The beginnings of a Guzzle-based, PHP Twilio client.

composer.json

{
    "require": {
        "guzzlehttp/guzzle": "~4.2",
        "guzzlehttp/guzzle-services": "~0.3.0",
        "guzzlehttp/retry-subscriber": "~1.0"
    },
    "authors": [
        {
            "name": "Jeremy Lindblom",
            "email": "jeremeamia@gmail.com"
        }
    ],
    "autoload": {
        "psr-4": {
            "Twilio\\": "src/"
        }
    }
}

test.php

<?php

require 'vendor/autoload.php';

$twilio = new Twilio\Client([
    'account_sid' => 'ACXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX',
    'auth_token'  => 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
]);

$result = $twilio->sendMessage([
    'From' => '+15551784133',
    'To'   => '+15559449534',
    'Body' => 'Hello, world!',
]);

echo "Message SID: {$result['sid']}\n";
print_r($result->toArray());

twilio-api.php

<?php return [
    'baseUrl' => 'https://api.twilio.com',
    'apiVersion' => '2010-04-01',
    'operations' => [
        'SendMessage' => [
            'httpMethod' => 'POST',
            'uri' => '/{ApiVersion}/Accounts/{AccountSid}/Messages.json',
            'responseModel' => 'Resource',
            'parameters' => [
                'AccountSid' => [
                    'required' => true,
                    'type'     => 'string',
                    'location' => 'uri',
                ],
                'ApiVersion' => [
                    'required' => true,
                    'type'     => 'string',
                    'location' => 'uri',
                ],
                'From' => [
                    'required' => true,
                    'type'     => 'string',
                    'location' => 'postField',
                ],
                'To' => [
                    'required' => true,
                    'type'     => 'string',
                    'location' => 'postField',
                ],
                'Body' => [
                    'type'     => 'string',
                    'location' => 'postField',
                ],
                'MediaUrl' => [
                    'type'     => 'string',
                    'location' => 'postField',
                ],
                'StatusCallback' => [
                    'type'     => 'string',
                    'location' => 'postField',
                ],
                'ApplicationSid' => [
                    'type'     => 'string',
                    'location' => 'postField',
                ],
            ],
        ],
    ],
    'models' => [
        'Resource' => [
            'type' => 'object',
            'additionalProperties' => [
                'location' => 'json',
            ]
        ],
    ]
];

Twilio_Client.php

<?php
namespace Twilio;

use GuzzleHttp\Client as HttpClient;
use GuzzleHttp\Collection;
use GuzzleHttp\Command\Guzzle\GuzzleClient;
use GuzzleHttp\Command\Guzzle\Description;
use GuzzleHttp\Command\Model;
use GuzzleHttp\Subscriber\Retry\RetrySubscriber;

/**
 * Web service client for Twilio
 *
 * @method Model sendMessage(array $config = [])
 */
class Client extends GuzzleClient
{
    /**
     * @param array $config
     */
    public function __construct(array $config = [])
    {
        // Create a collection object with defaults and required params set
        $config = Collection::fromConfig($config, [
            'max_retries'      => 3,
            'description_path' => __DIR__ . '/twilio-api.php'
        ], ['account_sid', 'auth_token']);

        // Ensure that the HTTP client and Service Description
        $this->handleHttpClientOptions($config);
        $this->handleDescriptionOptions($config);

        // Create the Twilio Client
        parent::__construct(
            $config['http_client'],
            $config['description'],
            $config->toArray()
        );

        // Ensure that the credentials are set
        $this->handleCredentialsOptions($config);

        // Ensure that ApiVersion is set
        $this->setConfig(
            'defaults/ApiVersion',
            $this->getDescription()->getApiVersion()
        );
    }

    /**
     * @param Collection $config
     */
    private function handleHttpClientOptions(Collection $config)
    {
        if ($config['http_client']) {
            // HTTP client was injected
            return;
        }

        $client = new HttpClient($config['http_client_options'] ?: []);

        // Attach request retry logic
        $client->getEmitter()->attach(new RetrySubscriber([
            'max' => $config['max_retries'],
            'filter' => RetrySubscriber::createChainFilter([
                RetrySubscriber::createStatusFilter(),
                RetrySubscriber::createCurlFilter(),
            ]),
        ]));

        $config['http_client'] = $client;
    }

    /**
     * @param Collection $config
     *
     * @throws \InvalidArgumentException
     */
    private function handleDescriptionOptions(Collection $config)
    {
        if ($config['description']) {
            // Service description was injected
            return;
        }

        // Load service description data
        $path = $config['description_path'];
        $data = file_exists($path) ? include $path : null;
        if (!is_array($data)) {
            throw new \InvalidArgumentException('Invalid description');
        }

        $config['description'] = new Description($data);
    }

    /**
     * @param Collection $config
     */
    private function handleCredentialsOptions(Collection $config)
    {
        if (!$this->getHttpClient()->getDefaultOption('auth')) {
            $this->getHttpClient()->setDefaultOption('auth', [
                $config['account_sid'],
                $config['auth_token'],
            ]);
        }

        $this->setConfig('defaults/AccountSid', $config['account_sid']);
    }
}