/**
 * @fileoverview AsyncLocalStorage-backed trace context (no logger dependency).
 * Split from trace.js to avoid circular imports with logger.js.
 * @module debug/trace-context
 */

import { AsyncLocalStorage } from 'node:async_hooks';
import { randomBytes } from 'node:crypto';

/**
 * @typedef {Object} TraceContext
 * @property {string} traceId
 * @property {string} [span]
 */

/** @type {AsyncLocalStorage<TraceContext>} */
export const traceStorage = new AsyncLocalStorage();

/**
 * Generate a short opaque trace id (16 hex chars).
 * @returns {string}
 */
export function generateTraceId() {
  return randomBytes(8).toString('hex');
}

/**
 * @returns {string|null}
 */
export function getTraceId() {
  return traceStorage.getStore()?.traceId ?? null;
}

/**
 * @returns {TraceContext|null}
 */
export function getTraceContext() {
  return traceStorage.getStore() ?? null;
}