/* $Id: gfx2d.c,v 5.5 2001/06/03 17:21:19 bertg Exp $
 *
 * XPilot, a multiplayer gravity war game.  Copyright (C) 1991-2001 by
 *
 *      Bjørn Stabell        <bjoern@xpilot.org>
 *      Ken Ronny Schouten   <ken@xpilot.org>
 *      Bert Gijsbers        <bert@xpilot.org>
 *      Dick Balaska         <dick@xpilot.org>
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <math.h>
#include <limits.h>
#include <ctype.h>

#ifndef _WINDOWS
# include <unistd.h>
#endif

#ifdef _WINDOWS
# include <io.h>
#endif

#include "version.h"
#include "config.h"
#include "gfx2d.h"
#include "error.h"
#include "const.h"
#include "portability.h"
#include "commonproto.h"


char gfx2d_version[] = VERSION;


#ifndef PATH_MAX
#define PATH_MAX	1023
#endif


extern char	*texturePath;		/* Path list of texture directories */


/*
    Purpose: initialize dimensions of a xp_picture structure and 
    allocate memory for it.
    Error handling is incomplete.

    return 0 on success.
    return -1 on error.
*/

int Picture_init(xp_picture_t *picture, int height, int width, int images)
{
    int			i;

    picture->height = height;
    picture->width = width;
    picture->images = images;
    picture->data  = (RGB_COLOR **) malloc(images * sizeof(RGB_COLOR*));

    if (!picture->data) {
	error("Not enough memory.");
	return -1;
    }
    for (i = 0; i < images; i++) {
	picture->data[i] = (RGB_COLOR *) malloc(picture->width * picture->height * 
						sizeof(RGB_COLOR));
	if (!picture->data[i]) {
	    error("Not enough memory.");
	    return -1;
	}
    }

    picture->bbox = (bbox_t *) malloc(images * sizeof(bbox_t));
    if (!picture->bbox) {
	error("Not enough memory.");
	return -1;
    }
    for (i = 0; i < images; i++) {
	/* set bounding box to safe values. */
	picture->bbox[i].xmin = 0;
	picture->bbox[i].xmax = width - 1;
	picture->bbox[i].ymin = 0;
	picture->bbox[i].ymax = height - 1;
    }

    return 0;
}

/*
 * Find full path for a picture filename.
 */
static int Picture_find_path(const char *filename, char *path, size_t path_size)
{
    char		*dir, *colon;
    int			len;

    if (!filename || !*filename) {
	return FALSE;
    }

    /*
     * Always try the plain filename first,
     * without using the texturePath.
     */
    if (access(filename, 4) == 0) {
	strlcpy(path, filename, path_size);
	return TRUE;
    }

    /*
     * If filename doesn't contain a slash
     * then we also try the texturePath, if it exists.
     */
    if (!strchr(filename, PATHNAME_SEP) && texturePath != NULL) {
	for (dir = texturePath; *dir; dir = colon) {
	    if (is_this_windows() ||
		!(colon = strchr(dir, ':'))) {
		len = strlen(dir);
		colon = &dir[len];
	    } else {
		len = colon - dir;
		colon++;
	    }
	    if (len > 0 && len + strlen(filename) + 1 < path_size) {
		memcpy(path, dir, len);
		if (path[len - 1] != PATHNAME_SEP) {
		    path[len++] = PATHNAME_SEP;
		}
		strlcpy(&path[len], filename, path_size - len);
		if (access(path, 4) == 0) {
		    return TRUE;
		}
	    }
	}
    }

    error("Can't find PPM file \"%s\"", filename);
	return(FALSE);
}

/*
 * Fetch next ASCII character from PPM file.
 * Strip comments starting with "#" from the input.
 * On error return EOF.
 */
static int Picture_getc(FILE *f)
{
    int			c;

    c = getc(f);
    if (c == '#') {
	do {
	    c = getc(f);
	} while (c != '\n' && c != EOF);
    }

