			if( img->format->BitsPerPixel != 8 ) {
				/* If the pixel isn't transparent, and isn't completely white: */
				if(!Transparent &&
					(val & img->format->Rmask) != img->format->Rmask &&
					(val & img->format->Gmask) != img->format->Gmask &&
					(val & img->format->Bmask) != img->format->Bmask)
					WhiteOnly=false;

			}
#endif

#if 0
			/* Is this the first non-invisible pixel on this row? */
			if(!Invisible && FirstVisible)
			{
				FirstVisible = false;

				Uint8 r, g, b;
				SDL_GetRGB(val, img->format, &r, &g, &b);

				if(!HaveAlphaValue) {
					/* We don't have the border color yet; set it. */
					HaveAlphaValue = true;
					AlphaColor[0] = r;
					AlphaColor[1] = g;
					AlphaColor[2] = b;
				} else if(HaveConsistentAlphaValue) {
					/* We already have an alpha color from the previous row;
					 * if it's not the same, it's inconsistent. */
					if(r != AlphaColor[0] || g != AlphaColor[1] || b != AlphaColor[2])
						HaveConsistentAlphaValue = false;
				}
			}
#endif

			row += img->format->BytesPerPixel;
		}
	}

	int ret = 0;
//	if(HaveConsistentAlphaValue) ret |= TRAIT_CONSISTENT_TRANSPARENT_COLOR;
	switch( alpha_type ) 
	{
	case NEEDS_NO_ALPHA:	ret |= TRAIT_NO_TRANSPARENCY;	break;
	case NEEDS_BOOL_ALPHA:	ret |= TRAIT_BOOL_TRANSPARENCY;	break;
	case NEEDS_FULL_ALPHA:									break;
	default:	ASSERT(0);
	}
//	if(WhiteOnly) ret |= TRAIT_WHITE_ONLY;
	return ret;
}