/* $Id: poly.c,v 1.21 2011/01/25 16:30:49 ellson Exp $ $Revision: 1.21 $ */
/* vim:set shiftwidth=4 ts=8: */

/*************************************************************************
 * 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
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: See CVS logs. Details at http://www.graphviz.org/
 *************************************************************************/

/* poly.c
 */

#include "neato.h"
#include <assert.h>
#include <string.h>
#include <math.h>
#include "poly.h"
#include "geom.h"
#include "mem.h"

#define BOX 1
#define ISBOX(p) ((p)->kind & BOX)
#define CIRCLE 2
#define ISCIRCLE(p) ((p)->kind & CIRCLE)

static int maxcnt = 0;
static Point *tp1 = NULL;
static Point *tp2 = NULL;
static Point *tp3 = NULL;

void polyFree()
{
    maxcnt = 0;
    free(tp1);
    free(tp2);
    free(tp3);
    tp1 = NULL;
    tp2 = NULL;
    tp3 = NULL;
}

void breakPoly(Poly * pp)
{
    free(pp->verts);
}

static void bbox(Point * verts, int cnt, Point * o, Point * c)
{
    double xmin, ymin, xmax, ymax;
    int i;

    xmin = xmax = verts->x;
    ymin = ymax = verts->y;
    for (i = 1; i < cnt; i++) {
	verts++;
	if (verts->x < xmin)
	    xmin = verts->x;
	if (verts->y < ymin)
	    ymin = verts->y;
	if (verts->x > xmax)
	    xmax = verts->x;
	if (verts->y > ymax)
	    ymax = verts->y;
    }
    o->x = xmin;
    o->y = ymin;
    c->x = xmax;
    c->y = ymax;
}

#ifdef OLD
static void inflate(Point * prev, Point * cur, Point * next, double margin)
{
    double theta = atan2(prev->y - cur->y, prev->x - cur->x);
    double phi = atan2(next->y - cur->y, next->x - cur->x);
    double beta = (theta + phi) / 2.0;
    double gamma = (M_PI + phi - theta) / 2.0;
    double denom;

    denom = cos(gamma);
    cur->x -= margin * (cos(beta)) / denom;
    cur->y -= margin * (sin(beta)) / denom;
}

static void inflatePts(Point * verts, int cnt, double margin)
{
    int i;
    Point first;
    Point savepoint;
    Point prevpoint;
    Point *prev = &prevpoint;
    Point *cur;
    Point *next;

    first = verts[0];
    prevpoint = verts[cnt - 1];
    cur = &verts[0];
    next = &verts[1];
    for (i = 0; i < cnt - 1; i++) {
	savepoint = *cur;
	inflate(prev, cur, next, margin);
	cur++;
	next++;
	prevpoint = savepoint;
    }

    next = &first;
    inflate(prev, cur, next, margin);
}
#else
static void inflatePts(Point * verts, int cnt, float xmargin, float ymargin)
{
    int i;
    Point *cur;

    cur = &verts[0];
    for (i = 0; i < cnt; i++) {
	cur->x *= xmargin;
	cur->y *= ymargin;
	cur++;
    }
}
#endif

static int isBox(Point * verts, int cnt)
{
    if (cnt != 4)
	return 0;

    if (verts[0].y == verts[1].y)
	return ((verts[2].y == verts[3].y) &&
		(verts[0].x == verts[3].x) && (verts[1].x == verts[2].x));
    else
	return ((verts[0].x == verts[1].x) &&
		(verts[2].x == verts[3].x) &&
		(verts[0].y == verts[3].y) && (verts[1].y == verts[2].y));
}

static Point makeScaledTransPoint(int x, int y, float dx, float dy)
{
    Point rv;
    rv.x = PS2INCH(x) + dx;
    rv.y = PS2INCH(y) + dy;
    return rv;
}

static Point makeScaledPoint(double x, double y)
{
    Point rv;
    rv.x = PS2INCH(x);
    rv.y = PS2INCH(y);
    return rv;
}

static Point *genRound(Agnode_t * n, int *sidep, float xm, float ym)
{
    int sides = 0;
    Point *verts;
    char *p = agget(n, "samplepoints");
    int i;

    if (p)
	sides = atoi(p);
    if (sides < 3)
	sides = DFLT_SAMPLE;
    verts = N_GNEW(sides, Point);
    for (i = 0; i < sides; i++) {
	verts[i].x =
	    (ND_width(n) / 2.0 + xm) * cos(i / (double) sides * M_PI * 2.0);
	verts[i].y =
	    (ND_height(n) / 2.0 + ym) * sin(i / (double) sides * M_PI * 2.0);
    }
    *sidep = sides;
    return verts;
}

