Development of plugins for OpenCart

RozetkaPay — an international payment service that is part of the EVO+Rozetka group of companies. Created based on the most well-known marketplaces in the country, it provides convenient, fast, and reliable payment solutions both online and offline (including through cash registers at online retail pickup points). We strive to make the purchasing process as simple and secure as possible. 

1. Develop a plugin for OpenCart for Express Checkout:
   1. Compatibility with versions 2.1, 2.3, 2.4, 3.0.
   2. Admin panel for settings.
   3. Integration of RozetkaPay API methods.

2. Functional requirements for plugins

   1. Ability to make a payment for an order through Express Checkout, flow:
      1. The user creates a cart with products.
      2. The user proceeds to the payment process.
      3. A payment scenario through Express Checkout must be implemented:
         • The user clicks the ''Buy with RozetkaPay'' button.
         • The endpoint create payment is called:
           • It is necessary to agree on the interaction protocol, which depends on the CMS system.
         • The response to the endpoint call returns a link for Express Checkout.
         • The user is automatically redirected to the received link to complete the payment.
         • After completing the payment, the user will be redirected to the URL specified in the request to create payment.
   2. Ability to receive callback in the merchant's admin panel with the result of payment/refund/cancellation of the order:
   3. Ability to call the resend callback method from the merchant's admin panel for resending the callback:
   4. Ability to call the payment info method from the merchant's admin panel to obtain payment information:
   5. Ability to call the cancel payment method from the merchant's admin panel.
      1. The method is applied in two cases:
         • Order cancellation:
           • Available for unpaid orders.
           • In the cancel payment request, the amount parameter must be empty.
         • Refund:
           • Available for paid orders.
           • For a full refund, the amount parameter should also be left empty.
           • For a partial refund, the value of the amount parameter needs to be specified.
   6. The plugin must support the input of API keys (api_key, secret_key). The keys will be used for authorizing API requests.

3.  Non-functional requirements for plugins

   1. The code must comply with OpenCart standards.
   2. Use of PHP version 7.4 or newer.
   3. Simple installation (archive with README).
   4. Compatibility with popular browsers.
   5. Requirements for the admin panel settings:
      1. Input of RozetkaPay API keys (api_key, secret_key).
      2. Toggle sandbox/production mode.
      3. Logging of API requests and responses.
   6. Client interface:
      1. The ''Buy with RozetkaPay'' button for payment through Express Checkout on the checkout page.

4. Expected results

   1. Plugins:
      1. Plugin archives for OpenCart (separately for each version).
      2. Plugin for WooCommerce.
   2. Documentation:
      1. Installation and setup instructions.
   3. Source code:
      1. Comments according to PHP standards.