<?php
  header("Access-Control-Allow-Origin: *");
  header("Content-Type: application/json; charset=UTF-8");
  header("Access-Control-Allow-Methods: POST");
  header("Access-Control-Allow-Headers: Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With");

	require_once('../../utils/config.php');
	require_once('../../utils/db.php');
	require_once('../../utils/strings.php');

  $method = $_SERVER['REQUEST_METHOD'];
  if ('POST' === $method) {
    parse_str(file_get_contents('php://input'), $_POST);
  }

	$connection = connect();
 
  $date = mysqli_real_escape_string($connection, $_POST["date"]);
  $time = mysqli_real_escape_string($connection, $_POST["time"]);
  
  $dow = (new DateTime($date))->format('w'); 

	$querystr = "SELECT * FROM li_plan, li_courses 
                WHERE li_plan.cid=li_courses.cid 
                  AND li_plan.day={$dow} 
                  AND li_plan.begin < '{$time}' 
                  AND li_plan.end > '{$time}'";
                  
  $result = mysqli_query($connection, $querystr);
  if($result->num_rows !== 0) {
  	while ($row = mysqli_fetch_object($result)) {
      
      $begin = new DateTime($row->begin);
      $end = new DateTime($row->end);
      
      $returnValue = (object) [
          'cid' => $row->cid,
          'name' => $row->name . ' ' . $row->description,
          'date' => $date,
          'begin' => $begin->format('H:i'),
          'end' => $end->format('H:i'),
          'students' => array()
        ];      
      
      break;
    }
    
    $querystr = "SELECT *, 1 AS visited FROM li_enroll, li_students
                 WHERE li_enroll.sid = li_students.sid
                   AND li_enroll.cid = {$returnValue->cid}
                   AND li_enroll.begin <= '{$date}'
                   AND li_enroll.end >= '{$date}' 
                   AND EXISTS(SELECT * FROM li_visits 
                              WHERE li_visits.sid = li_enroll.sid
                                AND li_visits.cid = li_enroll.cid
                                AND li_visits.date = '{$date}') 
                 UNION
                 SELECT *, 0 AS visited FROM li_enroll, li_students
                 WHERE li_enroll.sid = li_students.sid
                   AND li_enroll.cid = {$returnValue->cid} 
                   AND li_enroll.begin <= '{$date}'
                   AND li_enroll.end >= '{$date}' 
                   AND NOT EXISTS(SELECT * FROM li_visits 
                              WHERE li_visits.sid = li_enroll.sid
                                AND li_visits.cid = li_enroll.cid
                                AND li_visits.date = '{$date}')
                 ORDER BY lastname, firstname";

    $result2 = mysqli_query($connection, $querystr);
    if($result2->num_rows !== 0) {
    	while ($row = mysqli_fetch_object($result2)) {
        $student = (object) [
          'sid' => $row->sid,
          'firstname' => $row->firstname,
          'lastname' => $row->lastname,
          'visited' => $row->visited
        ];    
        
        array_push($returnValue->students, $student);
      }
    }
  }

 	mysqli_free_result($result);

  echo json_encode($returnValue);
?>