import "../core/true";

import "../math/abs";

import "../math/trigonometry";

import "clip";

var d3_geo_clipAntimeridian = d3_geo_clip(

d3_true,

d3_geo_clipAntimeridianLine,

d3_geo_clipAntimeridianInterpolate,

[-π, -π / 2]);

// Takes a line and cuts into visible segments. Return values:

// 0: there were intersections or the line was empty.

// 1: no intersections.

// 2: there were intersections, and the first and last segments should be

// rejoined.

function d3_geo_clipAntimeridianLine(listener) {

var λ0 = NaN,

φ0 = NaN,

sλ0 = NaN,

clean; // no intersections

return {

lineStart: function() {

listener.lineStart();

clean = 1;

},

point: function(λ1, φ1) {

var sλ1 = λ1 > 0 ? π : -π,

dλ = abs(λ1 - λ0);

if (abs(dλ - π) < ε) { // line crosses a pole

listener.point(λ0, φ0 = (φ0 + φ1) / 2 > 0 ? halfπ : -halfπ);

listener.point(sλ0, φ0);

listener.lineEnd();

listener.lineStart();

listener.point(sλ1, φ0);

listener.point(λ1, φ0);

clean = 0;

} else if (sλ0 !== sλ1 && dλ >= π) { // line crosses antimeridian

// handle degeneracies

if (abs(λ0 - sλ0) < ε) λ0 -= sλ0 * ε;

if (abs(λ1 - sλ1) < ε) λ1 -= sλ1 * ε;

φ0 = d3_geo_clipAntimeridianIntersect(λ0, φ0, λ1, φ1);

listener.point(sλ0, φ0);

listener.lineEnd();

listener.lineStart();

listener.point(sλ1, φ0);

clean = 0;

}

listener.point(λ0 = λ1, φ0 = φ1);

sλ0 = sλ1;

},

lineEnd: function() {

listener.lineEnd();

λ0 = φ0 = NaN;

},

// if there are intersections, we always rejoin the first and last segments.

clean: function() { return 2 - clean; }

};

}

function d3_geo_clipAntimeridianIntersect(λ0, φ0, λ1, φ1) {

var cosφ0,

cosφ1,

sinλ0_λ1 = Math.sin(λ0 - λ1);

return abs(sinλ0_λ1) > ε

? Math.atan((Math.sin(φ0) * (cosφ1 = Math.cos(φ1)) * Math.sin(λ1)

- Math.sin(φ1) * (cosφ0 = Math.cos(φ0)) * Math.sin(λ0))

/ (cosφ0 * cosφ1 * sinλ0_λ1))

: (φ0 + φ1) / 2;

}

function d3_geo_clipAntimeridianInterpolate(from, to, direction, listener) {

var φ;

if (from == null) {

φ = direction * halfπ;

listener.point(-π, φ);

listener.point( 0, φ);

listener.point( π, φ);

listener.point( π, 0);

listener.point( π, -φ);

listener.point( 0, -φ);

listener.point(-π, -φ);

listener.point(-π, 0);

listener.point(-π, φ);

} else if (abs(from[0] - to[0]) > ε) {

var s = from[0] < to[0] ? π : -π;

φ = direction * s / 2;

listener.point(-s, φ);

listener.point( 0, φ);

listener.point( s, φ);

} else {

listener.point(to[0], to[1]);

}

}