Updated mailgun plugin

21 files changed, 1027 insertions, 0 deletions

diff --git a/inc/mailgun/php-http/discovery/CHANGELOG.md b/inc/mailgun/php-http/discovery/CHANGELOG.md
new file mode 100644
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--- /dev/null
+++ b/inc/mailgun/php-http/discovery/CHANGELOG.md
@@ -0,0 +1,179 @@
+# Change Log
+
+
+## 1.2.1 - 2017-03-02
+
+### Fixed
+
+- Fixed minor issue with `MockClientStrategy`, also added more tests. 
+
+## 1.2.0 - 2017-02-12
+
+### Added
+
+- MockClientStrategy class.
+
+## 1.1.1 - 2016-11-27
+
+### Changed
+
+- Made exception messages clearer. `StrategyUnavailableException` is no longer the previous exception to `DiscoveryFailedException`.
+- `CommonClassesStrategy` is using `self` instead of `static`. Using `static` makes no sense when `CommonClassesStrategy` is final.
+
+## 1.1.0 - 2016-10-20
+
+### Added
+
+- Discovery support for Slim Framework factories
+
+## 1.0.0 - 2016-07-18
+
+### Added
+
+- Added back `Http\Discovery\NotFoundException` to preserve BC with 0.8 version. You may upgrade from 0.8.x and 0.9.x to 1.0.0 without any BC breaks.
+- Added interface `Http\Discovery\Exception` which is implemented by all our exceptions
+
+### Changed
+
+- Puli strategy renamed to Puli Beta strategy to prevent incompatibility with a future Puli stable
+
+### Deprecated
+
+- For BC reasons, the old `Http\Discovery\NotFoundException` (extending the new exception) will be thrown until version 2.0
+
+
+## 0.9.1 - 2016-06-28
+
+### Changed
+
+- Dropping PHP 5.4 support because we use the ::class constant.
+
+
+## 0.9.0 - 2016-06-25
+
+### Added
+
+- Discovery strategies to find classes
+
+### Changed
+
+- [Puli](http://puli.io) made optional
+- Improved exceptions
+- **[BC] `NotFoundException` moved to `Http\Discovery\Exception\NotFoundException`**
+
+
+## 0.8.0 - 2016-02-11
+
+### Changed
+
+- Puli composer plugin must be installed separately
+
+
+## 0.7.0 - 2016-01-15
+
+### Added
+
+- Temporary puli.phar (Beta 10) executable
+
+### Changed
+
+- Updated HTTPlug dependencies
+- Updated Puli dependencies
+- Local configuration to make tests passing
+
+### Removed
+
+- Puli CLI dependency
+
+
+## 0.6.4 - 2016-01-07
+
+### Fixed
+
+- Puli [not working](https://twitter.com/PuliPHP/status/685132540588507137) with the latest json-schema
+
+
+## 0.6.3 - 2016-01-04
+
+### Changed
+
+- Adjust Puli dependencies
+
+
+## 0.6.2 - 2016-01-04
+
+### Changed
+
+- Make Puli CLI a requirement
+
+
+## 0.6.1 - 2016-01-03
+
+### Changed
+
+- More flexible Puli requirement
+
+
+## 0.6.0 - 2015-12-30
+
+### Changed
+
+- Use [Puli](http://puli.io) for discovery
+- Improved exception messages
+
+
+## 0.5.0 - 2015-12-25
+
+### Changed
+
+- Updated message factory dependency (php-http/message)
+
+
+## 0.4.0 - 2015-12-17
+
+### Added
+
+- Array condition evaluation in the Class Discovery
+
+### Removed
+
+- Message factories (moved to php-http/utils)
+
+
+## 0.3.0 - 2015-11-18
+
+### Added
+
+- HTTP Async Client Discovery
+- Stream factories
+
+### Changed
+
+- Discoveries and Factories are final
+- Message and Uri factories have the type in their names
+- Diactoros Message factory uses Stream factory internally
+
+### Fixed
+
+- Improved docblocks for API documentation generation
+
+
+## 0.2.0 - 2015-10-31
+
+### Changed
+
+- Renamed AdapterDiscovery to ClientDiscovery
+
+
+## 0.1.1 - 2015-06-13
+
+### Fixed
+
+- Bad HTTP Adapter class name for Guzzle 5
+
+
+## 0.1.0 - 2015-06-12
+
+### Added
+
+- Initial release
diff --git a/inc/mailgun/php-http/discovery/LICENSE b/inc/mailgun/php-http/discovery/LICENSE
new file mode 100644
index 0000000..4558d6f
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/LICENSE
@@ -0,0 +1,19 @@
+Copyright (c) 2015-2016 PHP HTTP Team <team@php-http.org>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is furnished
+to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/inc/mailgun/php-http/discovery/README.md b/inc/mailgun/php-http/discovery/README.md
