/**
 * Request tracing for Portal API calls.
 *
 * Propagation in the Web SDK:
 * - Browser: High-level methods (backup, recover, sendAsset, provider.request) accept optional
 *   traceId or generate one. They pass it to handleRequestToIframeAndPost (postMessage) or
 *   to fetch headers (X-Portal-Trace-Id).
 * - Iframe: On each portal:* message, the iframe reads traceId from the message (top-level or
 *   data.traceId), calls setRequestTraceId(traceId), which sets it on Api, Mpc, ZeroX, etc.
 *   All REST and MPC calls made during that request then use the same trace ID (header or reqId).
 * - After the request completes, clearRequestTraceId() is called so the next message gets a
 *   fresh or caller-provided trace ID.
 */

/**
 * HTTP header name for request tracing.
 * Used by connect-api (client + custodian APIs) in the Web SDK.
 * Note: Other internal services may use different header names.
 */
export const X_PORTAL_TRACE_ID_HEADER = 'X-Portal-Trace-Id'

/**
 * Generates a UUID v4 trace ID for request correlation.
 * Uses crypto.randomUUID() when available; otherwise crypto.getRandomValues() for better
 * quality than Math.random(); falls back to Math.random() only when no crypto API exists.
 */
export function generateTraceId(): string {
  if (
    typeof crypto !== 'undefined' &&
    typeof (crypto as Crypto).randomUUID === 'function'
  ) {
    return (crypto as Crypto).randomUUID()
  }
  if (
    typeof crypto !== 'undefined' &&
    typeof (crypto as Crypto).getRandomValues === 'function'
  ) {
    return fallbackUuidV4WithCrypto(crypto as Crypto)
  }
  return fallbackUuidV4WithMathRandom()
}

function fallbackUuidV4WithCrypto(crypto: Crypto): string {
  const bytes = new Uint8Array(16)
  crypto.getRandomValues(bytes)
  bytes[6] = (bytes[6]! & 0x0f) | 0x40
  bytes[8] = (bytes[8]! & 0x3f) | 0x80
  const hex = Array.from(bytes, (b) => b.toString(16).padStart(2, '0')).join('')
  return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20)}`
}

function fallbackUuidV4WithMathRandom(): string {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
    const r = (Math.random() * 16) | 0
    const v = c === 'x' ? r : (r & 0x3) | 0x8
    return v.toString(16)
  })
}