edit-distance/myers-1986

import assert from 'assert';

import boundAlloc from './boundAlloc.js';
import arrayRealloc from './arrayRealloc.js';

/**
 * TwoWayRealloc.
 *
 * @param {Int8Array|Int16Array|Int32Array} B
 * @param {number} MAX
 * @param {number} li
 * @param {number} lj
 * @param {number} ri
 * @param {number} rj
 */
export default function twoWayRealloc(B, MAX, li, lj, ri, rj) {
    const HALF_MAX = ((MAX >> 1) + (MAX & 1)) | 0; // Ceil(MAX / 2);

    const lMAX = boundAlloc(HALF_MAX, li, lj);
    const rMAX = boundAlloc(HALF_MAX, ri, rj);
    const n = (((rMAX + 1) | 0) + lMAX) | 0;
    assert(rMAX + 1 < n);

    const V = arrayRealloc(lj, B);
    assert(V.length >= 2 * n);
    V.fill(li, 0, n);
    V.fill(lj, n, n << 1);
    const centerF = rMAX;
    const centerB = (n + lMAX) | 0;

    return {
        V,
        centerF,
        centerB,
    };
}