[Taler] Withdrawal Flow (was: Taler Android UX)

[Torsten Grote]

On 2020-04-10 04:00, Florian Dold wrote:
> But my bigger problem right now is that the big picture is not written
> down coherently anywhere.  It makes it rather difficult to discuss and
> keep track of what the current consensus is, as well as what the
> rationale for getting there was.

I know the problem ;)

> Can we please write this down in a new design document in docs.git?
> 
> Torsten, would you mind starting with this?

I can try, but also don't know the full picture, yet. So how about I do
a rough sketch here and if there's agreement, I turn that into a design
document?

1. user requests withdrawal from bank or cashier
   gets shown a QR code or clickable taler withdraw URI
2. user scans QR code with wallet or clicks link that opens in wallet
3. wallet takes user to a screen summarizing the withdrawal:
   a) withdrawal amount
   b) withdrawal fee
   c) selected exchange with button to change it
   d) back button that cancels
   e) Review ToS button or Confirm button (depending on whether the ToS
      for the selected exchange have been accepted)
4. user clicks "Review ToS" button
5. ToS are displayed and use clicks accept
   * back button brings user back to 3
   * accepting ToS brings user back to 3 with Confirm button
6. user clicks "Confirm Withdrawal" button
7. user is brought to transaction list that shows pending withdrawal
   * snackbar confirms that the withdrawal was accepted

If the ToS were already accepted, 4 and 5 are removed from the flow.

An issue with that flow is that the user sees the withdrawal summary
screen two times (according to Belen that might not be an issue).
Christian's preferred flow would avoid this issue by forcing the user to
select an exchange first and then show the ToS after the selection.
However, when the ToS change, that flow has an issue as well.

The above flow handles ToS changes gracefully by just inserting step 4
and 5 again.

So to me it seems we need to decide first if we force exchange selection
(at least on first withdraw in that currency) and if so, how we handle
ToS changes in the flow.

Kind Regards,
Torsten