<?php

namespace Catalyst\APIBundle\Security;

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\Security\Core\Authentication\Token\PreAuthenticatedToken;
use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
use Symfony\Component\Security\Core\Exception\AuthenticationException;
use Symfony\Component\Security\Core\Exception\CustomUserMessageAuthenticationException;
use Symfony\Component\Security\Core\Exception\BadCredentialsException;
use Symfony\Component\Security\Core\User\UserProviderInterface;
use Symfony\Component\Security\Http\Authentication\SimplePreAuthenticatorInterface;
use Symfony\Component\Security\Http\Authentication\AuthenticationFailureHandlerInterface;

use Doctrine\ORM\EntityManagerInterface;

use DateTime;

class APIKeyAuthenticator implements SimplePreAuthenticatorInterface, AuthenticationFailureHandlerInterface
{
    const HEADER_API_KEY        = 'X-Cata-API-Key';
    const HEADER_SIGNATURE      = 'X-Cata-Signature';
    const HEADER_DATE           = 'X-Cata-Date';

    const DATE_FORMAT           = 'D, d M Y H:i:s T';

    // 30 minute time limit
    const TIME_LIMIT            = 1800;

    protected $em;

    public function __construct(EntityManagerInterface $em)
    {
        $this->em = $em;
    }

    protected function getSecretKey($api_key)
    {
        return 'sldkfjlksdjflksdjflksdjflsjf';
    }

    protected function validateSignature($creds, $secret_key)
    {
        $elements = [
            $creds['method'],
            $creds['uri'],
            $creds['date'],
            $secret_key,
        ];
        $sig_source = implode('|', $elements);

        error_log($sig_source);

        // generate signature
        $raw_sig = hash_hmac('sha1', $sig_source, $secret_key, true);
        $enc_sig = base64_encode($raw_sig);

        error_log($enc_sig);

        if ($enc_sig != trim($creds['signature']))
            throw new CustomUserMessageAuthenticationException('Invalid signature.');

    }

    public function createToken(Request $req, $provider_key)
    {
        // api key header
        $api_key = $req->headers->get(self::HEADER_API_KEY);
        if ($api_key == null)
            throw new BadCredentialsException('No API key sent.');

        // check date from headers
        $hdate_string = $req->headers->get(self::HEADER_DATE);
        if ($hdate_string == null)
            throw new BadCredentialsException('No date specified.');

        $hdate = DateTime::createFromFormat(self::DATE_FORMAT, $hdate_string);
        if ($hdate == null)
            throw new BadCredentialsException('Invalid date specified.');

        // get number of seconds difference
        $date_now = new DateTime();
        $date_diff = abs($date_now->getTimestamp() - $hdate->getTimestamp());

        // time difference is too much
        if ($date_diff > self::TIME_LIMIT)
            throw new BadCredentialsException('Clock synchronization error.');

        // signature header
        $sig = $req->headers->get(self::HEADER_SIGNATURE);
        if ($sig == null)
            throw new BadCredentialsException('No signature sent.');

        // credentials
        $creds = [
            'api_key' => $api_key,
            'date' => $hdate_string,
            'signature' => $sig,
            'method' => $req->getRealMethod(),
            'uri' => $req->getRequestUri(),
        ];

        return new PreAuthenticatedToken(
            'anonymous',
            $creds,
            $provider_key
        );
    }

    public function supportsToken(TokenInterface $token, $provider_key)
    {
        return $token instanceof PreAuthenticatedToken && $token->getProviderKey() === $provider_key;
    }

    public function authenticateToken(TokenInterface $token, UserProviderInterface $user_provider, $provider_key)
    {
        if (!$user_provider instanceof APIKeyUserProvider)
        {
            throw new \InvalidArgumentException(
                sprintf(
                    'The user provider must be an instance of APIKeyUserProvider (%s was given).',
                    get_class($user_provider)
                )
            );
        }

        $creds = $token->getCredentials();
        $api_key = $creds['api_key'];
        $user = $user_provider->getUserByAPIKey($api_key);

        // check if api key is valid
        if (!$user)
            throw new CustomUserMessageAuthenticationException('Invalid API Key');

        // check if signature is valid
        $this->validateSignature($creds, $user->getSecretKey());

        // $user = $user_provider->loadUserByUsername($username);

        return new PreAuthenticatedToken(
            $user,
            $api_key,
            $provider_key,
            $user->getRoles()
        );
    }

    public function onAuthenticationFailure(Request $req, AuthenticationException $exception)
    {
        $data = [
            'success' => false,
            'error' => [
                'message' => $exception->getMessage(),
            ],
        ];
        return new JsonResponse($data, 401);
    }
}