# The REST API

All of what's possible to do with the website is also possible via a
web API. This document explains how the API is organized and how you can
query it.

The main supported data format is JSON. When using POST or PUT, you can
either pass data encoded in JSON or in `application/x-www-form-urlencoded`
format.

## Overall organisation

You can access three different things: projects, members and bills. You
can also get the balance for a project.

The examples here are using curl, feel free to use whatever you want to
do the same thing, curl is not a requirement.

### Authentication

To interact with bills and members, and for any action other than
creating a new project, you need to be authenticated. The simplest way
to authenticate is to use "basic" HTTP authentication with the project
ID and private code.

For instance, to obtain information about a project, using curl:

    $ curl --basic -u demo:demo https://ihatemoney.org/api/projects/demo

It is also possible to generate a token, and then use it later to
authenticate instead of basic auth. For instance, start by generating
the token (of course, you need to authenticate):

    $ curl --basic -u demo:demo https://ihatemoney.org/api/projects/demo/token
    {"token": "WyJ0ZXN0Il0.Rt04fNMmxp9YslCRq8hB6jE9s1Q"}

Make sure to store this token securely: it allows almost full access to the
project. For instance, use it to obtain information about the project
(replace `PROJECT_TOKEN` with the actual token):

    $ curl --oauth2-bearer "PROJECT_TOKEN" https://ihatemoney.org/api/projects/demo

This works by sending the token in the Authorization header, so doing it
"manually" with curl looks like:

    $ curl --header "Authorization: Bearer PROJECT_TOKEN" https://ihatemoney.org/api/projects/demo

This token can also be used to authenticate for a project on the web
interface, which can be useful to generate invitation links. You would
simply create an URL of the form:

    https://ihatemoney.org/demo/join/PROJECT_TOKEN

Such a link grants read-write access to the project associated with the token,
but it does not allow to change project settings.

### Projects

You can't list projects, for security reasons. But you can create,
update and delete one directly from the API.

The URLs are `/api/projects` and `/api/projects/<identifier>`.

#### Creating a project

A project needs the following arguments:

-   `name`: the project name (string)
-   `id`: the project identifier (string without special chars or
    spaces)
-   `password`: the project password / private code (string)
-   `contact_email`: the contact email, used to recover the private code (string)

Optional arguments:

-   `default_currency`: the default currency to use for a multi-currency
    project, in ISO 4217 format. Bills are converted to this currency
    for operations like balance or statistics. Default value: `XXX` (no
    currency).

Here is the command:

    $ curl -X POST https://ihatemoney.org/api/projects \
    -d 'name=yay&id=yay&password=yay&contact_email=yay@notmyidea.org'
    "yay"

As you can see, the API returns the identifier of the project. It might be different
from what you requested, because the ID is normalized (remove special characters,
change to lowercase, etc).

#### Getting information about the project

Getting information about the project:

    $ curl --basic -u demo:demo https://ihatemoney.org/api/projects/demo
    {
        "id": "demo",
        "name": "demonstration",
        "contact_email": "demo@notmyidea.org",
        "default_currency": "XXX",
        "members": [{"id": 11515, "name": "f", "weight": 1.0, "activated": true, "balance": 0},
                    {"id": 11531, "name": "g", "weight": 1.0, "activated": true, "balance": 0},
                    {"id": 11532, "name": "peter", "weight": 1.0, "activated": true, "balance": 5.0},
                    {"id": 11558, "name": "Monkey", "weight": 1.0, "activated": true, "balance": 0},
                    {"id": 11559, "name": "GG", "weight": 1.0, "activated": true, "balance": -5.0}]
    }

#### Updating a project

Updating a project is done with the `PUT` verb:

    $ curl --basic -u yay:yay -X PUT\
    https://ihatemoney.org/api/projects/yay -d\
    'name=yay&id=yay&current_password=yay&password=newyay&contact_email=youpi@notmyidea.org'

You need to give the current private code as the `current_password` field. This is a security
measure to ensure that knowledge of an auth token is not enough to update settings.

Note that in any case you can never change the ID of a project.

