/**
 * @file trilib.c
 * @brief library for loading triangles from an Alias triangle file
 */

#include "../../ufo2map/common/cmdlib.h"
#include "../../ufo2map/common/mathlib.h"
#include "trilib.h"

/* on disk representation of a face */

#define	FLOAT_START	99999.0
#define	FLOAT_END	-FLOAT_START
#define MAGIC       123322

/*#define NOISY 1 */

typedef struct {
	float v[3];
} vector;

typedef struct
{
	vector n;    /* normal */
	vector p;    /* point */
	vector c;    /* color */
	float  u;    /* u */
	float  v;    /* v */
} aliaspoint_t;

typedef struct {
	aliaspoint_t	pt[3];
} tf_triangle;


void ByteSwapTri (tf_triangle *tri)
{
	int		i;

	for (i=0 ; i<sizeof(tf_triangle)/4 ; i++) {
		((int *)tri)[i] = BigLong (((int *)tri)[i]);
	}
}

void LoadTriangleList (char *filename, triangle_t **pptri, int *numtriangles)
{
	FILE        *input;
	float       start;
	char        name[256], tex[256];
	int         i, count, magic;
	tf_triangle	tri;
	triangle_t	*ptri;
	int			iLevel;
	int			exitpattern;
	float		t;

	t = -FLOAT_START;
	*((unsigned char *)&exitpattern + 0) = *((unsigned char *)&t + 3);
	*((unsigned char *)&exitpattern + 1) = *((unsigned char *)&t + 2);
	*((unsigned char *)&exitpattern + 2) = *((unsigned char *)&t + 1);
	*((unsigned char *)&exitpattern + 3) = *((unsigned char *)&t + 0);

	if ((input = fopen(filename, "rb")) == 0)
		Error ("reader: could not open file '%s'", filename);

	iLevel = 0;

	if (fread(&magic, sizeof(int), 1, input) != 1)
		printf("LoadTriangleList: Read error\n");
	if (BigLong(magic) != MAGIC)
		Error ("%s is not a Alias object separated triangle file, magic number is wrong.", filename);

	ptri = malloc (MAXTRIANGLES * sizeof(triangle_t));

	*pptri = ptri;

	while (feof(input) == 0) {
		if (fread(&start,  sizeof(float), 1, input) < 1)
			break;
		*(int *)&start = BigLong(*(int *)&start);
		if (*(int *)&start != exitpattern) {
			if (start == FLOAT_START) {
				/* Start of an object or group of objects. */
				i = -1;
				do {
					/* There are probably better ways to read a string from */
					/* a file, but this does allow you to do error checking */
					/* (which I'm not doing) on a per character basis.      */
					++i;
					if (fread( &(name[i]), sizeof( char ), 1, input) != 1)
						printf("LoadTriangleList: Read error\n");
				} while( name[i] != '\0' );

/*				indent(); */
/*				fprintf(stdout,"OBJECT START: %s\n",name); */
				if (fread( &count, sizeof(int), 1, input) != 1)
					printf("LoadTriangleList: Read error\n");
				count = BigLong(count);
				++iLevel;
				if (count != 0) {
/*					indent(); */
/*					fprintf(stdout,"NUMBER OF TRIANGLES: %d\n",count); */

					i = -1;
					do {
						++i;
						if (fread( &(tex[i]), sizeof( char ), 1, input) != 1)
							printf("LoadTriangleList: Read error\n");
					} while( tex[i] != '\0' );

/*					indent(); */
/*					fprintf(stdout,"  Object texture name: '%s'\n",tex); */
				}

				/* Else (count == 0) this is the start of a group, and */
				/* no texture name is present. */
			} else if (start == FLOAT_END) {
				/* End of an object or group. Yes, the name should be */
				/* obvious from context, but it is in here just to be */
				/* safe and to provide a little extra information for */
				/* those who do not wish to write a recursive reader. */
				/* Mia culpa. */
				--iLevel;
				i = -1;
				do {
					++i;
					if (fread( &(name[i]), sizeof( char ), 1, input) != 1)
						printf("LoadTriangleList: Read error\n");
				} while( name[i] != '\0' );

/*				indent(); */
/*				fprintf(stdout,"OBJECT END: %s\n",name); */
				continue;
			}
		}

		/* read the triangles */
		for (i = 0; i < count; ++i) {
			int		j;

			if (fread( &tri, sizeof(tf_triangle), 1, input ) != 1)
				printf("LoadTriangleList: Read error\n");
			ByteSwapTri (&tri);
			for (j=0 ; j<3 ; j++) {
				int		k;

				for (k=0 ; k<3 ; k++) {
					ptri->verts[j][k] = tri.pt[j].p.v[k];
				}
			}

			ptri++;

			if ((ptri - *pptri) >= MAXTRIANGLES)
				Error ("Error: too many triangles; increase MAXTRIANGLES\n");
		}
	}

	*numtriangles = ptri - *pptri;

	fclose (input);
}