..
  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/>

.. target audience: developer, core developer

.. _corebank-api:

====================
Taler Core Bank API
====================

.. contents:: Table of Contents
  :local:

Introduction
------------

The Libeufin bank provides a minimal core banking system.  In addition to that,
it provides features for local/regional currencies.


Authentication
--------------

Some endpoints requires the client to authenticate using a bearer token. Tokens can be obtained or refreshed using the ``/accounts/$USERNAME/token`` endpoint.
This endpoint support authentication via HTTP Basic auth (RFC 7617). When using Basic authentication, the user-id must be the bank's username, and the password the password of the corresponding user.

The user ``admin`` is a special, hard-coded username. Some requests require the client to authenticate as administrator.

.. warning::

  Basic authentication for endpoints other than ``/accounts/$USERNAME/token`` has been deprecated and will no longer be supported in the next release.

.. http:post:: /accounts/$USERNAME/token

  Create an authentification token.

  **Request:**

  .. ts:def:: TokenRequest

    interface TokenRequest {
      // Scope for the token.
      scope: "readonly" | "readwrite" | "revenue";

      // Custom token validity duration
      duration?: RelativeTime;

      // Is the token refreshable into a new token during its
      // validity?
      // Refreshable tokens effectively provide indefinite
      // access if they are refreshed in time.
      refreshable?: boolean;

      // Optional token description
      // @since **v4**
      description?: string;
    }

  **Response:**

  :http:statuscode:`200 Ok`:
    The response is a `TokenSuccessResponse`

  **Details:**

  .. ts:def:: TokenSuccessResponse

    interface TokenSuccessResponse {
      // Expiration determined by the server.
      // Can be based on the token_duration
      // from the request, but ultimately the
      // server decides the expiration.
      expiration: Timestamp;

      // Opque access token.
      access_token: string;
    }

.. http:delete:: /accounts/$USERNAME/token

  Invalidate the access token that is being used to make the request.

  **Authentication:**  The client must authenticate with a valid access token.

.. http:get:: /accounts/$USERNAME/tokens

  Retrieve a subset of tokens related to $USERNAME.
  @since **v4**

  **Request:**

  :query delta: *Optional.*
    Takes value of the form ``N (-N)``, so that at most ``N`` values strictly older (younger) than ``start`` are returned.  Defaults to ``-20`` to return the last 20 entries.
  :query start: *Optional.*
    Row number threshold, see ``delta`` for its interpretation. Defaults to smallest or biggest row id possible according to ``delta`` sign.

  **Response:**

  :http:statuscode:`200 OK`:
    Response is a `TokenInfos`.
  :http:statuscode:`204 No content`:
    No tokens.

  **Details:**

  .. ts:def:: TokenInfos

    interface TokenInfos {
      tokens: TokenInfo[];
    }

  .. ts:def:: TokenInfo

    interface TokenInfo {
      // Time when the token was created.
      creation_time: Timestamp;

      // Expiration determined by the server.
      // Can be based on the token_duration
      // from the request, but ultimately the
      // server decides the expiration.
      expiration: Timestamp;

      // Scope for the token.
      scope: "readonly" | "readwrite" | "revenue";

      // Is the token refreshable into a new token during its
      // validity?
      // Refreshable tokens effectively provide indefinite
      // access if they are refreshed in time.
      refreshable: boolean;

      // Optional token description
      description?: string;

      // Time when the token was last used.
      last_access: Timestamp;

      // Opaque unique ID used for pagination.
      row_id: Integer;
    }

Bank Web UI
-----------

The web UI for the bank is typically served under ``/``.

Config
------

.. http:get:: /config

  Return the protocol version and configuration information about the bank.
  This specification corresponds to ``current`` protocol being version **v6**.

  **Response:**

  :http:statuscode:`200 OK`:
    Response is a `Config`.

  **Details:**

  .. ts:def:: Config

    interface Config {
      // Name of the API.
      name: "taler-corebank";

      // libtool-style representation of the Bank protocol version, see
      // https://www.gnu.org/software/libtool/manual/html_node/Versioning.html#Versioning
      // The format is "current:revision:age".
      version: string;

      // Bank display name to be used in user interfaces.
      // For consistency use "Taler Bank" if missing.
      // @since **v4**, will become mandatory in the next version.
      bank_name?: string;

      // Advertised base URL to use when you sharing an URL with another
      // program.
      // @since **v4**.
      base_url?: string;

      // If 'true' the server provides local currency conversion support
      // If 'false' some parts of the API are not supported and return 501
      allow_conversion: boolean;

      // If 'true' anyone can register
      // If 'false' only admin can
      allow_registrations: boolean;

      // If 'true' account can delete themselves
      // If 'false' only admin can delete accounts
      allow_deletions: boolean;

      // If 'true' anyone can edit their name
      // If 'false' only admin can
      allow_edit_name: boolean;

      // If 'true' anyone can edit their cashout account
      // If 'false' only admin can
      allow_edit_cashout_payto_uri: boolean;

      // Default debt limit for newly created accounts
      default_debit_threshold: Amount;

      // Currency used by this bank.
      currency: string;

      // How the bank SPA should render this currency.
      currency_specification: CurrencySpecification;

      // TAN channels supported by the server
      supported_tan_channels: TanChannel[];

