import Foundation

enum ServerListState {
  case loading
  case loaded
  case error(ConnectionError)
}

final class ServerListViewModel: ObservableObject {
  struct Dependencies {
    let connection: Connection
    let database: Database
    let router: RocketChatAppRouter
  }
  
  private let dependencies: Dependencies
  
  @Published private(set) var state: ServerListState = .loading
  
  init(dependencies: Dependencies) {
    self.dependencies = dependencies
  }
  
  private func handleSuccess(message: WatchMessage) {
    message.servers.forEach(dependencies.database.process(updatedServer:))
    state = .loaded
  }
  
  private func handleFailure(error: Error) {
    guard let connectionError = error as? ConnectionError else {
      return
    }
    
    state = .error(connectionError)
  }
  
  func loadServers() {
    dependencies.connection.sendMessage { [weak self] result in
      guard let self else {
        return
      }
      
      switch result {
      case .success(let message):
        DispatchQueue.main.async { self.handleSuccess(message: message) }
      case .failure(let error):
        DispatchQueue.main.async { self.handleFailure(error: error) }
      }
    }
  }
  
  func didTap(server: Server) {
    dependencies.router.route(to: .roomList(server))
  }
}