    return c;
}

/*
 * Verify last input character is a whitespace character
 * and skip all following whitespace.
 * On error return EOF.
 */
static int Picture_skip_whitespace(FILE *f, int c)
{
    if (!isspace(c)) {
	return EOF;
    }
    do {
	c = Picture_getc(f);
    } while (isspace(c));

    return c;
}

/*
 * Verify last input character is a digit
 * and extract a decimal value from the input stream.
 * On error return EOF.
 */
static int Picture_get_decimal(FILE *f, int c, int *dec)
{
    *dec = 0;
    for (; isdigit(c); c = Picture_getc(f)) {
	*dec = (10 * *dec) + (c - '0');
    }
    return c;
}

/* 
    Purpose: load images in to the xp_picture structure.
    format is only binary PPM's at the moment. 
    More error handling and a better understanding of the PPM standard 
    would be good. But suffices for a proof of concept.

    return 0 on success.
    return -1 on error.
*/
int Picture_load(xp_picture_t *picture, const char *filename)
{
    FILE		*f;
    int			c, c1, c2;
    int			x, y;
    int			r, g, b;
    int			p;
    int			width, height, maxval;
    int			images;
    char		path[PATH_MAX + 1];


    if (!Picture_find_path(filename, path, sizeof(path))) {
	error("Cannot find picture file \"%s\"", filename);
	return -1;
    }
    if ((f = fopen(path, "rb")) == NULL) {
	error("Cannot open \"%s\"", path);
	return -1;
    }

    errno = 0;
    if ((c1 = Picture_getc(f)) != 'P' ||
	(c2 = Picture_getc(f)) != '6') {
	error("\"%s\" does not contain a valid binary PPM file.\n",
	       path);
	fclose(f);
	return -1;
    }
    c = Picture_getc(f);
    c = Picture_skip_whitespace(f, c);
    c = Picture_get_decimal(f, c, &width);
    c = Picture_skip_whitespace(f, c);
    c = Picture_get_decimal(f, c, &height);
    c = Picture_skip_whitespace(f, c);
    c = Picture_get_decimal(f, c, &maxval);

    if (!isspace(c) || maxval != 255) {
	error("\"%s\" does not contain a valid binary PPM file.\n",
	       path);
	fclose(f);
	return -1;
    }

    /* images in file might be 1, and will be rotated later on */

    if (picture->width * picture->images == width || picture->width == width ) {
	images = width / picture->width;
    } else  {
	error("image size is wrong (%d %d) (%d %d)", 
	      picture->width, picture->height, width, height); 
	fclose(f);
	return -1;
    }

    for (y = 0 ; y < picture->height ; y++) {
	for (p = 0; p < images ; p++) {
	    for (x = 0; x < picture->width ; x++) {
		r = getc(f);
		g = getc(f);
		b = getc(f);
		Picture_set_pixel(picture, p, x, y, RGB24(r, g, b));
	    }
	}
    }

    fclose(f);

    return 0;
}

/*
    Purpose: We want to provide rotation, a picture which is rotated has 
    just 1 image with index=0 as source, which is rotated 360 degrees,
    more pictures = higher resolution.

    Note that this is done by traversing the target image, and selecting 
    the corresponding source colorvalue, this assures there will be no
    gaps in the image.
*/
void Picture_rotate(xp_picture_t *picture)
{
    int size, x, y, image;
    int color;    
    size = picture->height;
    for (image = 1; image < picture->images; image++) {
	for (y = 0; y < size; y++) {
	    for (x = 0; x < size; x++) {
		color = Picture_get_rotated_pixel(picture, x, y, image);
		Picture_set_pixel(picture, image, x, y, color);
	    }
	}
    }
}