      // Wire transfer type supported by the bank.
      // Defaults to 'iban' is missing
      // @since **v4**, will become mandatory in the next version.
      wire_type?: string;

      // Wire transfer execution fees. Only applies to bank transactions and withdrawals.
      // @since **v4**, will become mandatory in the next version.
      wire_transfer_fees?: Amount;

      // Minimum wire transfer amount allowed. Only applies to bank transactions and withdrawals.
      // @since **v4**, will become mandatory in the next version.
      min_wire_transfer_amount?: Amount;

      // Maximum wire transfer amount allowed. Only applies to bank transactions and withdrawals.
      // @since **v4**, will become mandatory in the next version.
      max_wire_transfer_amount?: Amount;
    }


Account Management
------------------

.. _bank-account-register:

.. http:post:: /accounts

  Create a new bank account.  Depending on the configuration,
  the account creation is self-serve, or only restricted to
  the administrators.

  **Request:**

  .. ts:def:: RegisterAccountRequest

    interface RegisterAccountRequest {
      // Username of the account
      username: string;

      // Password of the account used for authentication
      password: string;

      // Legal name of the account owner
      name: string;

      // Make this account visible to anyone?
      // Defaults to false.
      is_public?: boolean;

      // Make this account a taler exchange account?
      // If true:
      // - incoming transactions to the account that do not
      //   have a valid reserve public key are automatically
      // - the account provides the taler-wire-gateway-api endpoints
      // Defaults to false.
      is_taler_exchange?: boolean;

      // Addresses where to send the TAN for protected operations.
      contact_data?: ChallengeContactData;

      // IBAN 'payto' URI of a fiat bank account with a 'receiver-name' parameter.
      // If 'receiver-name' is missing, ``name`` will be used instead.
      // Payments will be sent to this bank account
      // when the user wants to convert the regional currency
      // back to fiat currency outside bank.
      cashout_payto_uri?: string;

      // Internal payto URI of this bank account.
      // Used mostly for testing, this field is ignored if the bank payment
      // method is not IBAN.
      payto_uri?: string;

      // If present, set the max debit allowed for this user
      // Only admin can set this property.
      debit_threshold?: Amount;

      // If present, set a custom minimum cashout amount for this account.
      // Only admin can set this property
      // @since **v4**
      min_cashout?: Amount;

      // If present, enables 2FA and set the TAN channel used for challenges
      // Only admin can set this property, other user can reconfig their account
      // after creation.
      tan_channel?: TanChannel;
    }

  .. ts:def:: ChallengeContactData

    interface ChallengeContactData {
      // E-Mail address
      email?: EmailAddress;

      // Phone number.
      phone?: PhoneNumber;
    }


  **Response:**

  :http:statuscode:`200 OK`:
    Response is a `RegisterAccountResponse`.
  :http:statuscode:`400 Bad request`:
    Input data was invalid.  For example, the client specified a invalid
    phone number or e-mail address.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`409 Conflict`:
    * ``TALER_EC_BANK_REGISTER_USERNAME_REUSE`` : username already used.
    * ``TALER_EC_BANK_REGISTER_PAYTO_URI_REUSE`` : payto URI already used.
    * ``TALER_EC_BANK_UNALLOWED_DEBIT`` : admin account does not have sufficient funds to grant bonus.
    * ``TALER_EC_BANK_RESERVED_USERNAME_CONFLICT`` : a reserved username was attempted, like ``admin`` or ``bank``
    * ``TALER_EC_BANK_NON_ADMIN_PATCH_DEBT_LIMIT`` : a non-admin user has tried to create an account with a customer debt limit.
    * ``TALER_EC_BANK_NON_ADMIN_SET_MIN_CASHOUT`` : a non-admin user has tried to create an account with a custom min cashout amount.
    * ``TALER_EC_BANK_NON_ADMIN_SET_TAN_CHANNEL`` : a non-admin user has tried to create an account with 2fa.
    * ``TALER_EC_BANK_TAN_CHANNEL_NOT_SUPPORTED``: ``tan_channel`` is not supported, check bank config to find supported ones.
    * ``TALER_EC_BANK_MISSING_TAN_INFO``: the user did not share any contact data where to send the TAN via ``tan_channel``.
    * ``TALER_EC_BANK_PASSWORD_TOO_SHORT``: password is shorter than 8 characters.
    * ``TALER_EC_BANK_PASSWORD_TOO_LONG``: password is longer than 64 characters.

  **Details:**

  .. ts:def:: RegisterAccountResponse

    interface RegisterAccountResponse {
      // Internal payto URI of this bank account.
      internal_payto_uri: string;
    }

.. _account-reconfig:

.. http:patch:: /accounts/$USERNAME

  Allows reconfiguring the account data of ``$USERNAME``.

