<?php

namespace Shaarli\Api;

use malkusch\lock\mutex\FlockMutex;
use Shaarli\Api\Exceptions\ApiAuthorizationException;
use Shaarli\Api\Exceptions\ApiException;
use Shaarli\Bookmark\BookmarkFileService;
use Shaarli\Config\ConfigManager;
use Slim\Container;
use Slim\Http\Request;
use Slim\Http\Response;

/**
 * Class ApiMiddleware
 *
 * This will be called before accessing any API Controller.
 * Its role is to make sure that the API is enabled, configured, and to validate the JWT token.
 *
 * If the request is validated, the controller is called, otherwise a JSON error response is returned.
 *
 * @package Api
 */
class ApiMiddleware
{
    /**
     * @var int JWT token validity in seconds (9 min).
     */
    public static $TOKEN_DURATION = 540;

    /**
     * @var Container: contains conf, plugins, etc.
     */
    protected $container;

    /**
     * @var ConfigManager instance.
     */
    protected $conf;

    /**
     * ApiMiddleware constructor.
     *
     * @param Container $container instance.
     */
    public function __construct($container)
    {
        $this->container = $container;
        $this->conf = $this->container->get('conf');
        $this->setLinkDb($this->conf);
    }

    /**
     * Middleware execution:
     *   - check the API request
     *   - execute the controller
     *   - return the response
     *
     * @param  Request  $request  Slim request
     * @param  Response $response Slim response
     * @param  callable $next     Next action
     *
     * @return Response response.
     */
    public function __invoke($request, $response, $next)
    {
        try {
            $this->checkRequest($request);
            $response = $next($request, $response);
        } catch (ApiException $e) {
            $e->setResponse($response);
            $e->setDebug($this->conf->get('dev.debug', false));
            $response = $e->getApiResponse();
        }

        return $response
            ->withHeader('Access-Control-Allow-Origin', '*')
            ->withHeader(
                'Access-Control-Allow-Headers',
                'X-Requested-With, Content-Type, Accept, Origin, Authorization'
            )
            ->withHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS')
        ;
    }

    /**
     * Check the request validity (HTTP method, request value, etc.),
     * that the API is enabled, and the JWT token validity.
     *
     * @param  Request $request  Slim request
     *
     * @throws ApiAuthorizationException The API is disabled or the token is invalid.
     */
    protected function checkRequest($request)
    {
        if (! $this->conf->get('api.enabled', true)) {
            throw new ApiAuthorizationException('API is disabled');
        }
        $this->checkToken($request);
    }

    /**
     * Check that the JWT token is set and valid.
     * The API secret setting must be set.
     *
     * @param  Request $request  Slim request
     *
     * @throws ApiAuthorizationException The token couldn't be validated.
     */
    protected function checkToken($request)
    {
        if (
            !$request->hasHeader('Authorization')
            && !isset($this->container->environment['REDIRECT_HTTP_AUTHORIZATION'])
        ) {
            throw new ApiAuthorizationException('JWT token not provided');
        }

        if (empty($this->conf->get('api.secret'))) {
            throw new ApiAuthorizationException('Token secret must be set in Shaarli\'s administration');
        }

        if (isset($this->container->environment['REDIRECT_HTTP_AUTHORIZATION'])) {
            $authorization = $this->container->environment['REDIRECT_HTTP_AUTHORIZATION'];
        } else {
            $authorization = $request->getHeaderLine('Authorization');
        }

        if (! preg_match('/^Bearer (.*)/i', $authorization, $matches)) {
            throw new ApiAuthorizationException('Invalid JWT header');
        }

        ApiUtils::validateJwtToken($matches[1], $this->conf->get('api.secret'));
    }

    /**
     * Instantiate a new LinkDB including private bookmarks,
     * and load in the Slim container.
     *
     * FIXME! LinkDB could use a refactoring to avoid this trick.
     *
     * @param ConfigManager $conf instance.
     */
    protected function setLinkDb($conf)
    {
        $linkDb = new BookmarkFileService(
            $conf,
            $this->container->get('pluginManager'),
            $this->container->get('history'),
            new FlockMutex(fopen(SHAARLI_MUTEX_FILE, 'r'), 2),
            true
        );
        $this->container['db'] = $linkDb;
    }
}