<?php
/**
 * @copyright Copyright (C) 2010-2021, the Friendica project
 *
 * @license GNU AGPL version 3 or any later version
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

namespace Friendica\Module\OAuth;

use Friendica\Core\Logger;
use Friendica\DI;
use Friendica\Module\BaseApi;
use Friendica\Security\OAuth;

/**
 * @see https://docs.joinmastodon.org/spec/oauth/
 * @see https://aaronparecki.com/oauth-2-simplified/
 */
class Authorize extends BaseApi
{
	private static $oauth_code = '';

	/**
	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
	 */
	protected function rawContent(array $request = [])
	{
		$request = self::getRequest([
			'force_login'   => '', // Forces the user to re-login, which is necessary for authorizing with multiple accounts from the same instance.
			'response_type' => '', // Should be set equal to "code".
			'client_id'     => '', // Client ID, obtained during app registration.
			'client_secret' => '', // Isn't normally provided. We will use it if present.
			'redirect_uri'  => '', // Set a URI to redirect the user to. If this parameter is set to "urn:ietf:wg:oauth:2.0:oob" then the authorization code will be shown instead. Must match one of the redirect URIs declared during app registration.
			'scope'         => 'read', // List of requested OAuth scopes, separated by spaces (or by pluses, if using query parameters). Must be a subset of scopes declared during app registration. If not provided, defaults to "read".
			'state'         => '',
		], $request);

		if ($request['response_type'] != 'code') {
			Logger::warning('Unsupported or missing response type', ['request' => $_REQUEST]);
			DI::mstdnError()->UnprocessableEntity(DI::l10n()->t('Unsupported or missing response type'));
		}

		if (empty($request['client_id']) || empty($request['redirect_uri'])) {
			Logger::warning('Incomplete request data', ['request' => $_REQUEST]);
			DI::mstdnError()->UnprocessableEntity(DI::l10n()->t('Incomplete request data'));
		}

		$application = OAuth::getApplication($request['client_id'], $request['client_secret'], $request['redirect_uri']);
		if (empty($application)) {
			DI::mstdnError()->UnprocessableEntity();
		}

		// @todo Compare the application scope and requested scope

		$redirect_request = $_REQUEST;
		unset($redirect_request['pagename']);
		$redirect = 'oauth/authorize?' . http_build_query($redirect_request);

		$uid = local_user();
		if (empty($uid)) {
			Logger::info('Redirect to login');
			DI::app()->redirect('login?return_path=' . urlencode($redirect));
		} else {
			Logger::info('Already logged in user', ['uid' => $uid]);
		}

		if (!OAuth::existsTokenForUser($application, $uid) && !DI::session()->get('oauth_acknowledge')) {
			Logger::info('Redirect to acknowledge');
			DI::app()->redirect('oauth/acknowledge?' . http_build_query(['return_path' => $redirect, 'application' => $application['name']]));
		}

		DI::session()->remove('oauth_acknowledge');

		$token = OAuth::createTokenForUser($application, $uid, $request['scope']);
		if (!$token) {
			DI::mstdnError()->UnprocessableEntity();
		}

		if ($application['redirect_uri'] != 'urn:ietf:wg:oauth:2.0:oob') {
			DI::app()->redirect($application['redirect_uri'] . (strpos($application['redirect_uri'], '?') ? '&' : '?') . http_build_query(['code' => $token['code'], 'state' => $request['state']]));
		}

		self::$oauth_code = $token['code'];
	}

	protected function content(array $request = []): string
	{
		if (empty(self::$oauth_code)) {
			return '';
		}

		return DI::l10n()->t('Please copy the following authentication code into your application and close this window: %s', self::$oauth_code);
	}
}