start_scanning.php

<?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 script serves the ajax requests of assignment scanning when users click the scan button on the assignment page.
 *
 * @package    plagiarism_programming
 * @copyright  2015 thanhtri, 2019 Benedikt Schneider (@Nullmann)
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
define('NO_OUTPUT_BUFFERING', true);

require_once(__DIR__ . '/../../config.php');
require_once(__DIR__ . '/scan_assignment.php');
require_once(__DIR__ . '/detection_tools.php');
require_login();

global $DB;

/*
 * This global is used to store the assignment currently processed
 * to record status if an unexpected error occurs.
 * It is an array containing stage (which is extract,moss,jplag) and cmid.
 */
global $processinginfo;

$cmid = required_param('cmid', PARAM_INT);
$task = required_param('task', PARAM_TEXT);

// User initiating the scanning must have grade right.
$context = context_module::instance($cmid);
require_capability('mod/assignment:grade', $context);

// Unblock the session to allow parallel running (if use default PHP session).
session_write_close();

$assignment = $DB->get_record('plagiarism_programming', array(
    'cmid' => $cmid
));

if (!$assignment) {
    echo 'Invalid assignment!';
}
// Possible values are scan, check and download.
if ($task == 'scan') {
    ignore_user_abort(true);
    set_time_limit(1 * DAYSECS); // Uploading may last very long, we cannot allow the script to wait for 1 day.
    register_shutdown_function('plagiarism_programming_handle_shutdown');
    $time = optional_param('time', 0, PARAM_INT);
    $processinginfo = array(
        'stage' => 'extract',
        'cmid' => $cmid
    );
    ob_implicit_flush(true);
    start_scan_assignment($assignment, $time);
} else if ($task == 'check') {
    $starttime = optional_param('time', 0, PARAM_INT);
    plagiarism_programming_check_status($assignment, $starttime);
} else if ($task == 'download') {
    ignore_user_abort(true);
    set_time_limit(0);
    plagiarism_programming_download_assignment($assignment);
}

/**
 * Scan an assignment with all the selected tools.
 * This function intend only to serve the ajax
 * request for scanning an assignment
 *
 * @param Object $assignment The record object of settings for the assignment.
 * @param Number $time The timestamp this request is issued at the client side, to synchronise it with the check status requests
 */
function start_scan_assignment($assignment, $time) {
    global $DB, $detectiontools;

    echo get_string('scanning_in_progress', 'plagiarism_programming') . "\n";
    // Reset the status of all tools to pending and clear the error message if it is finished or error.
    foreach ($detectiontools as $toolname => $tool) {
        if (isset($assignment->$toolname)) {
            $toolrecord = $DB->get_record('plagiarism_programming_' . $toolname, array(
                'settingid' => $assignment->id
            ));
            if ($toolrecord && ($toolrecord->status == 'finished' || $toolrecord->status == 'error')) {
                $toolrecord->status = 'pending';
                $toolrecord->message = '';
                $toolrecord->error_detail = '';
                $DB->update_record('plagiarism_programming_' . $toolname, $toolrecord);
            }
        }
    }

    // Register the timestamp. This helps the check status requests know that the status obtained is the current status of the.
    // System, in case it comes sooner.
    $assignment->starttime = $time;
    $DB->update_record('plagiarism_programming', $assignment);

    plagiarism_programming_create_temp_dir();
    plagiarism_programming_scan_assignment($assignment);
}

/**
 * Check the scanning status of the selected tools for an assignment.
 * The function will output a json object {toolname=>{stage:status,progress:percentage}}
 *
 * @param Object $assignment The record object of settings for the assignment.
 * @param Number $time The timestamp this request is issued at the client side, to synchronise it with the check status requests
 */
function plagiarism_programming_check_status($assignment, $time = 0) {
    global $DB, $detectiontools;

    $status = array();

    /* Check whether the timestamp is updated or not. If not, the status in DB is the old status */
    if ($time > 0 && $time != $assignment->starttime) {
        // This means that the scanning hasn't been started by the request simultaneously initiated with this yet.
        // This request comes faster than the other.
        foreach ($detectiontools as $toolname => $toolinfo) {
            if ($assignment->$toolname) {
                $status[$toolname] = array(
                    'stage' => 'initiating',
                    'progress' => 0
                );
            }
        }
        echo json_encode($status);
        return;
    }

    // The scanning has been initiated.
    foreach ($detectiontools as $toolname => $toolinfo) {
        if (!$assignment->$toolname) {
            continue;
        }
        $scaninfo = $DB->get_record('plagiarism_programming_' . $toolname, array(
            'settingid' => $assignment->id
        ));
        assert($scaninfo != null);

        $toolclassname = $toolinfo['class_name'];
        $toolclass = new $toolclassname();
        plagiarism_programming_check_scanning_status($assignment, $toolclass, $scaninfo);

        $status[$toolname] = array(
            'stage' => $scaninfo->status,
            'progress' => $scaninfo->progress
        );
        if ($scaninfo->status == 'finished') { // Send back the link.
            $status[$toolname]['link'] = $toolclass->display_link($assignment);
        } else if ($scaninfo->status == 'error') {
            $status[$toolname]['message'] = $scaninfo->message;
        }
    }
    echo json_encode($status);
}

/**
 * Download the similarity report of the selected tools.
 * This function only delegates to download_result in scan_assignment.php
 *
 * @param Object $assignment The record object of settings for the assignment.
 */
function plagiarism_programming_download_assignment($assignment) {
    global $DB, $detectiontools;
    foreach ($detectiontools as $toolname => $toolinfo) {
        if (!$assignment->$toolname) {
            continue;
        }
        $scaninfo = $DB->get_record('plagiarism_programming_' . $toolname, array(
            'settingid' => $assignment->id
        ));
        assert($scaninfo != null);

        if ($scaninfo->status == 'done') {
            $toolclassname = $toolinfo['class_name'];
            $toolclass = new $toolclassname();
            plagiarism_programming_download_result($assignment, $toolclass, $scaninfo);
        }
    }
}