Add online payment functionality + invoice mgmt to existing php/mysql site

CURRENT SITUATION Currently access to an online application is being sold through a simple PHP/MySQL website. New customers and returning customers can buy a number of months access to the online software. Current process : • new user signs up / returning customer logs in • user selects number of months access he/she wants to buy • after submitting the form details : o DB gets updated (new expiration date for user) o site admin receives an automatic email with all details for (manual) invoicing o user receives an automatic email with all the necessary details to make the (offline) payment Summarizing : currently no online payments possible & invoicing is completely manual. REQUIRED NEW FUNCTIONALITY 1. improved checkout & online payments • User must be able to choose between offline payment and online payment. • Offline payments can be done like in the current process (updating DB + mail to site admin + mail with payment instructions to customer). • For online payments, Multisafepay's Fastcheckout needs to be integrated - allowing payments via Visa/Mastercard/Maestro/Bancontact • When all steps of the online payment transaction have been done, DB gets updated (new expiration date for user), user is redirected to a simple landing page on the site & an email with the payment details is sent out to the site admin + the user 2. Online invoicing mgmt The process of invoice creation needs to be done automatically. After the customer has completed the purchase (both offline and online cases), a pdf invoice is created and mailed to the customer and a copy to the site admin. Site admin needs to be able to : • consult an overview of invoices per customer (indicating invoice number / amount / payment method / status) • consult a chronological list of all invoices (indicating invoice number / amount / payment method / status + print button) • search for a particular invoice through a search box • change the status of an individual invoice (open, overdue, paid, ...) • generate a list of overdue unpaid invoices