  **Request:**

  .. ts:def:: AccountReconfiguration

    interface AccountReconfiguration {
      // Addresses where to send the TAN for protected operations.
      contact_data?: ChallengeContactData;

      // IBAN 'payto' URI of a fiat bank account with a 'receiver-name' parameter.
      // If 'receiver-name' is missing, ``name`` will be used instead.
      // Payments will be sent to this bank account
      // when the user wants to convert the regional currency
      // back to fiat currency outside bank.
      // Only admin can change this property if not allowed in config
      cashout_payto_uri?: string;

      // If present, change the legal name associated with $username.
      // Only admin can change this property if not allowed in config
      name?: string;

      // Make this account visible to anyone?
      is_public?: boolean;

      // If present, change the max debit allowed for this user
      // Only admin can change this property.
      debit_threshold?: Amount;

      // If present, change the custom minimum cashout amount for this account.
      // Only admin can set this property
      // @since **v4**
      min_cashout?: Amount;

      // If present, enables 2FA and set the TAN channel used for challenges
      tan_channel?: TanChannel;
    }

  **Response:**

  :http:statuscode:`202 Accepted`:
    2FA is required for this operation. This returns the `Challenge` response.
  :http:statuscode:`204 No content`:
    Operation successful.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.
  :http:statuscode:`409 Conflict`:
    * ``TALER_EC_BANK_NON_ADMIN_PATCH_LEGAL_NAME`` : a non-admin user has tried to change their legal name.
    * ``TALER_EC_BANK_NON_ADMIN_PATCH_CASHOUT`` : a non-admin user has tried to change their cashout account.
    * ``TALER_EC_BANK_NON_ADMIN_PATCH_DEBT_LIMIT`` : a non-admin user has tried to change their debt limit.
    * ``TALER_EC_BANK_NON_ADMIN_SET_MIN_CASHOUT`` : a non-admin user has tried to change their custom min cashout amount.
    * ``TALER_EC_BANK_TAN_CHANNEL_NOT_SUPPORTED`` : ``tan_channel`` is not supported, check bank config to find supported ones.
    * ``TALER_EC_BANK_MISSING_TAN_INFO`` : the user did not share any contact data where to send the TAN via ``tan_channel``.


.. _account-password-reconfig:

.. http:patch:: /accounts/$USERNAME/auth

  Allows changing the account's password.


  **Request:**

  .. ts:def:: AccountPasswordChange

    interface AccountPasswordChange {
      // Old password. If present it need to match the current
      // password before updating.
      old_password?: string;
      // New password.
      new_password: string;
    }

  **Response:**

  :http:statuscode:`202 Accepted`:
    2FA is required for this operation. This returns the `Challenge` response.
  :http:statuscode:`204 No content`:
    Operation successful.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`409 Conflict`:
    * ``TALER_EC_BANK_NON_ADMIN_PATCH_MISSING_OLD_PASSWORD``: a non-admin user has tried to change their password whihout providing the current one.
    * ``TALER_EC_BANK_PATCH_BAD_OLD_PASSWORD`` : provided old password does not match current password.
    * ``TALER_EC_BANK_PASSWORD_TOO_SHORT``: new password is shorter than 8 characters.
    * ``TALER_EC_BANK_PASSWORD_TOO_LONG``: new password is longer than 64 characters.


.. _delete-account:

.. http:delete:: /accounts/$USERNAME

  Delete the account whose username is ``$USERNAME``.  The deletion
  succeeds only if the balance is *zero*.  Typically only available to
  the administrator, but can be configured to allow ordinary users too.

  **Response:**

  :http:statuscode:`202 Accepted`:
    2FA is required for this operation. This returns the `Challenge` response.
  :http:statuscode:`204 No content`:
    The account was successfully deleted.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.
  :http:statuscode:`409 Conflict`:
    * ``TALER_EC_BANK_RESERVED_USERNAME_CONFLICT`` : a reserved username was attempted, like ``admin`` or ``bank``.
    * ``TALER_EC_BANK_ACCOUNT_BALANCE_NOT_ZERO``: the account balance was not zero.

.. _account-list:

.. http:get:: /public-accounts

  Show those accounts whose histories are publicly visible.  For example,
  accounts from donation receivers.  As such, this request is unauthenticated.

  **Request:**

  :query limit: *Optional.*
    At most return the given number of results. Negative for descending by ``row_id``, positive for ascending by ``row_id``. Defaults to ``-20``. Since protocol v5.
  :query offset: *Optional.* 
    Starting ``row_id`` for :ref:`pagination <row-id-pagination>`. Since protocol v5.
  :query filter_name: *Optional.*
    Pattern to filter on the account's legal name.  Given
    the filter 'foo', all the results will **contain**
    'foo' in their legal name.  Without this option,
    all the existing accounts are returned.
  :query delta: *Optional.*
    Deprecated in protocol v5. Use *limit* instead.
  :query start: *Optional.*
    Deprecated in protocol v5. Use *offset* instead.

  **Response:**

  :http:statuscode:`200 OK`:
    Response is a `PublicAccountsResponse`.
  :http:statuscode:`204 No content`:
    No public account.

  **Details:**

  .. ts:def:: PublicAccountsResponse

    interface PublicAccountsResponse {
      public_accounts: PublicAccount[];
    }

  .. ts:def:: PublicAccount

    interface PublicAccount {
      // Username of the account
      username: string;

      // Internal payto URI of this bank account.
      payto_uri: string;

      // Current balance of the account
      balance: Balance;

      // Is this a taler exchange account?
      is_taler_exchange: boolean;

      // Opaque unique ID used for pagination.
      // @since **v4**, will become mandatory in the next version.
      row_id?: Integer;
    }

.. http:get:: /accounts

  Obtains a list of the accounts registered at the bank.
  It returns only the information that this API handles, without
  any balance or transactions list.
  This request is only available to the administrator.

