Added support for cooling down when Vend rate-limit has been hit (previous would get "Recieved null result from API" exception). Requires system time be correct otherwise cooldown does not work properly - set allow_time_slip=false to ignore this.

Note: Added public property $http_code on VendRequest so that VendAPI can determine whether it was a 400+ result and act accordingly.

Author: Bob Brown

src/VendAPI/VendAPI.php

@@ -44,6 +44,13 @@ class VendAPI
      */
     public $default_outlet = 'Main Outlet';
 
+    /**
+     * If rate limiting kicks in and the retry-after date is earlier than the current system time
+     * then this API will sleep for 60 seconds, otherwise an exception will be thrown.
+     * The right thing to do is ensure that your system has its time synchronised with a time server.
+     */
+    public $allow_time_slip = false;
+
     /**
      * @param string $url          url of your shop eg https://shopname.vendhq.com
      * @param string $tokenType    tokenType for api
@@ -111,6 +118,7 @@ public function getSales($options = array())
         $path = '';
         if (count($options)) {
             foreach ($options as $k => $v) {
+                $v = urlencode($v);  // ensure values with spaces etc are encoded properly
                 $path .= '/'.$k.'/'.$v;
             }
         }
@@ -273,6 +281,34 @@ private function _request($path, $data = null, $depage = null)
             throw new Exception("Error: Recieved null result from API");
         }
 
+        // Check for 400+ error:
+        if($this->requestr->http_code >= 400) {
+            if($this->requestr->http_code == 429) {    // Too Many Requests
+                $retry_after = strtotime($result->{'retry-after'});
+                if($retry_after < time()) {
+                    if($this->allow_time_slip) {
+                        // The date on the current machine must be out of sync ... sleep for a minute to give the API time to cool down
+                        sleep(60);
+                    } else {
+                        throw new Exception("Rate limit hit on API yet retry-after time given is in the past. Please check time of local system. Set \$allow-time-slip to true to work around this problem");
+                    }
+                }
+                if($this->debug) {
+                    echo "Vend API rate limit hit\n";
+                    echo "Time now on local system is ".date('r',time())."\n";
+                    echo "Sleeping until ".date('r', $retry_after)." (as advised by Vend API) ";
+                }
+                while(time() < $retry_after) {
+                    sleep(1);
+                    if($this->debug) { echo "."; }
+                }
+
+                // We've given the Vend API time to cool down - retry the original request:
+                return $this->_request($path, $data, $depage);
+            }
+            throw new Exception("Error: Unexpected HTTP ".$this->requestr->http_code." result from API");
+        }
+
         if ($depage && isset($result->pagination) && $result->pagination->page == 1) {
             for ($i=2; $i <= $result->pagination->pages; $i++) {
                 $paged_result = $this->_request(rtrim($path, '/').'/page/'.$i, $data, false);

src/VendAPI/VendRequest.php

@@ -25,6 +25,8 @@ class VendRequest
     private $http_header;
     private $http_body;
 
+    public $http_code;
+
     public function __construct($url, $username, $password)
     {
         $this->curl = curl_init();
@@ -35,7 +37,7 @@ public function __construct($url, $username, $password)
         $options = array(
             CURLOPT_RETURNTRANSFER => 1,
             CURLOPT_TIMEOUT => 120,
-            CURLOPT_FAILONERROR => 1,
+            CURLOPT_FAILONERROR => 0,    // 0 allows us to process the 400 responses (e.g. rate limits)
             CURLOPT_HTTPAUTH => CURLAUTH_ANY,
             CURLOPT_HTTPHEADER => array(
                 'Accept: application/json',
@@ -102,15 +104,15 @@ private function _request($path, $type)
         $this->setOpt(CURLOPT_URL, $this->url.$path);
 
         $this->response = $response = curl_exec($this->curl);
-
-        $header_size = curl_getinfo($this->curl, CURLINFO_HEADER_SIZE);
+        $curl_status = curl_getinfo($this->curl);
+        $this->http_code = $curl_status['http_code'];
+        $header_size = $curl_status['header_size'];
 
         $this->http_header = substr($response, 0, $header_size);
         $this->http_body = substr($response, $header_size);
 
-
         if ($this->debug) {
-            $this->curl_debug = curl_getinfo($this->curl);
+            $this->curl_debug = $status;
             $head = $foot = "\n";
             if (php_sapi_name() !== 'cli') {
                 $head = '<pre>';