diff --git a/src/Grant/AuthCodeGrant.php b/src/Grant/AuthCodeGrant.php
index c51954e3..1e967437 100644
--- a/src/Grant/AuthCodeGrant.php
+++ b/src/Grant/AuthCodeGrant.php
@@ -3,100 +3,151 @@
 namespace League\OAuth2\Server\Grant;
 
 use DateInterval;
-use DateTime;
 use League\OAuth2\Server\Exception\OAuthServerException;
+use League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface;
+use League\OAuth2\Server\ResponseTypes\AuthorizeClientResponseTypeInterface;
+use League\OAuth2\Server\ResponseTypes\LoginUserResponseTypeInterface;
 use League\OAuth2\Server\ResponseTypes\ResponseTypeInterface;
+use League\OAuth2\Server\Utils\KeyCrypt;
 use Psr\Http\Message\ServerRequestInterface;
+use Zend\Diactoros\Response;
+use Zend\Diactoros\Uri;
 
 class AuthCodeGrant extends AbstractGrant
 {
     /**
-     * @inheritdoc
+     * @var \League\OAuth2\Server\ResponseTypes\LoginUserResponseTypeInterface
      */
-    public function respondToRequest(
-        ServerRequestInterface $request,
-        ResponseTypeInterface $responseType,
-        DateInterval $tokenTTL,
-        $scopeDelimiter = ' '
+    private $loginUserResponseType;
+
+    /**
+     * @var \DateInterval
+     */
+    private $authCodeTTL;
+    /**
+     * @var \League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface
+     */
+    private $authCodeRepository;
+    /**
+     * @var \League\OAuth2\Server\ResponseTypes\AuthorizeClientResponseTypeInterface
+     */
+    private $authorizeClientResponseType;
+
+    /**
+     * @param \League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface           $authCodeRepository
+     * @param \DateInterval                                                            $authCodeTTL
+     * @param \League\OAuth2\Server\ResponseTypes\LoginUserResponseTypeInterface       $loginUserResponseType
+     * @param \League\OAuth2\Server\ResponseTypes\AuthorizeClientResponseTypeInterface $authorizeClientResponseType
+     */
+    public function __construct(
+        AuthCodeRepositoryInterface $authCodeRepository,
+        \DateInterval $authCodeTTL,
+        LoginUserResponseTypeInterface $loginUserResponseType,
+        AuthorizeClientResponseTypeInterface $authorizeClientResponseType
     ) {
-        if (
-            isset($request->getQueryParams()['response_type'])
-            && $request->getQueryParams()['response_type'] === 'code'
-            && isset($request->getQueryParams()['client_id'])
-        ) {
-            return $this->respondToAuthorizationRequest($request, $scopeDelimiter, $tokenTTL);
-        } elseif (
-            isset($request->getParsedBody()['grant_type'])
-            && $request->getParsedBody()['grant_type'] === 'authorization_code'
-        ) {
-            return $this->respondToAccessTokenRequest($request, $responseType, $tokenTTL);
-        } else {
-            throw OAuthServerException::serverError('respondToRequest() should not have been called');
-        }
+        $this->authCodeRepository = $authCodeRepository;
+        $this->authCodeTTL = $authCodeTTL;
+        $this->loginUserResponseType = $loginUserResponseType;
+        $this->authorizeClientResponseType = $authorizeClientResponseType;
     }
 
+
     /**
      * Respond to an authorization request
      *
      * @param \Psr\Http\Message\ServerRequestInterface $request
-     * @param string                                   $scopeDelimiter
-     * @param DateTime                                 $tokenTTL
+     *
+     * @return \Psr\Http\Message\ResponseInterface
+     * @throws \League\OAuth2\Server\Exception\OAuthServerException
      */
     protected function respondToAuthorizationRequest(
-        ServerRequestInterface $request,
-        $scopeDelimiter = ' ',
-        DateTime $tokenTTL
+        ServerRequestInterface $request
     ) {
-        // Get required params
-        /*$clientId = array_key_exists('client_id', $request->getQueryParams())
-            ? $request->getQueryParams()['client_id'] // $_GET['client_id']
-            : null;
-
+        $clientId = $this->getQueryStringParameter(
+            'client_id',
+            $request,
+            $this->getServerParameter('PHP_AUTH_USER', $request)
+        );
         if (is_null($clientId)) {
             throw OAuthServerException::invalidRequest('client_id', null, '`%s` parameter is missing');
         }
 
-        $redirectUri = array_key_exists('redirect_uri', $request->getQueryParams())
-            ? $request->getQueryParams()['redirect_uri'] // $_GET['redirect_uri']
-            : null;
-
+        $redirectUri = $this->getQueryStringParameter('redirect_uri', $request, null);
         if (is_null($redirectUri)) {
             throw OAuthServerException::invalidRequest('redirect_uri', null, '`%s` parameter is missing');
         }
 
-        // Validate client ID and redirect URI
         $client = $this->clientRepository->getClientEntity(
             $clientId,
-            $this->getIdentifier(),
             null,
-            $redirectUri
+            $redirectUri,
+            $this->getIdentifier()
         );
 
