functions.php

<?php

function executeQuery($db, $sql){
  if (!$result = $db->query($sql)){
    $message = array ("status" => "error","description" => "Database Error", "error" => $db->error);
    echo json_encode($message);
    die();
  }
  return $result;
}

function getUserId($db, $email){
  $sql = "SELECT * FROM `users` WHERE `email`=\"$email\"";
  $result = executeQuery($db, $sql);
  if ($result->num_rows>0){
    $row = $result->fetch_assoc();
    $userid = $row['userid'];
    return $userid;
  }else{
    return 0;
  }
}

function createGroup($db, $groupname, $members){
  $sql = "SELECT * FROM `groups` ORDER BY `groupid` DESC";
  $result = executeQuery($db, $sql);
  $row = $result->fetch_assoc();
  $groupid = $row['groupid'] + 1;
  $insert_sql = "INSERT INTO `groups` (groupid, groupname, members) VALUES(\"$groupid\", \"$groupname\", \"$members\")";
  $insert_result = executeQuery($db, $insert_sql);
  return $groupid;
}

function addUserToGroup($db, $userid, $groupid){
  $sql = "SELECT * FROM `groups` WHERE `groupid`=\"$groupid\"";
  $result = executeQuery($db, $sql);
  if ($result->num_rows>0){
    $row=$result->fetch_assoc();
    $groupname = $row['groupname'];
    $insert_sql = "INSERT INTO `usergroup` (userid, groupid, groupname) VALUES(\"$userid\", \"$groupid\", \"$groupname\")";
    $insert_result = executeQuery($db, $insert_sql);
    return 1;
  }else{
    $message = array ("status" => "error","description" => "Group Not Found");
    echo json_encode($message);
    die();
  }
}

function getOwnGroupId($db, $userid){
  $sql = "SELECT * FROM `usergroup` WHERE `userid`=\"$userid\" AND `own`=\"1\"";
  $result = executeQuery($db, $sql);
  if ($result->num_rows == 1){
    $row = $result->fetch_assoc();
    $groupid = $row['groupid'];
    return $groupid;
  }else{
    $message = array ("status" => "error","description" => "Own Group Error");
    echo json_encode($message);
    die();
  }
}

function getRelatedGroups($db, $groupid){
  $sql = "SELECT * FROM `usergroup` WHERE `groupid`=\"$groupid\"";
  $result = executeQuery($db, $sql);

  $relatedGroups=array();
  while($user=$result->fetch_assoc()){
    $userid = $user['userid'];
    $sql2 = "SELECT * FROM `usergroup` WHERE `userid`=\"$userid\" ";
    $result2 = executeQuery($db, $sql2);
    while ($group= $result2->fetch_assoc()){
      $groupid_indb = $group['groupid'];
      if ($groupid_indb == $groupid){
        continue;
      }
      if (!in_array($groupid_indb, $relatedGroups)){
        array_push($relatedGroups, $groupid_indb);
      }
    }
  }
  return $relatedGroups;
}

function checkIfRegIsPossible($db, $groupid, $event, $check){
  $relatedGroups = getRelatedGroups($db, $groupid);
  foreach ($relatedGroups as $relatedGroup) {
    $sql = "SELECT * FROM `$check` WHERE `groupid`=\"$relatedGroup\"";
    $result = executeQuery($db, $sql);
    while ($row = $result->fetch_assoc()){
      if ($row[$event] > 0){
        return 0;
      }
    }
  }
  return 1;
}
// testing
// require 'connect.php';
// print_r(getRelatedGroups($db, 1));
// echo checkIfRegIsPossible($db, 1, "techyhunt", "events");
?>