  **Request:**

  :query limit: *Optional.*
    At most return the given number of results. Negative for descending by ``row_id``, positive for ascending by ``row_id``. Defaults to ``-20``. Since protocol v5.
  :query offset: *Optional.* 
    Starting ``row_id`` for :ref:`pagination <row-id-pagination>`. Since protocol v5.
  :query filter_name: *Optional.*
    Pattern to filter on the account's legal name.  Given
    the filter 'foo', all the results will **contain**
    'foo' in their legal name.  Without this option,
    all the existing accounts are returned.
  :query delta: *Optional.*
    Deprecated in protocol v5. Use *limit* instead.
  :query start: *Optional.*
    Deprecated in protocol v5. Use *offset* instead.

  **Response:**

  :http:statuscode:`200 OK`:
    At least one account was found.
    The server responds with a `ListBankAccountsResponse` object.
  :http:statuscode:`204 No Content`:
    No accounts were found for the given request.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.

  **Details:**

  .. ts:def:: ListBankAccountsResponse

    interface ListBankAccountsResponse {
      accounts: AccountMinimalData[];
    }

  .. ts:def:: Balance

    interface Balance {
      amount: Amount;
      credit_debit_indicator: "credit" | "debit";
    }

  .. ts:def:: AccountMinimalData

    interface AccountMinimalData {
      // Username of the account
      username: string;

      // Legal name of the account owner.
      name: string;

      // Internal payto URI of this bank account.
      payto_uri: string;

      // Current balance of the account
      balance: Balance;

      // Number indicating the max debit allowed for the requesting user.
      debit_threshold: Amount;

      // Custom minimum cashout amount for this account.
      // If null or absent, the global conversion fee is used.
      // @since **v6**
      min_cashout?: Amount;

      // Is this account visible to anyone?
      is_public: boolean;

      // Is this a taler exchange account?
      is_taler_exchange: boolean;

      // Opaque unique ID used for pagination.
      // @since **v4**, will become mandatory in the next version.
      row_id?: Integer;

      // Current status of the account
      // active: the account can be used
      // deleted: the account has been deleted but is retained for compliance
      // reasons, only the administrator can access it
      // Defaults to 'active' is missing
      // @since **v4**, will become mandatory in the next version.
      status?: "active" | "deleted";
    }

.. _bank-account-info:

.. http:get:: /accounts/$USERNAME

  Obtains information relative to the account owned by
  ``$USERNAME``.  The request is available to the administrator
  and ``$USERNAME`` itself.

  **Response:**

  :http:statuscode:`200 OK`:
    The bank responds with an `AccountData` object.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.

  **Details:**

  .. ts:def:: AccountData

    interface AccountData {
      // Legal name of the account owner.
      name: string;

      // Available balance on the account.
      balance: Balance;

      // payto://-URI of the account.
      payto_uri: string;

      // Number indicating the max debit allowed for the requesting user.
      debit_threshold: Amount;

      // Custom minimum cashout amount for this account.
      // If null or absent, the global conversion fee is used.
      // @since **v6**
      min_cashout?: Amount;

      // Addresses where to send the TAN for transactions.
      // Currently only used for cashouts.
      // If missing, cashouts will fail.
      // In the future, might be used for other transactions
      // as well.
      contact_data?: ChallengeContactData;

      // IBAN 'payto' URI with a 'receiver-name'  parameter of a fiat bank
      // account where to send cashouts. This field is optional
      // because not all the accounts are required to participate
      // in the merchants' circuit.  One example is the exchange:
      // that never cashouts.  Registering these accounts can
      // be done via the access API.
      cashout_payto_uri?: string;

      // Is this account visible to anyone?
      is_public: boolean;

      // Is this a taler exchange account?
      is_taler_exchange: boolean;

      // Is 2FA enabled and what channel is used for challenges?
      tan_channel?: TanChannel;

      // Current status of the account
      // active: the account can be used
      // deleted: the account has been deleted but is retained for compliance
      // reasons, only the administrator can access it
      // Defaults to 'active' is missing
      // @since **v4**, will become mandatory in the next version.
      status?: "active" | "deleted";
    }

Transactions
------------

.. http:get:: /accounts/$USERNAME/transactions

  Retrieve a subset of transactions related to $USERNAME.

  **Request:**

  :query limit: *Optional.*
    At most return the given number of results. Negative for descending by ``row_id``, positive for ascending by ``row_id``. Defaults to ``-20``. Since protocol v5.
  :query offset: *Optional.* 
    Starting ``row_id`` for :ref:`pagination <row-id-pagination>`. Since protocol v5.
  :query timeout_ms: *Optional.*
    Timeout in milliseconds, for :ref:`long-polling <long-polling>`, to wait for at least one element to be shown. Only useful if *limit* is positive. Since protocol v5.
  :query delta: *Optional.*
    Deprecated in protocol v5. Use *limit* instead.
  :query start: *Optional.*
    Deprecated in protocol v5. Use *offset* instead.
  :query long_poll_ms: *Optional.*
    Deprecated in protocol v5. Use *timeout_ms* instead.

  **Response:**

  :http:statuscode:`200 OK`:
    The bank responds with an `BankAccountTransactionsResponse` object.
  :http:statuscode:`204 No content`:
    No transaction found.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.

  **Details:**

  .. ts:def:: BankAccountTransactionsResponse

    interface BankAccountTransactionsResponse {
      transactions: BankAccountTransactionInfo[];
    }

.. http:get:: /accounts/$USERNAME/transactions/$TRANSACTION_ID

  Retrieve the transaction whose identifier is ``TRANSACTION_ID``.

