sample/src/main/kotlin/com/airbnb/lottie/samples/utils/FragmentViewBindingDelegate.kt

package com.airbnb.lottie.samples.utils

import android.os.Handler
import android.os.Looper
import android.view.View
import androidx.fragment.app.Fragment
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleObserver
import androidx.lifecycle.OnLifecycleEvent
import androidx.viewbinding.ViewBinding
import kotlin.properties.ReadOnlyProperty
import kotlin.reflect.KProperty

/**
 * Create bindings for a view similar to bindView.
 *
 * To use, just call
 * private val binding: FHomeWorkoutDetailsBinding by viewBinding()
 * with your binding class and access it as you normally would.
 */
inline fun <reified T : ViewBinding> Fragment.viewBinding() = FragmentViewBindingDelegate(T::class.java, this)

class FragmentViewBindingDelegate<T : ViewBinding>(
        bindingClass: Class<T>,
        val fragment: Fragment
) : ReadOnlyProperty<Fragment, T> {
    private val clearBindingHandler by lazy(LazyThreadSafetyMode.NONE) { Handler(Looper.getMainLooper()) }
    private var binding: T? = null

    private val bindMethod = bindingClass.getMethod("bind", View::class.java)

    init {
        fragment.viewLifecycleOwnerLiveData.observe(fragment) { viewLifecycleOwner ->
            viewLifecycleOwner.lifecycle.addObserver(object : LifecycleObserver {
                @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
                fun onDestroy() {
                    // Lifecycle listeners are called before onDestroyView in a Fragment.
                    // However, we want views to be able to use bindings in onDestroyView
                    // to do cleanup so we clear the reference one frame later.
                    clearBindingHandler.post { binding = null }
                }
            })
        }
    }

    @Suppress("UNCHECKED_CAST")
    override fun getValue(thisRef: Fragment, property: KProperty<*>): T {
        binding?.let { return it }

        val lifecycle = fragment.viewLifecycleOwner.lifecycle
        if (!lifecycle.currentState.isAtLeast(Lifecycle.State.INITIALIZED)) {
            error("Cannot access view bindings. View lifecycle is ${lifecycle.currentState}!")
        }

        binding = bindMethod.invoke(null, thisRef.requireView()) as T
        return binding!!
    }
}