New payment API example

paymentexample.php

<?php

//buyable has one or many payments
    //should this be absolutely required?
$buyable;

//creating a new payment
    //this will inject the appropriate gateway automatically, if one exists
$payment = new PaypalPayment(); //or
$payment = Payment::create('PaypalPayment');

//adding info to payment
$data = array(
    'Amount' => 100.00,
    'PaidFor' => $buyable
);
$payment->setData($data);

//could have a few setters
$payment->setAmount(100.00); //could prevent negative payment values
$payment->setPaidFor($buyable);

//arrange where to redirect to after payment
    //if this payment is to be processed within the same request, the link can be stored in session, otherwise we can't really rely on session. Either store link in database, or somehow store the need to call Link('success') on buyable.
    //I don't like this solution. Can we mimic Form processing somehow? ...pass a controller and action somewhere?
$payment->redirectTo($buyable->Link('success'));
//or
$controller = $this->controller;
$action = 'vieworder';
$id = $buyable->ID;
$payment->returnTo($controller,$action,$id,$data);

//perform check/validation on payment
$payment->validate();


//start payment process
    //records IP address
Director::redirect($payment->redirect());
//or
$payment->process();
return;


//check payment status

//make another payment

My ideas about how payment could work.