<?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);

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;
}

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 mixed 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 string $acronym
 * @param string $description
 * @param int $grade
 */
function attendance_add_status($acronym, $description, $grade, $attendanceid, $setnumber = 0, $context = null, $cm = null) {
    global $DB;
    if (empty($context)) {
        $context = context_system::instance();
    }
    if ($acronym && $description) {
        $rec = new stdClass();
        $rec->attendanceid = $attendanceid;
        $rec->acronym = $acronym;
        $rec->description = $description;
        $rec->grade = $grade;
        $rec->setnumber = $setnumber; // Save which set it is part of.
        $rec->deleted = 0;
        $rec->visible = 1;
        $id = $DB->insert_record('attendance_statuses', $rec);
        $rec->id = $id;

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

/**
 * Remove a status variable from an attendance instance
 *
 * @param stdClass $status
 */
function attendance_remove_status($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 $visible
 */
function attendance_update_status($status, $acronym, $description, $grade, $visible, $context = null, $cm = null) {
    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;
    }
    $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;
}