All that you need is ... Data Provider! It's provide a data depend on a request

Each Data Provider implements interface Sata\FakeServerApi\DataProvider\IDataProvider Now there is only one method data that receive Psr\Http\Message\ServerRequestInterface and returns some data

It's an compose data provider. That retrieves routes with data providers It uses nikic/FastRoute under the hood, so every route should meet the requirements.

$provider = new RouterDataProvider([
    // limit and offset parameters only make sense
    '/local/articles[/]' => new PathDataProvider($filesystem, ['limit', 'offset']),
    // all other local data get from local data folder
    '/local/{trail:.*}' => new PathDataProvider($filesystem),
    // all r get from reddit (try request /r/PHP/hot.json)
    // requested every time cause of VoidCache
    '/r/{stub:.*}.json' => new ProxyDataProvider($redditGuzzle, $voidCache),
    // all r get from reddit (try request /get?your=paramter)
    '/get{stub:.*}' => new ProxyDataProvider($httpbinGuzzle, $cache),
    // all r get from reddit (try request /post?your=paramter with POST)
    '/post{stub:.*}' => new ProxyDataProvider($httpbinGuzzle, $cache)
]);

$data = $provider->data($request);

After request satisfy the route, new instance of a request (with matched parameters) pass to the target data provider.

Just returns content of specified file.

$provider = new FileDataProvider($filesystem, 'path/to/the/file.json');
$data = $provider->data($request);

It's receives an instance of League\Flysystem\Filesystem. About Flysystem read more here - thephpleague/flysystem.

Like a FileDataProvider it's returns a file content, but with some additional bahavior.

First of it's mount some folder (via Flysystem) to the request (or a visa versa). Also it can handle significant parameters.

For example, if you have an posts API, you can mount data/posts/ folder to all /posts requests. And of course, your API has a pagination logic. Like a /posts?page=1, /posts?page=2.

So by here is map of your request to the files

• /posts -> data/posts/default.json
• /posts?page=1 -> data/posts/page_1.json
• /posts?page=2 -> data/posts/page_2.json
• /posts?some=parameter -> data/posts/default.json

By default, if the file is not found the default file will be mounted.

$filesystem = new Filesystem(new Local(__DIR__ . '/data'));
$provider = new PathDataProvider($filesystem, ['page']);
$data = $provider->data($request);

Primarily this data provider used for a slow connections.

It's receives an instances of Guzzle Client and Doctrine Cache

So every request will be proxied to the remote server and saved in cache.

$cache = new FilesystemCache(__DIR__ . '/cache');
$voidCache = new VoidCache();
$filesystem = new Filesystem(new Local(__DIR__ . '/data'));
$redditGuzzle = new GuzzleHttp\Client(['base_uri' => 'https://www.reddit.com']);
$httpbinGuzzle = new GuzzleHttp\Client(['base_uri' => 'http://httpbin.org']);

// request everytime cause of VoidCache
$redditProvider = new ProxyDataProvider($redditGuzzle, $voidCache);
// request only once an save to the FilesystemCache
$httpbinProvider = new ProxyDataProvider($httpbinGuzzle, $cache);

There are really bad work with other response/request parameters. If your application relies on http statuses, so it's may be a huge problem.