/**
 * Options + query builder for the interchain-trace endpoints
 * (transaction.getInterchain / block.getInterchain).
 *
 * Anchor proofs are chained, so by default the trace returns the first anchor
 * per public chain; these options change how many and which chains are returned.
 */

export interface InterchainOptions {
  /**
   * Max interchain anchors returned per public chain, earliest-first.
   * 1 = the first anchor per chain (the service default); 0 = all anchors.
   */
  perChain?: number;
  /**
   * Interchain chain ids to include ("1" = ETH mainnet, "0" = BTC; testnet ids
   * differ). Omit to include every chain found.
   */
  chains?: string[];
}

/**
 * Builds the "?perChain=...&chains=..." suffix for the interchain trace
 * endpoints. Returns "" when no options are set (the server then applies its
 * defaults: one anchor per chain, all chains).
 */
export function buildInterchainQuery(options?: InterchainOptions): string {
  if (!options) return '';
  const parts: string[] = [];
  if (options.perChain !== undefined) {
    parts.push(`perChain=${encodeURIComponent(String(options.perChain))}`);
  }
  if (options.chains && options.chains.length > 0) {
    parts.push(`chains=${options.chains.map(encodeURIComponent).join(',')}`);
  }
  return parts.length ? `?${parts.join('&')}` : '';
}