docs: Add customer portal session example

examples/customer_portal_session.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+use Paddle\SDK\Exceptions\ApiError;
+use Paddle\SDK\Exceptions\SdkExceptions\MalformedResponse;
+use Paddle\SDK\Resources\CustomerPortalSessions\Operations\CreateCustomerPortalSession;
+
+require __DIR__ . '/../vendor/autoload.php';
+
+$environment = Paddle\SDK\Environment::tryFrom(getenv('PADDLE_ENVIRONMENT') ?: '') ?? Paddle\SDK\Environment::SANDBOX;
+$apiKey = getenv('PADDLE_API_KEY') ?: null;
+$customerId = getenv('PADDLE_CUSTOMER_ID') ?: null;
+$subscriptionId = getenv('PADDLE_SUBSCRIPTION_ID') ?: null;
+
+if (is_null($apiKey)) {
+    echo "You must provide the PADDLE_API_KEY in the environment:\n";
+    echo "PADDLE_API_KEY=your-key php examples/basic_usage.php\n";
+    exit(1);
+}
+
+$paddle = new Paddle\SDK\Client($apiKey, options: new Paddle\SDK\Options($environment));
+
+// ┌───
+// │ Create Customer Portal Session │
+// └────────────────────────────────┘
+try {
+    $customerPortalSession = $paddle->customerPortalSessions->create(
+        $customerId,
+        new CreateCustomerPortalSession([$subscriptionId]),
+    );
+} catch (ApiError|MalformedResponse $e) {
+    var_dump($e);
+    exit;
+}
+
+echo sprintf("Created Customer Portal Session: %s\n", $customerPortalSession->id);
+echo sprintf("  - Customer ID: %s\n", $customerPortalSession->customerId);
+echo sprintf("  - Created At: %s\n", $customerPortalSession->createdAt->format(DATE_RFC3339_EXTENDED));
+echo sprintf("  - General Overview URL: %s\n", $customerPortalSession->urls->general->overview);
+
+foreach ($customerPortalSession->urls->subscriptions as $subscriptionUrl) {
+    echo sprintf("  - Subscription URLs: %s\n", $subscriptionUrl->id);
+    echo sprintf("      - Update Subscription Payment Method URL: %s\n", $subscriptionUrl->updateSubscriptionPaymentMethod);
+    echo sprintf("      - Cancel URL: %s\n", $subscriptionUrl->cancelSubscription);
+}