/*
    Purpose: set the color value of a 1x1 pixel, 
    This is a convenient wrapper for the data array.
*/
void Picture_set_pixel(xp_picture_t *picture, int image, int x, int y, 
		       RGB_COLOR color)
{
    if (x < 0 || y < 0 || x>= picture->width || y>= picture->height) {
	/* this might be an error, but it can be a convenience to allow the
	function to be called with indexes out of range, so i won't introduce
	error handling here */
    } else {
	picture->data[image][x + y * picture->width] = color;
    }
}

/*
    Purpose: get the color value of a 1x1 pixel, 
    This is a wrapper for looking up in the data array.
*/
RGB_COLOR Picture_get_pixel(const xp_picture_t *picture, int image,
			    int x, int y)
{
    if (x < 0 || y < 0 || x>= picture->width || y>= picture->height) {
	return RGB24(0,0,0);
	/* this might be an error, but it can be a convenience to allow the
	function to be called with indexes out of range, so i won't introduce
	error handling here. Return value is defaulted to black.
	There is already code that relies on this behavior */
	
    } else {
	return picture->data[image][x + y * picture->width];
    }
}

/*
    Purpose: Find the color value of the 1x1 pixel with upperleft corner x,y.
    Note that x and y is doubles.
*/
static RGB_COLOR Picture_get_pixel_avg(
	const xp_picture_t	*picture,
	int			image, 
	double			x,
	double			y)
{    
    int		r_x, r_y;
    double	frac_x, frac_y;
    int		i;
    RGB_COLOR	c[4];
    double	p[4];
    double	r, g, b;

    frac_x = x - (int)(x);
    frac_y = y - (int)(y);

    r_x = (int)x;
    r_y = (int)y;

    c[0] = Picture_get_pixel(picture, image, r_x, r_y);
    c[1] = Picture_get_pixel(picture, image, r_x + 1, r_y);
    c[2] = Picture_get_pixel(picture, image, r_x, r_y + 1);
    c[3] = Picture_get_pixel(picture, image, r_x + 1, r_y + 1);
    
    p[0] = (1 - frac_x) * (1 - frac_y);
    p[1] = (frac_x) * (1 - frac_y);
    p[2] = (1 - frac_x) * frac_y;
    p[3] = frac_x * frac_y;
    
    r = 0;
    g = 0;
    b = 0;
    
    for (i = 0; i < 4; i++) {
	r += RED_VALUE(c[i]) * p[i];
	g += GREEN_VALUE(c[i]) * p[i];
	b += BLUE_VALUE(c[i]) * p[i];
    }
    return RGB24((unsigned char)r, (unsigned char)g, (unsigned char)b);
}

/* 
    Purpose: Rotate a point around the center of an image  
    and return the matching color in the base image.
    A picture that contains a rotated image uses all it images to make 
    a full 360 degree rotation, which is reflected in the angle calculation.
    (first image is ang=0 and is used to index the texture for the color value)
    Note: this function is used by the rotation code, 
    and that is why the it's rotating the "wrong" direction.
*/
RGB_COLOR Picture_get_rotated_pixel(const xp_picture_t *picture, 
				    int x, int y, int image)
{
    
    int		angle;
    double	rot_x, rot_y;

    angle = ((image  * RES) / picture->images) % 128;

    x -= picture->width / 2;
    y -= picture->height / 2;

    rot_x = (tcos(angle) * x - tsin(angle) * y) + picture->width / 2;
    rot_y = (tsin(angle) * x + tcos(angle) * y) + picture->height / 2;
 
    return (Picture_get_pixel_avg(picture, 0, rot_x, rot_y));
}



#if 0
/*notused*/
/*
    Purpose: A helper function for adding up color values.
*/
static void color_Add_weight(int *r, int *g, int *b, RGB_COLOR col, double weight)
{
    if (weight == 1) {
	*r += RED_VALUE(col);
	*g += GREEN_VALUE(col);
	*b += BLUE_VALUE(col);
    } else {
	*r += (int)(RED_VALUE(col) * weight);
        *g += (int)(GREEN_VALUE(col) * weight);
	*b += (int)(BLUE_VALUE(col) * weight);
    }
}
#endif


