Nexus API
###########

HTTP API
========

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

Currently every request made to nexus must be authenticated using the *HTTP
basic auth* mechanism.

Other authentication mechanisms (e.g. OpenID Connect) might
be supported in the future.

Users Management
----------------

.. http:get:: <nexus>/user

  Get information about the current user (based on the authentication information
  in this request).

  **Response:**

  .. ts:def:: GetUserResponse

     interface UserResponse {

       // User name
       username: string;

       // Is it a superuser?
       superuser: boolean;
     }

.. http:post:: <nexus>/users

  Create a new user.  Only the super-user can call this API.

  **Request:**

  The body is a `User` object.

  **Response:**

  :status 409 Conflict: Username is not available.

  **Details:**

  .. ts:def:: User

     interface User {

       // User name
       username: string;

       // Initial password
       password: string;
     }

Bank Account Management
-----------------------

.. http:get:: <nexus>/bank-accounts
  
  **Response:**

  A list of `BankAccount` objects
  that belong to the requester.

  .. ts:def:: BankAccount
     
     interface BankAccount {
       // mnemonic name identifying this bank account.
       account: string; 
       // IBAN
       iban: string;
       // BIC
       bic: string;
       // Legal subject owning the account.
       holder: string;
     }

.. http:post:: <nexus>/bank-accounts/prepared-payments/submit

  Ask nexus to submit one prepare payment at the bank.

  **Request:**

  .. ts:def:: SubmitPayment

     interface SubmitPayment {
       // Unique identifier of the (previously) prepared payment
       // to submit at the bank.
       uuid: string;

       // Specify the bank transport to use for the submission.
       transport?: Transport;
     }

    
  .. ts:def:: Transport

     interface Transport {

       // Transport type: 'ebics', 'local', 'fints' (forthcoming).
       // It must match one of the types actually implemented by
       // nexus.
       type: string;

       // A mnemonic identifier given by the user to one particular
       // transport instance.
       name: string;
     }

  :status 404 Not Found: the unique identifier **or**
    the bank transport could not be found in the system


.. http:get:: <nexus>/bank-accounts/<my-acct>/prepared-payments/$uuid
   
   Ask the status of payment ``$uuid``.

   **Response:**

   .. ts:def:: PaymentStatus

      interface PaymentStatus {

        // Payment unique identifier
        uuid: string;

        // True for submitted payments
        submitted: boolean;

        // Creditor IBAN
        creditorIban: string;

        // Creditor BIC
        creditorBic: string;

        // Creditor legal name
        creditorName: string;

        // Amount
        amount: string;

        // Subject
        subject: string;

        // Date of submission (in dashed form YYYY-MM-DD)
        submissionDate: string;

        // Date of preparation (in dashed form YYYY-MM-DD)
        preparationDate: string;
      }

.. http:post:: <nexus>/bank-accounts/<my-acct>/prepared-payments
  
  Ask nexus to prepare instructions for a new payment.
  Note that ``my-acct`` is the bank account that will be
  **debited** after this operation.

  **Request:**

  .. ts:def:: PreparedPaymentRequest

     interface PreparedPaymentRequest {
       // IBAN that will receive the payment.
       iban: string;
       // BIC hosting the IBAN.
       bic: string;
       // Legal subject that will receive the payment.
       name: string;
       // payment subject. 
       subject: string;
       // amount, in the format CURRENCY:XX.YY
       amount: string
     }

  **Response:**

  .. ts:def:: PreparedPaymentResponse
     
     interface PreparedPaymentResponse {

       // Opaque identifier to be communicated when
       // the user wants to submit the payment to the
       // bank.
       uuid: string;
     }

.. http:post:: <nexus>/bank-accounts/collected-transactions

  Nexus will download bank transactions from the given transport.

  **Request:**

  .. ts:def:: CollectedTransaction

     interface CollectedTransaction {
       // Optional field to specify the bank transport to
       // use for such operation.
       bankTransport?: Transport;
       // dashed date (YYYY-MM-DD) of the earliest payment
       // in the result. Optional, defaults to "earliest
       // possible" date.
       start: string;
       // dashed date (YYYY-MM-DD) of the earliest payment
       // in the result. Optional, defaults to "latest
       // possible" date.
       end: string;
     }

.. http:get:: <nexus>/bank-accounts/<my-acct>/collected-transactions

  Shows which transactions are stored locally at nexus.

  **Query parameters:**

  * **start** start (dashed YYYY-MM-DD) date of desired payments.
    Optional, defaults to "earliest possible" date
  * **end** end (dashed YYYY-MM-DD) date of desired payments.
    Optional, defaults to "earliest possible" date


  **Response:** A list of `Transaction` objects.

  .. ts:def:: Transaction

     interface Transaction {
       // local bank account involved in the transaction.
       account: string;

       // counterpart IBAN
       counterpartIban: string;

       // counterpart BIC
       counterpartBic: string;

       // counterpart holder name
       counterpartName: string;

       // amount, in the format [-]CURRENCY:XX.YY,
       // where the minus sign as prefix indicates
       // a debit for the user's bank account.
       amount: string;

       // Dashed date YYYY-MM(01-12)-DD(01-31) of the transaction.
       date: string;

       // Payment subject.
       subject: string;
     }

Bank Transports
---------------

Bank transports connect the local LibEuFin bank account
to the real bank.

.. http:post:: <nexus>/bank-transports
  
  Activate a new bank transport for the requesting user.

  **Request:**

  .. ts:def:: BankTransport

     interface BankTransport {

       transport: Transport;

       // Restore a previous transport.  Take precedence
       // over the 'new' field.
       backup?: TransportBackup;
       
       // Data to create a fresh bank transport without
       // restoring any backup.
       data?: TransportNew;
     }


  .. ts:def:: TransportNew

     interface TransportNew {

       // This type is strictly dependent on
       // the transport being created.  For Ebics,
       // it will contain the required fields (as strings):
       // 'ebicsURL', 'userID', 'partnerID', 'hostID', and
       // the optional 'systemID'.
  
       // Other transport types, like 'local' (used for testing
       // purposes skipping any interaction with the bank service)
       // and 'fints' are all work in progress!

     }


  .. ts:def:: TransportBackup
     
     interface TransportBackup {

       // The information needed in this type depend entirely
       // on which transport is being restored.

     }

  **Response:**

  :status 409 Conflict: The ``name`` field exists already for
    the requesting user.

.. http:post:: <nexus>/bank-transports/sendMSG.
  
  Perform the ``MSG`` operation offered by ``transport-name``
  **without** affecting the nexus database.

  **Request:**
  
  A `Transport` object.

  **Response:**

  :status 404 Not Found: ``transport-name`` doesn't exist for
    the requesting user.

.. http:post:: <nexus>/bank-transports/<transport-name>/syncMSG.
  
  Some transports **do** have operations that aren't semantically
  related to a bank account but need to be stored locally at the nexus.
  One typical example is the downloading of the bank's keys vie the
  EBICS transport.  This API lets the user perform the ``MSG``
  operation that should result in new data being stored locally
  at the nexus.

  **Response:**

  :status 404 Not Found: ``transport-name`` doesn't exist for
    the requesting user.