..
  This file is part of GNU TALER.
  Copyright (C) 2014-2024 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU Affero General Public License as published by the Free Software
  Foundation; either version 2.1, or (at your option) any later version.

  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details.

  You should have received a copy of the GNU Affero General Public License along with
  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>

  @author Florian Dold
  @author Marcello Stanisci
  @author Christian Grothoff


.. target audience: operator

Regional Currency Custom Setup Manual
#####################################

This manual describes how to setup a regional currency manually. If you want a guided setup you can follow the :doc:`automated setup manual<regional-automated-manual>`.

.. contents:: Table of Contents
  :local:

.. include:: ../frags/regional-manual-architecture.rst

Custom Manual Setup
===================

You first need to setup the :ref:`libeufin-bank<libeufin-bank>` and integrate it with a Taler exchange.

If you don't want your regional currency to be backed by a fiat currency, you can stop here.

Enabling Currency Conversion
++++++++++++++++++++++++++++

You need to setup the :ref:`libeufin-nexus<libeufin-nexus>` using a bank account at a bank dealing in fiat currency that
offers an online banking protocol supported by LibEuFin Nexus.

Next, you have to enable conversion and should ensure that at least one TAN
channel for :ref:`multi-factor authentication <libeufin-mfa>` is configured.

The following snippet shows how to enable conversion in ``libeufin-bank`` configuration:

.. code-block:: ini

  [libeufin-bank]
  ALLOW_CONVERSION = YES
  FIAT_CURRENCY = EUR

Make sure to (re)start the libeufin-bank after changing
these configuration options:

.. code-block:: console

  # systemctl restart libeufin-bank


Web-based Configuration
+++++++++++++++++++++++

Now you have to set the conversion rates and the ``admin`` debt limit via the bank's web interface as the ``admin`` user.

.. _regional-conversion-setup:

Configuring the Exchange for Conversion
+++++++++++++++++++++++++++++++++++++++

This section explains how to enable currency conversion at the exchange,
which is critical for wallets to know how to wire fiat currency to an
exchange to obtain regional currency.

You will need to use the ``taler-exchange-offline`` tool to inform the
exchange about the **fiat** bank account that can be used for cash in
operations and also specify the URL for currency conversion.  Additionally,
you may also configure restrictions on the bank accounts that may originate
the funds, for example, to prevent international wire transfers that may expose
you to additional compliance risks.

Given the ``$IBAN`` of the fiat currency bank account and ``$NAME`` as
the (URL-encoded) name of the exchange-account owner, the following
``taler-exchange-offline`` invocation can be used to notify wallets about
the possibility of currency conversion (cash in):

.. code-block:: console

  # taler-exchange-offline \
      enable-account \
        payto://iban/$IBAN?receiver-name=$NAME \
        conversion-url "$CONVERSION_URL" \
        debit-restriction \
          deny \
        credit-restriction \
          regex \
            'payto://iban/.*/CH.*?receiver-name=.*' \
            'Swiss only' \
            '{ "de" : "nur Schweiz", \
               "fr" : "Suisse uniquement" }'
      upload

Here, the ``$CONVERSION_URL`` must be set to the base URL of the conversion
endpoint of the bank, which should be
``https://bank.$DOMAIN/conversion-info/`` in our setup.  Note that you can
leave out the "credit-restriction" if you want to allow international inbound
wire transfers.  The "debit-restriction" is largely mandatory as in this setup
the taler-exchange-transfer is only configured to deal with the regional
currency bank.  Crediting fiat bank accounts must thus be done via the
cash-out functionality of the regional currency bank account.

.. note::

  The above command adds a **second** bank account to the exchange.
  You (or the guided setup script) should have already enabled the
  regional currency bank account (without any "conversion-url").

System ON!
++++++++++

The last step is to enable libeufin-nexus to :ref:`import incoming bank
transactions <receive-transaction-data>` (cash in) and to :ref:`trigger
outgoing bank transactions <sending-payments>` (cash out).

.. code-block:: console

  # systemctl enable --now libeufin-nexus.target


Configuring exchange terms
++++++++++++++++++++++++++

You can use your own terms of service and privacy policy. You can use the default templates in ``/usr/share/taler/terms`` as a guide.
Assuming you have custom terms of service and privacy policy ``rst`` teamplte files at ``TOS_PATH`` and ``PRIVACY_PATH``, the following commands generate the terms files:

.. code-block:: console

  # taler-terms-generator -i "$TOS_PATH"
  # taler-terms-generator -i "$PRIVACY_PATH"

You now have to specify the terms file names in the exchange config:

.. code-block:: console

  # TERMS_ETAG="$(basename "$TOS_PATH" .rst)"
  # PRIVACY_ETAG="$(basename "$PRIVACY_PATH" .rst)"

.. code-block:: ini

  [exchange]
  TERMS_ETAG=${TERMS_ETAG}
  PRIVACY_ETAG=${PRIVACY_ETAG}

Make sure to restart taler-exchange after changing these configuration options:

.. code-block:: console

  # systemctl restart taler-exchange.target

.. include:: ../frags/regional-manual-use.rst