#define PUTPT(P,X,Y) ((P).x=(X),(P).y=(Y))

void makeAddPoly(Poly * pp, Agnode_t * n, float xmargin, float ymargin)
{
    int i;
    int sides;
    Point *verts;
    polygon_t *poly;
    boxf b;

    if (ND_clust(n)) {
	Point b;
	sides = 4;
	b.x = ND_width(n) / 2.0 + xmargin;
	b.y = ND_height(n) / 2.0 + ymargin;
	pp->kind = BOX;
	verts = N_GNEW(sides, Point);
	PUTPT(verts[0], b.x, b.y);
	PUTPT(verts[1], -b.x, b.y);
	PUTPT(verts[2], -b.x, -b.y);
	PUTPT(verts[3], b.x, -b.y);
    } else
	switch (shapeOf(n)) {
	case SH_POLY:
	    poly = (polygon_t *) ND_shape_info(n);
	    sides = poly->sides;

	    if (streq(ND_shape(n)->name, "box"))
		pp->kind = BOX;
	    else if (streq(ND_shape(n)->name, "polygon")
		     && isBox(poly->vertices, sides))
		pp->kind = BOX;
	    else if ((poly->sides < 3) && poly->regular)
		pp->kind = CIRCLE;
	    else
		pp->kind = 0;

	    if (sides >= 3) {	/* real polygon */
		verts = N_GNEW(sides, Point);
		if (pp->kind == BOX) {
			/* To do an additive margin, we rely on knowing that
			 * the vertices are CCW starting from the UR
			 */
		    verts[0].x = PS2INCH(poly->vertices[0].x) + xmargin;
		    verts[0].y = PS2INCH(poly->vertices[0].y) + ymargin;
		    verts[1].x = PS2INCH(poly->vertices[1].x) - xmargin;
		    verts[1].y = PS2INCH(poly->vertices[1].y) + ymargin;
		    verts[2].x = PS2INCH(poly->vertices[2].x) - xmargin;
		    verts[2].y = PS2INCH(poly->vertices[2].y) - ymargin;
		    verts[3].x = PS2INCH(poly->vertices[3].x) + xmargin;
		    verts[3].y = PS2INCH(poly->vertices[3].y) - ymargin;
 
		}
		else {
		    for (i = 0; i < sides; i++) {
                        double h = LEN(poly->vertices[i].x,poly->vertices[i].y);
		        verts[i].x = poly->vertices[i].x * (1.0 + xmargin/h);
		        verts[i].y = poly->vertices[i].y * (1.0 + ymargin/h);
		        verts[i].x = PS2INCH(verts[i].x);
		        verts[i].y = PS2INCH(verts[i].y);
		    }
		}
	    } else
		verts = genRound(n, &sides, xmargin, ymargin);
	    break;
	case SH_RECORD:
	    sides = 4;
	    verts = N_GNEW(sides, Point);
	    b = ((field_t *) ND_shape_info(n))->b;
	    verts[0] = makeScaledTransPoint(b.LL.x, b.LL.y, -xmargin, -ymargin);
	    verts[1] = makeScaledTransPoint(b.UR.x, b.LL.y, xmargin, -ymargin);
	    verts[2] = makeScaledTransPoint(b.UR.x, b.UR.y, xmargin, ymargin);
	    verts[3] = makeScaledTransPoint(b.LL.x, b.UR.y, -xmargin, ymargin);
	    pp->kind = BOX;
	    break;
	case SH_POINT:
	    pp->kind = CIRCLE;
	    verts = genRound(n, &sides, xmargin, ymargin);
	    break;
	default:
	    agerr(AGERR, "makeAddPoly: unknown shape type %s\n",
		  ND_shape(n)->name);
	    exit(1);
	}

    pp->verts = verts;
    pp->nverts = sides;
    bbox(verts, sides, &pp->origin, &pp->corner);

