functions.php

<?php
if (!defined("RFID_STATUS_FILE")) {
    define("RFID_STATUS_FILE", "rfid_status");
}
if (!defined("RFID_STATUS_READING")) {
    define("RFID_STATUS_READING", "r");
}
if (!defined("RFID_STATUS_PAIRING")) {
    define("RFID_STATUS_PAIRING", "p");
}
if (!defined("PAIRING_EMPLOYEE_ID_FILE")) {
    define("PAIRING_EMPLOYEE_ID_FILE", "pairing_employee_id_file");
}

function getEmployeesWithRfid()
{
    $query = "SELECT employee_id, rfid_serial FROM employee_rfid";
    $db = getDatabase();
    $statement = $db->query($query);
    return $statement->fetchAll();
}

function onRfidSerialRead($rfidSerial)
{
    if (getReaderStatus() === RFID_STATUS_PAIRING) {
        pairEmployeeWithRfid($rfidSerial, getPairingEmployeeId());
        setReaderStatus(RFID_STATUS_READING);
    } else {
        $employee = getEmployeeByRfidSerial($rfidSerial);
        if ($employee) {
            saveEmployeeAttendance($employee->id);
        }
    }
}
function saveEmployeeAttendance($employeeId)
{

    $date = date("Y-m-d");
    $status = "presence";
    $query = "INSERT INTO employee_attendance(employee_id, date, status) VALUES (?, ?, ?)";
    $db = getDatabase();
    $statement = $db->prepare($query);
    return $statement->execute([$employeeId, $date, $status]);
}

function setReaderForEmployeePairing($employeeId)
{
    setReaderStatus(RFID_STATUS_PAIRING);
    setPairingEmployeeId($employeeId);
}

function setPairingEmployeeId($employeeId)
{
    file_put_contents(PAIRING_EMPLOYEE_ID_FILE, $employeeId);
}

function getPairingEmployeeId()
{
    return file_get_contents(PAIRING_EMPLOYEE_ID_FILE);
}

function pairEmployeeWithRfid($rfidSerial, $employeeId)
{
    removeRfidFromEmployee($rfidSerial);
    $query = "INSERT INTO employee_rfid(employee_id, rfid_serial) VALUES (?, ?)";
    $db = getDatabase();
    $statement = $db->prepare($query);
    return $statement->execute([$employeeId, $rfidSerial]);
}

function removeRfidFromEmployee($rfidSerial)
{
    $query = "DELETE FROM employee_rfid WHERE rfid_serial = ?";
    $db = getDatabase();
    $statement = $db->prepare($query);
    return $statement->execute([$rfidSerial]);
}

function getEmployeeByRfidSerial($rfidSerial)
{
    $query = "SELECT e.id, e.name FROM employees e INNER JOIN employee_rfid
    ON employee_rfid.employee_id = e.id
    WHERE employee_rfid.rfid_serial = ?";

    $db = getDatabase();
    $statement = $db->prepare($query);
    $statement->execute([$rfidSerial]);
    return $statement->fetchObject();
}
function getEmployeeRfidById($employeeId)
{
    $query = "SELECT rfid_serial FROM employee_rfid WHERE employee_id = ?";
    $db = getDatabase();
    $statement = $db->prepare($query);
    $statement->execute([$employeeId]);
    return $statement->fetchObject();
}

function getReaderStatus()
{
    return file_get_contents(RFID_STATUS_FILE);
}

function setReaderStatus($newStatus)
{
    if (!in_array($newStatus, [RFID_STATUS_PAIRING, RFID_STATUS_READING])) {
        return;
    }

    file_put_contents(RFID_STATUS_FILE, $newStatus);
}