new file mode 100644
index 0000000..7c5151e
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/README.md
@@ -0,0 +1,46 @@
+# HTTPlug Discovery
+
+[![Latest Version](https://img.shields.io/github/release/php-http/discovery.svg?style=flat-square)](https://github.com/php-http/discovery/releases)
+[![Software License](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat-square)](LICENSE)
+[![Build Status](https://img.shields.io/travis/php-http/discovery.svg?style=flat-square)](https://travis-ci.org/php-http/discovery)
+[![Code Coverage](https://img.shields.io/scrutinizer/coverage/g/php-http/discovery.svg?style=flat-square)](https://scrutinizer-ci.com/g/php-http/discovery)
+[![Quality Score](https://img.shields.io/scrutinizer/g/php-http/discovery.svg?style=flat-square)](https://scrutinizer-ci.com/g/php-http/discovery)
+[![Total Downloads](https://img.shields.io/packagist/dt/php-http/discovery.svg?style=flat-square)](https://packagist.org/packages/php-http/discovery)
+
+**Finds installed HTTPlug implementations and PSR-7 message factories.**
+
+
+## Install
+
+Via Composer
+
+``` bash
+$ composer require php-http/discovery
+```
+
+
+## Documentation
+
+Please see the [official documentation](http://php-http.readthedocs.org/en/latest/discovery.html).
+
+
+## Testing
+
+``` bash
+$ composer test
+```
+
+
+## Contributing
+
+Please see our [contributing guide](http://docs.php-http.org/en/latest/development/contributing.html).
+
+
+## Security
+
+If you discover any security related issues, please contact us at [security@php-http.org](mailto:security@php-http.org).
+
+
+## License
+
+The MIT License (MIT). Please see [License File](LICENSE) for more information.
diff --git a/inc/mailgun/php-http/discovery/composer.json b/inc/mailgun/php-http/discovery/composer.json
new file mode 100644
index 0000000..128af59
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/composer.json
@@ -0,0 +1,48 @@
+{
+    "name": "php-http/discovery",
+    "description": "Finds installed HTTPlug implementations and PSR-7 message factories",
+    "license": "MIT",
+    "keywords": ["http", "discovery", "client", "adapter", "message", "factory", "psr7"],
+    "homepage": "http://php-http.org",
+    "authors": [
+        {
+            "name": "Márk Sági-Kazár",
+            "email": "mark.sagikazar@gmail.com"
+        }
+    ],
+    "require": {
+        "php": "^5.5 || ^7.0"
+    },
+    "require-dev": {
+        "php-http/httplug": "^1.0",
+        "php-http/message-factory": "^1.0",
+        "puli/composer-plugin": "1.0.0-beta10",
+        "phpspec/phpspec": "^2.4",
+        "henrikbjorn/phpspec-code-coverage" : "^2.0.2"
+    },
+    "suggest": {
+        "puli/composer-plugin": "Sets up Puli which is recommended for Discovery to work. Check http://docs.php-http.org/en/latest/discovery.html for more details.",
+        "php-http/message": "Allow to use Guzzle, Diactoros or Slim Framework factories"
+    },
+    "autoload": {
+        "psr-4": {
+            "Http\\Discovery\\": "src/"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "spec\\Http\\Discovery\\": "spec/"
+        }
+    },
+    "scripts": {
+        "test": "vendor/bin/phpspec run",
+        "test-ci": "vendor/bin/phpspec run -c phpspec.ci.yml"
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-master": "1.3-dev"
+        }
+    },
+    "prefer-stable": true,
+    "minimum-stability": "beta"
+}
diff --git a/inc/mailgun/php-http/discovery/src/ClassDiscovery.php b/inc/mailgun/php-http/discovery/src/ClassDiscovery.php
new file mode 100644
index 0000000..2c3e877
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/ClassDiscovery.php
@@ -0,0 +1,207 @@
+<?php
+
+namespace Http\Discovery;
+
+use Http\Discovery\Exception\ClassInstantiationFailedException;
+use Http\Discovery\Exception\DiscoveryFailedException;
+use Http\Discovery\Exception\StrategyUnavailableException;
+
+/**
+ * Registry that based find results on class existence.