#### Deleting a project

Just send a DELETE request ont the project URI :

    $ curl --basic -u demo:demo -X DELETE https://ihatemoney.org/api/projects/demo

### Members

You can get all the members with a `GET` on
`/api/projects/<id>/members`:

    $ curl --basic -u demo:demo https://ihatemoney.org/api/projects/demo/members\
    [{"weight": 1, "activated": true, "id": 31, "name": "Arnaud"},
     {"weight": 1, "activated": true, "id": 32, "name": "Alexis"},
     {"weight": 1, "activated": true, "id": 33, "name": "Olivier"},
     {"weight": 1, "activated": true, "id": 34, "name": "Jeanne"}]

Add a member with a `POST` request on `/api/projects/<id>/members`:

    $ curl --basic -u demo:demo -X POST\
    https://ihatemoney.org/api/projects/demo/members -d 'name=tatayoyo'
    35

You can also `PUT` a new version of a member (changing its name):

    $ curl --basic -u demo:demo -X PUT\
    https://ihatemoney.org/api/projects/demo/members/36\
    -d 'name=yeaaaaah'
    {"activated": true, "id": 36, "name": "yeaaaaah", "weight": 1}

Delete a member with a `DELETE` request on
`/api/projects/<id>/members/<member-id>`:

    $ curl --basic -u demo:demo -X DELETE\
    https://ihatemoney.org/api/projects/demo/members/35
    "OK

### Bills

You can get the list of bills by doing a `GET` on
`/api/projects/<id>/bills` :

    $ curl --basic -u demo:demo https://ihatemoney.org/api/projects/demo/bills

Or get a specific bill by ID:

    $ curl --basic -u demo:demo https://ihatemoney.org/api/projects/demo/bills/42
    {
      "id": 42,
      "payer_id": 11,
      "owers": [
        {
          "id": 22,
          "name": "Alexis",
          "weight": 1,
          "activated": true
        }
      ],
      "amount": 100,
      "date": "2020-12-24",
      "creation_date": "2021-01-13",
      "what": "Raclette du nouvel an",
      "external_link": "",
      "original_currency": "XXX",
      "converted_amount": 100
    }

`amount` is expressed in the `original_currency` of the bill, while
`converted_amount` is expressed in the project `default_currency`. Here,
they are the same.

Add a bill with a `POST` query on `/api/projects/<id>/bills`. You need
the following required parameters:

-   `what`: what has been paid (string)
-   `payer`: paid by who? (id)
-   `payed_for`: for who ? (id). To set multiple id, simply pass the
    parameter multiple times (x-www-form-urlencoded) or pass a list of
    id (JSON).
-   `amount`: amount payed (float)

And optional parameters:

-   `date`: the date of the bill (`yyyy-mm-dd` format). Defaults to
    current date if not provided.
-   `original_currency`: the currency in which `amount` has been paid
    (ISO 4217 code). Only makes sense for a project with currencies.
    Defaults to the project `default_currency`.
-   `external_link`: an optional URL associated with the bill.

Returns the id of the created bill :

    $ curl --basic -u demo:demo -X POST\
    https://ihatemoney.org/api/projects/demo/bills\
    -d "date=2011-09-10&what=raclette&payer=1&payed_for=3&payed_for=5&amount=200"
    80

You can also `PUT` a new version of the bill at
`/api/projects/<id>/bills/<bill-id>`:

    $ curl --basic -u demo:demo -X PUT\
    https://ihatemoney.org/api/projects/demo/bills/80\
    -d "date=2011-09-10&what=raclette&payer=1&payed_for=3&payed_for=5&payed_for=1&amount=250"
    80

And you can of course `DELETE` them at
`/api/projects/<id>/bills/<bill-id>`:

    $ curl --basic -u demo:demo -X DELETE\
    https://ihatemoney.org/api/projects/demo/bills/80\
    "OK"

### Statistics

You can get some project stats with a `GET` on
`/api/projects/<id>/statistics`:

    $ curl --basic -u demo:demo https://ihatemoney.org/api/projects/demo/statistics
    [
        {
            "member": {"activated": true, "id": 1, "name": "alexis", "weight": 1.0},
            "paid": 25.5,
            "spent": 15,
            "balance": 10.5
        },
        {
            "member": {"activated": true, "id": 2, "name": "jeanne", "weight": 1.0},
            "paid": 5,
            "spent": 15.5,
            "balance": -10.5
        }
    ]

### Currencies

You can get a list of supported currencies with a `GET` on
`/api/currencies`:

    $ curl --basic https://ihatemoney.org/api/currencies
    [
        "XXX",
        "AED",
        "AFN",
        .
        .
        .
        "ZAR",
        "ZMW",
        "ZWL"
    ]


