persephone/Persephone/Services/Extensions/AlbumArtService+Remote.swift

//
//  AlbumArtService+Remote.swift
//  Persephone
//
//  Created by Daniel Barber on 2019/3/17.
//  Copyright © 2019 Dan Barber. All rights reserved.
//

import Cocoa
import SwiftyJSON
import PromiseKit
import PMKFoundation

extension AlbumArtService {
  enum MusicBrainzError: Error {
    case noArtworkAvailable
  }

  func getRemoteArtwork() -> Promise<NSImage> {
    return Promise { seal in
      let albumArtWorkItem = DispatchWorkItem {
        self.getArtworkFromMusicBrainz().pipe(to: seal.resolve)
      }

      AlbumArtQueue.shared.addToQueue(workItem: albumArtWorkItem)
    }
  }

  func getArtworkFromMusicBrainz() -> Promise<NSImage> {
    var search = URLComponents(string: "https://musicbrainz.org/ws/2/release/")!
    search.query = "query=artist:\(album.artist) AND release:\(album.title) AND country:US&limit=1&fmt=json"

    return URLSession.shared.dataTask(.promise, with: search.url!).validate()
      .compactMap {
        JSON($0.data)
      }.compactMap {
        $0["releases"][0]["id"].string
      }.compactMap {
        URLComponents(string: "https://coverartarchive.org/release/\($0)/front-500")?.url
      }.then { (url: URL?) -> Promise<(data: Data, response: URLResponse)> in
        return URLSession.shared.dataTask(.promise, with: url!).validate()
      }.compactMap {
        NSImage(data: $0.data)?.toFitBox(
          size: NSSize(width: self.cachedArtworkSize, height: self.cachedArtworkSize)
        )
      }.recover { error -> Promise<NSImage> in
        if case PMKHTTPError.badStatusCode(404, _, _) = error {
          throw MusicBrainzError.noArtworkAvailable
        } else {
          throw error
        }
      }
  }
}