  **Response:**

  :http:statuscode:`200 OK`:
    The bank responds with an `BankAccountTransactionInfo` object.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.

  **Details:**

  .. ts:def:: BankAccountTransactionInfo

    interface BankAccountTransactionInfo {
      creditor_payto_uri: string;
      debtor_payto_uri: string;

      amount: Amount;
      direction: "debit" | "credit";

      subject: string;

      // Transaction unique ID.  Matches
      // $TRANSACTION_ID from the URI.
      row_id: Integer;
      date: Timestamp;
    }

.. http:post:: /accounts/$USERNAME/transactions

  Create a new transaction where the bank account with the label ``USERNAME`` is **debited**.

  **Request:**

  .. ts:def:: CreateTransactionRequest

    interface CreateTransactionRequest {
      // Address in the Payto format of the wire transfer receiver.
      // It needs at least the 'message' query string parameter.
      payto_uri: string;

      // Transaction amount (in the $currency:x.y format), optional.
      // However, when not given, its value must occupy the 'amount'
      // query string parameter of the 'payto' field.  In case it
      // is given in both places, the payto_uri's takes the precedence.
      amount: string;

      // Nonce to make the request idempotent.  Requests with the same
      // ``request_uid`` that differ in any of the other fields
      // are rejected.
      // @since **v4**, will become mandatory in the next version.
      request_uid?: ShortHashCode;
    }

  **Response:**

  :http:statuscode:`200 Ok`:
    The bank responds with an `CreateTransactionResponse` object.
  :http:statuscode:`202 Accepted`:
    2FA is required for this operation. This returns the `Challenge` response.
  :http:statuscode:`400 Bad Request`:
    The request was invalid or the payto://-URI used unacceptable features.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.
  :http:statuscode:`409 Conflict`:
    * ``TALER_EC_BANK_SAME_ACCOUNT`` : creditor account is the same than ``USERNAME``.
    * ``TALER_EC_BANK_UNKNOWN_CREDITOR`` : creditor account was not found.
    * ``TALER_EC_BANK_UNALLOWED_DEBIT`` : the account does not have sufficient funds or the amount is too low or too high.
    * ``TALER_EC_BANK_TRANSFER_REQUEST_UID_REUSED``: an operation with the same ``request_uid`` but different details has been submitted before.

  **Details:**

  .. ts:def:: CreateTransactionResponse

    interface CreateTransactionResponse {
      // ID identifying the transaction being created
      row_id: Integer;
    }

Account withdrawals
-------------------

.. http:post:: /accounts/$USERNAME/withdrawals

  Create a withdrawal operation, resulting in a ``taler://withdraw`` URI.

  **Request:**

  The request must be a `BankAccountCreateWithdrawalRequest`.

  **Response:**

  :http:statuscode:`200 Ok`:
    The bank responds with an `BankAccountCreateWithdrawalResponse` object.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.
  :http:statuscode:`409 Conflict`:
    The account does not have sufficient funds.

  **Details:**

  .. ts:def:: BankAccountCreateWithdrawalRequest

    interface BankAccountCreateWithdrawalRequest {
      // Amount to withdraw.  If given, the wallet
      // cannot change the amount.
      // Optional since **v6**.
      amount?: Amount;

      // Suggested amount to withdraw. The wallet can
      // still change the suggestion.
      // @since **v6**
      suggested_amount?: Amount;
    }

  .. ts:def:: BankAccountCreateWithdrawalResponse

    interface BankAccountCreateWithdrawalResponse {
      // ID identifying the operation being created
      withdrawal_id: string;

      // URI that can be passed to the wallet to initiate the withdrawal
      taler_withdraw_uri: string;
    }

.. http:post:: /accounts/$USERNAME/withdrawals/$WITHDRAWAL_ID/confirm

  Confirms ``WITHDRAWAL_ID`` operation.  Has no effect on an already confirmed
  withdrawal operation.  This call is responsible for wiring the funds to the
  exchange.

  **Request:**

  .. ts:def:: BankAccountConfirmWithdrawalRequest

    interface BankAccountConfirmWithdrawalRequest {

      // Selected amount to be transferred. Optional if the
      // backend already knows the amount.
      // @since **v6**
      amount?: Amount;
    }


  **Response:**

  :http:statuscode:`202 Accepted`:
    2FA is required for this operation. This returns the `Challenge` response.
  :http:statuscode:`204 No content`:
    The withdrawal operation has been confirmed.
  :http:statuscode:`404 Not found`:
    The operation was not found.
  :http:statuscode:`409 Conflict`:
    * ``TALER_EC_BANK_CONFIRM_ABORT_CONFLICT`` : the withdrawal has been aborted previously and can't be confirmed.
    * ``TALER_EC_BANK_CONFIRM_INCOMPLETE`` : the withdraw operation cannot be confirmed because no exchange and reserve public key selection happened before.
    * ``TALER_EC_BANK_UNALLOWED_DEBIT`` : the account does not have sufficient funds or the amount is too low or too high.
    * ``TALER_EC_BANK_AMOUNT_DIFFERS`` : the specified amount will not work for this withdrawal (since **v6**).
    * ``TALER_EC_BANK_AMOUNT_REQUIRED`` : the backend requires an amount to be specified  (since **v6**).

