/*
 * Copyright (C) 2026 Mateusz Gruszczynski @linuxiarz.pl
 * Source-Available Code / Dual-Licensed.
 * See LICENSE.md for terms.
 */

// Preserve existing nodes. Remove stale entries first: otherwise deleting a
// user near the start of a 1000-person list would move every following node.
// `desired` must contain each node at most once.
export function reconcileChildren(container, desired) {
  const retained = new Set(desired);
  for (const node of [...container.childNodes]) {
    if (!retained.has(node)) node.remove();
  }
  let cursor = container.firstChild;
  for (const node of desired) {
    if (node === cursor) cursor = cursor.nextSibling;
    else container.insertBefore(node, cursor);
  }
}