Currency - endpoint

<?php

/*

This file is subject to the terms and conditions defined in
file 'LICENSE', which is part of this source code package.

© 2022 OtteIT s.r.o.
All Rights Reserved.

Author: Vilem Otte <dev@otte.cz>

*/

/**
 * Read currency record
 *
 * @param id Reference, references ID in currency table
 *
 * @return _ JSON, result (HTTP response code), error (in case of any), currency (either blank array or holding resulting record as JSON)
 */

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(__DIR__."/../../db.php");
require_once(__DIR__."/../../util.php");
require_once(__DIR__."/currency.php");
require_once(__DIR__."/../../session/session.php");
require_once(__DIR__."/../../auth/auth.php");
require_once(__DIR__."/../../permission/permission.php");

// Session set up
$auth = new Auth();
$session = new Session();

// Payload requirements
$data = json_decode(file_get_contents("php://input"));

$payloadError = Util::PayloadCheck($data);
if ($payloadError != false)
{
    http_response_code(200);
    echo json_encode(array("result" => 500, "error" => $payloadError));

    exit();
}

// Connect to database, attach to session
$db = new Database();
$session->SetDB($db);

// Require user authentication
$auth_id = $session->GetUserID($auth);
if ($auth_id != null)
{
    // Check permission - generic record read can only be performed by admins, users can only see their records
    $permission = new Permission($db);
    $permissionCheck = $permission->Check($auth_id, "rum", Permission::READ | Permission::WRITE | Permission::WRITE_SELF);

    if ($permissionCheck == true)
    {
        // Permission check success - read record
        $currency = new Rum_Currency($db);

        if ($data->id != null)
        {
            $currency->id = intval($data->id);
        }

        $result = $currency->Read();

        if ($result != null)
        {
            // Successfully read record
            http_response_code(200);
            echo json_encode(array("result" => 200, "currency" => $result));
        }
        else
        {
            if ($db->GetLastError())
            {
                // DB Error during record reading
                http_response_code(200);
                echo json_encode(array("result" => 500, "error" => $db->GetLastError()));
            }
            else
            {
                // Successfully read, but no record matching
                http_response_code(200);
                echo json_encode(array("result" => 200, "currency" => []));
            }
        }
    }
    else if ($permissionCheck === false)
    {
        // Permission check failure
        http_response_code(200);
        echo json_encode(array("result" => 401, "error" => "Unauthorized: Permission level too low."));
    }
    else
    {
        // DB Error during permission check
        http_response_code(200);
        echo json_encode(array("result" => 500, "error" => $db->GetLastError()));
    }
}
else
{
    // User unauthorized
    http_response_code(200);
    echo json_encode(array("result" => 401, "error" => "Unauthorized"));
}

// Close database connection
$db->Disconnect();

?>