<?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/>.

/**
 * local functions and constants for module attendance
 *
 * @package   mod_attendance
 * @copyright  2011 Artem Andreev <andreev.artem@gmail.com>
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

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

require_once($CFG->libdir . '/gradelib.php');
require_once(dirname(__FILE__).'/renderhelpers.php');

define('ATT_VIEW_DAYS', 1);
define('ATT_VIEW_WEEKS', 2);
define('ATT_VIEW_MONTHS', 3);
define('ATT_VIEW_ALLPAST', 4);
define('ATT_VIEW_ALL', 5);
define('ATT_VIEW_NOTPRESENT', 6);
define('ATT_VIEW_SUMMARY', 7);

define('ATT_SORT_DEFAULT', 0);
define('ATT_SORT_LASTNAME', 1);
define('ATT_SORT_FIRSTNAME', 2);

define('ATTENDANCE_AUTOMARK_DISABLED', 0);
define('ATTENDANCE_AUTOMARK_ALL', 1);
define('ATTENDANCE_AUTOMARK_CLOSE', 2);
/**
 * Get statuses,
 *
 * @param int $attid
 * @param bool $onlyvisible
 * @param int $statusset
 * @return array
 */
function attendance_get_statuses($attid, $onlyvisible=true, $statusset = -1) {
    global $DB;

    // Set selector.
    $params = array('aid' => $attid);
    $setsql = '';
    if ($statusset >= 0) {
        $params['statusset'] = $statusset;
        $setsql = ' AND setnumber = :statusset ';
    }

    if ($onlyvisible) {
        $statuses = $DB->get_records_select('attendance_statuses', "attendanceid = :aid AND visible = 1 AND deleted = 0 $setsql",
                                            $params, 'setnumber ASC, grade DESC');
    } else {
        $statuses = $DB->get_records_select('attendance_statuses', "attendanceid = :aid AND deleted = 0 $setsql",
                                            $params, 'setnumber ASC, grade DESC');
    }

    return $statuses;
}

/**
 * Get the name of the status set.
 *
 * @param int $attid
 * @param int $statusset
 * @param bool $includevalues
 * @return string
 */
function attendance_get_setname($attid, $statusset, $includevalues = true) {
    $statusname = get_string('statusset', 'mod_attendance', $statusset + 1);
    if ($includevalues) {
        $statuses = attendance_get_statuses($attid, true, $statusset);
        $statusesout = array();
        foreach ($statuses as $status) {
            $statusesout[] = $status->acronym;
        }
        if ($statusesout) {
            if (count($statusesout) > 6) {
                $statusesout = array_slice($statusesout, 0, 6);
                $statusesout[] = '&helip;';
            }
            $statusesout = implode(' ', $statusesout);
            $statusname .= ' ('.$statusesout.')';
        }
    }

    return $statusname;
}

/**
 * Get users courses and the relevant attendances.
 *
 * @param int $userid
 * @return array
 */
function attendance_get_user_courses_attendances($userid) {
    global $DB;

    $usercourses = enrol_get_users_courses($userid);

    list($usql, $uparams) = $DB->get_in_or_equal(array_keys($usercourses), SQL_PARAMS_NAMED, 'cid0');

    $sql = "SELECT att.id as attid, att.course as courseid, course.fullname as coursefullname,
                   course.startdate as coursestartdate, att.name as attname, att.grade as attgrade
              FROM {attendance} att
              JOIN {course} course
                   ON att.course = course.id
             WHERE att.course $usql
          ORDER BY coursefullname ASC, attname ASC";

    $params = array_merge($uparams, array('uid' => $userid));

    return $DB->get_records_sql($sql, $params);
}

/**
 * Used to calculate a fraction based on the part and total values
 *
 * @param float $part - part of the total value
 * @param float $total - total value.
 * @return float the calculated fraction.
 */
function attendance_calc_fraction($part, $total) {
    if ($total == 0) {
        return 0;
    } else {
        return $part / $total;
    }
}

/**
 * Check to see if statusid in use to help prevent deletion etc.
 *
 * @param integer $statusid
 */
function attendance_has_logs_for_status($statusid) {
    global $DB;
    return $DB->record_exists('attendance_log', array('statusid' => $statusid));
}

/**
 * Helper function to add sessiondate_selector to add/update forms.
 *
 * @param MoodleQuickForm $mform
 */
function attendance_form_sessiondate_selector (MoodleQuickForm $mform) {

    $mform->addElement('date_selector', 'sessiondate', get_string('sessiondate', 'attendance'));

    for ($i = 0; $i <= 23; $i++) {
        $hours[$i] = sprintf("%02d", $i);
    }
    for ($i = 0; $i < 60; $i += 5) {
        $minutes[$i] = sprintf("%02d", $i);
    }

