class DiffAdapter(private val item: Item) :
    ListAdapter<Pair<String, Double>, DiffViewHolder>(MyDiff()) {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = DiffViewHolder(
        LayoutInflater.from(parent.context).inflate(R.layout.item_converter, parent, false)
    )

    override fun onBindViewHolder(holder: DiffViewHolder, position: Int) {
        val measure = item.measures[position]

        holder.onBind(measure.first, item.value * measure.second, object : TextWatcher {
            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {

            }

            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
                item.value = s.toString().toDouble() / measure.second
                holder.itemView.post { notifyDataSetChanged() }
            }

            override fun afterTextChanged(s: Editable?) {
            }
        }) { v, hasFocus ->
            if (hasFocus) {
                item.measures.add(0, item.measures.removeAt(position))
                notifyItemMoved(position, 0)
            }
        }
    }

    override fun getItemCount(): Int {
        return item.measures.size
    }
}

class DiffViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

    val labelTv: TextView = itemView.findViewById(R.id.label_tv)
    val measureEdit: EditText = itemView.findViewById(R.id.measure_edit)

    fun onBind(
        label: String,
        currentValue: Double,
        watcher: TextWatcher,
        listener: View.OnFocusChangeListener
    ) {
        labelTv.text = label
        measureEdit.setText(currentValue.toString())
        measureEdit.addTextChangedListener(watcher)
        measureEdit.onFocusChangeListener = listener
    }

}

class MyDiff : DiffUtil.ItemCallback<Pair<String, Double>>() {
    override fun areItemsTheSame(
        oldItem: Pair<String, Double>,
        newItem: Pair<String, Double>
    ): Boolean {
        return oldItem.first == newItem.first
    }

    override fun areContentsTheSame(
        oldItem: Pair<String, Double>,
        newItem: Pair<String, Double>
    ): Boolean {
        return oldItem.first == newItem.first && oldItem.second == newItem.second
    }
}