The Payment Service coordinates the complete payment workflow using Stripe integration and job management.

Payment Workflow

Checkout Creation

1. Validate Stripe configuration
2. Calculate pricing with markup
3. Create job record in database
4. Generate Stripe checkout session
5. Return checkout URL for redirect

Payment Completion

1. Receive Stripe webhook notification
2. Validate payment intent
3. Update job status to ‘pending’
4. Trigger upscaling workflow
5. Send confirmation to customer

Stripe Configuration

Environment Management
Automatic selection based on settings:

$config = PaymentService::get_stripe_config();
// Returns appropriate keys for test/live mode

Configuration Validation

$result = PaymentService::validate_configuration();
// Returns WP_Error for issues or true for valid setup

Checkout Session Creation

Session Configuration

$session = $stripe->checkout->sessions->create([
    'payment_method_types' => ['card'],
    'line_items' => [{
        'price_data' => [
            'currency' => 'usd',
            'product_data' => [
                'name' => 'High-Resolution Image (4x)',
                'description' => '2000x2000 → 8000x8000 pixels'
            ],
            'unit_amount' => $amount_cents
        ],
        'quantity' => 1
    }],
    'mode' => 'payment',
    'success_url' => $success_url,
    'cancel_url' => $cancel_url,
    'metadata' => [
        'job_id' => $job_id,
        'plugin' => 'sell-my-images'
    ]
]);

Webhook Processing

Supported Events

• checkout.session.completed – Payment successful
• payment_intent.payment_failed – Payment declined
• checkout.session.expired – Session timeout

Security Validation

// Verify webhook signature
$payload = @file_get_contents('php://input');
$sig_header = $_SERVER['HTTP_STRIPE_SIGNATURE'];
$event = StripeWebhook::constructEvent($payload, $sig_header, $webhook_secret);

Refund Management

Automatic Refunds
Failed processing triggers automatic refunds:

public function process_refund($job_id, $reason) {
    $job = JobManager::get_job($job_id);
    $refund = $this->stripe->refunds->create([
        'payment_intent' => $job->stripe_payment_intent_id,
        'reason' => 'requested_by_customer',
        'metadata' => [
            'job_id' => $job_id,
            'failure_reason' => $reason
        ]
    ]);
}

Refund Tracking

• Complete audit trail in database
• Customer notification emails
• Admin reporting integration
• Financial reconciliation support

Error Handling

Payment Failures

• Card declined: Customer notification
• Insufficient funds: Retry suggestion
• Network errors: Graceful degradation
• API limits: Queuing system

Recovery Mechanisms

• Automatic retry for transient errors
• Manual admin intervention support
• Customer support integration
• Detailed error logging

Success/Cancel URLs

URL Generation

$success_url = add_query_arg([
    'smi_payment' => 'success',
    'job_id' => $job_id,
    'session_id' => '{CHECKOUT_SESSION_ID}'
], $return_url);

Status Handling

• JavaScript detection of URL parameters
• Modal display of payment status
• Automatic job status polling
• User experience optimization

Integration Points

Job Management

• Create job before payment
• Update status on completion
• Link payment intent to job
• Coordinate with upscaling service

Customer Communication

• Email confirmation on payment
• Processing status updates
• Completion notifications
• Support contact information