import {assert} from "./../utils/assert";
import { TESSvertex, TESShalfEdge } from "../mesh/index";

export class Geom {

	static vertEq (u: TESSvertex, v: TESSvertex) {
		return u.s === v.s && u.t === v.t;
	}

	/* Returns TRUE if u is lexicographically <= v. */
	static vertLeq(u: TESSvertex, v: TESSvertex) {
		return u.s < v.s || (u.s === v.s && u.t <= v.t);
	}

	/* Versions of VertLeq, EdgeSign, EdgeEval with s and t transposed. */
	static transLeq(u: TESSvertex, v: TESSvertex) {
		return u.t < v.t || (u.t === v.t && u.s <= v.s);
	}

	static edgeGoesLeft(e: TESShalfEdge) {
		return Geom.vertLeq(e.Dst, e.Org);
	}

	static edgeGoesRight(e: TESShalfEdge) {
		return Geom.vertLeq(e.Org, e.Dst);
	}

	static vertL1dist(u: TESSvertex, v: TESSvertex) {
		return Math.abs(u.s - v.s) + Math.abs(u.t - v.t);
	}

	//TESSreal tesedgeEval( TESSvertex *u, TESSvertex *v, TESSvertex *w )
	static edgeEval(u: TESSvertex, v: TESSvertex, w: TESSvertex) {
		/* Given three vertices u,v,w such that VertLeq(u,v) && VertLeq(v,w),
		 * evaluates the t-coord of the edge uw at the s-coord of the vertex v.
		 * Returns v->t - (uw)(v->s), ie. the signed distance from uw to v.
		 * If uw is vertical (and thus passes thru v), the result is zero.
		 *
		 * The calculation is extremely accurate and stable, even when v
		 * is very close to u or w.  In particular if we set v->t = 0 and
		 * let r be the negated result (this evaluates (uw)(v->s)), then
		 * r is guaranteed to satisfy MIN(u->t,w->t) <= r <= MAX(u->t,w->t).
		 */
		assert(Geom.vertLeq(u, v) && Geom.vertLeq(v, w));

		var gapL = v.s - u.s;
		var gapR = w.s - v.s;

		if (gapL + gapR > 0.0) {
			if (gapL < gapR) {
				return v.t - u.t + (u.t - w.t) * (gapL / (gapL + gapR));
			} else {
				return v.t - w.t + (w.t - u.t) * (gapR / (gapL + gapR));
			}
		}
		/* vertical line */
		return 0.0;
	}

	//TESSreal tesedgeSign( TESSvertex *u, TESSvertex *v, TESSvertex *w )
	static edgeSign(u: TESSvertex, v: TESSvertex, w: TESSvertex) {
		/* Returns a number whose sign matches EdgeEval(u,v,w) but which
		 * is cheaper to evaluate.  Returns > 0, == 0 , or < 0
		 * as v is above, on, or below the edge uw.
		 */
		assert(Geom.vertLeq(u, v) && Geom.vertLeq(v, w));

		var gapL = v.s - u.s;
		var gapR = w.s - v.s;

		if (gapL + gapR > 0.0) {
			return (v.t - w.t) * gapL + (v.t - u.t) * gapR;
		}
		/* vertical line */
		return 0.0;
	}

	/***********************************************************************
	 * Define versions of EdgeSign, EdgeEval with s and t transposed.
	 */

	//TESSreal testransEval( TESSvertex *u, TESSvertex *v, TESSvertex *w )
	static transEval(u: TESSvertex, v: TESSvertex, w: TESSvertex) {
		/* Given three vertices u,v,w such that TransLeq(u,v) && TransLeq(v,w),
		 * evaluates the t-coord of the edge uw at the s-coord of the vertex v.
		 * Returns v->s - (uw)(v->t), ie. the signed distance from uw to v.
		 * If uw is vertical (and thus passes thru v), the result is zero.
		 *
		 * The calculation is extremely accurate and stable, even when v
		 * is very close to u or w.  In particular if we set v->s = 0 and
		 * let r be the negated result (this evaluates (uw)(v->t)), then
		 * r is guaranteed to satisfy MIN(u->s,w->s) <= r <= MAX(u->s,w->s).
		 */
		assert(Geom.transLeq(u, v) && Geom.transLeq(v, w));

		var gapL = v.t - u.t;
		var gapR = w.t - v.t;

		if (gapL + gapR > 0.0) {
			if (gapL < gapR) {
				return v.s - u.s + (u.s - w.s) * (gapL / (gapL + gapR));
			} else {
				return v.s - w.s + (w.s - u.s) * (gapR / (gapL + gapR));
			}
		}
		/* vertical line */
		return 0.0;
	}

	//TESSreal testransSign( TESSvertex *u, TESSvertex *v, TESSvertex *w )
	static transSign(u: TESSvertex, v: TESSvertex, w: TESSvertex) {
		/* Returns a number whose sign matches TransEval(u,v,w) but which
		 * is cheaper to evaluate.  Returns > 0, == 0 , or < 0
		 * as v is above, on, or below the edge uw.
		 */
		assert(Geom.transLeq(u, v) && Geom.transLeq(v, w));

		var gapL = v.t - u.t;
		var gapR = w.t - v.t;

		if (gapL + gapR > 0.0) {
			return (v.s - w.s) * gapL + (v.s - u.s) * gapR;
		}
		/* vertical line */
		return 0.0;
	}

