export default function sortKD(ids, coords, nodeSize, left, right, depth) {
    if (right - left <= nodeSize) return;

    const m = (left + right) >> 1;

    select(ids, coords, m, left, right, depth % 2);

    sortKD(ids, coords, nodeSize, left, m - 1, depth + 1);
    sortKD(ids, coords, nodeSize, m + 1, right, depth + 1);
}

function select(ids, coords, k, left, right, inc) {

    while (right > left) {
        if (right - left > 600) {
            const n = right - left + 1;
            const m = k - left + 1;
            const z = Math.log(n);
            const s = 0.5 * Math.exp(2 * z / 3);
            const sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * (m - n / 2 < 0 ? -1 : 1);
            const newLeft = Math.max(left, Math.floor(k - m * s / n + sd));
            const newRight = Math.min(right, Math.floor(k + (n - m) * s / n + sd));
            select(ids, coords, k, newLeft, newRight, inc);
        }

        const t = coords[2 * k + inc];
        let i = left;
        let j = right;

        swapItem(ids, coords, left, k);
        if (coords[2 * right + inc] > t) swapItem(ids, coords, left, right);

        while (i < j) {
            swapItem(ids, coords, i, j);
            i++;
            j--;
            while (coords[2 * i + inc] < t) i++;
            while (coords[2 * j + inc] > t) j--;
        }

        if (coords[2 * left + inc] === t) swapItem(ids, coords, left, j);
        else {
            j++;
            swapItem(ids, coords, j, right);
        }

        if (j <= k) left = j + 1;
        if (k <= j) right = j - 1;
    }
}

function swapItem(ids, coords, i, j) {
    swap(ids, i, j);
    swap(coords, 2 * i, 2 * j);
    swap(coords, 2 * i + 1, 2 * j + 1);
}

function swap(arr, i, j) {
    const tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
}