Add code comments and improve error messages

src/Cache/ArrayCache.php

@@ -2,17 +2,26 @@
 
 namespace OpenApi\Cache;
 
+/**
+ * In-memory cache implementation
+ * Data is stored in PHP arrays and cleared at end of script execution
+ */
 class ArrayCache implements CacheInterface
 {
     private array $cache = [];
     private array $expiry = [];
 
+    /**
+     * Retrieve value from cache
+     * Returns null if key doesn't exist or has expired
+     */
     public function get(string $key): mixed
     {
         if (!isset($this->cache[$key])) {
             return null;
         }
 
+        // Check if expired
         if (isset($this->expiry[$key]) && time() > $this->expiry[$key]) {
             $this->delete($key);
             return null;
@@ -21,26 +30,35 @@ public function get(string $key): mixed
         return $this->cache[$key];
     }
 
+    /**
+     * Save value to cache with expiration
+     */
     public function save(string $key, mixed $value, int $ttl = 3600): bool
     {
         $this->cache[$key] = $value;
         $this->expiry[$key] = time() + $ttl;
-        
+
         return true;
     }
 
+    /**
+     * Delete value from cache
+     */
     public function delete(string $key): bool
     {
         unset($this->cache[$key], $this->expiry[$key]);
-        
+
         return true;
     }
 
+    /**
+     * Clear all cached values
+     */
     public function clear(): bool
     {
         $this->cache = [];
         $this->expiry = [];
-        
+
         return true;
     }
 }

src/Cache/CacheInterface.php

@@ -2,10 +2,32 @@
 
 namespace OpenApi\Cache;
 
+/**
+ * Cache interface for SDK implementations
+ */
 interface CacheInterface
 {
+    /**
+     * Retrieve value from cache
+     */
     public function get(string $key): mixed;
+
+    /**
+     * Save value to cache with TTL
+     *
+     * @param string $key Cache key
+     * @param mixed $value Value to store
+     * @param int $ttl Time-to-live in seconds (default: 3600)
+     */
     public function save(string $key, mixed $value, int $ttl = 3600): bool;
+
+    /**
+     * Delete value from cache
+     */
     public function delete(string $key): bool;
+
+    /**
+     * Clear all cached values
+     */
     public function clear(): bool;
 }

src/Client.php

@@ -2,23 +2,40 @@
 
 namespace OpenApi;
 
-class Client 
+/**
+ * Generic HTTP client for OpenAPI services
+ * Handles REST operations with Bearer token authentication
+ */
+class Client
 {
     private string $token;
 
+    /**
+     * Initialize client with Bearer token
+     */
     public function __construct(string $token)
     {
         $this->token = $token;
     }
 
+    /**
+     * Execute HTTP request
+     *
+     * @param string $method HTTP method (GET, POST, PUT, DELETE, PATCH)
+     * @param string $url Target URL
+     * @param mixed $payload Request body (for POST/PUT/PATCH)
+     * @param array|null $params Query parameters (for GET) or form data (for other methods)
+     * @return string Response body
+     */
     public function request(string $method, string $url, mixed $payload = null, ?array $params = null): string
     {
+        // Append query parameters for GET requests
         if ($params && $method === 'GET') {
             $url .= '?' . http_build_query($params);
         }
 
         $ch = curl_init();
-        
+
         curl_setopt_array($ch, [
             CURLOPT_URL => $url,
             CURLOPT_RETURNTRANSFER => true,
@@ -30,12 +47,14 @@ public function request(string $method, string $url, mixed $payload = null, ?arr
             ]
         ]);
 
+        // Add JSON payload for POST/PUT/PATCH requests
         if ($payload && in_array($method, ['POST', 'PUT', 'PATCH'])) {
             curl_setopt($ch, CURLOPT_POSTFIELDS, is_string($payload) ? $payload : json_encode($payload));
         }
 
+        // Add form data for non-GET requests
         if ($params && $method !== 'GET') {
-            curl_setopt($ch, CURLOPT_POSTFIELDS, 
+            curl_setopt($ch, CURLOPT_POSTFIELDS,
                 is_string($params) ? $params : http_build_query($params));
         }
 
@@ -44,37 +63,54 @@ public function request(string $method, string $url, mixed $payload = null, ?arr
         $error = curl_error($ch);
         curl_close($ch);
 
+        // TODO: Provide more graceful error message with connection context (timeout, DNS, SSL, etc.)
         if ($response === false) {
             throw new Exception("cURL Error: " . $error);
         }
 
+        // TODO: Parse response body and provide structured error details (error code, message, request ID)
         if ($httpCode >= 400) {
             throw new Exception("HTTP Error {$httpCode}: " . $response);
         }
 
         return $response;
     }
 
+    /**
+     * Perform GET request
+     */
     public function get(string $url, ?array $params = null): string
     {
         return $this->request('GET', $url, null, $params);
     }
 
+    /**
+     * Perform POST request
+     */
     public function post(string $url, mixed $payload = null): string
     {
         return $this->request('POST', $url, $payload);
     }
 
+    /**
+     * Perform PUT request
+     */
     public function put(string $url, mixed $payload = null): string
     {
         return $this->request('PUT', $url, $payload);
     }
 
+    /**
+     * Perform DELETE request
+     */
     public function delete(string $url): string
     {
         return $this->request('DELETE', $url);
     }
 
+    /**
+     * Perform PATCH request
+     */
     public function patch(string $url, mixed $payload = null): string
     {
         return $this->request('PATCH', $url, $payload);

src/Exception.php

@@ -2,13 +2,26 @@
 
 namespace OpenApi;
 
+/**
+ * Custom exception for OpenAPI SDK
+ * Stores HTTP response details for better error handling
+ */
 class Exception extends \Exception
 {
     private mixed $serverResponse = null;
     private mixed $headers = null;
     private mixed $rawResponse = null;
     private ?int $httpCode = null;
 
+    /**
+     * Store server response details
+     * TODO: Utilize this method in Client and OauthClient to provide structured error context
+     *
+     * @param mixed $response Parsed server response
+     * @param mixed $headers Response headers
+     * @param mixed $rawResponse Raw response body
+     * @param int|null $httpCode HTTP status code
+     */
     public function setServerResponse(mixed $response, mixed $headers = null, mixed $rawResponse = null, ?int $httpCode = null): void
     {
         $this->serverResponse = $response;
@@ -17,21 +30,33 @@ public function setServerResponse(mixed $response, mixed $headers = null, mixed
         $this->httpCode = $httpCode;
     }
 
+    /**
+     * Get parsed server response
+     */
     public function getServerResponse(): mixed
     {
         return $this->serverResponse;
     }
 
+    /**
+     * Get response headers
+     */
     public function getHeaders(): mixed
     {
         return $this->headers;
     }
 
+    /**
+     * Get raw response body
+     */
     public function getRawResponse(): mixed
     {
         return $this->rawResponse;
     }
 
+    /**
+     * Get HTTP status code
+     */
     public function getHttpCode(): ?int
     {
         return $this->httpCode;