	//int tesvertCCW( TESSvertex *u, TESSvertex *v, TESSvertex *w )
	static vertCCW(u: TESSvertex, v: TESSvertex, w: TESSvertex) {
		/* For almost-degenerate situations, the results are not reliable.
		 * Unless the floating-point arithmetic can be performed without
		 * rounding errors, *any* implementation will give incorrect results
		 * on some degenerate inputs, so the client must have some way to
		 * handle this situation.
		 */
		return u.s * (v.t - w.t) + v.s * (w.t - u.t) + w.s * (u.t - v.t) >= 0.0;
	}

	/* Given parameters a,x,b,y returns the value (b*x+a*y)/(a+b),
	 * or (x+y)/2 if a==b==0.  It requires that a,b >= 0, and enforces
	 * this in the rare case that one argument is slightly negative.
	 * The implementation is extremely stable numerically.
	 * In particular it guarantees that the result r satisfies
	 * MIN(x,y) <= r <= MAX(x,y), and the results are very accurate
	 * even when a and b differ greatly in magnitude.
	 */
	static interpolate(a: number, x:number, b:number, y:number) {
		return (
			(a = a < 0 ? 0 : a),
			(b = b < 0 ? 0 : b),
			a <= b
				? b === 0
					? (x + y) / 2
					: x + (y - x) * (a / (a + b))
				: y + (x - y) * (b / (a + b))
		);
	}

	/*
	#ifndef FOR_TRITE_TEST_PROGRAM
	#define Interpolate(a,x,b,y)	RealInterpolate(a,x,b,y)
	#else

	// Claim: the ONLY property the sweep algorithm relies on is that
	// MIN(x,y) <= r <= MAX(x,y).  This is a nasty way to test that.
	#include <stdlib.h>
	extern int RandomInterpolate;

	double Interpolate( double a, double x, double b, double y)
	{
		printf("*********************%d\n",RandomInterpolate);
		if( RandomInterpolate ) {
			a = 1.2 * drand48() - 0.1;
			a = (a < 0) ? 0 : ((a > 1) ? 1 : a);
			b = 1.0 - a;
		}
		return RealInterpolate(a,x,b,y);
	}
	#endif*/

	static intersect(o1: TESSvertex, d1: TESSvertex, o2: TESSvertex, d2:TESSvertex, v: TESSvertex) {
		/* Given edges (o1,d1) and (o2,d2), compute their point of intersection.
		 * The computed point is guaranteed to lie in the intersection of the
		 * bounding rectangles defined by each edge.
		 */
		var z1, z2;
		var t;

		/* This is certainly not the most efficient way to find the intersection
		 * of two line segments, but it is very numerically stable.
		 *
		 * Strategy: find the two middle vertices in the VertLeq ordering,
		 * and interpolate the intersection s-value from these.  Then repeat
		 * using the TransLeq ordering to find the intersection t-value.
		 */

		if (!Geom.vertLeq(o1, d1)) {
			t = o1;
			o1 = d1;
			d1 = t;
		} //swap( o1, d1 ); }
		if (!Geom.vertLeq(o2, d2)) {
			t = o2;
			o2 = d2;
			d2 = t;
		} //swap( o2, d2 ); }
		if (!Geom.vertLeq(o1, o2)) {
			t = o1;
			o1 = o2;
			o2 = t;
			t = d1;
			d1 = d2;
			d2 = t;
		} //swap( o1, o2 ); swap( d1, d2 ); }

		if (!Geom.vertLeq(o2, d1)) {
			/* Technically, no intersection -- do our best */
			v.s = (o2.s + d1.s) / 2;
		} else if (Geom.vertLeq(d1, d2)) {
			/* Interpolate between o2 and d1 */
			z1 = Geom.edgeEval(o1, o2, d1);
			z2 = Geom.edgeEval(o2, d1, d2);
			if (z1 + z2 < 0) {
				z1 = -z1;
				z2 = -z2;
			}
			v.s = Geom.interpolate(z1, o2.s, z2, d1.s);
		} else {
			/* Interpolate between o2 and d2 */
			z1 = Geom.edgeSign(o1, o2, d1);
			z2 = -Geom.edgeSign(o1, d2, d1);
			if (z1 + z2 < 0) {
				z1 = -z1;
				z2 = -z2;
			}
			v.s = Geom.interpolate(z1, o2.s, z2, d2.s);
		}

		/* Now repeat the process for t */

		if (!Geom.transLeq(o1, d1)) {
			t = o1;
			o1 = d1;
			d1 = t;
		} //swap( o1, d1 ); }
		if (!Geom.transLeq(o2, d2)) {
			t = o2;
			o2 = d2;
			d2 = t;
		} //swap( o2, d2 ); }
		if (!Geom.transLeq(o1, o2)) {
			t = o1;
			o1 = o2;
			o2 = t;
			t = d1;
			d1 = d2;
			d2 = t;
		} //swap( o1, o2 ); swap( d1, d2 ); }

		if (!Geom.transLeq(o2, d1)) {
			/* Technically, no intersection -- do our best */
			v.t = (o2.t + d1.t) / 2;
		} else if (Geom.transLeq(d1, d2)) {
			/* Interpolate between o2 and d1 */
			z1 = Geom.transEval(o1, o2, d1);
			z2 = Geom.transEval(o2, d1, d2);
			if (z1 + z2 < 0) {
				z1 = -z1;
				z2 = -z2;
			}
			v.t = Geom.interpolate(z1, o2.t, z2, d1.t);
		} else {
			/* Interpolate between o2 and d2 */
			z1 = Geom.transSign(o1, o2, d1);
			z2 = -Geom.transSign(o1, d2, d1);
			if (z1 + z2 < 0) {
				z1 = -z1;
				z2 = -z2;
			}
			v.t = Geom.interpolate(z1, o2.t, z2, d2.t);
		}
	}
}