Support for discovering psr-18 clients (#121)

* Support for discovering psr-18 clients

* Make sure we can support non-httplug psr-18 clients

* cs

* Make sure one can find a PSR-18 client

* minors

* Created a PSR18ClientDiscovery

* cs

* s/PSR18/PSR-18

Author: Nyholm

composer.json

@@ -14,7 +14,7 @@
         "php": "^5.5 || ^7.0"
     },
     "require-dev": {
-        "php-http/httplug": "^1.0|^2.0",
+        "php-http/httplug": "^1.0 || ^2.0",
         "php-http/message-factory": "^1.0",
         "puli/composer-plugin": "1.0.0-beta10",
         "phpspec/phpspec": "^2.4",

src/Psr18ClientDiscovery.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace Http\Discovery;
+
+use Http\Discovery\Exception\DiscoveryFailedException;
+use Psr\Http\Client\ClientInterface;
+
+/**
+ * Finds a PSR-18 HTTP Client.
+ *
+ * @author Tobias Nyholm <[email protected]>
+ */
+final class Psr18ClientDiscovery extends ClassDiscovery
+{
+    /**
+     * Finds a PSR-18 HTTP Client.
+     *
+     * @return ClientInterface
+     *
+     * @throws Exception\NotFoundException
+     */
+    public static function find()
+    {
+        try {
+            $client = static::findOneByType(ClientInterface::class);
+        } catch (DiscoveryFailedException $e) {
+            throw new \Http\Discovery\Exception\NotFoundException(
+                'No PSR-18 clients found. Make sure to install a package providing "psr/http-client-implementation". Example: "php-http/guzzle6-adapter".',
+                0,
+                $e
+            );
+        }
+
+        return static::instantiateClass($client);
+    }
+}

src/Strategy/CommonClassesStrategy.php

@@ -15,6 +15,7 @@
 use Http\Message\MessageFactory\DiactorosMessageFactory;
 use Http\Message\StreamFactory\DiactorosStreamFactory;
 use Http\Message\UriFactory\DiactorosUriFactory;
+use Psr\Http\Client\ClientInterface as Psr18Client;
 use Zend\Diactoros\Request as DiactorosRequest;
 use Http\Message\MessageFactory\SlimMessageFactory;
 use Http\Message\StreamFactory\SlimStreamFactory;
@@ -80,13 +81,27 @@ final class CommonClassesStrategy implements DiscoveryStrategy
                 'condition' => [\Buzz\Client\FileGetContents::class, \Buzz\Message\ResponseBuilder::class],
             ],
         ],
+        Psr18Client::class => [],
     ];
 
     /**
      * {@inheritdoc}
      */
     public static function getCandidates($type)
     {
+        if (Psr18Client::class === $type) {
+            $candidates = self::$classes[PSR18Client::class];
+
+            // HTTPlug 2.0 clients implements PSR18Client too.
+            foreach (self::$classes[HttpClient::class] as $c) {
+                if (is_subclass_of($c['class'], Psr18Client::class)) {
+                    $candidates[] = $c;
+                }
+            }
+
+            return $candidates;
+        }
+
         if (isset(self::$classes[$type])) {
             return self::$classes[$type];
         }