MaterialDividerVerticalOnlyWithFirstItem

/**
 * Inspiration and main resource taken from [com.google.android.material.divider.MaterialDividerItemDecoration]
 *
 * Divider is solving only vertical scrolling use case.
 * It divides items that are vertically scrolled + "divides" the first item (paints divider on top)
 *
 * Will not paint a full rectangle if the [RecyclerView] scrolls only in one direction, because
 * the dividers are pointed on top. So the dividers "stays on top" whenever scrolling.
 */
class MaterialDividerVerticalOnlyWithFirstItem(
    private val context: Context,
    private val gridSpanSize: Int = 1,
) : RecyclerView.ItemDecoration() {

    private var dividerDrawable: Drawable

    private var thickness = 0
    private var insetStart = 0
    private var insetEnd = 0
    private val tempRect = Rect()

    @ColorInt private var color = 0

    init {
        this.color = ContextCompat.getColor(context, R.color.cardStroke)
        this.thickness = context.dpToPx(1)
        this.insetStart = context.dpToPx(12)
        this.insetEnd = context.dpToPx(12)
        dividerDrawable = ShapeDrawable()
        setDividerColor(color)
    }

    override fun onDraw(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
        if (parent.layoutManager == null) {
            return
        }
        drawOnFirstItemForVertical(c, parent)
        drawForVerticalOrientation(c, parent)
    }

    private fun drawOnFirstItemForVertical(canvas: Canvas, parent: RecyclerView) {
        canvas.save()
        var left: Int
        var right: Int
        if (parent.clipToPadding) {
            left = parent.paddingLeft
            right = parent.width - parent.paddingRight
            canvas.clipRect(
                left, parent.paddingTop, right, parent.height - parent.paddingBottom
            )
        } else {
            left = 0
            right = parent.width
        }
        val isRtl = ViewCompat.getLayoutDirection(parent) == ViewCompat.LAYOUT_DIRECTION_RTL
        left += if (isRtl) insetEnd else insetStart
        right -= if (isRtl) insetStart else insetEnd
        val childCount = parent.childCount
        if (childCount > 0) {
            val child = parent.getChildAt(0)
            parent.getDecoratedBoundsWithMargins(child, tempRect)
            // Take into consideration any translationY added to the view.
            val bottom: Int = tempRect.top - Math.round(child.translationY)
            val top: Int = bottom + thickness
            dividerDrawable.setBounds(left, top, right, bottom)
            dividerDrawable.draw(canvas)
        }
        canvas.restore()
    }

    private fun drawForVerticalOrientation(canvas: Canvas, parent: RecyclerView) {
        canvas.save()
        var left: Int
        var right: Int
        if (parent.clipToPadding) {
            left = parent.paddingLeft
            right = parent.width - parent.paddingRight
            canvas.clipRect(
                left, parent.paddingTop, right, parent.height - parent.paddingBottom
            )
        } else {
            left = 0
            right = parent.width
        }
        val isRtl = ViewCompat.getLayoutDirection(parent) == ViewCompat.LAYOUT_DIRECTION_RTL
        left += if (isRtl) insetEnd else insetStart
        right -= if (isRtl) insetStart else insetEnd
        val childCount = parent.childCount
        for (i in 0 until childCount) {
            val child = parent.getChildAt(i)
            parent.getDecoratedBoundsWithMargins(child, tempRect)
            // Take into consideration any translationY added to the view.
            val bottom: Int = tempRect.bottom + Math.round(child.translationY)
            val top: Int = bottom - dividerDrawable.intrinsicHeight - thickness
            dividerDrawable.setBounds(left, top, right, bottom)
            dividerDrawable.draw(canvas)
        }
        canvas.restore()
    }

    /**
     * Draws a divider for the horizontal orientation of the recycler view. The divider itself will be
     * vertical.
     */
    fun setDividerColor(@ColorInt color: Int) {
        this.color = color
        dividerDrawable = DrawableCompat.wrap(dividerDrawable)
        DrawableCompat.setTint(dividerDrawable, color)
    }

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        val pos = parent.getChildAdapterPosition(view)
        if (pos < gridSpanSize) {
            outRect[0, 0, 0] = 0
            outRect.top = thickness
            outRect.bottom = dividerDrawable.intrinsicHeight + thickness
        } else {
            outRect[0, 0, 0] = 0
            outRect.bottom = dividerDrawable.intrinsicHeight + thickness
        }
    }
}