The Onboarding Fragment

OnboardingFragment.kt

class OnboardingFragment : DialogFragment() {
    private val indicators = mutableListOf<View>()
    private var currentPosition = 0

    private fun attachNextButtonListener() {
        next.setOnClickListener {
            when (currentPosition) {
                0 -> next.navigate(R.id.firstTransition, R.id.secondTransition)
                1 -> next.navigate(R.id.secondTransition, R.id.thirdTransition)
                else -> dismiss()
            }
        }
    }

    private fun attachPreviousButtonListener() {
        previous.setOnClickListener {
            when (currentPosition) {
                2 -> previous.navigate(R.id.thirdTransition, R.id.secondTransition)
                1 -> previous.navigate(R.id.secondTransition, R.id.firstTransition)
            }
        }
    }

   private fun Button.navigate(startId: Int, endId: Int) {
        currentPosition = if (id == R.id.next) {
            currentPosition.inc()
        } else {
            currentPosition.dec()
        }
        updateNavState()
        if (endId == R.id.thirdTransition) {
            navContainer.setBackgroundColor(resources.getColor(R.color.color_onboarding_page3))
            next.setText(R.string.button_text_complete)
        } else {
            next.setText(R.string.button_text_next)
            navContainer.setBackgroundColor(resources.getColor(R.color.onboarding_background))
        }
        motionLayout.setTransition(startId, endId)
        motionLayout.transitionToEnd()
        updateIndicators()
    }

    private fun updateIndicators() {
        indicators.forEachIndexed { index, view ->
            val background = when (index) {
                currentPosition -> R.drawable.selected_dot
                else -> R.drawable.un_selected_dot
            }
            view.setBackgroundDrawable(context?.getDrawable(background))
        }
    }
}