Move the Guzzle client from being injected into the API class.

[OAFCROB]

Move the Guzzle client from being injected into the API class, as the external users shouldn't have to know that the API calls are made by Guzzle client within this package.

A current usage would look something like this;

$api = new ResellerClubApi(
                new ResellerClubApiConfig(
                    'auth-key',
                    'api-key',
                    'env'
                ),
                new GuzzleClient
            );

Probably should be more like this;

$api = new ResellerClubApi(
                new ResellerClubApiConfig(
                    'auth-key',
                    'api-key',
                    'env'
                )
            );

[martinbean]

The SDK will need some more of client to make API requests. I feel it should still be injected, as it is a dependency of the class.

If the issue is hard-relying on Guzzle, then it could be abstracted out into some sort of “transport adapter” thing. So, the class would type-hint on an interface, and then you would have a class that implements that interface and passes methods to Guzzle:

public function __construct(Config $config, TransportAdapter $transport)
{
    //
}

use Psr\Http\Message\ResponseInterface;

interface TransportAdapter
{
    public function get($uri, array $parameters): ResponseInterface;
    public function post($uri, array $parameters): Psr\Http\Message\ResponseInterface;
}

use GuzzleHttp\Client;
use Psr\Http\Message\ResponseInterface;

class GuzzleTransportAdapter implements AdapterInterface
{
    public function __construct(Client $client)
    {
        $this->client = $client;
    }

    public function get($uri, array $parameters): ResponseInterface
    {
        return $this->client->get($uri, [
            'query' => $parameters,
        ]);
    }

    public function post($uri, array $parameters): ResponseInterface
    {
        return $this->client->post($uri, [
            'form_params' => $parameters,
        ]);
    }
}