rv.kt

private val ITEM_VIEW_TYPE_HEADER = 0
private val ITEM_VIEW_TYPE_ITEM = 1

class TopRatedMovieAdapter(private val clickListener: MovieListener) :
    ListAdapter<DataItem, RecyclerView.ViewHolder>(MovieNightDiffCallback()) {


    private val adapterScope = CoroutineScope(Dispatchers.Default)

    fun addHeaderAndSubmitList(list: List<SmallMovieList>?) {
        adapterScope.launch {
            val items = when (list) {
                null -> listOf(DataItem.Header)
                else -> list.map { DataItem.MovieItem(it) } + listOf(DataItem.Header)
            }
            withContext(Dispatchers.Main) {
                submitList(items)
            }
        }
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {

        when (holder) {
            is ViewHolder -> {
                val movieItem = getItem(position) as DataItem.MovieItem

                holder.itemView.setOnClickListener {
                    clickListener.onClick(movieItem.movie)
                }
                holder.bind(movieItem.movie)
            }
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
        return when (viewType) {
            ITEM_VIEW_TYPE_HEADER -> TextViewHolder.from(parent)
            ITEM_VIEW_TYPE_ITEM -> ViewHolder.from(parent)
            else -> throw ClassCastException("Unknown viewType ${viewType}")
        }
    }

    override fun getItemViewType(position: Int): Int {
        return when (getItem(position)) {
            is DataItem.Header -> ITEM_VIEW_TYPE_HEADER
            is DataItem.MovieItem -> ITEM_VIEW_TYPE_ITEM
        }
    }

    class TextViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        companion object {
            fun from(parent: ViewGroup): TextViewHolder {
                val layoutInflater = LayoutInflater.from(parent.context)
                val view = layoutInflater.inflate(R.layout.button_full, parent, false)
                return TextViewHolder(view)
            }
        }
    }

    class ViewHolder private constructor(val binding: ItemBinding) :
        RecyclerView.ViewHolder(binding.root) {

        fun bind(item: SmallMovieList) {
            binding.movie = item
            binding.executePendingBindings()
        }

        companion object {
            fun from(parent: ViewGroup): ViewHolder {
                val layoutInflater = LayoutInflater.from(parent.context)
                val binding = ItemBinding.inflate(layoutInflater, parent, false)
                return ViewHolder(binding)
            }
        }
    }
}

class MovieNightDiffCallback : DiffUtil.ItemCallback<DataItem>() {
    override fun areItemsTheSame(oldItem: DataItem, newItem: DataItem): Boolean {
        return oldItem.id == newItem.id
    }

    @SuppressLint("DiffUtilEquals")
    override fun areContentsTheSame(oldItem: DataItem, newItem: DataItem): Boolean {
        return oldItem == newItem
    }
}


sealed class DataItem {
    data class MovieItem(val movie: SmallMovieList) : DataItem() {
        override val id = movie.id.toLong()
    }

    object Header : DataItem() {
        override val id = Long.MIN_VALUE
    }

    abstract val id: Long
}

class MovieListener(val clickListener: (movie: SmallMovieList) -> Unit) {
    fun onClick(movie: SmallMovieList) = clickListener(movie)
}