# Contributing

We're huge fans of open-source, and absolutely we love getting good contributions to **segmentio/integrations**! These docs will tell you everything you need to know about how to add your own integration to the library with a pull request, so we can merge it in for everyone else to use.

## Getting Setup

  To start, you need a couple of tools that will help you integrate as fast as possible:

  - [Khaos](https://github.com/segmentio/khaos) (`npm i -g khaos`)
  - [kahos-segmentio-integration](https://github.com/segmentio/khaos-segmentio-integration) (`khaos install segmentio/khaos-segmentio-integration integration`)

Once you have those tools installed, `cd` into your fork and run:

  ```bash
  $ khaos create integration lib/<slug>
  ```

Khaos will ask you a couple of question and create the integration skeleton for you!
See our [tracking API](https://segment.io/docs/tracking-api/) to check what each method does.

  - __identify__ - does your integration support the identify method ?
  - __track__ - does your integration support the track method ?
  - __page__ - does your integration support the page method ?
  - __screen__ - does your integration support the screen method ?
  - __group__ - does your integration support the group method ?
  - __alias__ - does your integration support the alias method ?
  - __mapper__ - the mapper helps you map raw `msg` to something the integration API will accept.
  - __docs__ - docs link
  - __endpoint__ - api endpoint

![khaos](https://cldup.com/WpoOLwogvU.png)

### Channels

We currently have 3 channels, add all channels you want your integration to support.
Note that if your integration is bundled in analytics.js you should omit the `client` channel.

  ```js
  channels(['server', 'mobile', 'client'])
  ```

### Settings

When a Segment user first turns on the integration, they'll be asked to enter settings specific to the integration.

![](https://i.cloudup.com/btVoto0faC.png)

These are typically fields like:

  - API Keys
  - whether to track pageviews
  - mappings from Segment events to integration specific events


As a good rule of thumb, any option in the integration should be a separate key in the `settings` object. These will be stored as `this.settings` on the integration itself.


_Segment teammates_: `settings` should match up with those found in the [`integration-metadata`](https://github.com/segmentio/integration-metadata) repo.


### Validation

You can ensure the settings has `key`, or the message has `path` easily using `ensure()`.

```js
.ensure('settings.apiKey')
.ensure('message.userId')
.ensure('message.context.ip')
```

The above example will ensure that the user has an `apiKey` and the message has an `userId` and `ip`, otherwise the integration
will reject the call automatically.

### Dynamic validation.

You can dymanically decide to reject a message by providing a function to `.ensure()`.

```js
/**
 * Mixpanel requires an `.apiKey` on `track`
 * if the message is older than 5 days.
 */

Mixpanel.ensure(function(msg, settings){
  if (settings.apiKey) return;
  if ('track' != msg.type()) return;
  if (!shouldImport(msg)) return;
  return this.invalid('.apiKey is required if "track" message is older than 5 days.');
});
```

Note that for invalid settings you must use `.invalid(msg)`, for invalid
messages you must use `.reject(msg)`.

### Validation tests

The generated integration will contain some tests.

```js
it('should have the correct settings', function(){
  test
    .name('My Integration')
    .channels(['server', 'mobile', 'client'])
    .ensure('settings.apiKey')
    .ensure('message.userId')
    .ensure('message.context.ip')
    .retries(2);
});

describe('.validate()', function() {
  var msg;

  beforeEach(function(){
    msg = {
      userId: 'user-id',
      type: 'identify',
      context: { ip: '0.0.0.0' }
    };
  });

  it('should not be valid without an api key', function(){
    delete settings.apiKey;
    test.invalid(msg, settings);
  });

  it('should not be valid without a userId', function(){
    delete msg.userId;
    test.invalid(msg, settings);
  });

  it('should not be valid without a context.ip', function(){
    delete msg.context.ip;
    test.invalid(msg, settings);
  });

  it('should be valid with complete message and settings', function(){
    test.valid(msg, settings);
  });
});
```

### Mapper

To see what methods are available on `msg`, check out [facade](https://github.com/segmentio/facade).

A mapper should receive a raw `msg` of `Facade` and return a payload, the payload
is then passed to the method in order to send it out:

Suppose the API only accepts `$user_id` and `$name`
You can add a `mapper.identify` that does the mappings for you.


```js
// my-integration/mapper.js
exports.identify = function(msg, settings){
  return {
    $user_id: msg.userId(),
    $name: msg.name(),
  }
};
```

Then `identify` will receive `{ $user_id: '811a5bdd', $name: 'john doe' }` to send.

```js
// my-integration/index.js
MyIntegration.prototype.identify = function(payload, fn){
  return this
    .post()
    .auth(this.settings.apiKey)
    .type('json')
    .send(payload)
    .end(this.handle(fn));
};
```

### Dynamic Mapper

It's useful to dynamically call the mapper sometimes and not have it
do it's magic behind the scenes.

To call the mapper directly make sure you remove `.mapper(mapper)`
from the integration generator, that way `identify()` will receive
the message and can just call / not call the mapper.

```js
var MyIntegration = module.exports = integration('My Integration')
  .endpoint('https://api.my-integration.com/v1')
  .ensure('settings.apiKey')
  .ensure('message.userId')
  .mapper(mapper)
  .retries(2);
```

```js
var MyIntegration = module.exports = integration('My Integration')
  .endpoint('https://api.my-integration.com/v1')
  .ensure('settings.apiKey')
  .ensure('message.userId')
  .retries(2);
```

```js
MyIntegration.prototype.identify = function(msg, fn){
  var json = mapper.identify(msg);
  return this;
};
```

### Mapper tests

The generated integration will contain `test/fixtures/*.json`,
Each `json` file contains `input` and `output`, where input
is just the raw message you expect to receive, and output is
the raw payload you expect to be sent.

to test them out, simply call `test.maps('my-fixture-name')`:

```js
  describe('identify', function(){
    it('should map basic identify', function(){
      test.maps('identify-basic');
    });
  });
```

### Request tests

You can reuse the generated fixtures to test requests as well:

```js
  it('should send basic identify', function(done){
    var json = test.fixture('identify-basic');
    test
      .identify(json.input)
      .sends(json.output)
      .expects(200)
      .end(done);
  });
```

### Running tests

You can run your integration tests just by passing it's title to `GREP` env variable.

```bash
$ GREP=MyIntegration make test
```

### Checklist

  - When making a fix, first write a breaking test for it
  - Make sure your tests are complete and passing
  - Make sure you follow the style of the rest of our integrations
  - Run `make lint` and make sure that it doesn't complain
  - Make sure new intgration tests have fixtures
  - Send demo account credentials to integrations@segment.io (teammates: put them in Meldium)

### That's it!

You can now submit the PR for review :D