+ *
+ * @author David de Boer <david@ddeboer.nl>
+ * @author Márk Sági-Kazár <mark.sagikazar@gmail.com>
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+abstract class ClassDiscovery
+{
+    /**
+     * A list of strategies to find classes.
+     *
+     * @var array
+     */
+    private static $strategies = [
+        Strategy\PuliBetaStrategy::class,
+        Strategy\CommonClassesStrategy::class,
+    ];
+
+    /**
+     * Discovery cache to make the second time we use discovery faster.
+     *
+     * @var array
+     */
+    private static $cache = [];
+
+    /**
+     * Finds a class.
+     *
+     * @param string $type
+     *
+     * @return string|\Closure
+     *
+     * @throws DiscoveryFailedException
+     */
+    protected static function findOneByType($type)
+    {
+        // Look in the cache
+        if (null !== ($class = self::getFromCache($type))) {
+            return $class;
+        }
+
+        $exceptions = [];
+        foreach (self::$strategies as $strategy) {
+            try {
+                $candidates = call_user_func($strategy.'::getCandidates', $type);
+            } catch (StrategyUnavailableException $e) {
+                $exceptions[] = $e;
+                continue;
+            }
+
+            foreach ($candidates as $candidate) {
+                if (isset($candidate['condition'])) {
+                    if (!self::evaluateCondition($candidate['condition'])) {
+                        continue;
+                    }
+                }
+
+                // save the result for later use
+                self::storeInCache($type, $candidate);
+
+                return $candidate['class'];
+            }
+        }
+
+        throw DiscoveryFailedException::create($exceptions);
+    }
+
+    /**
+     * Get a value from cache.
+     *
+     * @param string $type
+     *
+     * @return string|null
+     */
+    private static function getFromCache($type)
+    {
+        if (!isset(self::$cache[$type])) {
+            return;
+        }
+
+        $candidate = self::$cache[$type];
+        if (isset($candidate['condition'])) {
+            if (!self::evaluateCondition($candidate['condition'])) {
+                return;
+            }
+        }
+
+        return $candidate['class'];
+    }
+
+    /**
+     * Store a value in cache.
+     *
+     * @param string $type
+     * @param string $class
+     */
+    private static function storeInCache($type, $class)
+    {
+        self::$cache[$type] = $class;
+    }
+
+    /**
+     * Set new strategies and clear the cache.
+     *
+     * @param array $strategies string array of fully qualified class name to a DiscoveryStrategy
+     */
+    public static function setStrategies(array $strategies)
+    {
+        self::$strategies = $strategies;
+        self::clearCache();
+    }
+
+    /**
+     * Append a strategy at the end of the strategy queue.
+     *
+     * @param string $strategy Fully qualified class name to a DiscoveryStrategy
+     */
+    public static function appendStrategy($strategy)
+    {
+        self::$strategies[] = $strategy;
+        self::clearCache();
+    }
+
+    /**
+     * Prepend a strategy at the beginning of the strategy queue.
+     *
+     * @param string $strategy Fully qualified class name to a DiscoveryStrategy
+     */
+    public static function prependStrategy($strategy)
+    {
+        array_unshift(self::$strategies, $strategy);
+        self::clearCache();
+    }
+
+    /**
+     * Clear the cache.
