import SwiftUI
import UniformTypeIdentifiers

enum FilePreviewState: Equatable {
  case unloaded
  case loading
  case loaded
  case failed
}

enum FilePreviewType: Equatable {
  case unknown
  case image
  case text
}

@Observable
final class FilePreview: HotlineFilePreviewClientDelegate {
  @ObservationIgnored let info: PreviewFileInfo
  @ObservationIgnored var client: HotlineFilePreviewClient? = nil
  
  var state: FilePreviewState = .unloaded
  var progress: Double = 0.0
  
  var data: Data? = nil
  
  #if os(iOS)
  var image: UIImage? = nil
  #elseif os(macOS)
  var image: NSImage? = nil
  #endif
  
  var text: String? = nil
  var styledText: NSAttributedString? = nil
  
  var previewType: FilePreviewType {
    let fileExtension = (info.name as NSString).pathExtension
    if let fileType = UTType(filenameExtension: fileExtension) {
      if fileType.isSubtype(of: .image) {
        return .image
      }
      else if fileType.isSubtype(of: .text) {
        return .text
      }
    }
    return .unknown
  }
  
  init(info: PreviewFileInfo) {
    self.info = info
    
    self.client = HotlineFilePreviewClient(address: info.address, port: UInt16(info.port), reference: info.id, size: UInt32(info.size))
    self.client?.delegate = self
  }
  
  func download() {
    self.client?.start()
  }
  
  func cancel() {
    self.client?.cancel()
  }
  
  func hotlineTransferStatusChanged(client: any HotlineTransferClient, reference: UInt32, status: HotlineTransferStatus, timeRemaining: TimeInterval) {
    print("FilePreview: Download status changed:", status)
    
    switch status {
    case .unconnected:
      state = .unloaded
      progress = 0.0
    case .connecting:
      state = .loading
      progress = 0.0
    case .connected:
      state = .loading
      progress = 0.0
    case .progress(let p):
      state = .loading
      progress = p
    case .failed(_):
      state = .failed
      progress = 0.0
    case .completing:
      state = .loading
      progress = 1.0
    case .completed:
      state = .loaded
      progress = 1.0
    }
  }
  
  func hotlineFilePreviewComplete(client: HotlineFilePreviewClient, reference: UInt32, data: Data) {
    self.state = .loaded
    self.data = data
    
    switch self.previewType {
    case .image:
      #if os(iOS)
      self.image = UIImage(data: data)
      #elseif os(macOS)
      self.image = NSImage(data: data)
      #endif
    case .text:
      let encoding: UInt = NSString.stringEncoding(for: data, convertedString: nil, usedLossyConversion: nil)
      if encoding != 0 {
        self.text = String(data: data, encoding: String.Encoding(rawValue: encoding))
      }
      else {
        self.text = String(data: data, encoding: .utf8)
      }
    case .unknown:
      return
    }
  }
}