.. http:post:: /accounts/$USERNAME/withdrawals/$WITHDRAWAL_ID/abort

  Aborts ``WITHDRAWAL_ID`` operation.  Has no effect on an already aborted
  operation.

  **Response:**

  :http:statuscode:`204 No content`:
    The withdrawal operation has been aborted.
  :http:statuscode:`404 Not found`:
    The withdrawal operation was not found.
  :http:statuscode:`409 Conflict`:
    The withdrawal operation has been confirmed previously and can't be aborted.

.. http:get:: /withdrawals/$WITHDRAWAL_ID

  Retrieve public information about ``WITHDRAWAL_ID`` withdrawal operation.
  Does not require further authentication as knowledge of ``WITHDRAWAL_ID``
  serves as an authenticator.

  **Request:**
  
  :query old_state:
    *Optional.* Defaults to "pending".
  :query timeout_ms: *Optional.*
    Timeout in milliseconds, for :ref:`long-polling <long-polling>`, to wait for the operation state to be different from *old_state*. Since protocol v5.
  :query long_poll_ms: *Optional.*
    Deprecated in protocol v5. Use *timeout_ms* instead.

  **Response:**

  :http:statuscode:`200 Ok`:
    The bank responds with an `WithdrawalPublicInfo` object.
  :http:statuscode:`404 Not found`:
    The operation was not found.

  **Details:**

  .. ts:def:: WithdrawalPublicInfo

    interface WithdrawalPublicInfo {
      // Current status of the operation
      // pending: the operation is pending parameters selection (exchange and reserve public key)
      // selected: the operations has been selected and is pending confirmation
      // aborted: the operation has been aborted
      // confirmed: the transfer has been confirmed and registered by the bank
      status: "pending" | "selected" | "aborted" | "confirmed";

      // Amount that will be withdrawn with this operation
      // (raw amount without fee considerations).  Only
      // given once the amount is fixed and cannot be changed.
      // Optional since **v6**.
      amount?: Amount;

      // Suggestion for the amount to be withdrawn with this
      // operation.  Given if a suggestion was made but the
      // user may still change the amount.
      // Optional since **v6**.
      suggested_amount?: Amount;

      // Account username
      username: string;

      // Reserve public key selected by the exchange,
      // only non-null if ``status`` is ``selected`` or ``confirmed``.
      selected_reserve_pub?: string;

      // Exchange account selected by the wallet
      // only non-null if ``status`` is ``selected`` or ``confirmed``.
      selected_exchange_account?: string;
    }

Cashouts
--------

.. _account-cashout:

.. http:post:: /accounts/$USERNAME/cashouts

  Initiates a conversion to fiat currency.  The fiat
  bank account to be
  credited is the one specified at registration time via the
  *cashout_payto_uri* parameter.  The regional bank account
  is specified via ``$USERNAME``.

  .. note::

    Consult the `cashout rates call <cashout-rates_>`_ to learn
    about any applicable fee or exchange rate.


  **Request:**

  .. ts:def:: CashoutRequest

    interface CashoutRequest {
      // Nonce to make the request idempotent.  Requests with the same
      // ``request_uid`` that differ in any of the other fields
      // are rejected.
      request_uid: ShortHashCode;

      // Optional subject to associate to the
      // cashout operation.  This data will appear
      // as the incoming wire transfer subject in
      // the user's fiat bank account.
      subject?: string;

      // That is the plain amount that the user specified
      // to cashout.  Its $currency is the (regional) currency of the
      // bank instance.
      amount_debit: Amount;

      // That is the amount that will effectively be
      // transferred by the bank to the user's fiat bank
      // account.
      // It is expressed in the fiat currency and
      // is calculated after the cashout fee and the
      // exchange rate.  See the /cashout-rate call.
      // The client needs to calculate this amount
      // correctly based on the amount_debit and the cashout rate,
      // otherwise the request will fail.
      amount_credit: Amount;
    }

  **Response:**

  :http:statuscode:`200 OK`:
    The cashout request was correctly created.
    This returns the `CashoutResponse` response.
  :http:statuscode:`202 Accepted`:
    2FA is required for this operation. This returns the `Challenge` response.
  :http:statuscode:`404 Not found`:
    The account pointed by ``$USERNAME`` was not found.
  :http:statuscode:`409 Conflict`:
    * ``TALER_EC_BANK_TRANSFER_REQUEST_UID_REUSED``: an operation with the same ``request_uid`` but different details has been submitted before.
    * ``TALER_EC_BANK_BAD_CONVERSION``: exchange rate was calculated incorrectly by the client.
    * ``TALER_EC_BANK_BANK_CONVERSION_AMOUNT_TO_SMALL``: the amount of the cashout is too small.
    * ``TALER_EC_BANK_UNALLOWED_DEBIT``: the account does not have sufficient funds or the amount is too low or too high.
    * ``TALER_EC_BANK_CONFIRM_INCOMPLETE``: the user did not share any cashout payto to uri where to wire funds.
  :http:statuscode:`501 Not Implemented`:
    * ``TALER_EC_BANK_TAN_CHANNEL_NOT_SUPPORTED``: the chosen ``tan_channel`` is not currently supported.
    * This server does not support conversion, client should check config response.

