import android.graphics.Typeface
import android.os.Handler
import android.os.Looper
import android.view.View
import android.widget.ImageView
import android.widget.TextView
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.LinearSmoothScroller
import androidx.recyclerview.widget.RecyclerView
class TwoRecyclerViews(
    private val recyclerViewHorizontal: RecyclerView,
    private val recyclerViewVertical: RecyclerView,
    private var indices: List<Int>,
    private var isSmoothScroll: Boolean = false,
private var attached = false
private var horizontalRecyclerState = RecyclerView.SCROLL_STATE_IDLE
private var verticalRecyclerState = RecyclerView.SCROLL_STATE_IDLE
private val smoothScrollerVertical: RecyclerView.SmoothScroller =
    object : LinearSmoothScroller(recyclerViewVertical.context) {
        override fun getVerticalSnapPreference(): Int {
            return SNAP_TO_START
fun attach() {
    recyclerViewHorizontal.adapter
        ?: throw RuntimeException("Cannot attach with no Adapter provided to RecyclerView")
    recyclerViewVertical.adapter
        ?: throw RuntimeException("Cannot attach with no Adapter provided to RecyclerView")
    updateFirstPosition()
    notifyIndicesChanged()
    attached = true
private fun detach() {
    recyclerViewVertical.clearOnScrollListeners()
    recyclerViewHorizontal.clearOnScrollListeners()
fun reAttach() {
    detach()
    attach()
private fun updateFirstPosition() {
    Handler(Looper.getMainLooper()).postDelayed({
        val view = recyclerViewHorizontal.findViewHolderForLayoutPosition(0)?.itemView
        val textView = view?.findViewById<TextView>(R.id.horizontalCategoryName)
        val imageView = view?.findViewById<ImageView>(R.id.categorySelectionIndicator)
        imageView?.visibility = View.VISIBLE
        textView?.setTypeface(null, Typeface.BOLD)
        textView?.setTextColor(recyclerViewVertical.context.getColor(R.color.primary_1))
    }, 100)
fun isAttached() = attached
private fun notifyIndicesChanged() {
    recyclerViewHorizontal.addOnScrollListener(onHorizontalScrollListener)
    recyclerViewVertical.addOnScrollListener(onVerticalScrollListener)
private val onHorizontalScrollListener = object : RecyclerView.OnScrollListener() {
    override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
        horizontalRecyclerState = newState
    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)
        val linearLayoutManager: LinearLayoutManager =
            recyclerView.layoutManager as LinearLayoutManager?
                ?: throw RuntimeException("No LinearLayoutManager attached to the RecyclerView.")
        var itemPosition =
            linearLayoutManager.findFirstCompletelyVisibleItemPosition()
        if (itemPosition == -1) {
            itemPosition =
                linearLayoutManager.findFirstVisibleItemPosition()
        if (horizontalRecyclerState == RecyclerView.SCROLL_STATE_DRAGGING ||
            horizontalRecyclerState == RecyclerView.SCROLL_STATE_SETTLING
            for (position in indices.indices) {
                val view = recyclerView.findViewHolderForLayoutPosition(indices[position])?.itemView
                val textView = view?.findViewById<TextView>(R.id.horizontalCategoryName)
                val imageView = view?.findViewById<ImageView>(R.id.categorySelectionIndicator)
                if (itemPosition == indices[position]) {
                    if (isSmoothScroll) {
                        smoothScrollerVertical.targetPosition = indices[position]
                        recyclerViewVertical.layoutManager?.startSmoothScroll(smoothScrollerVertical)
                    } else {
                        (recyclerViewVertical.layoutManager as LinearLayoutManager?)?.scrollToPositionWithOffset(
                            indices[position], 16.dpToPx()
                    imageView?.visibility = View.VISIBLE
                    textView?.setTypeface(null, Typeface.BOLD)
                    textView?.setTextColor(recyclerView.context.getColor(R.color.primary_1))
                } else {
                    imageView?.visibility = View.GONE
                    textView?.setTypeface(null, Typeface.NORMAL)
                    textView?.setTextColor(recyclerView.context.getColor(R.color.secondary_5))
private val onVerticalScrollListener = object : RecyclerView.OnScrollListener() {
    override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
        verticalRecyclerState = newState
    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)
        val linearLayoutManager: LinearLayoutManager =
            recyclerView.layoutManager as LinearLayoutManager?
                ?: throw RuntimeException("No LinearLayoutManager attached to the RecyclerView.")
        var itemPosition =
            linearLayoutManager.findFirstCompletelyVisibleItemPosition()
        if (itemPosition == -1) {
            itemPosition =
                linearLayoutManager.findFirstVisibleItemPosition()
        if (verticalRecyclerState == RecyclerView.SCROLL_STATE_DRAGGING ||
            verticalRecyclerState == RecyclerView.SCROLL_STATE_SETTLING
            for (position in indices.indices) {
                val view = recyclerViewHorizontal.findViewHolderForAdapterPosition(indices[position])?.itemView
                val textView = view?.findViewById<TextView>(R.id.horizontalCategoryName)
                val imageView = view?.findViewById<ImageView>(R.id.categorySelectionIndicator)
                if (itemPosition == indices[position]) {
                    (recyclerViewHorizontal.layoutManager as LinearLayoutManager?)?.scrollToPositionWithOffset(
                        indices[position], 16.dpToPx()
                    imageView?.visibility = View.VISIBLE
                    textView?.setTypeface(null, Typeface.BOLD)
                    textView?.setTextColor(recyclerViewVertical.context.getColor(R.color.primary_1))
                } else {
                    imageView?.visibility = View.GONE
                    textView?.setTypeface(null, Typeface.NORMAL)
                    textView?.setTextColor(recyclerViewVertical.context.getColor(R.color.secondary_5))