feat: read BusProNet base data from the MyE&P API

src/MyEp/Api/AccessTokenProvider.php

@@ -0,0 +1,139 @@
+<?php
+
+namespace App\MyEp\Api;
+
+use Psr\Cache\CacheItemPoolInterface;
+use Psr\Cache\InvalidArgumentException;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+use Symfony\Contracts\HttpClient\Exception\ExceptionInterface as TransportException;
+use Symfony\Contracts\HttpClient\HttpClientInterface;
+
+/**
+ * Obtains and caches the client_credentials access token for the MyE&P API.
+ *
+ * MyE&P issues short-lived tokens (ten minutes), so a token is kept in the shared
+ * cache until shortly before it expires rather than requested per call.
+ */
+class AccessTokenProvider
+{
+    private const CACHE_KEY = 'myep.api.access_token';
+
+    /**
+     * Assumed token lifetime when the response omits expires_in.
+     */
+    private const DEFAULT_LIFETIME = 600;
+
+    /**
+     * Dropped from every lifetime so a token is never handed out in the seconds
+     * before it expires.
+     */
+    private const EXPIRY_MARGIN = 60;
+
+    private const MINIMUM_LIFETIME = 30;
+
+    private array $config;
+
+    public function __construct(
+        private readonly HttpClientInterface $myepClient,
+        private readonly CacheItemPoolInterface $cache,
+        private readonly LoggerInterface $logger,
+        array $options,
+    ) {
+        $this->config = $this->resolveOptions($options);
+    }
+
+    /**
+     * @throws ApiException
+     */
+    public function getToken(): string
+    {
+        try {
+            $item = $this->cache->getItem(self::CACHE_KEY);
+        } catch (InvalidArgumentException $e) {
+            throw new ApiException('Unable to read the cached MyE&P access token', 0, $e);
+        }
+
+        if ($item->isHit()) {
+            return $item->get();
+        }
+
+        [$token, $lifetime] = $this->requestToken();
+
+        $item->set($token);
+        $item->expiresAfter($lifetime);
+        $this->cache->save($item);
+
+        return $token;
+    }
+
+    /**
+     * Drops the cached token so the next call fetches a fresh one. Used when the API
+     * rejects a token the cache still considered valid.
+     */
+    public function invalidate(): void
+    {
+        try {
+            $this->cache->deleteItem(self::CACHE_KEY);
+        } catch (InvalidArgumentException) {
+            // the key is a constant, so it cannot be malformed; nothing to recover from
+        }
+    }
+
+    /**
+     * @return array{0: string, 1: int} the token and the seconds it may be cached for
+     *
+     * @throws ApiException
+     */
+    private function requestToken(): array
+    {
+        try {
+            $response = $this->myepClient->request('POST', $this->config['token_path'], [
+                'body' => [
+                    'grant_type' => 'client_credentials',
+                    'client_id' => $this->config['client_id'],
+                    'client_secret' => $this->config['client_secret'],
+                    'scope' => $this->config['scope'],
+                ],
+            ]);
+
+            $statusCode = $response->getStatusCode();
+            $payload = $response->toArray(false);
+        } catch (TransportException $e) {
+            $this->logger->error('Unable to obtain a MyE&P access token', [
+                'client_id' => $this->config['client_id'],
+                'exception' => $e,
+            ]);
+
+            throw new ApiException('Unable to obtain a MyE&P access token', 0, $e);
+        }
+
+        $token = $payload['access_token'] ?? null;
+
+        if (200 !== $statusCode || false === is_string($token) || '' === $token) {
+            $this->logger->error('MyE&P rejected the access token request', [
+                'client_id' => $this->config['client_id'],
+                'status_code' => $statusCode,
+                'error' => $payload['error'] ?? null,
+            ]);
+
+            throw new ApiException('MyE&P rejected the access token request with status '.$statusCode);
+        }
+
+        $expiresIn = (int) ($payload['expires_in'] ?? self::DEFAULT_LIFETIME);
+
+        return [$token, max(self::MINIMUM_LIFETIME, $expiresIn - self::EXPIRY_MARGIN)];
+    }
+
+    private function resolveOptions(array $options): array
+    {
+        $optionsResolver = new OptionsResolver();
+        $optionsResolver->setRequired(['client_id', 'client_secret']);
+        $optionsResolver->setDefaults([
+            'token_path' => 'token',
+            'scope' => 'api',
+        ]);
+
+        return $optionsResolver->resolve($options);
+    }
+}