+     */
+    public static function clearCache()
+    {
+        self::$cache = [];
+    }
+
+    /**
+     * Evaluates conditions to boolean.
+     *
+     * @param mixed $condition
+     *
+     * @return bool
+     */
+    protected static function evaluateCondition($condition)
+    {
+        if (is_string($condition)) {
+            // Should be extended for functions, extensions???
+            return class_exists($condition);
+        } elseif (is_callable($condition)) {
+            return $condition();
+        } elseif (is_bool($condition)) {
+            return $condition;
+        } elseif (is_array($condition)) {
+            $evaluatedCondition = true;
+
+            // Immediately stop execution if the condition is false
+            for ($i = 0; $i < count($condition) && false !== $evaluatedCondition; ++$i) {
+                $evaluatedCondition &= static::evaluateCondition($condition[$i]);
+            }
+
+            return $evaluatedCondition;
+        }
+
+        return false;
+    }
+
+    /**
+     * Get an instance of the $class.
+     *
+     * @param string|\Closure $class A FQCN of a class or a closure that instantiate the class.
+     *
+     * @return object
+     *
+     * @throws ClassInstantiationFailedException
+     */
+    protected static function instantiateClass($class)
+    {
+        try {
+            if (is_string($class)) {
+                return new $class();
+            }
+
+            if (is_callable($class)) {
+                return $class();
+            }
+        } catch (\Exception $e) {
+            throw new ClassInstantiationFailedException('Unexpected exception when instantiating class.', 0, $e);
+        }
+
+        throw new ClassInstantiationFailedException('Could not instantiate class because parameter is neither a callable nor a string');
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/Exception.php b/inc/mailgun/php-http/discovery/src/Exception.php
new file mode 100644
index 0000000..973c908
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Exception.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace Http\Discovery;
+
+/**
+ * An interface implemented by all discovery related exceptions.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+interface Exception
+{
+}
diff --git a/inc/mailgun/php-http/discovery/src/Exception/ClassInstantiationFailedException.php b/inc/mailgun/php-http/discovery/src/Exception/ClassInstantiationFailedException.php
new file mode 100644
index 0000000..e95bf5d
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Exception/ClassInstantiationFailedException.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace Http\Discovery\Exception;
+
+use Http\Discovery\Exception;
+
+/**
+ * Thrown when a class fails to instantiate.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+final class ClassInstantiationFailedException extends \RuntimeException implements Exception
+{
+}
diff --git a/inc/mailgun/php-http/discovery/src/Exception/DiscoveryFailedException.php b/inc/mailgun/php-http/discovery/src/Exception/DiscoveryFailedException.php
new file mode 100644
index 0000000..304b727
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Exception/DiscoveryFailedException.php
@@ -0,0 +1,51 @@
+<?php
+
+namespace Http\Discovery\Exception;
+
+use Http\Discovery\Exception;
+
+/**
+ * Thrown when all discovery strategies fails to find a resource.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+final class DiscoveryFailedException extends \Exception implements Exception
+{
+    /**
+     * @var \Exception[]
+     */
+    private $exceptions;
+
+    /**
+     * @param string       $message
+     * @param \Exception[] $exceptions
+     */
+    public function __construct($message, array $exceptions = [])
+    {
+        $this->exceptions = $exceptions;
+
+        parent::__construct($message);
+    }
+
+    /**
+     * @param \Exception[] $exceptions
+     */
+    public static function create($exceptions)
+    {
+        $message = 'Could not find resource using any discovery strategy. Find more information at http://docs.php-http.org/en/latest/discovery.html#common-errors';
+        foreach ($exceptions as $e) {
+            $message .= "\n - ".$e->getMessage();
+        }
+        $message .= "\n\n";
+
+        return new self($message, $exceptions);
+    }
+
+    /**
+     * @return \Exception[]
+     */
+    public function getExceptions()
+    {
+        return $this->exceptions;
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/Exception/NotFoundException.php b/inc/mailgun/php-http/discovery/src/Exception/NotFoundException.php
new file mode 100644
index 0000000..befbf48
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Exception/NotFoundException.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Http\Discovery\Exception;
+
+use Http\Discovery\Exception;
+
+/**
+ * Thrown when a discovery does not find any matches.