  **Details:**

  .. ts:def:: CashoutResponse

    interface CashoutResponse {
      // ID identifying the operation being created
      cashout_id: Integer;
    }

.. _circuit-cashout-details:

.. http:get:: /accounts/$USERNAME/cashouts/$CASHOUT_ID

  Returns information about the status of the ``$CASHOUT_ID`` operation.
  The request is available to the administrator and the account owner.

  **Response:**

  :http:statuscode:`200 OK`:
    Response is a `CashoutStatusResponse`.
  :http:statuscode:`404 Not found`:
    The cashout operation was not found.
  :http:statuscode:`501 Not implemented`:
    This server does not support conversion, client should check config response.

  **Details:**

  .. ts:def:: CashoutStatusResponse

    interface CashoutStatusResponse {
      // Amount debited to the regional bank account.
      amount_debit: Amount;

      // Amount credited to the fiat bank account.
      amount_credit: Amount;

      // Transaction subject.
      subject: string;

      // Time when the cashout was created.
      creation_time: Timestamp;
    }

.. _circuit-cashouts:

.. http:get:: /accounts/$USERNAME/cashouts

  Returns the list of all cash-out operations for an account.

  **Request:**

  :query limit: *Optional.*
    At most return the given number of results. Negative for descending by ``cashout_id``, positive for ascending by ``cashout_id``. Defaults to ``-20``. Since protocol **v5**.
  :query offset: *Optional.* 
    Starting ``cashout_id`` for :ref:`pagination <row-id-pagination>`. Since protocol v5.
  :query delta: *Optional.*
    Deprecated in protocol v5. Use *limit* instead.
  :query start: *Optional.*
    Deprecated in protocol v5. Use *offset* instead.

  **Response:**

  :http:statuscode:`200 OK`:
    Response is a `Cashouts`.
  :http:statuscode:`204 No Content`:
    No cash-out operations were found.
  :http:statuscode:`501 Not implemented`:
    This server does not support conversion, client should check config response.

  **Details:**

  .. ts:def:: Cashouts

    interface Cashouts {
      // Every string represents a cash-out operation ID.
      cashouts: CashoutInfo[];
    }

  .. ts:def:: CashoutInfo

    interface CashoutInfo {
      cashout_id: Integer;
    }

.. http:get:: /cashouts

  Returns the list of all cash-out operations for **all** accounts.

  Can only be used by the administrators.

  **Request:**

  :query limit: *Optional.*
    At most return the given number of results. Negative for descending by ``cashout_id``, positive for ascending by ``cashout_id``. Defaults to ``-20``. Since protocol v5.
  :query offset: *Optional.* 
    Starting ``cashout_id`` for :ref:`pagination <row-id-pagination>`. Since protocol v5.
  :query delta: *Optional.*
    Deprecated in protocol v5. Use *limit* instead.
  :query start: *Optional.*
    Deprecated in protocol v5. Use *offset* instead.

  .. note::

    We might want to add a filter in the future to only
    query pending cashout operations.

  **Response:**

  :http:statuscode:`200 OK`:
    Response is a `GlobalCashouts`.
  :http:statuscode:`204 No Content`:
    No cash-out operations were found.
  :http:statuscode:`501 Not implemented`:
    This server does not support conversion, client should check config response.

  **Details:**

  .. ts:def:: GlobalCashouts

    interface GlobalCashouts {
      cashouts: GlobalCashoutInfo[];
    }

  .. ts:def:: GlobalCashoutInfo

    interface GlobalCashoutInfo {
      cashout_id: Integer;
      username: string;
    }

.. _cashout-rates:

2FA
---

.. http:post:: /accounts/$USERNAME/challenge/$CHALLENGE_ID

  Send TAN code for the ``CHALLENGE_ID`` challenge.

  This request can be posted several times to trigger TAN retransmission when the current code has expired or too many confirmation attempts have been made.

  **Response:**

  :http:statuscode:`200 OK`:
    The TAN code have been sent. This returns `TanTransmission` response.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`404 Not Found`:
    The challenge was not found.
  :http:statuscode:`502 Bad Gateway`:
    * ``TALER_EC_BANK_TAN_CHANNEL_SCRIPT_FAILED``: TAN transmition via ``tan_channel`` failed.

  **Details:**

  .. ts:def:: TanTransmission

    interface TanTransmission {
      // Channel of the last successful transmission of the TAN challenge.
      tan_channel: TanChannel;

      // Info of the last successful transmission of the TAN challenge.
      tan_info: string;
    }

  .. ts:def:: Challenge

    interface Challenge {
      // Unique identifier of the challenge to solve to run this protected
      // operation.
      challenge_id: string;
    }

  .. ts:def:: TanChannel

    enum TanChannel {
      SMS = "sms",
      EMAIL = "email"
    }


.. http:post:: /accounts/$USERNAME/challenge/$CHALLENGE_ID/confirm

  Solves the ``CHALLENGE_ID`` challenge and allows performing the protected operation.

  When the challenge is confirmed, you can call the protected endpoint again with ``CHALLENGE_ID`` in the ``X-Challenge-Id`` HTTP header and an empty request body.