    if (sides > maxcnt)
	maxcnt = sides;
}

void makePoly(Poly * pp, Agnode_t * n, float xmargin, float ymargin)
{
    int i;
    int sides;
    Point *verts;
    polygon_t *poly;
    boxf b;

    if (ND_clust(n)) {
	Point b;
	sides = 4;
	b.x = ND_width(n) / 2.0;
	b.y = ND_height(n) / 2.0;
	pp->kind = BOX;
	verts = N_GNEW(sides, Point);
	PUTPT(verts[0], b.x, b.y);
	PUTPT(verts[1], -b.x, b.y);
	PUTPT(verts[2], -b.x, -b.y);
	PUTPT(verts[3], b.x, -b.y);
    } else
	switch (shapeOf(n)) {
	case SH_POLY:
	    poly = (polygon_t *) ND_shape_info(n);
	    sides = poly->sides;
	    if (sides >= 3) {	/* real polygon */
		verts = N_GNEW(sides, Point);
		for (i = 0; i < sides; i++) {
		    verts[i].x = PS2INCH(poly->vertices[i].x);
		    verts[i].y = PS2INCH(poly->vertices[i].y);
		}
	    } else
		verts = genRound(n, &sides, 0, 0);

	    if (streq(ND_shape(n)->name, "box"))
		pp->kind = BOX;
	    else if (streq(ND_shape(n)->name, "polygon")
		     && isBox(verts, sides))
		pp->kind = BOX;
	    else if ((poly->sides < 3) && poly->regular)
		pp->kind = CIRCLE;
	    else
		pp->kind = 0;

	    break;
	case SH_RECORD:
	    sides = 4;
	    verts = N_GNEW(sides, Point);
	    b = ((field_t *) ND_shape_info(n))->b;
	    verts[0] = makeScaledPoint(b.LL.x, b.LL.y);
	    verts[1] = makeScaledPoint(b.UR.x, b.LL.y);
	    verts[2] = makeScaledPoint(b.UR.x, b.UR.y);
	    verts[3] = makeScaledPoint(b.LL.x, b.UR.y);
	    pp->kind = BOX;
	    break;
	case SH_POINT:
	    pp->kind = CIRCLE;
	    verts = genRound(n, &sides, 0, 0);
	    break;
	default:
	    agerr(AGERR, "makePoly: unknown shape type %s\n",
		  ND_shape(n)->name);
	    exit(1);
	}

#ifdef OLD
    if (margin != 0.0)
	inflatePts(verts, sides, margin);
#else
    if ((xmargin != 1.0) || (ymargin != 1.0))
	inflatePts(verts, sides, xmargin, ymargin);
#endif

    pp->verts = verts;
    pp->nverts = sides;
    bbox(verts, sides, &pp->origin, &pp->corner);

    if (sides > maxcnt)
	maxcnt = sides;
}

static int
pintersect(Point originp, Point cornerp, Point originq, Point cornerq)
{
    return ((originp.x <= cornerq.x) && (originq.x <= cornerp.x) &&
	    (originp.y <= cornerq.y) && (originq.y <= cornerp.y));
}

#define Pin 1
#define Qin 2
#define Unknown 0

#define advance(A,B,N) (B++, A = (A+1)%N)

static int edgesIntersect(Point * P, Point * Q, int n, int m)
{
    int a = 0;
    int b = 0;
    int aa = 0;
    int ba = 0;
    int a1, b1;
    Point A, B;
    double cross;
    int bHA, aHB;
    Point p;
    int inflag = Unknown;
    /* int      i = 0; */
    /* int      Reset = 0; */

    do {
	a1 = (a + n - 1) % n;
	b1 = (b + m - 1) % m;

	subpt(&A, P[a], P[a1]);
	subpt(&B, Q[b], Q[b1]);

	cross = area_2(origin, A, B);
	bHA = leftOf(P[a1], P[a], Q[b]);
	aHB = leftOf(Q[b1], Q[b], P[a]);

	/* If A & B intersect, update inflag. */
	if (intersection(P[a1], P[a], Q[b1], Q[b], &p))
	    return 1;