/*
    Purpose: find color values from x + xfrac to x + xfrac + scale.
    This is the most called function in the scaling routine, so i address the picture data directly.
*/

static void Picture_scale_x_slice(const xp_picture_t * picture, int image, int *r, int *g, int *b, int x, int y, double xscale, double xfrac, double yfrac)

{
    double weight;
    RGB_COLOR col;
    RGB_COLOR *image_data = picture->data[image] + x + y * picture->width ;
    
    if (xscale > xfrac) {
	col = *image_data;
	weight = xfrac * yfrac;
	*r += (int)(RED_VALUE(col) * weight);
        *g += (int)(GREEN_VALUE(col) * weight);
	*b += (int)(BLUE_VALUE(col) * weight);
	    
	xscale -= xfrac;
	image_data++;

        weight = yfrac;
	if (yfrac == 1) {
    	    while(xscale >= 1.0) {
		col = *image_data;
		*r += (int)(RED_VALUE(col));
		*g += (int)(GREEN_VALUE(col));
		*b += (int)(BLUE_VALUE(col));
		image_data++;
		xscale -=1.0;
	    }
	} else {
	    while(xscale >= 1.0) {
		col = *image_data;
		*r += (int)(RED_VALUE(col) * weight);
		*g += (int)(GREEN_VALUE(col) * weight);
		*b += (int)(BLUE_VALUE(col) * weight);
		image_data++;
		xscale -=1.0;
	    }
	}
    } 
    if (xscale > 0) {
	col = *image_data;
	weight = yfrac * xscale;
	*r += (int)(RED_VALUE(col) * weight);
        *g += (int)(GREEN_VALUE(col) * weight);
	*b += (int)(BLUE_VALUE(col) * weight);
    }
}

/*
    Purpose: Calculate the average color of a rectangle in an image, 
    This is used by the scaling algorithm.
*/

RGB_COLOR Picture_get_pixel_area(const xp_picture_t *picture, int image, 
				 double x1, double y1, double dx, double dy)
{
    int r ,g, b;
    double area;

    int x,y;
    double xfrac, yfrac; 
    
    r = 0;
    g = 0;
    b = 0;

    x = (int)x1;
    y = (int)y1;

    xfrac = (x+1) - x1;
    yfrac = (y+1) - y1;

    area = dx * dy;

    if (dy > yfrac) {
	Picture_scale_x_slice(picture, image, &r, &g, &b, x, y, dx, xfrac, yfrac);
	dy -=yfrac;
	y++;
	while(dy >= 1.0) {
	    Picture_scale_x_slice(picture, image, &r, &g, &b, x, y, dx, xfrac, 1);
	    y++;
	    dy -=1.0;
	}
    }
    if (dy > 0)
	Picture_scale_x_slice(picture, image, &r, &g, &b, x, y, dx, xfrac, dy);
 
    return RGB24((unsigned char)(r/area), (unsigned char)(g/area), (unsigned char)(b/area));
}

/*
    Purpose: We want to know the bounding box of a picture,
    so that we can reduce the number of operations done on
    a picture.
*/
void Picture_get_bounding_box(xp_picture_t *picture)
{
    int		x, y, p;
    int		color;
    bbox_t	*box;

    for (p = 0; p < picture->images ; p++) {
	box = &picture->bbox[p];
	box->xmin = picture->width - 1;
	box->xmax = 0;
	box->ymin = picture->height - 1;
	box->ymax = 0;

	for (y = 0 ; y < picture->height ; y++) {
	    for (x = 0; x < picture->width ; x++) {
		color = Picture_get_pixel(picture, p, x, y);
		if (color) {
		    if (box->xmin > x) box->xmin = x;
		    if (box->xmax < x) box->xmax = x;
		    if (box->ymin > y) box->ymin = y;
		    if (box->ymax < y) box->ymax = y;
		}
	    }
	}
    }
}