import {hasher} from "@chainsafe/persistent-merkle-tree";
import {byteArrayEquals} from "@lodestar/utils";

export const SYNC_COMMITTEES_DEPTH = 4;
export const SYNC_COMMITTEES_INDEX = 11;

/**
 * Verify that the given ``leaf`` is on the merkle branch ``proof``
 * starting with the given ``root``.
 *
 * Browser friendly version of verifyMerkleBranch
 */
export function isValidMerkleBranch(
  leaf: Uint8Array,
  proof: Uint8Array[],
  depth: number,
  index: number,
  root: Uint8Array
): boolean {
  let value = leaf;
  for (let i = 0; i < depth; i++) {
    if (Math.floor(index / 2 ** i) % 2) {
      value = hasher.digest64(proof[i], value);
    } else {
      value = hasher.digest64(value, proof[i]);
    }
  }
  return byteArrayEquals(value, root);
}