/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: Details at https://graphviz.org
 *************************************************************************/

#include <neatogen/neato.h>
#include <neatogen/mem.h>
#include <neatogen/info.h>
#include <neatogen/edges.h>
#include <math.h>


double pxmin, pxmax, pymin, pymax;	/* clipping window */

static Freelist efl;

void edgeinit(void)
{
    freeinit(&efl, sizeof(Edge));
}

Edge *gvbisect(Site * s1, Site * s2)
{
    double dx, dy, adx, ady;
    Edge *newedge;

    newedge = getfree(&efl);

    newedge->reg[0] = s1;
    newedge->reg[1] = s2;
    ref(s1);
    ref(s2);
    newedge->ep[0] = NULL;
    newedge->ep[1] = NULL;

    dx = s2->coord.x - s1->coord.x;
    dy = s2->coord.y - s1->coord.y;
    adx = fabs(dx);
    ady = fabs(dy);
    newedge->c =
	s1->coord.x * dx + s1->coord.y * dy + (dx * dx + dy * dy) * 0.5;
    if (adx > ady) {
	newedge->a = 1.0;
	newedge->b = dy / dx;
	newedge->c /= dx;
    } else {
	newedge->b = 1.0;
	newedge->a = dx / dy;
	newedge->c /= dy;
    };

    return (newedge);
}


static void doSeg(Edge * e, double x1, double y1, double x2, double y2)
{
    addVertex(e->reg[0], x1, y1);
    addVertex(e->reg[0], x2, y2);
    addVertex(e->reg[1], x1, y1);
    addVertex(e->reg[1], x2, y2);
}

void clip_line(Edge * e)
{
    Site *s1, *s2;
    double x1, x2, y1, y2;

    if (e->a == 1.0 && e->b >= 0.0) {
	s1 = e->ep[1];
	s2 = e->ep[0];
    } else {
	s1 = e->ep[0];
	s2 = e->ep[1];
    }

    if (e->a == 1.0) {
	if (s1 != NULL) {
	    y1 = s1->coord.y;
	    if (y1 > pymax)
		return;
	    else if (y1 >= pymin)
		x1 = s1->coord.x;
	    else {
		y1 = pymin;
		x1 = e->c - e->b * y1;
	    }
	} else {
	    y1 = pymin;
	    x1 = e->c - e->b * y1;
	}

	if (s2 != NULL) {
	    y2 = s2->coord.y;
	    if (y2 < pymin)
		return;
	    else if (y2 <= pymax)
		x2 = s2->coord.x;
	    else {
		y2 = pymax;
		x2 = e->c - e->b * y2;
	    }
	} else {
	    y2 = pymax;
	    x2 = e->c - e->b * y2;
	}

	if ((x1 > pxmax && x2 > pxmax) || (x1 < pxmin && x2 < pxmin))
	    return;
	if (x1 > pxmax) {
	    x1 = pxmax;
	    y1 = (e->c - x1) / e->b;
	};
	if (x1 < pxmin) {
	    x1 = pxmin;
	    y1 = (e->c - x1) / e->b;
	};
	if (x2 > pxmax) {
	    x2 = pxmax;
	    y2 = (e->c - x2) / e->b;
	};
	if (x2 < pxmin) {
	    x2 = pxmin;
	    y2 = (e->c - x2) / e->b;
	};
    } else {
	if (s1 != NULL) {
	    x1 = s1->coord.x;
	    if (x1 > pxmax)
		return;
	    else if (x1 >= pxmin)
		y1 = s1->coord.y;
	    else {
		x1 = pxmin;
		y1 = e->c - e->a * x1;
	    }
	} else {
	    x1 = pxmin;
	    y1 = e->c - e->a * x1;
	}

	if (s2 != NULL) {
	    x2 = s2->coord.x;
	    if (x2 < pxmin)
		return;
	    else if (x2 <= pxmax)
		y2 = s2->coord.y;
	    else {
		x2 = pxmax;
		y2 = e->c - e->a * x2;
	    }
	} else {
	    x2 = pxmax;
	    y2 = e->c - e->a * x2;
	}

	if ((y1 > pymax && y2 > pymax) || (y1 < pymin && y2 < pymin))
	    return;
	if (y1 > pymax) {
	    y1 = pymax;
	    x1 = (e->c - y1) / e->a;
	};
	if (y1 < pymin) {
	    y1 = pymin;
	    x1 = (e->c - y1) / e->a;
	};
	if (y2 > pymax) {
	    y2 = pymax;
	    x2 = (e->c - y2) / e->a;
	};
	if (y2 < pymin) {
	    y2 = pymin;
	    x2 = (e->c - y2) / e->a;
	};
    }

    doSeg(e, x1, y1, x2, y2);
}

void endpoint(Edge * e, int lr, Site * s)
{
    e->ep[lr] = s;
    ref(s);
    if (e->ep[re - lr] == NULL)
	return;
    clip_line(e);
    deref(e->reg[le]);
    deref(e->reg[re]);
    makefree(e, &efl);
}