/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

/* Graphics support functions for drivers and replacements for driver functions
** for use with the graphical state manager
*/

#include "sci/gfx/gfx_system.h"
#include "sci/gfx/gfx_tools.h"
#include "sci/gfx/line.h"
#include "sci/gfx/crossblit.h"

namespace Sci {

int gfx_crossblit_alpha_threshold = 128;

inline void gfx_draw_line_buffer(byte *buffer, int linewidth, int pixelwidth, Common::Point start, Common::Point end, unsigned int color) {
	switch (pixelwidth) {

	case 1:
		_gfx_draw_line_buffer<1>(buffer, linewidth, start, end, color);
		return;

	case 2:
		_gfx_draw_line_buffer<2>(buffer, linewidth, start, end, color);
		return;

	case 3:
		_gfx_draw_line_buffer<3>(buffer, linewidth, start, end, color);
		return;

	case 4:
		_gfx_draw_line_buffer<4>(buffer, linewidth, start, end, color);
		return;

	default:
		GFXERROR("pixelwidth=%d not supported!\n", pixelwidth);
		return;

	}
}

void gfx_draw_line_pixmap_i(gfx_pixmap_t *pxm, Common::Point start, Common::Point end, int color) {
	gfx_draw_line_buffer(pxm->index_data, pxm->index_xl, 1, start, end, color);
}

void gfx_draw_box_buffer(byte *buffer, int linewidth, rect_t zone, int color) {
	byte *dest = buffer + zone.x + (linewidth * zone.y);
	int i;

	if (zone.xl <= 0 || zone.yl <= 0)
		return;

	for (i = 0; i < zone.yl; i++) {
		memset(dest, color, zone.xl);
		dest += linewidth;
	}
}

void gfx_draw_box_pixmap_i(gfx_pixmap_t *pxm, rect_t box, int color) {
	gfx_clip_box_basic(&box, pxm->index_xl - 1, pxm->index_yl - 1);

	gfx_draw_box_buffer(pxm->index_data, pxm->index_xl, box, color);
}

static void (*crossblit_fns[5])(byte *, byte *, int, int, int, int, byte *, int, int, unsigned int, unsigned int, byte *, int, int, int) = { NULL,
	_gfx_crossblit<1, false, false>,
	_gfx_crossblit<2, false, false>,
	_gfx_crossblit<3, false, false>,
	_gfx_crossblit<4, false, false>
};

static void (*crossblit_fns_P[5])(byte *, byte *, int, int, int, int, byte *, int, int, unsigned int, unsigned int, byte *, int, int, int) = { NULL,
	_gfx_crossblit<1, true, false>,
	_gfx_crossblit<2, true, false>,
	_gfx_crossblit<3, true, false>,
	_gfx_crossblit<4, true, false>
};

static void (*crossblit_fns_RA[5])(byte *, byte *, int, int, int, int, byte *, int, int, unsigned int, unsigned int, byte *, int, int, int) = { NULL,
	_gfx_crossblit<1, false, true>,
	_gfx_crossblit<2, false, true>,
	_gfx_crossblit<3, false, true>,
	_gfx_crossblit<4, false, true>
};

static void (*crossblit_fns_P_RA[5])(byte *, byte *, int, int, int, int, byte *, int, int, unsigned int, unsigned int, byte *, int, int, int) = { NULL,
	_gfx_crossblit<1, true, true>,
	_gfx_crossblit<2, true, true>,
	_gfx_crossblit<3, true, true>,
	_gfx_crossblit<4, true, true>
};

void _gfx_crossblit_simple(byte *dest, byte *src, int dest_line_width, int src_line_width, int xl, int yl, int bpp) {
	int line_width = xl * bpp;
	int i;

	for (i = 0; i < yl; i++) {
		memcpy(dest, src, line_width);
		dest += dest_line_width;
		src += src_line_width;
	}
}

int gfx_crossblit_pixmap(gfx_mode_t *mode, gfx_pixmap_t *pxm, int priority, rect_t src_coords, rect_t dest_coords,
						 byte *dest, int dest_line_width, byte *priority_dest, int priority_line_width, int priority_skip, int flags) {
	int maxx = 320 * mode->xfact;
	int maxy = 200 * mode->yfact;
	byte *src = pxm->data;
	byte *alpha = pxm->alpha_map ? pxm->alpha_map : pxm->data;
	byte *priority_pos = priority_dest;
	unsigned int alpha_mask, alpha_min;
	int bpp = mode->bytespp;
	int bytes_per_alpha_pixel = pxm->alpha_map ? 1 : bpp;
	int bytes_per_alpha_line =  bytes_per_alpha_pixel * pxm->xl;
	int xl = pxm->xl, yl = pxm->yl;
	int xoffset = (dest_coords.x < 0) ? - dest_coords.x : 0;
	int yoffset = (dest_coords.y < 0) ? - dest_coords.y : 0;
	int revalpha = mode->flags & GFX_MODE_FLAG_REVERSE_ALPHA;

	if (src_coords.x + src_coords.xl > xl)
		src_coords.xl = xl - src_coords.x;

	if (src_coords.y + src_coords.yl > yl)
		src_coords.yl = yl - src_coords.y;

