Add multiple servers support to PHP client (#1964)

* add multiple server support

* update php samples

* update wording

* make variables optional

samples/client/petstore/php/OpenAPIClient-php/lib/Configuration.php

@@ -426,4 +426,59 @@ class Configuration
 
         return $keyWithPrefix;
     }
+
+    /**
+     * Returns an array of host settings
+     *
+     * @return an array of host settings
+     */
+    public function getHostSettings()
+    {
+        return array(
+          array(
+            "url" => "http://petstore.swagger.io:80/v2",
+            "description" => "No description provided",
+          )
+        );
+    }
+
+    /**
+     * Returns URL based on the index and variables
+     *
+     * @param index array index of the host settings
+     * @param variables hash of variable and the corresponding value (optional)
+     * @return URL based on host settings
+     */
+    public function getHostFromSettings($index, $variables = null)
+    {
+        if (null === $variables) {
+            $variables = array();
+        }
+
+        $hosts = $this->getHostSettings();
+
+        // check array index out of bound
+        if ($index < 0 || $index > sizeof($hosts)) {
+            throw new \InvalidArgumentException("Invalid index $index when selecting the host. Must be less than ".sizeof($hosts));
+        }
+
+        $host = $hosts[$index];
+        $url = $host["url"];
+
+        // go through variable and assign a value
+        foreach ($host["variables"] as $name => $variable) {
+            if (array_key_exists($name, $variables)) { // check to see if it's in the variables provided by the user
+                if (in_array($variables[$name], $variable["enum_values"])) { // check to see if the value is in the enum
+                    $url = str_replace("{".$name."}", $variables[$name], $url);
+                } else {
+                    throw new \InvalidArgumentException("The variable `$name` in the host URL has invalid value ".$variables[$name].". Must be ".join(',', $variable["enum_values"]).".");
+                }
+            } else {
+                // use default value
+                $url = str_replace("{".$name."}", $variable["default_value"], $url);
+            }
+        }
+
+        return $url;
+    }
 }