1
import { z } from 'zod';
2
 
3
const tagSchema = z
4
  .string()
5
  .max(256)
6
  .refine((value) => new TextEncoder().encode(value).byteLength <= 256 && !/\p{Cc}/u.test(value));
7
export const trackSchema = z
8
  .object({
9
    title: tagSchema.refine((value) => value.trim().length > 0),
10
    artist: tagSchema,
11
    durationMs: z.number().int().positive().max(600000).multipleOf(20),
12
  })
13
  .strict();
14
 
15
export type Track = z.infer<typeof trackSchema>;
16
 
17
export const nowPlayingSchema = z
18
  .object({
19
    revision: z.number().int().min(0).max(0xffff_ffff),
20
    trackIndex: z.number().int().min(0).max(31),
21
    trackCount: z.number().int().min(1).max(32),
22
    track: trackSchema.nullable(),
23
  })
24
  .strict()
25
  .refine((value) => value.trackIndex < value.trackCount);
26
 
27
export type NowPlaying = z.infer<typeof nowPlayingSchema>;
28
 
29
/** Wrapping sequence comparison within one publisher generation. */
30
export function newerRevision(next: number, previous: number): boolean {
31
  const distance = (next - previous) >>> 0;
32
  return distance > 0 && distance < 0x8000_0000;
33
}
34
 
35
export function sameNowPlaying(a: NowPlaying, b: NowPlaying): boolean {
36
  return (
37
    a.revision === b.revision &&
38
    a.trackIndex === b.trackIndex &&
39
    a.trackCount === b.trackCount &&
40
    a.track?.title === b.track?.title &&
41
    a.track?.artist === b.track?.artist &&
42
    a.track?.durationMs === b.track?.durationMs
43
  );
44
}