quiztech-assessment-platform/src/Includes/payments.php

<?php

namespace Quiztech\AssessmentPlatform\Includes;

use Quiztech\AssessmentPlatform\Gateways\StripeGateway;
/**
 * File for handling payment integration logic.
 *
 * @package Quiztech
 */

// If this file is called directly, abort.
if ( ! \defined( 'WPINC' ) ) {
	die; // It's a language construct, not a function in the global namespace
}

/**
 * Initiate the credit purchase process.
 * This would typically be called via an AJAX handler or form submission.
 * It should interact with the chosen payment gateway handler.
 *
 * @param int $user_id The ID of the user making the purchase.
 * @param string $item_id Identifier for the credit pack or item being purchased.
 * @param int $quantity The quantity being purchased.
 * @return mixed Gateway-specific response (e.g., redirect URL, session ID) or WP_Error on failure.
 */
function quiztech_initiate_credit_purchase( $user_id, $item_id, $quantity = 1 ) {
 // --- Implementation Required ---
 // 1. Validate input: Ensure $user_id is valid, $item_id exists, $quantity is positive integer.
 // 2. Get Item Details: Fetch price and credits amount for $item_id (requires defining how items are stored - e.g., CPT, options).
 // 3. Get Active Gateway: Read plugin settings (e.g., get_option('quiztech_settings')) to find the configured gateway slug.
 $active_gateway = 'stripe'; // Placeholder: Replace with dynamic logic reading settings.

 if ( 'stripe' === $active_gateway ) {
 	$gateway = new StripeGateway();
 	// 4. Pass Metadata: Gather necessary data (user_id, item_id, quantity, credits_amount, price)
 	//    and pass it appropriately to the gateway's initiatePayment method, likely for Stripe metadata.
 	$result = $gateway->initiatePayment( $user_id, $item_id, $quantity /*, $metadata_array */ ); // Example modification
 	return $result; // Return whatever the gateway method returns (e.g., session ID, URL, WP_Error)
 }

	// If no active or supported gateway found
	return new \WP_Error( 'no_gateway', \__( 'No active or supported payment gateway configured.', 'quiztech' ) );
}

/**
 * Handle incoming payment gateway webhooks.
 * This needs to be registered as a REST endpoint or admin-ajax handler.
 */
function quiztech_handle_payment_webhook() {
 // --- Implementation Required ---
 // Identify the gateway. This typically requires unique endpoints per gateway.
 // Example: Register '/webhook/stripe' and '/webhook/paypal'. The endpoint itself identifies the gateway.
 $gateway_slug = 'stripe'; // Placeholder: Determine dynamically based on the requested endpoint.

 if ( 'stripe' === $gateway_slug ) {
 	$payload = @file_get_contents('php://input');
		$signature = isset($_SERVER['HTTP_STRIPE_SIGNATURE']) ? $_SERVER['HTTP_STRIPE_SIGNATURE'] : '';

		if ( empty($payload) || empty($signature) ) {
			\wp_send_json_error( 'Missing payload or signature for Stripe webhook.', 400 );
			return; // Exit
		}

		$gateway = new StripeGateway();
		$handled = $gateway->handleWebhook( $payload, $signature );

		if ( $handled ) {
			// The handleWebhook method should call quiztech_process_successful_payment internally if needed.
			\wp_send_json_success( 'Webhook processed.', 200 );
		} else {
			\wp_send_json_error( 'Stripe webhook verification or processing failed.', 400 );
		}
		return; // Exit
	}

	// Handle other gateways or errors if no matching gateway found
	\wp_send_json_error( 'Invalid or unsupported webhook request.', 400 );
}

// --- Implementation Required ---
// Register the webhook handler(s) using WordPress REST API (recommended for webhooks).
// Example (needs proper implementation, likely in a dedicated class or main plugin file):
// add_action( 'rest_api_init', function () {
//   register_rest_route( 'quiztech/v1', '/webhook/stripe', array( // Use gateway-specific endpoint
//     'methods' => 'POST',
//     'callback' => 'quiztech_handle_payment_webhook',
//     'permission_callback' => '__return_true' // IMPORTANT: Implement proper permission checks!
//   ) );
// } );


/**
 * Process a successful payment notification from a gateway webhook.
 * This function is typically called *by* the gateway-specific webhook handler.
 *
 * @param int $user_id The user ID who made the purchase.
 * @param int $credits_purchased The number of credits purchased.
 * @param string $transaction_id The gateway's transaction ID.
 * @param string $gateway_slug Slug of the gateway (e.g., 'stripe').
 * @return bool True on success, false on failure.
 */
function quiztech_process_successful_payment( $user_id, $credits_purchased, $transaction_id, $gateway_slug ) {
	if ( ! $user_id || ! $credits_purchased > 0 || empty( $transaction_id ) || empty( $gateway_slug ) ) {
		// Log error: Invalid data received for payment processing.
		return false;
	}

	// --- Implementation Required ---
	// Add checks to prevent processing the same transaction ID multiple times.
	// This typically involves:
	// 1. Storing processed transaction IDs (e.g., in post meta on the user_evaluation, a dedicated log table, or user meta).
	// 2. Querying this storage before updating the balance. If the ID exists, return true (or log) without updating again.
	// 3. Saving the transaction ID after successfully updating the balance.

	// Update the user's credit balance
	$result = quiztech_update_user_credit_balance(
		$user_id,
		(int) $credits_purchased,
		\sprintf( '%s_purchase_%s', $gateway_slug, $transaction_id )
	);

	if ( false !== $result ) {
		// Optional: Log successful transaction details somewhere (custom table?)
		// Optional: Send purchase confirmation email to user
		// do_action('quiztech_credits_purchased', $user_id, $credits_purchased, $transaction_id, $gateway_slug);
		return true;
	} else {
		// Log error: Failed to update credit balance for user $user_id after successful payment $transaction_id.
		return false;
	}
}

?>