  **Request:**

  .. ts:def:: ChallengeSolve

    interface ChallengeSolve {
      // The TAN code that solves $CHALLENGE_ID
      tan: string;
    }

  **Response:**

  :http:statuscode:`204 No Content`:
    The challenge is confirmed.
  :http:statuscode:`401 Unauthorized`:
    Invalid credentials or missing rights.
  :http:statuscode:`404 Not Found`:
    The challenge was not found.
  :http:statuscode:`409 Conflict`:
    * ``TALER_EC_BANK_TAN_CHALLENGE_FAILED`` : wrong TAN.
    * ``TALER_EC_BANK_TAN_CHALLENGE_EXPIRED`` : expired TAN.
  :http:statuscode:`429 Too many requests`:
    Too many failed confirmation attempts, a new TAN must be requested.


Monitor
-------

.. http:get:: /monitor

  When the bank provides conversion between the local currency and an
  external one, this call lets the bank administrator monitor the cashin
  and cashout operations that were made from and to the external currency.
  It shows as well figures related to internal payments made by a Taler
  exchange component to internal bank accounts. Timeframes are in UTC.

  **Request:**

  :query timeframe: *Optional*.
    This parameter admits one of the following values. Defaults to 'hour'.

    * hour
    * day
    * month
    * year

  :query date_s: *Optional*.
    Non-negative date in seconds after the UNIX Epoch. Defaults to current time.
    @since **v4**

  :query which: *Optional*.
    This parameter points at a particular element of the *timeframe* parameter.
    Following are the admitted values for each one.
    Defaults to the last snapshot taken of the *timeframe* parameter.
    @deprecated since **v4**

    * hour: from 00 to 23
    * day: from 1 to the last day of the current month.
    * month: from 1 to 12
    * year: Gregorian year in the YYYY format.

  **Response:**

  :http:statuscode:`200 OK`:
    The bank responds with `MonitorResponse`.
  :http:statuscode:`400 Bad Request`:
    This error may indicate that the *which* parameter is not appropriate for the selected *timeframe*.  For example, timeframe=month and which=20 would result in this error.

  **Details:**

  .. note::

    API consumers may combine the values in the response with other
    factors to serve different views to their users.

  .. ts:def:: MonitorResponse

    // Union discriminated by the "type" field.
    type MonitorResponse =
      | MonitorNoConversion
      | MonitorWithConversion;

  .. ts:def:: MonitorNoConversion

    // Monitoring stats when conversion is not supported
    interface MonitorNoConversion {
      type: "no-conversions";

      // How many payments were made to a Taler exchange by another
      // bank account.
      talerInCount: Integer;

      // Overall volume that has been paid to a Taler
      // exchange by another bank account.
      talerInVolume: Amount;

      // How many payments were made by a Taler exchange to another
      // bank account.
      talerOutCount: Integer;

      // Overall volume that has been paid by a Taler
      // exchange to another bank account.
      talerOutVolume: Amount;
    }

  .. ts:def:: MonitorWithConversion

    // Monitoring stats when conversion is supported
    interface MonitorWithConversion {
      type: "with-conversions";

      // How many cashin operations were confirmed by a
      // wallet owner. Note: wallet owners
      // are NOT required to be customers of the libeufin-bank.
      cashinCount: Integer;

      // Overall regional currency that has been paid by the regional admin account
      // to regional bank accounts to fulfill all the confirmed cashin operations.
      cashinRegionalVolume: Amount;

      // Overall fiat currency that has been paid to the fiat admin account
      // by fiat bank accounts to fulfill all the confirmed cashin operations.
      cashinFiatVolume: Amount;

      // How many cashout operations were confirmed.
      cashoutCount: Integer;

      // Overall regional currency that has been paid to the regional admin account
      // by fiat bank accounts to fulfill all the confirmed cashout operations.
      cashoutRegionalVolume: Amount;

      // Overall fiat currency that has been paid by the fiat admin account
      // to fiat bank accounts to fulfill all the confirmed cashout operations.
      cashoutFiatVolume: Amount;

      // How many payments were made to a Taler exchange by another
      // bank account.
      talerInCount: Integer;

      // Overall volume that has been paid to a Taler
      // exchange by another bank account.
      talerInVolume: Amount;

      // How many payments were made by a Taler exchange to another
      // bank account.
      talerOutCount: Integer;

      // Overall volume that has been paid by a Taler
      // exchange to another bank account.
      talerOutVolume: Amount;
    }


Endpoints for Integrated Sub-APIs
---------------------------------

.. http:any:: /taler-integration/*

  All endpoints under this prefix are specified by the.
  :doc:`GNU Taler bank integration API </core/api-bank-integration>`.
  This API handles the communication with Taler wallets.


.. http:any:: /accounts/$USERNAME/taler-wire-gateway/*

   All endpoints under this prefix are specified
   by the :doc:`GNU Taler wire gateway API </core/api-bank-wire>`.

   The endpoints are only available for accounts configured with ``is_taler_exchange=true``.


.. http:any:: /accounts/$USERNAME/taler-revenue/*

   All endpoints under this prefix are specified
   by the :doc:`GNU Taler Revenue API </core/api-bank-revenue>`.


.. http:any:: /conversion-info/*

   All endpoints under this prefix are specified
   by the :doc:`GNU Taler Conversion Info API </core/api-bank-conversion-info>`.


.. http:post:: /ebicshost

   EBICS base URL.  This URL allows clients to make EBICS requests to one of
   the configured EBICS hosts.

   The Taler bank can be configured to serve bank account transactions and
   allow payment initiations via the EBICS protocol.

   This is an optional feature, not all implementations of the API support it.