Extensions to Android Arch Components

arch.components.kt

package uz.gap.messenger.ext

import android.arch.lifecycle.*
import android.support.v4.app.Fragment
import android.support.v4.app.FragmentActivity
import uz.gap.messenger.connection.SocketModel.MessageStatus

/**
 * created at 3/31/18
 *
 * @author Ozodrukh
 * @version 1.0
 */


inline fun <reified T : ViewModel> FragmentActivity.viewModelOf(tag: String? = null): T {
  return if (tag == null) {
    ViewModelProviders.of(this).get(T::class.java)
  } else {
    ViewModelProviders.of(this).get(tag, T::class.java)
  }
}

inline fun <reified T : ViewModel> Fragment.viewModelOf(tag: String? = null): T {
  return if (tag == null) {
    ViewModelProviders.of(this).get(T::class.java)
  } else {
    ViewModelProviders.of(this).get(tag, T::class.java)
  }
}

inline fun <reified T : ViewModel> Fragment.activityViewModelOf(tag: String? = null): T {
  return if (tag == null) {
    ViewModelProviders.of(activity!!).get(T::class.java)
  } else {
    ViewModelProviders.of(activity!!).get(tag, T::class.java)
  }
}

/**
 * Simple observer that used with kotlin to avoid null checks iach time
 */
inline fun <T> LiveData<T>.safeObserve(owner: LifecycleOwner, crossinline block: (T) -> Unit) {
  observe(owner, Observer { response -> response?.let(block) })
}


fun <K, T> LiveData<K>.then(transformer: (K) -> LiveData<T>?): LiveData<T> {
  return Transformations.switchMap<K, T>(this, transformer)
}

inline fun <T, K> LiveData<MessageStatus<T>>.thenWhenResponded(crossinline transformer: (MessageStatus<T>)
-> LiveData<MessageStatus<K>>?): LiveData<MessageStatus<K>> {

  return then {
    return@then if (it.delivered() && it.responded()) transformer(it) else null
  }
}