    $sesendtime = array();
    $sesendtime[] =& $mform->createElement('static', 'from', '', get_string('from', 'attendance'));
    $sesendtime[] =& $mform->createElement('select', 'starthour', get_string('hour', 'form'), $hours, false, true);
    $sesendtime[] =& $mform->createElement('select', 'startminute', get_string('minute', 'form'), $minutes, false, true);
    $sesendtime[] =& $mform->createElement('static', 'to', '', get_string('to', 'attendance'));
    $sesendtime[] =& $mform->createElement('select', 'endhour', get_string('hour', 'form'), $hours, false, true);
    $sesendtime[] =& $mform->createElement('select', 'endminute', get_string('minute', 'form'), $minutes, false, true);
    $mform->addGroup($sesendtime, 'sestime', get_string('time', 'attendance'), array(' '), true);
}

/**
 * Count the number of status sets that exist for this instance.
 *
 * @param int $attendanceid
 * @return int
 */
function attendance_get_max_statusset($attendanceid) {
    global $DB;

    $max = $DB->get_field_sql('SELECT MAX(setnumber) FROM {attendance_statuses} WHERE attendanceid = ? AND deleted = 0',
        array($attendanceid));
    if ($max) {
        return $max;
    }
    return 0;
}

/**
 * Returns the maxpoints for each statusset
 *
 * @param array $statuses
 * @return array
 */
function attendance_get_statusset_maxpoints($statuses) {
    $statussetmaxpoints = array();
    foreach ($statuses as $st) {
        if (!isset($statussetmaxpoints[$st->setnumber])) {
            $statussetmaxpoints[$st->setnumber] = $st->grade;
        }
    }
    return $statussetmaxpoints;
}

/**
 * Update user grades
 *
 * @param mod_attendance_structure|stdClass $attendance
 * @param array $userids
 */
function attendance_update_users_grade($attendance, $userids=array()) {
    global $DB;

    if (empty($attendance->grade)) {
        return false;
    }

    list($course, $cm) = get_course_and_cm_from_instance($attendance->id, 'attendance');

    $summary = new mod_attendance_summary($attendance->id, $userids);

    if (empty($userids)) {
        $context = context_module::instance($cm->id);
        $userids = array_keys(get_enrolled_users($context, 'mod/attendance:canbelisted', 0, 'u.id'));
    }

    if ($attendance->grade < 0) {
        $dbparams = array('id' => -($attendance->grade));
        $scale = $DB->get_record('scale', $dbparams);
        $scalearray = explode(',', $scale->scale);
        $attendancegrade = count($scalearray);
    } else {
        $attendancegrade = $attendance->grade;
    }

    $grades = array();
    foreach ($userids as $userid) {
        $grades[$userid] = new stdClass();
        $grades[$userid]->userid = $userid;

        if ($summary->has_taken_sessions($userid)) {
            $usersummary = $summary->get_taken_sessions_summary_for($userid);
            $grades[$userid]->rawgrade = $usersummary->takensessionspercentage * $attendancegrade;
        } else {
            $grades[$userid]->rawgrade = null;
        }
    }

    return grade_update('mod/attendance', $course->id, 'mod', 'attendance', $attendance->id, 0, $grades);
}

/**
 * Add an attendance status variable
 *
 * @param stdClass $status
 * @return bool
 */
function attendance_add_status($status) {
    global $DB;
    if (empty($status->context)) {
        $status->context = context_system::instance();
    }

    if (!empty($status->acronym) && !empty($status->description)) {
        $status->deleted = 0;
        $status->visible = 1;
        $status->setunmarked = 0;

        $id = $DB->insert_record('attendance_statuses', $status);
        $status->id = $id;

        $event = \mod_attendance\event\status_added::create(array(
            'objectid' => $status->attendanceid,
            'context' => $status->context,
            'other' => array('acronym' => $status->acronym,
                             'description' => $status->description,
                             'grade' => $status->grade)));
        if (!empty($status->cm)) {
            $event->add_record_snapshot('course_modules', $status->cm);
        }
        $event->add_record_snapshot('attendance_statuses', $status);
        $event->trigger();
        return true;
    } else {
        return false;
    }
}

