Payments: single transaction mode for multiple purchases from different vendors

[AlexTr]

Add setting in payment module to enable "single transaction mode for multiple purchases from different vendors" (or it maybe it's better to implement it as separate Payment module instead of setting in existing module).

It has many benefits:

• money from all purchases will be received by one master user and other vendors can't specify their own payment methods
• it's one site-wide shopping cart instead of separate shopping cart for each vendor, so purchase from multiple vendors can be done in one transaction
• it's possible to buy any number of products from different vendors using buyer's preferred payment provider (paypal, chargebee, credits)
• site owner can get some sort of commission from all purchases on the site

In this mode we need to pass vendor ID for every purchased product, so we'll be able to track whom item is sold. When vendor's product is purchases, vendor receives credits according to specified credits conversion rate. Later vendor can exchange received credits to real money using different exchange rate or using the same rate but with some commission deducted.

Master user payment tools need to be updated to include sub-vendor ID field. Vendors payment tools will have limited functionality in this mode, most tools should be read-only, however variant where vendor adds transaction without affecting any balance can be also considered.

Some things to take into account:

• when refund is processed, then it should deduct credits from the vendors balance automatically using the specified exchange rate
• make it mandatory to keep some positive balance for vendors to be able to process refunds
• system should work even when vendor has negative credits balance
• ability to payout to vendor when vendor has some minimal credits
• some tools for bulk payout to vendors
• master payment tools should be accessible by different accounts or maybe just make it under Org profile, so multiple users can have access to payment tools

[AntonLV]

It would be better to update currently available Payments app that it can be used in two modes:

1. Multi-shopping carts (currently available).
2. Single shopping cart.

Some things to take into account:

1. The very first version can be created without Credits' based payouts to vendors. Site owner can organize the payouts manually or so.
2. In 'single transaction mode' we cannot use Stripe and/or ChargeBee because they require to create plans (products) on their end. So, we need to: 2.1. Develop our own 'Time Tracking' mechanism which will track subscriptions and initialize payments when it's needed. 2.2. Update Credits to allow subscription payments which will use newly developed 'Time Tracking' mechanism. 2.3. Integrate PayPal subscriptions and PayPal Mass Payments. Read more about up to date PayPal API here: https://developer.paypal.com/docs/checkout/integrate/

[AntonLV]

Execute during the next update:

ALTER TABLE `bx_payment_subscriptions` ADD `status` varchar(32) NOT NULL default 'unpaid';
UPDATE `bx_payment_subscriptions` SET `status`='active' WHERE `paid` <> 0;
ALTER TABLE `bx_payment_subscriptions` DROP `paid`;

ALTER TABLE `bx_payment_subscriptions_deleted` ADD `status` varchar(32) NOT NULL default 'unpaid';
UPDATE `bx_payment_subscriptions_deleted` SET `status`='active' WHERE `paid` <> 0;
ALTER TABLE `bx_payment_subscriptions_deleted` DROP `paid`;