/**
 * Ordered hop log from Zapier input through every module to the response.
 * @module trace
 */

export class TraceBus {
  constructor() {
    this.events = [];
    this.t0 = Date.now();
  }

  now() {
    return Date.now() - this.t0;
  }

  /**
   * @param {{
   *   module: string,
   *   hop: string,
   *   dir?: 'in'|'out'|'internal',
   *   address?: string,
   *   status?: 'ok'|'silent'|'error'|'retry'|'delay'|'skip',
   *   payload?: object,
   *   note?: string,
   *   durationMs?: number
   * }} e
   */
  emit(e) {
    const ev = {
      seq: this.events.length + 1,
      tMs: this.now(),
      module: e.module,
      hop: e.hop,
      dir: e.dir || 'internal',
      address: e.address || '',
      status: e.status || 'ok',
      payload: e.payload ?? null,
      note: e.note || '',
      durationMs: e.durationMs ?? 0,
    };
    this.events.push(ev);
    return ev;
  }
}