/**
 * Remove a status variable from an attendance instance
 *
 * @param stdClass $status
 * @param stdClass $context
 * @param stdClass $cm
 */
function attendance_remove_status($status, $context = null, $cm = null) {
    global $DB;
    if (empty($context)) {
        $context = context_system::instance();
    }
    $DB->set_field('attendance_statuses', 'deleted', 1, array('id' => $status->id));
    $event = \mod_attendance\event\status_removed::create(array(
        'objectid' => $status->id,
        'context' => $context,
        'other' => array(
            'acronym' => $status->acronym,
            'description' => $status->description
        )));
    if (!empty($cm)) {
        $event->add_record_snapshot('course_modules', $cm);
    }
    $event->add_record_snapshot('attendance_statuses', $status);
    $event->trigger();
}

/**
 * Update status variable for a particular Attendance module instance
 *
 * @param stdClass $status
 * @param string $acronym
 * @param string $description
 * @param int $grade
 * @param bool $visible
 * @param stdClass $context
 * @param stdClass $cm
 * @param int $studentavailability
 * @param bool $setunmarked
 * @return array
 */
function attendance_update_status($status, $acronym, $description, $grade, $visible,
                                  $context = null, $cm = null, $studentavailability = null, $setunmarked = false) {
    global $DB;

    if (empty($context)) {
        $context = context_system::instance();
    }

    if (isset($visible)) {
        $status->visible = $visible;
        $updated[] = $visible ? get_string('show') : get_string('hide');
    } else if (empty($acronym) || empty($description)) {
        return array('acronym' => $acronym, 'description' => $description);
    }

    $updated = array();

    if ($acronym) {
        $status->acronym = $acronym;
        $updated[] = $acronym;
    }
    if ($description) {
        $status->description = $description;
        $updated[] = $description;
    }
    if (isset($grade)) {
        $status->grade = $grade;
        $updated[] = $grade;
    }
    if (isset($studentavailability)) {
        if (empty($studentavailability)) {
            if ($studentavailability !== '0') {
                $studentavailability = null;
            }
        }

        $status->studentavailability = $studentavailability;
        $updated[] = $studentavailability;
    }
    if ($setunmarked) {
        $status->setunmarked = 1;
    } else {
        $status->setunmarked = 0;
    }
    $DB->update_record('attendance_statuses', $status);

    $event = \mod_attendance\event\status_updated::create(array(
        'objectid' => $status->attendanceid,
        'context' => $context,
        'other' => array('acronym' => $acronym, 'description' => $description, 'grade' => $grade,
            'updated' => implode(' ', $updated))));
    if (!empty($cm)) {
        $event->add_record_snapshot('course_modules', $cm);
    }
    $event->add_record_snapshot('attendance_statuses', $status);
    $event->trigger();
}

/**
 * Similar to core random_string function but only lowercase letters.
 * designed to make it relatively easy to provide a simple password in class.
 *
 * @param int $length The length of the string to be created.
 * @return string
 */
function attendance_random_string($length=6) {
    $randombytes = random_bytes_emulate($length);
    $pool = 'abcdefghijklmnopqrstuvwxyz';
    $pool .= '0123456789';
    $poollen = strlen($pool);
    $string = '';
    for ($i = 0; $i < $length; $i++) {
        $rand = ord($randombytes[$i]);
        $string .= substr($pool, ($rand % ($poollen)), 1);
    }
    return $string;
}

/**
 * Check to see if this session is open for student marking.
 *
 * @param stdclass $sess the session record from attendance_sessions.
 * @return boolean
 */
function attendance_can_student_mark($sess) {
    $canmark = false;
    $attconfig = get_config('attendance');
    if (!empty($attconfig->studentscanmark) && !empty($sess->studentscanmark)) {
        if (empty($attconfig->studentscanmarksessiontime)) {
            $canmark = true;
        } else {
            $duration = $sess->duration;
            if (empty($duration)) {
                $duration = $attconfig->studentscanmarksessiontimeend * 60;
            }
            if ($sess->sessdate < time() && time() < ($sess->sessdate + $duration)) {
                $canmark = true;
            }
        }
    }
    return $canmark;
}

/**
 * Generate worksheet for Attendance export
 *
 * @param stdclass $data The data for the report
 * @param string $filename The name of the file
 * @param string $format excel|ods
 *
 */
function attendance_exporttotableed($data, $filename, $format) {
    global $CFG;

    if ($format === 'excel') {
        require_once("$CFG->libdir/excellib.class.php");
        $filename .= ".xls";
        $workbook = new MoodleExcelWorkbook("-");
    } else {
        require_once("$CFG->libdir/odslib.class.php");
        $filename .= ".ods";
        $workbook = new MoodleODSWorkbook("-");
    }
    // Sending HTTP headers.
    $workbook->send($filename);
    // Creating the first worksheet.
    $myxls = $workbook->add_worksheet('Attendances');
    // Format types.
    $formatbc = $workbook->add_format();
    $formatbc->set_bold(1);

