Function applyTransformDiff

packages/2d/src/lib/utils/diff.ts:101–148

(
  current: T[],
  diff: TransformDiff<T>,
  cloner: (original: T) => T,
)

}

export function applyTransformDiff<T extends Idable>(
  current: T[],
  diff: TransformDiff<T>,
  cloner: (original: T) => T,
): ApplyTransformResult<T> {
  function insert(item: TransformDiffItem<T>) {
    let idIndex = -1;
    const index = item.before
      ? current.findIndex(({id}) => {
          if (id === item.before?.id) {
            idIndex++;
            if (idIndex === item.beforeIdIndex) return true;
          }
          return false;
        })
      : 0;
    current.splice(index + 1, 0, item.current);
  }

  const result: ApplyTransformResult<T> = {
    inserted: diff.inserted.map(item => ({
      item,
      order: item.currentIndex,
    })),
  };

  for (const item of diff.transformed) {
    if (!item.insert) continue;

    const from = item.from;
    item.from = {
      ...item.to,
      current: cloner(from.current),
    };
    result.inserted.push({
      item: item.from,
      order: item.to.currentIndex,
    });
  }

  result.inserted.sort((a, b) => a.order - b.order);

  for (const item of result.inserted) {
    insert(item.item);
  }

  return result;
}