record-shop/server/src/discogs.ts

import type { SerialQueue } from './queue.js'

export interface DiscogsReleaseSummary {
  id: number
  artist: string
  title: string
  year: number | null
  formats: string[]
  labels: string[]
  country: string | null
  catno: string | null
  thumbUrl: string | null
}

export interface DiscogsReleaseFull extends DiscogsReleaseSummary {
  genres: string[]
  tracklist: { position: string; title: string }[]
  coverUrl: string | null
  barcodes: string[]
}

export class DiscogsError extends Error {
  constructor(
    public status: number,
    message: string
  ) {
    super(message)
    this.name = new.target.name
  }
}
export class DiscogsAuthError extends DiscogsError {
  constructor() {
    super(401, 'discogs token rejected')
  }
}
export class DiscogsRateLimitError extends DiscogsError {
  constructor() {
    super(429, 'discogs rate limit hit')
  }
}

const USER_AGENT = 'record-shop/0.1.0'

function splitTitle(title: string): { artist: string; title: string } {
  const idx = title.indexOf(' - ')
  if (idx === -1) return { artist: '', title }
  return { artist: title.slice(0, idx), title: title.slice(idx + 3) }
}

export function toYear(year: unknown): number | null {
  const n = Number(year)
  return Number.isInteger(n) && n > 0 ? n : null
}

export function mapSearchResult(r: any): DiscogsReleaseSummary {
  const src = r ?? {}
  const { artist, title } = splitTitle(String(src.title ?? ''))
  return {
    id: Number(src.id),
    artist,
    title,
    year: toYear(src.year),
    formats: Array.isArray(src.format) ? src.format.filter((f: any) => f != null).map(String) : [],
    labels: Array.isArray(src.label) ? src.label.filter((l: any) => l != null).map(String) : [],
    country: src.country ?? null,
    catno: src.catno ?? null,
    thumbUrl: src.thumb ?? src.cover_image ?? null,
  }
}

export function mapRelease(r: any): DiscogsReleaseFull {
  const src = r ?? {}
  return {
    id: Number(src.id),
    artist: Array.isArray(src.artists) && src.artists[0] ? String(src.artists[0]?.name ?? '') : '',
    title: String(src.title ?? ''),
    year: toYear(src.year),
    formats: Array.isArray(src.formats) ? src.formats.map((f: any) => String(f?.name ?? '')) : [],
    labels: Array.isArray(src.labels) ? src.labels.map((l: any) => String(l?.name ?? '')) : [],
    country: src.country ?? null,
    catno: Array.isArray(src.labels) && src.labels[0] ? (src.labels[0]?.catno ?? null) : null,
    thumbUrl: src.thumb ?? (src.images?.[0]?.uri ?? null),
    genres: Array.isArray(src.genres) ? src.genres.filter((g: any) => g != null).map(String) : [],
    tracklist: Array.isArray(src.tracklist)
      ? src.tracklist
          .filter((t: any) => t?.title)
          .map((t: any) => ({ position: String(t?.position ?? ''), title: String(t?.title ?? '') }))
      : [],
    coverUrl: src.images?.[0]?.uri ?? null,
    barcodes: Array.isArray(src.identifiers)
      ? src.identifiers
          .filter((i: any) => i?.type === 'Barcode' && i?.value)
          .map((i: any) => String(i.value))
      : [],
  }
}

export class DiscogsClient {
  private token: string
  private fetchImpl: typeof fetch
  private baseUrl: string
  private queue?: SerialQueue

  constructor(token: string, fetchImpl: typeof fetch = fetch, baseUrl = 'https://api.discogs.com', queue?: SerialQueue) {
    this.token = token
    this.fetchImpl = fetchImpl
    this.baseUrl = baseUrl
    this.queue = queue
  }

  private async get(path: string, params: Record<string, string> = {}): Promise<any> {
    const doFetch = async (): Promise<any> => {
      const url = new URL(`${this.baseUrl}${path}`)
      for (const [k, v] of Object.entries(params)) url.searchParams.set(k, v)
      let res: Response
      try {
        res = await this.fetchImpl(url.toString(), {
          headers: {
            Authorization: `Discogs token=${this.token}`,
            'User-Agent': USER_AGENT,
            Accept: 'application/json',
          },
        })
      } catch {
        throw new DiscogsError(0, 'could not reach api.discogs.com')
      }
      if (res.status === 401) throw new DiscogsAuthError()
      if (res.status === 429) throw new DiscogsRateLimitError()
      if (!res.ok) throw new DiscogsError(res.status, `discogs HTTP ${res.status}`)
      try {
        return await res.json()
      } catch {
        throw new DiscogsError(res.status, 'discogs returned a non-JSON response')
      }
    }
    return this.queue ? this.queue.run(doFetch) : doFetch()
  }

  async searchByBarcode(barcode: string): Promise<DiscogsReleaseSummary[]> {
    const body = await this.get('/database/search', { barcode, type: 'release', per_page: '20' })
    const results: any[] = Array.isArray(body?.results) ? body.results : []
    return results.map(mapSearchResult)
  }

  async searchByText(query: string, format?: string): Promise<DiscogsReleaseSummary[]> {
    const params: Record<string, string> = { q: query, type: 'release', per_page: '20' }
    if (format) params.format = format
    const body = await this.get('/database/search', params)
    const results: any[] = Array.isArray(body?.results) ? body.results : []
    return results.map(mapSearchResult)
  }

  async getRelease(id: number): Promise<DiscogsReleaseFull> {
    const body = await this.get(`/releases/${id}`)
    return mapRelease(body)
  }
}