A simple component which is created when user clicks the cancel order button in the app. It is responsible for showing a confirmation dialog and actually cancelling the order by making an API call.

order_cancelation_component.kt

class OrderCancellationComponent(private val context: Context,
                                 private val api: Api,
                                 private val orderNumber: String) {

    interface Callbacks { 
        fun onOrderCancelledSuccessfully()
        fun onOrderCancellationFailed()
    }
  
    var callbacks: Callbacks? = null // Callbacks for communication with the parent component
    private val cancelOrderDialog: DialogCard // A wrapper over bottom sheet dialog

    init {
        // Each component can attach a container view in the Activity. 
        // This behaviour is abstracted by the DialogCard. 
        // All a component needs to do is inflate a view to show in the dialog. 
        val contentView = LayoutInflater.from(context).inflate(R.layout.dialog_cancel_order, null)
        cancelOrderDialog = DialogCard(context, contentView)
      
        val cancelButton = contentView.findViewById<Button>(R.id.btn_cancel)
        cancelButton.setOnClickListener {
            cancelOrder()              
        }
    }
 
    // Shows the confirmation dialog when invoked by the parent.
    fun showConfirmationDialog() {
        cancelOrderDialog.show()
    }
  
    // Dimsisses the dialog when back is pressed. 
    fun onBackPress() { 
        dismiss() 
    }

    // Dismisses the dialog
    private fun dismiss() {
        cancelOrderDialog.dismiss()
    }

    // Makes an API call to acually cancel the order.
    private fun cancelOrder() {
        subscription = api.cancelOrder(...)
            .subscribe({
                override fun onSuccess(...) { 
                  dismiss() 
                  callbacks?.onOrderCancelled()
                }

                override fun onError(e: Throwable) {
                  Toast.makeText(activity, "Could not cancel order", Toast.LENGTH_LONG).show()
                  callbacks?.onOrderCancelAPIFailed()
                }
            })
    }
}