+ *
+ * @final do NOT extend this class, not final for BC reasons
+ *
+ * @author Márk Sági-Kazár <mark.sagikazar@gmail.com>
+ */
+/*final */class NotFoundException extends \RuntimeException implements Exception
+{
+}
diff --git a/inc/mailgun/php-http/discovery/src/Exception/PuliUnavailableException.php b/inc/mailgun/php-http/discovery/src/Exception/PuliUnavailableException.php
new file mode 100644
index 0000000..a6ade73
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Exception/PuliUnavailableException.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace Http\Discovery\Exception;
+
+/**
+ * Thrown when we can't use Puli for discovery.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+final class PuliUnavailableException extends StrategyUnavailableException
+{
+}
diff --git a/inc/mailgun/php-http/discovery/src/Exception/StrategyUnavailableException.php b/inc/mailgun/php-http/discovery/src/Exception/StrategyUnavailableException.php
new file mode 100644
index 0000000..89ecf35
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Exception/StrategyUnavailableException.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Http\Discovery\Exception;
+
+use Http\Discovery\Exception;
+
+/**
+ * This exception is thrown when we cannot use a discovery strategy. This is *not* thrown when
+ * the discovery fails to find a class.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+class StrategyUnavailableException extends \RuntimeException implements Exception
+{
+}
diff --git a/inc/mailgun/php-http/discovery/src/HttpAsyncClientDiscovery.php b/inc/mailgun/php-http/discovery/src/HttpAsyncClientDiscovery.php
new file mode 100644
index 0000000..6ef60e7
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/HttpAsyncClientDiscovery.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Http\Discovery;
+
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\Exception\DiscoveryFailedException;
+
+/**
+ * Finds an HTTP Asynchronous Client.
+ *
+ * @author Joel Wurtz <joel.wurtz@gmail.com>
+ */
+final class HttpAsyncClientDiscovery extends ClassDiscovery
+{
+    /**
+     * Finds an HTTP Async Client.
+     *
+     * @return HttpAsyncClient
+     *
+     * @throws Exception\NotFoundException
+     */
+    public static function find()
+    {
+        try {
+            $asyncClient = static::findOneByType(HttpAsyncClient::class);
+        } catch (DiscoveryFailedException $e) {
+            throw new NotFoundException(
+                'No HTTPlug async clients found. Make sure to install a package providing "php-http/async-client-implementation". Example: "php-http/guzzle6-adapter".',
+                0,
+                $e
+            );
+        }
+
+        return static::instantiateClass($asyncClient);
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/HttpClientDiscovery.php b/inc/mailgun/php-http/discovery/src/HttpClientDiscovery.php
new file mode 100644
index 0000000..2654b7e
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/HttpClientDiscovery.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Http\Discovery;
+
+use Http\Client\HttpClient;
+use Http\Discovery\Exception\DiscoveryFailedException;
+
+/**
+ * Finds an HTTP Client.
+ *
+ * @author Márk Sági-Kazár <mark.sagikazar@gmail.com>
+ */
+final class HttpClientDiscovery extends ClassDiscovery
+{
+    /**
+     * Finds an HTTP Client.
+     *
+     * @return HttpClient
+     *
+     * @throws Exception\NotFoundException
+     */
+    public static function find()
+    {
+        try {
+            $client = static::findOneByType(HttpClient::class);
+        } catch (DiscoveryFailedException $e) {
+            throw new NotFoundException(
+                'No HTTPlug clients found. Make sure to install a package providing "php-http/client-implementation". Example: "php-http/guzzle6-adapter".',
+                0,
+                $e
+            );
+        }
+
+        return static::instantiateClass($client);
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/MessageFactoryDiscovery.php b/inc/mailgun/php-http/discovery/src/MessageFactoryDiscovery.php
new file mode 100644
index 0000000..c21b9bf
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/MessageFactoryDiscovery.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Http\Discovery;
+
+use Http\Discovery\Exception\DiscoveryFailedException;
+use Http\Message\MessageFactory;
+
+/**
+ * Finds a Message Factory.
