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import {extent, thresholdSturges, tickStep, range} from "d3-array";
import {slice} from "./array";
import ascending from "./ascending";
import area from "./area";
import constant from "./constant";
import contains from "./contains";
import noop from "./noop";
var cases = [
[],
[[[1.0, 1.5], [0.5, 1.0]]],
[[[1.5, 1.0], [1.0, 1.5]]],
[[[1.5, 1.0], [0.5, 1.0]]],
[[[1.0, 0.5], [1.5, 1.0]]],
[[[1.0, 1.5], [0.5, 1.0]], [[1.0, 0.5], [1.5, 1.0]]],
[[[1.0, 0.5], [1.0, 1.5]]],
[[[1.0, 0.5], [0.5, 1.0]]],
[[[0.5, 1.0], [1.0, 0.5]]],
[[[1.0, 1.5], [1.0, 0.5]]],
[[[0.5, 1.0], [1.0, 0.5]], [[1.5, 1.0], [1.0, 1.5]]],
[[[1.5, 1.0], [1.0, 0.5]]],
[[[0.5, 1.0], [1.5, 1.0]]],
[[[1.0, 1.5], [1.5, 1.0]]],
[[[0.5, 1.0], [1.0, 1.5]]],
[]
];
export default function() {
var dx = 1,
dy = 1,
threshold = thresholdSturges,
smooth = smoothLinear;
function contours(values) {
var tz = threshold(values);
// Convert number of thresholds into uniform thresholds.
if (!Array.isArray(tz)) {
var domain = extent(values), start = domain[0], stop = domain[1];
tz = tickStep(start, stop, tz);
tz = range(Math.floor(start / tz) * tz, Math.floor(stop / tz) * tz, tz);
} else {
tz = tz.slice().sort(ascending);
}
return tz.map(function(value) {
return contour(values, value);
});
}
// Accumulate, smooth contour rings, assign holes to exterior rings.
// Based on https://github.com/mbostock/shapefile/blob/v0.6.2/shp/polygon.js
function contour(values, value) {
var polygons = [],
holes = [];
isorings(values, value, function(ring) {
smooth(ring, values, value);
if (area(ring) > 0) polygons.push([ring]);
else holes.push(ring);
});
holes.forEach(function(hole) {
for (var i = 0, n = polygons.length, polygon; i < n; ++i) {
if (contains((polygon = polygons[i])[0], hole) !== -1) {
polygon.push(hole);
return;
}
}
});
return {
type: "MultiPolygon",
value: value,
coordinates: polygons
};
}
// Marching squares with isolines stitched into rings.
// Based on https://github.com/topojson/topojson-client/blob/v3.0.0/src/stitch.js
function isorings(values, value, callback) {
var fragmentByStart = new Array,
fragmentByEnd = new Array,
x, y, t0, t1, t2, t3;
// Special case for the first row (y = -1, t2 = t3 = 0).
x = y = -1;
t1 = values[0] >= value;
cases[t1 << 1].forEach(stitch);
while (++x < dx - 1) {
t0 = t1, t1 = values[x + 1] >= value;
cases[t0 | t1 << 1].forEach(stitch);
}
cases[t1 << 0].forEach(stitch);
// General case for the intermediate rows.
while (++y < dy - 1) {
x = -1;
t1 = values[y * dx + dx] >= value;
t2 = values[y * dx] >= value;
cases[t1 << 1 | t2 << 2].forEach(stitch);
while (++x < dx - 1) {
t0 = t1, t1 = values[y * dx + dx + x + 1] >= value;
t3 = t2, t2 = values[y * dx + x + 1] >= value;
cases[t0 | t1 << 1 | t2 << 2 | t3 << 3].forEach(stitch);
}
cases[t1 | t2 << 3].forEach(stitch);
}
// Special case for the last row (y = dy - 1, t0 = t1 = 0).
x = -1;
t2 = values[y * dx] >= value;
cases[t2 << 2].forEach(stitch);
while (++x < dx - 1) {
t3 = t2, t2 = values[y * dx + x + 1] >= value;
cases[t2 << 2 | t3 << 3].forEach(stitch);
}
cases[t2 << 3].forEach(stitch);
function stitch(line) {
var start = [line[0][0] + x, line[0][1] + y],
end = [line[1][0] + x, line[1][1] + y],
startIndex = index(start),
endIndex = index(end),
f, g;
if (f = fragmentByEnd[startIndex]) {
if (g = fragmentByStart[endIndex]) {
delete fragmentByEnd[f.end];
delete fragmentByStart[g.start];
if (f === g) {
f.ring.push(end);
callback(f.ring);
} else {
fragmentByStart[f.start] = fragmentByEnd[g.end] = {start: f.start, end: g.end, ring: f.ring.concat(g.ring)};
}
} else {
delete fragmentByEnd[f.end];
f.ring.push(end);
fragmentByEnd[f.end = endIndex] = f;
}
} else if (f = fragmentByStart[endIndex]) {
if (g = fragmentByEnd[startIndex]) {
delete fragmentByStart[f.start];
delete fragmentByEnd[g.end];
if (f === g) {
f.ring.push(end);
callback(f.ring);
} else {
fragmentByStart[g.start] = fragmentByEnd[f.end] = {start: g.start, end: f.end, ring: g.ring.concat(f.ring)};
}
} else {
delete fragmentByStart[f.start];
f.ring.unshift(start);
fragmentByStart[f.start = startIndex] = f;
}
} else {
fragmentByStart[startIndex] = fragmentByEnd[endIndex] = {start: startIndex, end: endIndex, ring: [start, end]};
}
}
}
function index(point) {
return point[0] * 2 + point[1] * (dx + 1) * 4;
}
function smoothLinear(ring, values, value) {
ring.forEach(function(point) {
var x = point[0],
y = point[1],
xt = x | 0,
yt = y | 0,
v0,
v1 = values[yt * dx + xt];
if (x > 0 && x < dx && xt === x) {
v0 = values[yt * dx + xt - 1];
point[0] = x + (value - v0) / (v1 - v0) - 0.5;
}
if (y > 0 && y < dy && yt === y) {
v0 = values[(yt - 1) * dx + xt];
point[1] = y + (value - v0) / (v1 - v0) - 0.5;
}
});
}
contours.contour = contour;
contours.size = function(_) {
if (!arguments.length) return [dx, dy];
var _0 = Math.ceil(_[0]), _1 = Math.ceil(_[1]);
if (!(_0 > 0) || !(_1 > 0)) throw new Error("invalid size");
return dx = _0, dy = _1, contours;
};
contours.thresholds = function(_) {
return arguments.length ? (threshold = typeof _ === "function" ? _ : Array.isArray(_) ? constant(slice.call(_)) : constant(_), contours) : threshold;
};
contours.smooth = function(_) {
return arguments.length ? (smooth = _ ? smoothLinear : noop, contours) : smooth === smoothLinear;
};
return contours;
}
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