export const PI_RUNTIME_MILESTONES = [
  'worker.queue_wait',
  'worker.spawn',
  'rpc.ready',
  'session.open',
  'resources.ready',
  'prompt.accepted',
  'agent.settled',
] as const;

export type PiRuntimeMilestone = (typeof PI_RUNTIME_MILESTONES)[number];

export interface PiRuntimeTelemetryEvent {
  milestone: PiRuntimeMilestone;
  conversationRef: string;
  workerGeneration: number;
  spanId: string;
  runRef?: string;
  cold: boolean;
  durationMs: number;
  at: number;
}

export interface PiRuntimeMilestoneInput {
  milestone: PiRuntimeMilestone;
  conversationId: string;
  workerGeneration: number;
  runId?: string;
  cold: boolean;
  durationMs: number;
  at: number;
}

function shortRef(value: string): string {
  const normalized = value.replace(/[^A-Za-z0-9]/g, '');
  return normalized.slice(-8).toLowerCase() || 'unknown';
}

export function createPiRuntimeTelemetryEvent(
  input: PiRuntimeMilestoneInput,
): PiRuntimeTelemetryEvent {
  const conversationRef = shortRef(input.conversationId);
  const runRef = input.runId ? shortRef(input.runId) : undefined;
  return {
    milestone: input.milestone,
    conversationRef,
    workerGeneration: input.workerGeneration,
    spanId: runRef
      ? `${conversationRef}:${runRef}`
      : `${conversationRef}:worker-${input.workerGeneration}`,
    ...(runRef ? { runRef } : {}),
    cold: input.cold,
    durationMs: Math.max(0, Math.round(input.durationMs)),
    at: input.at,
  };
}