-        if (($client instanceof ClientEntityInterface) === false) {
+        if (!$client instanceof ClientEntityInterface) {
+            $this->emitter->emit(new Event('client.authentication.failed', $request));
+
             throw OAuthServerException::invalidClient();
         }
 
-        $state = array_key_exists('state', $request->getQueryParams())
-            ? $request->getQueryParams()['state'] // $_GET['state']
-            : null;
+        $scopes = $this->validateScopes($request, $client, $redirectUri);
+        $queryString = http_build_query($request->getQueryParams());
 
-        // Validate any scopes that are in the request
-        $scopeParam = array_key_exists('scope', $request->getQueryParams())
-            ? $request->getQueryParams()['scope'] // $_GET['scope']
-            : '';
-        $scopes = $this->validateScopes($scopeParam, $scopeDelimiter, $client);
+        // Check if the user has been validated
+        $userIdCookieParam = $this->getCookieParameter('oauth_user_id', $request, null);
+        if ($userIdCookieParam === null) {
+            return $this->loginUserResponseType->handle($client, $scopes, $queryString, $this->pathToPrivateKey);
+        } else {
+            try {
+                $userId = KeyCrypt::decrypt($userIdCookieParam, $this->pathToPublicKey);
+            } catch (\LogicException $e) {
+                throw OAuthServerException::serverError($e->getMessage());
+            }
+        }
 
-        // Create a new authorization code
-        $authCode = new AuthCodeEntity();
-        $authCode->setIdentifier(SecureKey::generate());
-        $authCode->setExpiryDateTime((new \DateTime())->add($authCodeTTL));
-        $authCode->setClient($client);
-        $authCode->setUserIdentifier($userEntity->getIdentifier());
+        // Check the user has approved the request
+        $userApprovedCookieParam = $this->getCookieParameter('oauth_user_approved_client', $request, null);
+        if ($userApprovedCookieParam === null) {
+            return $this->authorizeClientResponseType->handle($client, $scopes, $queryString, $this->pathToPrivateKey);
+        } else {
+            try {
+                $userApprovedClient = KeyCrypt::decrypt($userApprovedCookieParam, $this->pathToPublicKey);
+            } catch (\LogicException $e) {
+                throw OAuthServerException::serverError($e->getMessage());
+            }
+        }
 
-        // Associate scopes with the session and access token
-        foreach ($scopes as $scope) {
-            $authCode->addScope($scope);
-        }*/
+        $stateParameter = $this->getQueryStringParameter('state', $request);
+
+        $redirectUri = new Uri($redirectUri);
+        parse_str($redirectUri->getQuery(), $redirectPayload);
+        if ($stateParameter !== null) {
+            $redirectPayload['state'] = $stateParameter;
+        }
+
+        if ($userApprovedClient === 1) {
+            $authCode = $this->issueAuthCode(
+                $this->authCodeTTL,
+                $client,
+                $userId,
+                $redirectUri,
+                $scopes
+            );
+            $this->authCodeRepository->persistNewAuthCode($authCode);
+
+            $redirectPayload['code'] = $authCode->getIdentifier();
+
+            return new Response(
+                'php://memory',
+                302,
+                [
+                    'Location' => $redirectUri->withQuery(http_build_query($redirectPayload)),
+                ]
+            );
+        }
+
+        $exception = OAuthServerException::accessDenied('The user denied the request', (string) $redirectUri);
+        return $exception->generateHttpResponse();
     }
 
     /**
@@ -127,10 +178,41 @@ class AuthCodeGrant extends AbstractGrant
                 && isset($request->getQueryParams()['response_type'])
                 && $request->getQueryParams()['response_type'] === 'code'
                 && isset($request->getQueryParams()['client_id'])
-            ) || (
-                isset($request->getParsedBody()['grant_type'])
-                && $request->getParsedBody()['grant_type'] === 'authorization_code'
-            )
+            ) || (parent::canRespondToRequest($request))
         );
     }
+
+    /**
+     * Return the grant identifier that can be used in matching up requests
+     *
+     * @return string
+     */
+    public function getIdentifier()
+    {
+        return 'authorization_code';
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function respondToRequest(
+        ServerRequestInterface $request,
+        ResponseTypeInterface $responseType,
+        \DateInterval $accessTokenTTL
+    ) {
+        if (
+            isset($request->getQueryParams()['response_type'])
+            && $request->getQueryParams()['response_type'] === 'code'
+            && isset($request->getQueryParams()['client_id'])
+        ) {
+            return $this->respondToAuthorizationRequest($request);
+        } elseif (
+            isset($request->getParsedBody()['grant_type'])
+            && $request->getParsedBody()['grant_type'] === 'authorization_code'
+        ) {
+            return $this->respondToAccessTokenRequest($request, $responseType, $accessTokenTTL);
+        } else {
+            throw OAuthServerException::serverError('respondToRequest() should not have been called');
+        }
+    }
 }