	// --???--
	if (src_coords.y > yl)
		return GFX_OK;
	if (src_coords.x > xl)
		return GFX_OK;
	// --???--

	if (dest_coords.x + xl >= maxx)
		xl = maxx - dest_coords.x;
	if (dest_coords.y + yl >= maxy)
		yl = maxy - dest_coords.y;

	xl -= xoffset;
	yl -= yoffset;

	if (!pxm->data)
		return GFX_ERROR;

	if (xl <= 0 || yl <= 0)
		return GFX_OK;

	// Set destination offsets

	// Set x offsets
	if (!(flags & GFX_CROSSBLIT_FLAG_DATA_IS_HOMED))
		dest += dest_coords.x * bpp;
	priority_pos += dest_coords.x * priority_skip;

	// Set y offsets
	if (!(flags & GFX_CROSSBLIT_FLAG_DATA_IS_HOMED))
		dest += dest_coords.y * dest_line_width;
	priority_pos += dest_coords.y * priority_line_width;

	// Set source offsets
	if (xoffset += src_coords.x) {
		dest_coords.x = 0;
		src += xoffset * bpp;
		alpha += xoffset * bytes_per_alpha_pixel;
	}


	if (yoffset += src_coords.y) {
		dest_coords.y = 0;
		src += yoffset * bpp * pxm->xl;
		alpha += yoffset * bytes_per_alpha_line;
	}

	// Adjust length for clip box
	if (xl > src_coords.xl)
		xl = src_coords.xl;
	if (yl > src_coords.yl)
		yl = src_coords.yl;

	// now calculate alpha
	if (pxm->alpha_map)
		alpha_mask = 0xff;
	else {
		int shift_nr = 0;

		alpha_mask = mode->alpha_mask;
		if (!alpha_mask && pxm->alpha_map) {
			GFXERROR("Invalid alpha mode: both pxm->alpha_map and alpha_mask are white!\n");
			return GFX_ERROR;
		}

		if (alpha_mask) {
			while (!(alpha_mask & 0xff)) {
				alpha_mask >>= 8;
				shift_nr++;
			}
			alpha_mask &= 0xff;
		}

#ifdef SCUMM_BIG_ENDIAN
		alpha += (mode->bytespp) - (shift_nr + 1);
#else
		alpha += shift_nr;
#endif
	}

		if (alpha_mask & 0xff)
			alpha_min = ((alpha_mask * gfx_crossblit_alpha_threshold) >> 8) & alpha_mask;
		else
			alpha_min = ((alpha_mask >> 8) * gfx_crossblit_alpha_threshold) & alpha_mask;

		if (revalpha)
			alpha_min = 255 - alpha_min; // Since we use it for the reverse effect

		if (!alpha_mask)
			_gfx_crossblit_simple(dest, src, dest_line_width, pxm->xl * bpp, xl, yl, bpp);
		else

			if (priority == GFX_NO_PRIORITY) {
				if (bpp > 0 && bpp < 5)
					((revalpha) ? crossblit_fns_RA : crossblit_fns)[bpp](dest, src, dest_line_width, pxm->xl * bpp,
					        xl, yl, alpha, bytes_per_alpha_line, bytes_per_alpha_pixel, alpha_mask, alpha_min,
					        0, 0, 0, 0);
				else {
					GFXERROR("Invalid mode->bytespp: %d\n", mode->bytespp);
					return GFX_ERROR;
				}
			} else { // priority
				if (bpp > 0 && bpp < 5)
					((revalpha) ? crossblit_fns_P_RA : crossblit_fns_P)[bpp](dest, src, dest_line_width, pxm->xl * bpp,
					        xl, yl, alpha, bytes_per_alpha_line, bytes_per_alpha_pixel, alpha_mask, alpha_min,
					        priority_pos, priority_line_width, priority_skip, priority);
				else {
					GFXERROR("Invalid mode->bytespp: %d\n", mode->bytespp);
					return GFX_ERROR;
				}
			}

	return GFX_OK;
}

} // End of namespace Sci