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import { robotMessageSchema } from '@/shared/contracts/robot.ts';
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import type { RobotMessage } from '@/shared/contracts/robot.ts';
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export type SpectrumFrame = {
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  pts: number;
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  positionMs: number;
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  paused: boolean;
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  bands: Uint8Array;
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  revision?: number;
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};
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export function parseRobot(data: unknown): RobotMessage | undefined {
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  if (typeof data !== 'string' || data.length > 4096) return;
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  try {
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    const parsed = robotMessageSchema.safeParse(JSON.parse(data));
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    return parsed.success ? parsed.data : undefined;
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  } catch {
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    return;
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  }
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}
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/** Wrapping transport milliseconds order frames across track changes and song restarts. */
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export function newerTimestamp(next: number, previous: number): boolean {
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  const distance = (next - previous) >>> 0;
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  return distance > 0 && distance < 0x8000_0000;
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}
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export function parseSpectrum(data: unknown, previous?: number): SpectrumFrame | undefined {
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  if (!(data instanceof ArrayBuffer) || (data.byteLength !== 44 && data.byteLength !== 48)) return;
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  const view = new DataView(data);
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  const version = view.getUint8(0);
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  if (
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    !((version === 1 && data.byteLength === 44) || (version === 2 && data.byteLength === 48)) ||
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    view.getUint8(1) > 1
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  )
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    return;
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  const pts = view.getUint32(4, true);
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  if (previous !== undefined && !newerTimestamp(pts, previous)) return;
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  return {
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    pts,
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    positionMs: view.getUint32(8, true),
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    paused: view.getUint8(1) === 1,
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    bands: new Uint8Array(data, 12, 32).slice(),
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    ...(version === 2 ? { revision: view.getUint32(44, true) } : {}),
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  };
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}
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export function commandId(): string {
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  // getRandomValues also works on a phone's HTTP development origin.
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  return Array.from(crypto.getRandomValues(new Uint8Array(16)), (byte) =>
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    byte.toString(16).padStart(2, '0'),
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  ).join('');
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}