/**
 * How a release got its name, as releases.source stores it (a smallint; voyager 3, migration 6000). The names are
 * what the edge, the spot inspector and the API use; the numbers never change meaning once written.
 */
export const SOURCES = {
  /** A name the subject announces ("name" yEnc (k/N)). */
  subject: 1,
  /** The post's files, named after the first file (no release name in the subject). */
  post: 2,
  /** The files' shared stem. */
  stem: 3,
  /** A Spotnet spot's files that matched no release. */
  spot: 4,
  /** An NZB's files. */
  nzb: 5,
  /** One poster's files that differ only by a number sequence, or share a prefix (voyager 3). */
  album: 6,
  /** An obfuscated post's stem, read from the yEnc body (identity.ts: weak). */
  'weak-stem': 7,
} as const

export type Source = keyof typeof SOURCES

const NAMES = Object.fromEntries(
  Object.entries(SOURCES).map(([name, code]) => [code, name])
) as Record<number, Source>

/** The code of a source name; throws for an unknown one (a typo would write a wrong number for good). */
export function sourceCode(name: string): number {
  const code = SOURCES[name as Source]
  if (code === undefined) throw new Error(`Unknown release source "${name}"`)
  return code
}

/** The name of a stored code; "unknown" for one not listed (never written, but a row might be read by an older build). */
export function sourceName(code: number | string | null | undefined): Source | 'unknown' {
  return NAMES[Number(code)] ?? 'unknown'
}