<?php
    $serverIP = "";
    $databaseIP = "";
    $databaseUser = "";
    $databasePass = "";
    $databaseName = "";
    $database = new mysqli( $databaseIP, $databaseUser, $databasePass, $databaseName);

    header("Content-Type: application/json");

    if(mysqli_connect_errno()){
        $response['status'] = 503;
        $response['message'] = "Database server is down.";
    }

    if($_SERVER['REMOTE_ADDR']==$serverIP){
        if(!empty($_POST)){
            $insertSQL = "INSERT INTO acs VALUES('".$_POST['cardid']."')";
            if($database->query($insertSQL) && isset($_POST['cardid'])){
                $response['status'] = 200;
                $response['message'] = $_POST['cardid']." was added to the database.";
            }
            elseif (isset($_POST['cardid'])) {
                $response['status'] = 400;
                $response['message'] = "CARD ALREADY EXISTS.";
            }
            else{
                $response['status'] = 400;
                $response['message'] = "INVALID REQUEST";
            }
        }
        else{
            $response['status'] = 400;
            $response['message'] = "INVALID REQUEST";
        }
    }
    else{
        $response['status'] = 401;
        $response['message'] = "UNAUTHORIZED ACCESS";
    }
    echo json_encode($response);