Some improves

README.md

@@ -5,7 +5,6 @@ A simple PHP client for the Salesforce REST API
 
 Install with composer:
 ```
-composer config repositories.salesforce-rest-api vcs https://github.com/gmo/salesforce-rest-api
 composer require "gmo/salesforce-rest-api:^1.0"
 ```
 
@@ -22,11 +21,9 @@ $authentication = new Salesforce\Authentication\PasswordAuthentication(
 	"ClientId",
 	"ClientSecret",
 	"Username",
-	"Password",
-	"SecurityToken",
-	new Http\Client()
+	"Password[+SecurityToken]"
 );
-$salesforce = new Salesforce\Client($authentication, new Http\Client(), "na5");
+$salesforce = new Salesforce\Client($authentication);
 
 try {
 	$contactQueryResults = $salesforce->query("SELECT AccountId, LastName

composer.json

@@ -2,9 +2,10 @@
   "name": "gmo/salesforce-rest-api",
   "license": "MIT",
   "require": {
-    "psr/log": "1.0.0",
-    "guzzle/guzzle": "3.9.2",
-    "php": ">=5.3"
+    "psr/log": "^1.0",
+    "php": "^7.1",
+    "guzzlehttp/guzzle": "^6.3",
+    "doctrine/collections": "^1.4"
   },
   "autoload": {
     "psr-4": {

src/Authentication/AuthenticationBag.php

@@ -0,0 +1,57 @@
+<?php
+declare(strict_types=1);
+
+namespace Gmo\Salesforce\Authentication;
+
+
+class AuthenticationBag implements AuthenticationBagInterface
+{
+
+    /** @var  string */
+    protected $token;
+
+    /** @var  string */
+    protected $instanceUrl;
+
+    /** @var  string */
+    protected $tokenType;
+
+    /** @var  \DateTime */
+    protected $issuedAt;
+
+    protected $signature;
+
+    public function __construct(array $jsonResponse)
+    {
+        $this->token = $jsonResponse['access_token'];
+        $this->instanceUrl = $jsonResponse['instance_url'];
+        $this->tokenType = $jsonResponse['token_type'];
+        $this->issuedAt = (new \DateTime())->setTimestamp((int) $jsonResponse['issued_at']);
+        $this->signature = $jsonResponse['access_token'];
+    }
+
+    public function getToken()
+    {
+        return $this->token;
+    }
+
+    public function getInstanceUrl()
+    {
+        return $this->instanceUrl;
+    }
+
+    public function getTokenType()
+    {
+        return $this->tokenType;
+    }
+
+    public function issuedAt()
+    {
+        return $this->issuedAt;
+    }
+
+    public function getSignature()
+    {
+        return $this->signature;
+    }
+}

src/Authentication/AuthenticationBagInterface.php

@@ -0,0 +1,19 @@
+<?php
+declare(strict_types=1);
+
+namespace Gmo\Salesforce\Authentication;
+
+
+interface AuthenticationBagInterface
+{
+    public function getToken();
+
+    public function getInstanceUrl();
+
+    public function getTokenType();
+
+    public function issuedAt();
+
+    public function getSignature();
+
+}

src/Authentication/AuthenticationInterface.php

@@ -1,12 +1,14 @@
 <?php
+declare(strict_types=1);
+
 namespace Gmo\Salesforce\Authentication;
 
 use Gmo\Salesforce\Exception;
 
 interface AuthenticationInterface
 {
     /**
-     * @return string
+     * @return AuthenticationBagInterface
      * @throws Exception\SalesforceAuthentication
      */
     public function getAccessToken();

src/Authentication/PasswordAuthentication.php

@@ -1,14 +1,26 @@
 <?php
+declare(strict_types=1);
+
 namespace Gmo\Salesforce\Authentication;
 
-use Guzzle\Http;
+use GuzzleHttp as Http;
 use Psr\Log\LoggerAwareInterface;
 use Psr\Log\LoggerInterface;
 use Psr\Log\NullLogger;
 use Gmo\Salesforce\Exception;
 
 class PasswordAuthentication implements AuthenticationInterface, LoggerAwareInterface
 {
+    const SALESFORCE_SANDBOX_LOGIN_URL = 'https://test.salesforce.com/';
+
+    const SALESFORCE_LOGIN_URL = 'https://login.salesforce.com/';
+
+    const LOGIN_INSTANCES = [
+        self::SALESFORCE_SANDBOX_LOGIN_URL,
+        self::SALESFORCE_LOGIN_URL
+    ];
+
+    const LOGIN_URL = '/services/oauth2/token';
 
     /** @var LoggerInterface */
     protected $log;
@@ -20,53 +32,42 @@ class PasswordAuthentication implements AuthenticationInterface, LoggerAwareInte
     protected $username;
     /** @var string */
     protected $password;
-    /** @var string */
-    protected $securityToken;
-    /** @var string */
-    protected $accessToken;
-    /** @var Http\Client */
-    private $guzzle;
+    /** @var AuthenticationBagInterface|null */
+    protected $responseBag;
+    /** @var Http\ClientInterface */
+    private $http;
 
     public function __construct(
         $clientId,
         $clientSecret,
         $username,
         $password,
-        $securityToken,
-        Http\Client $guzzle,
-        LoggerInterface $log = null,
-        $loginApiUrl = "https://login.salesforce.com/services/"
+        $loginApiUrl = self::SALESFORCE_SANDBOX_LOGIN_URL,
+        Http\ClientInterface $guzzle = null
     ) {
-        $this->log = $log ?: new NullLogger();
+        $this->log = new NullLogger();
         $this->clientId = $clientId;
         $this->clientSecret = $clientSecret;
         $this->username = $username;
         $this->password = $password;
-        $this->securityToken = $securityToken;
-        $this->guzzle = $guzzle;
-        $this->guzzle->setBaseUrl($loginApiUrl);
+        $this->http = $guzzle ?? new Http\Client(['base_uri' => $loginApiUrl]);
     }
 
-    /**
-     * @inheritdoc
-     */
-    public function getAccessToken()
+    public function getAccessToken(): AuthenticationBagInterface
     {
-        if ($this->accessToken) {
-            return $this->accessToken;
+        if ($this->responseBag) {
+            return $this->responseBag;
         }
 
-        $postFields = array(
+        $postFields = [
             'grant_type' => 'password',
             'client_id' => $this->clientId,
             'client_secret' => $this->clientSecret,
             'username' => $this->username,
-            'password' => $this->password . $this->securityToken,
-        );
-        $request = $this->guzzle->post('oauth2/token', null, $postFields);
-        $request->setAuth('user', 'pass');
-        $response = $request->send();
-        $responseBody = $response->getBody();
+            'password' => $this->password,
+        ];
+        $response = $this->http->post(self::LOGIN_URL, ['form_params' => $postFields]);
+        $responseBody = $response->getBody()->getContents();
         $jsonResponse = json_decode($responseBody, true);
 
         if ($response->getStatusCode() !== 200) {
@@ -84,14 +85,14 @@ public function getAccessToken()
             throw new Exception\SalesforceAuthentication($message);
         }
 
-        $this->accessToken = $jsonResponse['access_token'];
+        $this->responseBag = new AuthenticationBag($jsonResponse);
 
-        return $this->accessToken;
+        return $this->responseBag;
     }
 
     public function invalidateAccessToken()
     {
-        $this->accessToken = null;
+        $this->responseBag = null;
     }
 
     /**