	/* Advance rules. */
	if ((cross == 0) && !bHA && !aHB) {
	    if (inflag == Pin)
		advance(b, ba, m);
	    else
		advance(a, aa, n);
	} else if (cross >= 0)
	    if (bHA)
		advance(a, aa, n);
	    else {
		advance(b, ba, m);
	} else {		/* if ( cross < 0 ) */

	    if (aHB)
		advance(b, ba, m);
	    else
		advance(a, aa, n);
	}

    } while (((aa < n) || (ba < m)) && (aa < 2 * n) && (ba < 2 * m));

    return 0;

}

/* inPoly:
 * Return 1 if q is inside polygon vertex[]
 * Assume points are in CCW order
 */
static int inPoly(Point vertex[], int n, Point q)
{
    int i, i1;			/* point index; i1 = i-1 mod n */
    double x;			/* x intersection of e with ray */
    double crossings = 0;	/* number of edge/ray crossings */

    if (tp3 == NULL)
	tp3 = N_GNEW(maxcnt, Point);

    /* Shift so that q is the origin. */
    for (i = 0; i < n; i++) {
	tp3[i].x = vertex[i].x - q.x;
	tp3[i].y = vertex[i].y - q.y;
    }

    /* For each edge e=(i-1,i), see if crosses ray. */
    for (i = 0; i < n; i++) {
	i1 = (i + n - 1) % n;

	/* if edge is horizontal, test to see if the point is on it */
	if ((tp3[i].y == 0) && (tp3[i1].y == 0)) {
	    if ((tp3[i].x * tp3[i1].x) < 0) {
		return 1;
	    } else {
		continue;
	    }
	}

	/* if e straddles the x-axis... */
	if (((tp3[i].y >= 0) && (tp3[i1].y <= 0)) ||
	    ((tp3[i1].y >= 0) && (tp3[i].y <= 0))) {
	    /* e straddles ray, so compute intersection with ray. */
	    x = (tp3[i].x * tp3[i1].y - tp3[i1].x * tp3[i].y)
		/ (double) (tp3[i1].y - tp3[i].y);

	    /* if intersect at origin, we've found intersection */
	    if (x == 0)
		return 1;;

	    /* crosses ray if strictly positive intersection. */
	    if (x > 0) {
		if ((tp3[i].y == 0) || (tp3[i1].y == 0)) {
		    crossings += .5;	/* goes thru vertex */
		} else {
		    crossings += 1.0;
		}
	    }
	}
    }

    /* q inside if an odd number of crossings. */
    if ((((int) crossings) % 2) == 1)
	return 1;
    else
	return 0;
}

static int inBox(Point p, Point origin, Point corner)
{
    return ((p.x <= corner.x) &&
	    (p.x >= origin.x) && (p.y <= corner.y) && (p.y >= origin.y));

}

static void transCopy(Point * inp, int cnt, Point off, Point * outp)
{
    int i;

    for (i = 0; i < cnt; i++) {
	outp->x = inp->x + off.x;
	outp->y = inp->y + off.y;
	inp++;
	outp++;
    }
}

int polyOverlap(Point p, Poly * pp, Point q, Poly * qp)
{
    Point op, cp;
    Point oq, cq;

    /* translate bounding boxes */
    addpt(&op, p, pp->origin);
    addpt(&cp, p, pp->corner);
    addpt(&oq, q, qp->origin);
    addpt(&cq, q, qp->corner);

    /* If bounding boxes don't overlap, done */
    if (!pintersect(op, cp, oq, cq))
	return 0;

    if (ISBOX(pp) && ISBOX(qp))
	return 1;
    if (ISCIRCLE(pp) && ISCIRCLE(qp)) {
	double d =
	    (pp->corner.x - pp->origin.x + qp->corner.x - qp->origin.x);
	double dx = p.x - q.x;
	double dy = p.y - q.y;
	if ((dx * dx + dy * dy) > (d * d) / 4.0)
	    return 0;
	else
	    return 1;
    }

    if (tp1 == NULL) {
	tp1 = N_GNEW(maxcnt, Point);
	tp2 = N_GNEW(maxcnt, Point);
    }

    transCopy(pp->verts, pp->nverts, p, tp1);
    transCopy(qp->verts, qp->nverts, q, tp2);
    return (edgesIntersect(tp1, tp2, pp->nverts, qp->nverts) ||
	    (inBox(*tp1, oq, cq) && inPoly(tp2, qp->nverts, *tp1)) ||
	    (inBox(*tp2, op, cp) && inPoly(tp1, pp->nverts, *tp2)));
}
