<?php

// This file is part of Moodle - http://moodle.org/
// 
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// Moodle 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 General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * This file contains the backend webservice contact functionality for the DTA plugin
 *
 * @package    assignsubmission_dta
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */



/**
 * Backend webservice contact utility class
 *
 * @package    assignsubmission_dta
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
namespace assignsubmission_dta;

defined('MOODLE_INTERNAL') || die();

class dta_backend_utils {

    /**
     * Component name for the plugin.
     */
    const COMPONENT_NAME = 'assignsubmission_dta';

    /**
     * Returns the base URL of the backend webservice as configured in the administration settings.
     * @return string Backend host base URL
     */
    private static function get_backend_baseurl(): string {
        $backendaddress = get_config(self::COMPONENT_NAME, 'backendHost');

        if (empty($backendaddress)) {
            \core\notification::error(get_string('backendHost_not_set', self::COMPONENT_NAME));
        }

        return $backendaddress;
    }

    /**
     * Sends the configuration text file uploaded by the teacher to the backend.
     *
     * @param \assign $assignment Assignment this test-config belongs to
     * @param \stored_file $file Uploaded test-config
     * @return bool True if no error occurred
     */
    public static function send_testconfig_to_backend($assignment, $file): bool {
        $backendaddress = self::get_backend_baseurl();
        if (empty($backendaddress)) {
            return true;
        }

        // Set endpoint for test upload.
        $url = $backendaddress . '/v1/unittest';

        // Prepare params.
        $params = [
            'unitTestFile' => $file,
            'assignmentId' => $assignment->get_instance()->id,
        ];

        // If request returned null, return false to indicate failure.
        if (is_null(self::post($url, $params))) {
            return false;
        } else {
            return true;
        }
    }

    /**
     * Sends submission config or archive to backend to be tested.
     *
     * @param \assign $assignment Assignment for the submission
     * @param int $submissionid Submission ID of the current file
     * @param \stored_file $file Submission config file or archive with submission
     * @return string|null JSON string with test results or null on error
     */
    public static function send_submission_to_backend($assignment, $submissionid, $file): ?string {
        $backendaddress = self::get_backend_baseurl();
        if (empty($backendaddress)) {
            return null;
        }

        // Set endpoint for submission upload.
        $url = $backendaddress . '/v1/task/' . $submissionid;

        // Prepare params.
        $params = [
            'taskFile' => $file,
            'assignmentId' => $assignment->get_instance()->id,
        ];

        return self::post($url, $params);
    }

    /**
     * Posts the given params to the given URL and returns the response as a string.
     * @param string $url Full URL to request to
     * @param array $params Parameters for HTTP request
     *
     * @return string|null Received body on success or null on error
     */
    private static function post($url, $params): ?string {
        if (!isset($url) || !isset($params)) {
            return null;
        }

        $options = ['CURLOPT_RETURNTRANSFER' => true];

        $curl = new \curl();
        $response = $curl->post($url, $params, $options);

        // Check state of request, if response code is a 2xx return the answer.
        $info = $curl->get_info();
        if ($info['http_code'] >= 200 && $info['http_code'] < 300) {
            return $response;
        }

        // Something went wrong, return null and give an error message.
        debugging(self::COMPONENT_NAME . ': Post file to server was not successful: http_code=' . $info['http_code']);

        if ($info['http_code'] >= 400 && $info['http_code'] < 500) {
            \core\notification::error(get_string('http_client_error_msg', self::COMPONENT_NAME));
            return null;
        } else if ($info['http_code'] >= 500 && $info['http_code'] < 600) {
            \core\notification::error(get_string('http_server_error_msg', self::COMPONENT_NAME));
            return null;
        } else {
            \core\notification::error(get_string('http_unknown_error_msg', self::COMPONENT_NAME) . $info['http_code'] . $response);
            return null;
        }
    }
}