    $myxls->write(0, 0, get_string('course'), $formatbc);
    $myxls->write(0, 1, $data->course);
    $myxls->write(1, 0, get_string('group'), $formatbc);
    $myxls->write(1, 1, $data->group);

    $i = 3;
    $j = 0;
    foreach ($data->tabhead as $cell) {
        // Merge cells if the heading would be empty (remarks column).
        if (empty($cell)) {
            $myxls->merge_cells($i, $j - 1, $i, $j);
        } else {
            $myxls->write($i, $j, $cell, $formatbc);
        }
        $j++;
    }
    $i++;
    $j = 0;
    foreach ($data->table as $row) {
        foreach ($row as $cell) {
            $myxls->write($i, $j++, $cell);
        }
        $i++;
        $j = 0;
    }
    $workbook->close();
}

/**
 * Generate csv for Attendance export
 *
 * @param stdclass $data The data for the report
 * @param string $filename The name of the file
 *
 */
function attendance_exporttocsv($data, $filename) {
    $filename .= ".txt";

    header("Content-Type: application/download\n");
    header("Content-Disposition: attachment; filename=\"$filename\"");
    header("Expires: 0");
    header("Cache-Control: must-revalidate,post-check=0,pre-check=0");
    header("Pragma: public");

    echo get_string('course')."\t".$data->course."\n";
    echo get_string('group')."\t".$data->group."\n\n";

    echo implode("\t", $data->tabhead)."\n";
    foreach ($data->table as $row) {
        echo implode("\t", $row)."\n";
    }
}

/**
 * Get session data for form.
 * @param stdClass $formdata moodleform - attendance form.
 * $param mod_attendance_structure $att - used to get attendance level subnet.
 * @return array.
 */
function attendance_construct_sessions_data_for_add($formdata, mod_attendance_structure $att) {
    global $CFG;

    $sesstarttime = $formdata->sestime['starthour'] * HOURSECS + $formdata->sestime['startminute'] * MINSECS;
    $sesendtime = $formdata->sestime['endhour'] * HOURSECS + $formdata->sestime['endminute'] * MINSECS;
    $sessiondate = $formdata->sessiondate + $sesstarttime;
    $duration = $sesendtime - $sesstarttime;
    $now = time();

    if (empty(get_config('attendance', 'studentscanmark'))) {
        $formdata->studentscanmark = 0;
    }

    $sessions = array();
    if (isset($formdata->addmultiply)) {
        $startdate = $sessiondate;
        $enddate = $formdata->sessionenddate + DAYSECS; // Because enddate in 0:0am.

        if ($enddate < $startdate) {
            return null;
        }

        // Getting first day of week.
        $sdate = $startdate;
        $dinfo = usergetdate($sdate);
        if ($CFG->calendar_startwday === '0') { // Week start from sunday.
            $startweek = $startdate - $dinfo['wday'] * DAYSECS; // Call new variable.
        } else {
            $wday = $dinfo['wday'] === 0 ? 7 : $dinfo['wday'];
            $startweek = $startdate - ($wday - 1) * DAYSECS;
        }

        $wdaydesc = array(0 => 'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat');

        while ($sdate < $enddate) {
            if ($sdate < $startweek + WEEKSECS) {
                $dinfo = usergetdate($sdate);
                if (isset($formdata->sdays) && array_key_exists($wdaydesc[$dinfo['wday']], $formdata->sdays)) {
                    $sess = new stdClass();
                    $sess->sessdate = make_timestamp($dinfo['year'], $dinfo['mon'], $dinfo['mday'],
                        $formdata->sestime['starthour'], $formdata->sestime['startminute']);
                    $sess->duration = $duration;
                    $sess->descriptionitemid = $formdata->sdescription['itemid'];
                    $sess->description = $formdata->sdescription['text'];
                    $sess->descriptionformat = $formdata->sdescription['format'];
                    $sess->timemodified = $now;
                    if (isset($formdata->studentscanmark)) { // Students will be able to mark their own attendance.
                        $sess->studentscanmark = 1;
                        if (!empty($formdata->usedefaultsubnet)) {
                            $sess->subnet = $att->subnet;
                        } else {
                            $sess->subnet = $formdata->subnet;
                        }
                        $sess->automark = $formdata->automark;
                        $sess->automarkcompleted = 0;
                        if (!empty($formdata->randompassword)) {
                            $sess->studentpassword = attendance_random_string();
                        } else {
                            $sess->studentpassword = $formdata->studentpassword;
                        }
                    } else {
                        $sess->studentpassword = '';
                        $sess->subnet = '';
                        $sess->automark = 0;
                        $sess->automarkcompleted = 0;
                    }
                    $sess->statusset = $formdata->statusset;

