persephone/Persephone/MPDClient/Extensions/MPDClient+Songs.swift

//
//  MPDClient+Songs.swift
//  Persephone
//
//  Created by Daniel Barber on 2019/7/19.
//  Copyright © 2019 Dan Barber. All rights reserved.
//

import Foundation
import mpdclient

extension MPDClient {
  func fetchAlbumArt(song: MPDSong, callback: @escaping (Data?) -> Void) {
    enqueueCommand(
      command: .fetchAlbumArt,
      userData: ["song": song, "callback": callback]
    )
  }
  
  func searchSongs(_ terms: [MPDClient.MPDTag: String]) -> [MPDSong] {
    var songs: [MPDSong] = []

    mpd_search_db_songs(self.connection, true)
    for (tag, term) in terms {
      mpd_search_add_tag_constraint(self.connection, MPD_OPERATOR_DEFAULT, tag.mpdTag(), term)
    }
    mpd_search_commit(self.connection)

    while let song = mpd_recv_song(self.connection) {
      songs.append(MPDSong(song))
    }

    return songs
  }
  
  func sendFetchAlbumArt(for song: MPDSong, callback: @escaping (Data?) -> Void) -> Void {
    var imageData: Data?
    var currentOffset: Int32 = 0
    
    var size: Int?
    
    while size == nil || currentOffset < size! {
      mpd_send_albumart(self.connection, song.uri, String(currentOffset))
      
      guard let sizePair = mpd_recv_pair(self.connection) else {
        mpd_connection_clear_error(self.connection)
        return
      }
      size = Int(MPDPair(sizePair).value)
      mpd_return_pair(self.connection, sizePair)

      if imageData == nil {
        imageData = Data(count: size!)
      }
            
      let binaryPair = MPDPair(mpd_recv_pair(self.connection))
      let chunkSize = Int(binaryPair.value)!
      mpd_return_pair(self.connection, binaryPair.pair)
      
      _ = imageData![currentOffset...].withUnsafeMutableBytes { (pointer) in
        mpd_recv_binary(self.connection, pointer, chunkSize)
      }
      
      guard mpd_response_finish(self.connection) else { return }
      
      currentOffset += Int32(chunkSize)
    }
    
    DispatchQueue.main.async {
      callback(imageData)
    }
  }
}