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import adder from "./adder";
import {areaStream, areaRingSum} from "./area";
import {cartesian, cartesianCross, cartesianNormalizeInPlace, spherical} from "./cartesian";
import {abs, degrees, epsilon, radians} from "./math";
import stream from "./stream";
var lambda0, phi0, lambda1, phi1, // bounds
lambda2, // previous lambda-coordinate
lambda00, phi00, // first point
p0, // previous 3D point
deltaSum = adder(),
ranges,
range;
var boundsStream = {
point: boundsPoint,
lineStart: boundsLineStart,
lineEnd: boundsLineEnd,
polygonStart: function() {
boundsStream.point = boundsRingPoint;
boundsStream.lineStart = boundsRingStart;
boundsStream.lineEnd = boundsRingEnd;
deltaSum.reset();
areaStream.polygonStart();
},
polygonEnd: function() {
areaStream.polygonEnd();
boundsStream.point = boundsPoint;
boundsStream.lineStart = boundsLineStart;
boundsStream.lineEnd = boundsLineEnd;
if (areaRingSum < 0) lambda0 = -(lambda1 = 180), phi0 = -(phi1 = 90);
else if (deltaSum > epsilon) phi1 = 90;
else if (deltaSum < -epsilon) phi0 = -90;
range[0] = lambda0, range[1] = lambda1;
},
sphere: function() {
lambda0 = -(lambda1 = 180), phi0 = -(phi1 = 90);
}
};
function boundsPoint(lambda, phi) {
ranges.push(range = [lambda0 = lambda, lambda1 = lambda]);
if (phi < phi0) phi0 = phi;
if (phi > phi1) phi1 = phi;
}
function linePoint(lambda, phi) {
var p = cartesian([lambda * radians, phi * radians]);
if (p0) {
var normal = cartesianCross(p0, p),
equatorial = [normal[1], -normal[0], 0],
inflection = cartesianCross(equatorial, normal);
cartesianNormalizeInPlace(inflection);
inflection = spherical(inflection);
var delta = lambda - lambda2,
sign = delta > 0 ? 1 : -1,
lambdai = inflection[0] * degrees * sign,
phii,
antimeridian = abs(delta) > 180;
if (antimeridian ^ (sign * lambda2 < lambdai && lambdai < sign * lambda)) {
phii = inflection[1] * degrees;
if (phii > phi1) phi1 = phii;
} else if (lambdai = (lambdai + 360) % 360 - 180, antimeridian ^ (sign * lambda2 < lambdai && lambdai < sign * lambda)) {
phii = -inflection[1] * degrees;
if (phii < phi0) phi0 = phii;
} else {
if (phi < phi0) phi0 = phi;
if (phi > phi1) phi1 = phi;
}
if (antimeridian) {
if (lambda < lambda2) {
if (angle(lambda0, lambda) > angle(lambda0, lambda1)) lambda1 = lambda;
} else {
if (angle(lambda, lambda1) > angle(lambda0, lambda1)) lambda0 = lambda;
}
} else {
if (lambda1 >= lambda0) {
if (lambda < lambda0) lambda0 = lambda;
if (lambda > lambda1) lambda1 = lambda;
} else {
if (lambda > lambda2) {
if (angle(lambda0, lambda) > angle(lambda0, lambda1)) lambda1 = lambda;
} else {
if (angle(lambda, lambda1) > angle(lambda0, lambda1)) lambda0 = lambda;
}
}
}
} else {
ranges.push(range = [lambda0 = lambda, lambda1 = lambda]);
}
if (phi < phi0) phi0 = phi;
if (phi > phi1) phi1 = phi;
p0 = p, lambda2 = lambda;
}
function boundsLineStart() {
boundsStream.point = linePoint;
}
function boundsLineEnd() {
range[0] = lambda0, range[1] = lambda1;
boundsStream.point = boundsPoint;
p0 = null;
}
function boundsRingPoint(lambda, phi) {
if (p0) {
var delta = lambda - lambda2;
deltaSum.add(abs(delta) > 180 ? delta + (delta > 0 ? 360 : -360) : delta);
} else {
lambda00 = lambda, phi00 = phi;
}
areaStream.point(lambda, phi);
linePoint(lambda, phi);
}
function boundsRingStart() {
areaStream.lineStart();
}
function boundsRingEnd() {
boundsRingPoint(lambda00, phi00);
areaStream.lineEnd();
if (abs(deltaSum) > epsilon) lambda0 = -(lambda1 = 180);
range[0] = lambda0, range[1] = lambda1;
p0 = null;
}
// Finds the left-right distance between two longitudes.
// This is almost the same as (lambda1 - lambda0 + 360°) % 360°, except that we want
// the distance between ±180° to be 360°.
function angle(lambda0, lambda1) {
return (lambda1 -= lambda0) < 0 ? lambda1 + 360 : lambda1;
}
function rangeCompare(a, b) {
return a[0] - b[0];
}
function rangeContains(range, x) {
return range[0] <= range[1] ? range[0] <= x && x <= range[1] : x < range[0] || range[1] < x;
}
export default function(feature) {
var i, n, a, b, merged, deltaMax, delta;
phi1 = lambda1 = -(lambda0 = phi0 = Infinity);
ranges = [];
stream(feature, boundsStream);
// First, sort ranges by their minimum longitudes.
if (n = ranges.length) {
ranges.sort(rangeCompare);
// Then, merge any ranges that overlap.
for (i = 1, a = ranges[0], merged = [a]; i < n; ++i) {
b = ranges[i];
if (rangeContains(a, b[0]) || rangeContains(a, b[1])) {
if (angle(a[0], b[1]) > angle(a[0], a[1])) a[1] = b[1];
if (angle(b[0], a[1]) > angle(a[0], a[1])) a[0] = b[0];
} else {
merged.push(a = b);
}
}
// Finally, find the largest gap between the merged ranges.
// The final bounding box will be the inverse of this gap.
for (deltaMax = -Infinity, n = merged.length - 1, i = 0, a = merged[n]; i <= n; a = b, ++i) {
b = merged[i];
if ((delta = angle(a[1], b[0])) > deltaMax) deltaMax = delta, lambda0 = b[0], lambda1 = a[1];
}
}
ranges = range = null;
return lambda0 === Infinity || phi0 === Infinity
? [[NaN, NaN], [NaN, NaN]]
: [[lambda0, phi0], [lambda1, phi1]];
}
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