                    attendance_fill_groupid($formdata, $sessions, $sess);
                }
                $sdate += DAYSECS;
            } else {
                $startweek += WEEKSECS * $formdata->period;
                $sdate = $startweek;
            }
        }
    } else {
        $sess = new stdClass();
        $sess->sessdate = $sessiondate;
        $sess->duration = $duration;
        $sess->descriptionitemid = $formdata->sdescription['itemid'];
        $sess->description = $formdata->sdescription['text'];
        $sess->descriptionformat = $formdata->sdescription['format'];
        $sess->timemodified = $now;
        $sess->studentscanmark = 0;
        $sess->subnet = '';
        $sess->studentpassword = '';
        $sess->automark = 0;
        $sess->automarkcompleted = 0;

        if (isset($formdata->studentscanmark) && !empty($formdata->studentscanmark)) {
            // Students will be able to mark their own attendance.
            $sess->studentscanmark = 1;
            if (!empty($formdata->randompassword)) {
                $sess->studentpassword = attendance_random_string();
            } else if (!empty($formdata->studentpassword)) {
                $sess->studentpassword = $formdata->studentpassword;
            }
            if (!empty($formdata->usedefaultsubnet)) {
                $sess->subnet = $att->subnet;
            } else {
                $sess->subnet = $formdata->subnet;
            }

            if (!empty($formdata->automark)) {
                $sess->automark = $formdata->automark;
            }
        }
        $sess->statusset = $formdata->statusset;

        attendance_fill_groupid($formdata, $sessions, $sess);
    }

    return $sessions;
}

/**
 * Helper function for attendance_construct_sessions_data_for_add().
 *
 * @param stdClass $formdata
 * @param stdClass $sessions
 * @param stdClass $sess
 */
function attendance_fill_groupid($formdata, &$sessions, $sess) {
    if ($formdata->sessiontype == mod_attendance_structure::SESSION_COMMON) {
        $sess = clone $sess;
        $sess->groupid = 0;
        $sessions[] = $sess;
    } else {
        foreach ($formdata->groups as $groupid) {
            $sess = clone $sess;
            $sess->groupid = $groupid;
            $sessions[] = $sess;
        }
    }
}

/**
 * Generates a summary of points for the courses selected.
 *
 * @param array $courseids optional list of courses to return
 * @param string $orderby - optional order by param
 * @return stdClass
 */
function attendance_course_users_points($courseids = array(), $orderby = '') {
    global $DB;

    $where = '';
    $params = array();
    $where .= ' AND ats.sessdate < :enddate ';
    $params['enddate'] = time();

    $joingroup = 'LEFT JOIN {groups_members} gm ON (gm.userid = atl.studentid AND gm.groupid = ats.groupid)';
    $where .= ' AND (ats.groupid = 0 or gm.id is NOT NULL)';

    if (!empty($courseids)) {
        list($insql, $inparams) = $DB->get_in_or_equal($courseids, SQL_PARAMS_NAMED);
        $where .= ' AND c.id ' . $insql;
        $params = array_merge($params, $inparams);
    }

    $sql = "SELECT courseid, coursename, sum(points) / sum(maxpoints) as percentage FROM (
SELECT a.id, a.course as courseid, c.fullname as coursename, atl.studentid AS userid, COUNT(DISTINCT ats.id) AS numtakensessions,
                        SUM(stg.grade) AS points, SUM(stm.maxgrade) AS maxpoints
                   FROM mdl_attendance_sessions ats
                   JOIN mdl_attendance a ON a.id = ats.attendanceid
                   JOIN mdl_course c ON c.id = a.course
                   JOIN mdl_attendance_log atl ON (atl.sessionid = ats.id)
                   JOIN mdl_attendance_statuses stg ON (stg.id = atl.statusid AND stg.deleted = 0 AND stg.visible = 1)
                   JOIN (SELECT attendanceid, setnumber, MAX(grade) AS maxgrade
                           FROM mdl_attendance_statuses
                          WHERE deleted = 0
                            AND visible = 1
                         GROUP BY attendanceid, setnumber) stm
                     ON (stm.setnumber = ats.statusset AND stm.attendanceid = ats.attendanceid)
                  {$joingroup}
                  WHERE ats.sessdate >= c.startdate
                    AND ats.lasttaken != 0
                    {$where}
                GROUP BY a.id, a.course, c.fullname, atl.studentid
                ) p GROUP by courseid, coursename {$orderby}";

    return $DB->get_records_sql($sql, $params);
}