Add readme, contributing guide, changelog and license file

CHANGELOG.md

+# Changelog
+All Notable changes to `oauth2-meetup` will be documented in this file
+
+
+## 0.1.0 - 2018-02-12
+
+### Added
+- Initial release!
+
+### Deprecated
+- Nothing
+
+### Fixed
+- Nothing
+
+### Removed
+- Nothing
+
+### Security
+- Nothing

CONTRIBUTING.md

+# Contributing
+
+Contributions are **welcome** and will be fully **credited**.
+
+We accept contributions via Pull Requests on [GitLab](https://gitlab.com/WitteStier/oauth2-meetup).
+
+
+## Pull Requests
+
+- **[PSR-2 Coding Standard](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md)** - The easiest way to apply the conventions is to install [PHP Code Sniffer](http://pear.php.net/package/PHP_CodeSniffer).
+
+- **Add tests!** - Your patch won't be accepted if it doesn't have tests.
+
+- **Document any change in behaviour** - Make sure the README and any other relevant documentation are kept up-to-date.
+
+- **Consider our release cycle** - We try to follow SemVer. Randomly breaking public APIs is not an option.
+
+- **Create topic branches** - Don't ask us to pull from your master branch.
+
+- **One pull request per feature** - If you want to do more than one thing, send multiple pull requests.
+
+- **Send coherent history** - Make sure each individual commit in your pull request is meaningful. If you had to make multiple intermediate commits while developing, please squash them before submitting.
+
+- **Ensure tests pass!** - Please run the tests (see below) before submitting your pull request, and make sure they pass. We won't accept a patch until all tests pass.
+
+- **Ensure no coding standards violations** - Please run PHP Code Sniffer using the PSR-2 standard (see below) before submitting your pull request. A violation will cause the build to fail, so please make sure there are no violations. We can't accept a patch if the build fails.
+
+
+## Running Tests
+
+``` bash
+./vendor/bin/phpunit
+```
+
+
+## Running PHP Code Sniffer
+
+``` bash
+./vendor/bin/phpcs src --standard=psr2 -sp
+```
+
+**Happy coding**!

LICENSE

+MIT License
+
+Copyright (c) 2018 WitteStier
+
+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.

README.md

+Meetup Provider for OAuth 2.0 Client
+====================================
+
+This package provides Meetup.com OAuth 2.0 support for the PHP League's [OAuth 2.0 Client](https://github.com/thephpleague/oauth2-client).
+
+
+## Requirements
+
+The following versions of PHP are supported.
+
+* PHP 7.0
+* PHP 7.1
+* PHP 7.2
+
+
+## Installation
+
+To install, use composer:
+
+``` bash
+composer require wittestier/oauth2-meetup
+```
+
+
+## Usage
+
+### Authorization Code Flow
+
+``` php
+$provider = new \WitteStier\OAuth2\Client\Provider\Meetup([
+    'clientId' => '{meetup-consumer-key}',
+    'clientSecret' => '{meetup-consumer-secret}',
+    'redirectUri' => '{meetup-consumer-redirect-uri}',
+]);
+
+// If we don't have an authorization code then get one.
+if (isset($_GET['code']) === false) {
+
+    // Fetch the authorization URL from the provider; this returns the urlAuthorize option and generates and applies 
+    // any necessary parameters (e.g. state).
+    $authorizationUrl = $provider->getAuthorizationUrl();
+
+    // Get the state generated for you and store it to the session.
+    $_SESSION['oauth2state'] = $provider->getState();
+
+    // Redirect the user to the authorization URL.
+    header('Location: ' . $authorizationUrl);
+    exit;
+
+// Check given state against previously stored one to mitigate CSRF attack.
+} elseif (empty($_GET['state']) === true || ($_GET['state'] !== $_SESSION['oauth2state'])) {
+
+    unset($_SESSION['oauth2state']);
+    exit('Invalid state');
+
+} else {
+
+    try {
+
+        // Try to get an access token using the authorization code grant.
+        $grant = new League\OAuth2\Client\Grant\AuthorizationCode();
+        $accessToken = $provider->getAccessToken($grant, [
+            'code' => $_GET['code']
+        ]);
+
+    } catch (\League\OAuth2\Client\Provider\Exception\IdentityProviderException $e) {
+
+        // Failed to get the access token or user details.
+        exit($e->getMessage());
+
+    }
+
+    // We have an access token, which we may use in authenticated requests against the service provider's API.
+    echo $accessToken->getToken() . "\n";
+    echo $accessToken->getRefreshToken() . "\n";
+    echo $accessToken->getExpires() . "\n";
+    echo ($accessToken->hasExpired() ? 'expired' : 'not expired') . "\n";
+
+    try {
+
+        // Using the access token, we may look up details about the resource owner.
+        $resourceOwner = $provider->getResourceOwner($accessToken);
+
+        var_export($resourceOwner->toArray());
+
+   } catch (\League\OAuth2\Client\Provider\Exception\IdentityProviderException $e) {
+
+        // Failed to get the access token or user details.
+        exit($e->getMessage());
+
+    }
+
+}
+
+```
+
+### Managing Scopes
+
+When creating your Meetup authorization URL, you can specify the state and scopes your application may authorize.
+
+``` php
+$options = [
+    'state' => 'OPTIONAL_CUSTOM_CONFIGURED_STATE',
+    'scope' => [ 'ageless', 'basic', 'event_management', 'group_edit', 'group_content_edit', 'group_join', 'messaging', 'profile_edit', 'reporting', 'rsvp' ],
+];
+
+$authorizationUrl = $provider->getAuthorizationUrl($options);
+```
+
+If neither are defined, the provider will utilize internal defaults.
+
+At the time of authoring this documentation, the [following scopes are available.](https://www.meetup.com/meetup_api/auth/#oauth2-scopes)
+
+### Refreshing a Token
+
+``` php
+$provider = new \WitteStier\OAuth2\Client\Provider\Meetup([
+    'clientId' => '{meetup-consumer-key}',
+    'clientSecret' => '{meetup-consumer-secret}',
+    'redirectUri' => '{meetup-consumer-redirect-uri}',
+]);
+
+// Fetch your token from a datastore.
+$token = fetchAccessToken();
+
+$refreshToken = $token->getRefreshToken();
+
+if ($token->hasExpired() === true) {
+
+    $grant = new League\OAuth2\Client\Grant\RefreshToken();
+    $newAccessToken = $provider->getAccessToken($grant, [
+        'refresh_token' => $token->getRefreshToken()
+    ]);
+
+    // Purge old access token and store new access token to your data store.
+
+}
+
+```
+
+
+## Testing
+
+``` bash
+$ ./vendor/bin/phpunit
+# Or
+$ composer test
+```
+
+``` bash
+$ ./vendor/bin/phpcs src --standard=psr2 -sp
+# Or
+$ composer check
+```
+
+
+## Contributing
+
+Please see [CONTRIBUTING](https://gitlab.com/WitteStier/oauth2-meetup/blob/master/CONTRIBUTING.md) for details.
+
+
+## Credits
+
+- [WitteStier](https://gitlab.com/WitteStier)
+- [All Contributors](https://gitlab.com/WitteStier/oauth2-meetup/graphs/master)
+
+
+## License
+
+The MIT License (MIT). Please see [License File](https://gitlab.com/WitteStier/oauth2-meetup/blob/master/LICENSE) for more information.
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