$connection = new \Picqer\Financials\Exact\Connection();
$connection->setRedirectUrl('CALLBACK_URL'); // Same as entered online in the App Center
$connection->setExactClientId('CLIENT_ID');
$connection->setExactClientSecret('CLIENT_SECRET');
$connection->redirectForAuthorization();

$connection = new \Picqer\Financials\Exact\Connection();
$connection->setRedirectUrl('CALLBACK_URL');
$connection->setExactClientId('CLIENT_ID');
$connection->setExactClientSecret('CLIENT_SECRET');

if (getValue('authorizationcode')) {
    // Retrieves authorizationcode from database
    $connection->setAuthorizationCode(getValue('authorizationcode'));
}

if (getValue('accesstoken')) {
    // Retrieves accesstoken from database
    $connection->setAccessToken(unserialize(getValue('accesstoken')));
}

if (getValue('refreshtoken')) {
    // Retrieves refreshtoken from database
    $connection->setRefreshToken(getValue('refreshtoken'));
}

if (getValue('expires_in')) {
    // Retrieves expires timestamp from database
    $connection->setTokenExpires(getValue('expires_in'));
}

// Make the client connect and exchange tokens
try {
    $connection->connect();
} catch (\Exception $e)
{
    throw new Exception('Could not connect to Exact: ' . $e->getMessage());
}

// Save the new tokens for next connections
setValue('accesstoken', serialize($connection->getAccessToken()));
setValue('refreshtoken', $connection->getRefreshToken());

// Optionally, save the expiry-timestamp. This prevents exchanging valid tokens (ie. saves you some requests)
setValue('expires_in', $connection->getTokenExpires());

// Optionally, set the lock and unlock callbacks to prevent multiple request for acquiring a new refresh token with the same refresh token.
$connection->setAcquireAccessTokenLockCallback('CALLBACK_FUNCTION');
$connection->setAcquireAccessTokenUnlockCallback('CALLBACK_FUNCTION');

$connection->getDailyLimit(); // Retrieve your daily limit
$connection->getDailyLimitRemaining(); // Retrieve the remaining amount of API calls for this day
$connection->getDailyLimitReset(); // Retrieve the timestamp for when the limit will reset
$connection->getMinutelyLimit(); // Retrieve your limit per minute
$connection->getMinutelyLimitRemaining(); // Retrieve the amount of API calls remaining for this minute
$connection->getMinutelyLimitReset(); // Retrieve the timestamp for when the minutely limit will reset

$connection->setWaitOnMinutelyRateLimitHit(true);

// Optionally set administration, otherwise use the current administration of the user
$connection->setDivision(123456);

// Create a new account
$account = new \Picqer\Financials\Exact\Account($connection);
$account->AddressLine1 = 'Customers address line';
$account->AddressLine2 = 'Customer address line 2';
$account->City = 'Customer city';
$account->Code = 'Customer code';
$account->Country = 'Customer country';
$account->IsSales = 'true';
$account->Name = 'Customer name';
$account->Postcode = 'Customer postcode';
$account->Status = 'C';
$account->save();

// Add a product in Exact
$item = new \Picqer\Financials\Exact\Item($connection);
$item->Code = 'product code';
$item->CostPriceStandard = 2.50;
$item->Description = 'product description';
$item->IsSalesItem = true;
$item->SalesVatCode = 'VH';
$item->save();

// Retrieve an item by id
$item = new \Picqer\Financials\Exact\Item($connection);
$id = '097A82A9-6EF7-4EDC-8036-3F7559D9EF82';
$item->find($id);

// List items
$item = new \Picqer\Financials\Exact\Item($connection);
$item->get();

// List items with filter (using a filter always returns a collection) and loop through the result
$item = new \Picqer\Financials\Exact\Item($connection);
$items = $item->filter("Code eq '$item->Code'"); // Uses filters as described in Exact API docs (odata filters)
foreach($items as $itemObject){
    $attrs = (array) $itemObject->attributes(); // Turns the endpoint properties into an array
    $picture = $itemObject->download();         // Fetches an image string instead of the url
    // Do something with $attrs and or $picture, e.g. imagecreatefromstring($picture) 
}

// Create new invoice with invoice lines
$invoiceLines[] = [
    'Item'      => $item->ID,
    'Quantity'  => 1,
    'UnitPrice' => $item->CostPriceStandard
];

$salesInvoice = new \Picqer\Financials\Exact\SalesInvoice($connection);
$salesInvoice->InvoiceTo = $account->ID;
$salesInvoice->OrderedBy = $account->ID;
$salesInvoice->YourRef = 'Invoice reference';
$salesInvoice->SalesInvoiceLines = $invoiceLines;
$salesInvoice->save();

// Print and email the invoice
$printedInvoice = new \Picqer\Financials\Exact\PrintedSalesInvoice($connection);
$printedInvoice->InvoiceID = $salesInvoice->InvoiceID;
$printedInvoice->SendEmailToCustomer = true;
$printedInvoice->SenderEmailAddress = "[email protected]";
$printedInvoice->DocumentLayout = "401f3020-35cd-49a2-843a-d904df0c09ff";
$printedInvoice->ExtraText = "Some additional text";
$printedInvoice->save();

$item = new \Picqer\Financials\Exact\Item($connection);
$item->getAsGenerator();
$item->filterAsGenerator('IsWebshopItem eq 1');

$connection = new \Picqer\Financials\Exact\Connection();
$connection->setRedirectUrl('CALLBACK_URL');
$connection->setExactClientId('CLIENT_ID');
$connection->setExactClientSecret('CLIENT_SECRET');
$connection->setBaseUrl('https://start.exactonline.de');

$test = new \Picqer\Financials\Exact\GeneralJournalEntry($connection);
var_dump($test->filter('', '', 'EntryID, FinancialYear'));

$test = new \Picqer\Financials\Exact\GeneralJournalEntry($connection);
var_dump($test->filter('', '', '', ['$top'=> 1]));