+ *
+ * @author Márk Sági-Kazár <mark.sagikazar@gmail.com>
+ */
+final class MessageFactoryDiscovery extends ClassDiscovery
+{
+    /**
+     * Finds a Message Factory.
+     *
+     * @return MessageFactory
+     *
+     * @throws Exception\NotFoundException
+     */
+    public static function find()
+    {
+        try {
+            $messageFactory = static::findOneByType(MessageFactory::class);
+        } catch (DiscoveryFailedException $e) {
+            throw new NotFoundException(
+                'No message factories found. To use Guzzle, Diactoros or Slim Framework factories install php-http/message and the chosen message implementation.',
+                0,
+                $e
+            );
+        }
+
+        return static::instantiateClass($messageFactory);
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/NotFoundException.php b/inc/mailgun/php-http/discovery/src/NotFoundException.php
new file mode 100644
index 0000000..d59dadb
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/NotFoundException.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace Http\Discovery;
+
+/**
+ * Thrown when a discovery does not find any matches.
+ *
+ * @author Márk Sági-Kazár <mark.sagikazar@gmail.com>
+ *
+ * @deprecated since since version 1.0, and will be removed in 2.0. Use {@link \Http\Discovery\Exception\NotFoundException} instead.
+ */
+final class NotFoundException extends \Http\Discovery\Exception\NotFoundException
+{
+}
diff --git a/inc/mailgun/php-http/discovery/src/Strategy/CommonClassesStrategy.php b/inc/mailgun/php-http/discovery/src/Strategy/CommonClassesStrategy.php
new file mode 100644
index 0000000..cbed15d
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Strategy/CommonClassesStrategy.php
@@ -0,0 +1,76 @@
+<?php
+
+namespace Http\Discovery\Strategy;
+
+use GuzzleHttp\Psr7\Request as GuzzleRequest;
+use Http\Message\MessageFactory\GuzzleMessageFactory;
+use Http\Message\StreamFactory\GuzzleStreamFactory;
+use Http\Message\UriFactory\GuzzleUriFactory;
+use Http\Message\MessageFactory\DiactorosMessageFactory;
+use Http\Message\StreamFactory\DiactorosStreamFactory;
+use Http\Message\UriFactory\DiactorosUriFactory;
+use Zend\Diactoros\Request as DiactorosRequest;
+use Http\Message\MessageFactory\SlimMessageFactory;
+use Http\Message\StreamFactory\SlimStreamFactory;
+use Http\Message\UriFactory\SlimUriFactory;
+use Slim\Http\Request as SlimRequest;
+use Http\Adapter\Guzzle6\Client as Guzzle6;
+use Http\Adapter\Guzzle5\Client as Guzzle5;
+use Http\Client\Curl\Client as Curl;
+use Http\Client\Socket\Client as Socket;
+use Http\Adapter\React\Client as React;
+use Http\Adapter\Buzz\Client as Buzz;
+
+/**
+ * @internal
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+final class CommonClassesStrategy implements DiscoveryStrategy
+{
+    /**
+     * @var array
+     */
+    private static $classes = [
+        'Http\Message\MessageFactory' => [
+            ['class' => GuzzleMessageFactory::class, 'condition' => [GuzzleRequest::class, GuzzleMessageFactory::class]],
+            ['class' => DiactorosMessageFactory::class, 'condition' => [DiactorosRequest::class, DiactorosMessageFactory::class]],
+            ['class' => SlimMessageFactory::class, 'condition' => [SlimRequest::class, SlimMessageFactory::class]],
+        ],
+        'Http\Message\StreamFactory' => [
+            ['class' => GuzzleStreamFactory::class, 'condition' => [GuzzleRequest::class, GuzzleStreamFactory::class]],
+            ['class' => DiactorosStreamFactory::class, 'condition' => [DiactorosRequest::class, DiactorosStreamFactory::class]],
+            ['class' => SlimStreamFactory::class, 'condition' => [SlimRequest::class, SlimStreamFactory::class]],
