#include<general.h>
#include<cross-section.h>
#include<coord.h>
#include<cairo/cairo.h>
/** @brief Calculates cross-section of vesicle with plane.
 *
 * Function returns points of cross-section of vesicle with plane. Plane is described with equation $ax+by+cz+d=0$. Algorithm extracts coordinates of each vertex of a vesicle and then:
 *
 * if a distance of point to plane (given by equation $D=\frac{ax_0+by_0+cz_0+d}{\sqrt{a^2+b^2+c^2}}$, where $x_0$, $y_0$ and $z_0$ are coordinates of a given vertex) is less than maximal allowed distance between vertices {\tt sqrt(vesicle->dmax)} than vertex is a candidate for crossection calculation.
 *
 */
ts_coord_list *get_crossection_with_plane(ts_vesicle *vesicle,ts_double a,ts_double b,ts_double c, ts_double d){


	ts_uint i, j,k,l;
	ts_double pp,Dsq; // distance from the plane squared
	ts_double ppn1; // distance from the plane squared of a neighbor
	ts_vertex *vtx;
	ts_uint ntria=0; // number triangles
	ts_triangle *tria[2]; // list of triangles
	ts_coord_list *pts=init_coord_list();
	for(i=0;i<vesicle->vlist->n;i++){
		vtx=vesicle->vlist->vtx[i];

		pp=vtx->x*a+vtx->y*b+vtx->z*c+d;
		Dsq=pp*pp/(a*a+b*b+c*c);
		if(Dsq<vesicle->dmax){
			for(j=0;j<vtx->neigh_no;j++){
				ppn1=vtx->neigh[j]->x*a+vtx->neigh[j]->y*b+vtx->neigh[j]->z*c+d;
				if(pp*ppn1<=0){ //the combination of vertices are good candidates for a crossection
					//find triangle that belongs to the two vertices
					ntria=0;
					for(k=0;k<vtx->tristar_no;k++){
						if(vtx->tristar[k]->vertex[0]==vtx && ( vtx->tristar[k]->vertex[1]==vtx->neigh[j] || vtx->tristar[k]->vertex[2]==vtx->neigh[j]) ){ 
							//triangle found.
							tria[ntria]=vtx->tristar[k];
							ntria++;
						}
					}
					// if ntria !=1 there is probably something wrong I would say...
					if(ntria==0) continue;
				/*	if(ntria!=1) { //there should be 2 triangles. of course, all some of them will be doubled.
						fprintf(stderr,"ntria=%u\n",ntria);
						fatal ("Error in mesh. 2 triangles not found",123123);
					} */
					//find the two intersections (in general) to form a intersection line
					for(l=0;l<ntria;l++){
					//we add intersection line between two points for each of the triangles found above.
						add_crosssection_point(pts,a,b,c,d,tria[l]->vertex[0], tria[l]->vertex[1]);
						add_crosssection_point(pts,a,b,c,d,tria[l]->vertex[0], tria[l]->vertex[2]);
						add_crosssection_point(pts,a,b,c,d,tria[l]->vertex[1], tria[l]->vertex[2]);

					}
				}
			}
		}
	}
	return pts;
}



ts_bool add_crosssection_point(ts_coord_list *pts, ts_double a, ts_double b, ts_double c, ts_double d, ts_vertex *vtx1, ts_vertex *vtx2){
	ts_double pp=vtx1->x*a+vtx1->y*b+vtx1->z*c+d;
	ts_double pp2=vtx2->x*a+vtx1->y*b+vtx2->z*c+d;
	if(pp*pp2<=0){
	ts_double u=pp/(a*(vtx1->x-vtx2->x)+b*(vtx1->y-vtx2->y)+c*(vtx1->z-vtx2->z));
	add_coord(pts, vtx1->x+u*(vtx2->x - vtx1->x),
		vtx1->y+u*(vtx2->y - vtx1->y),		
		vtx1->z+u*(vtx2->z - vtx1->z),
		TS_COORD_CARTESIAN);
	
	return TS_SUCCESS;
	} else {
	return TS_FAIL;
	}
}

/** Saves calculated crossection as a png image */
ts_bool crossection_to_png(ts_coord_list *pts, char *filename){

	cairo_surface_t *surface;
	cairo_t *cr;
	ts_uint i;
	surface = cairo_image_surface_create (CAIRO_FORMAT_RGB24, 1800, 1800);
	cr = cairo_create (surface);
	cairo_rectangle(cr, 0.0, 0.0, 1800,1800);
	cairo_set_source_rgb(cr, 0.3, 0.3, 0.3);
	cairo_fill(cr);
	cairo_set_line_width (cr, 5.0/30.0);
	cairo_translate(cr, 900,900);
	cairo_scale (cr, 30, 30);
	cairo_set_source_rgb (cr, 1.0, 1.0, 1.0);

	for(i=0;i<pts->n;i+=2){
		cairo_move_to(cr, pts->coord[i]->e1, pts->coord[i]->e2);
		cairo_line_to(cr, pts->coord[i+1]->e1, pts->coord[i+1]->e2);
	}
	cairo_stroke(cr);
	cairo_surface_write_to_png (surface,filename);
	cairo_surface_finish (surface);	
	return TS_SUCCESS;
}


ts_bool save_crossection_snapshot(ts_coord_list *pts, ts_uint timestepno){
	char filename[255];
    	sprintf(filename,"timestep_%.6u.png",timestepno);
	crossection_to_png(pts,filename);
	return TS_SUCCESS;
}