+        ],
+        'Http\Message\UriFactory' => [
+            ['class' => GuzzleUriFactory::class, 'condition' => [GuzzleRequest::class, GuzzleUriFactory::class]],
+            ['class' => DiactorosUriFactory::class, 'condition' => [DiactorosRequest::class, DiactorosUriFactory::class]],
+            ['class' => SlimUriFactory::class, 'condition' => [SlimRequest::class, SlimUriFactory::class]],
+        ],
+        'Http\Client\HttpAsyncClient' => [
+            ['class' => Guzzle6::class, 'condition' => Guzzle6::class],
+            ['class' => Curl::class, 'condition' => Curl::class],
+            ['class' => React::class, 'condition' => React::class],
+        ],
+        'Http\Client\HttpClient' => [
+            ['class' => Guzzle6::class, 'condition' => Guzzle6::class],
+            ['class' => Guzzle5::class, 'condition' => Guzzle5::class],
+            ['class' => Curl::class, 'condition' => Curl::class],
+            ['class' => Socket::class, 'condition' => Socket::class],
+            ['class' => Buzz::class, 'condition' => Buzz::class],
+            ['class' => React::class, 'condition' => React::class],
+        ],
+    ];
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function getCandidates($type)
+    {
+        if (isset(self::$classes[$type])) {
+            return self::$classes[$type];
+        }
+
+        return [];
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/Strategy/DiscoveryStrategy.php b/inc/mailgun/php-http/discovery/src/Strategy/DiscoveryStrategy.php
new file mode 100644
index 0000000..641485a
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Strategy/DiscoveryStrategy.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace Http\Discovery\Strategy;
+
+use Http\Discovery\Exception\StrategyUnavailableException;
+
+/**
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+interface DiscoveryStrategy
+{
+    /**
+     * Find a resource of a specific type.
+     *
+     * @param string $type
+     *
+     * @return array The return value is always an array with zero or more elements. Each
+     *               element is an array with two keys ['class' => string, 'condition' => mixed].
+     *
+     * @throws StrategyUnavailableException if we cannot use this strategy.
+     */
+    public static function getCandidates($type);
+}
diff --git a/inc/mailgun/php-http/discovery/src/Strategy/MockClientStrategy.php b/inc/mailgun/php-http/discovery/src/Strategy/MockClientStrategy.php
new file mode 100644
index 0000000..ea464cf
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Strategy/MockClientStrategy.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Http\Discovery\Strategy;
+
+use Http\Client\HttpClient;
+use Http\Mock\Client as Mock;
+
+/**
+ * Find the Mock client.
+ *
+ * @author Sam Rapaport <me@samrapdev.com>
+ */
+final class MockClientStrategy implements DiscoveryStrategy
+{
+    /**
+     * {@inheritdoc}
+     */
+    public static function getCandidates($type)
+    {
+        return ($type === HttpClient::class)
+            ? [['class' => Mock::class, 'condition' => Mock::class]]
+            : [];
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/Strategy/PuliBetaStrategy.php b/inc/mailgun/php-http/discovery/src/Strategy/PuliBetaStrategy.php
new file mode 100644
index 0000000..2666fb3
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/Strategy/PuliBetaStrategy.php
@@ -0,0 +1,91 @@
+<?php
+
+namespace Http\Discovery\Strategy;
+
+use Http\Discovery\Exception\PuliUnavailableException;
+use Puli\Discovery\Api\Discovery;
+use Puli\GeneratedPuliFactory;
+
+/**
+ * Find candidates using Puli.
+ *
+ * @internal
+ * @final
+ *
+ * @author David de Boer <david@ddeboer.nl>
+ * @author Márk Sági-Kazár <mark.sagikazar@gmail.com>
+ */
+class PuliBetaStrategy implements DiscoveryStrategy
+{
+    /**
+     * @var GeneratedPuliFactory
+     */
+    protected static $puliFactory;
+
+    /**
+     * @var Discovery
+     */
+    protected static $puliDiscovery;
+
+    /**
+     * @return GeneratedPuliFactory
+     *
+     * @throws PuliUnavailableException
+     */
+    private static function getPuliFactory()
+    {
+        if (null === self::$puliFactory) {
+            if (!defined('PULI_FACTORY_CLASS')) {
+                throw new PuliUnavailableException('Puli Factory is not available');
+            }
+
+            $puliFactoryClass = PULI_FACTORY_CLASS;
+
+            if (!class_exists($puliFactoryClass)) {
+                throw new PuliUnavailableException('Puli Factory class does not exist');
+            }
+
+            self::$puliFactory = new $puliFactoryClass();
+        }
+
+        return self::$puliFactory;
+    }
+
+    /**
+     * Returns the Puli discovery layer.
+     *
+     * @return Discovery
+     *
+     * @throws PuliUnavailableException
+     */
+    private static function getPuliDiscovery()
+    {
+        if (!isset(self::$puliDiscovery)) {
+            $factory = self::getPuliFactory();
+            $repository = $factory->createRepository();
+
+            self::$puliDiscovery = $factory->createDiscovery($repository);
+        }
+
+        return self::$puliDiscovery;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function getCandidates($type)
+    {
+        $returnData = [];
+        $bindings = self::getPuliDiscovery()->findBindings($type);
+
+        foreach ($bindings as $binding) {
+            $condition = true;
+            if ($binding->hasParameterValue('depends')) {
+                $condition = $binding->getParameterValue('depends');
+            }
+            $returnData[] = ['class' => $binding->getClassName(), 'condition' => $condition];
+        }
+
+        return $returnData;
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/StreamFactoryDiscovery.php b/inc/mailgun/php-http/discovery/src/StreamFactoryDiscovery.php
new file mode 100644
index 0000000..7bcc8ce
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/StreamFactoryDiscovery.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Http\Discovery;
+
+use Http\Discovery\Exception\DiscoveryFailedException;
+use Http\Message\StreamFactory;
+
+/**
+ * Finds a Stream Factory.
+ *
+ * @author Михаил Красильников <m.krasilnikov@yandex.ru>
+ */
+final class StreamFactoryDiscovery extends ClassDiscovery
+{
+    /**
+     * Finds a Stream Factory.
+     *
+     * @return StreamFactory
+     *
+     * @throws Exception\NotFoundException
+     */
+    public static function find()
+    {
+        try {
+            $streamFactory = static::findOneByType(StreamFactory::class);
+        } catch (DiscoveryFailedException $e) {
+            throw new NotFoundException(
+                'No stream factories found. To use Guzzle, Diactoros or Slim Framework factories install php-http/message and the chosen message implementation.',
+                0,
+                $e
+            );
+        }
+
+        return static::instantiateClass($streamFactory);
+    }
+}
diff --git a/inc/mailgun/php-http/discovery/src/UriFactoryDiscovery.php b/inc/mailgun/php-http/discovery/src/UriFactoryDiscovery.php
new file mode 100644
index 0000000..1eef1e6
--- /dev/null
+++ b/inc/mailgun/php-http/discovery/src/UriFactoryDiscovery.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Http\Discovery;
+
+use Http\Discovery\Exception\DiscoveryFailedException;
+use Http\Message\UriFactory;
+
+/**
+ * Finds a URI Factory.
+ *
+ * @author David de Boer <david@ddeboer.nl>
+ */
+final class UriFactoryDiscovery extends ClassDiscovery
+{
+    /**
+     * Finds a URI Factory.
+     *
+     * @return UriFactory
+     *
+     * @throws Exception\NotFoundException
+     */
+    public static function find()
+    {
+        try {
+            $uriFactory = static::findOneByType(UriFactory::class);
+        } catch (DiscoveryFailedException $e) {
+            throw new NotFoundException(
+                'No uri factories found. To use Guzzle, Diactoros or Slim Framework factories install php-http/message and the chosen message implementation.',
+                0,
+                $e
+            );
+        }
+
+        return static::instantiateClass($uriFactory);
+    }
+}