Implement plugin API for custom functions

language/de-DE/de-DE.plg_vmshipment_rules_shipping.ini

@@ -51,3 +51,6 @@ VMSHIPMENT_RULES_EVALUATE_LISTFUNCTION_CONTAIN_ARGS="List function '%s' requires
 VMSHIPMENT_RULES_EVALUATE_LISTFUNCTION_UNKNOWN="Unknown list function '%s' encountered. (Full rule: '%s')" 
 
 VMSHIPMENT_RULES_NOSHIPPING_MESSAGE="%s"
+
+VMSHIPMENT_RULES_CUSTOMFUNCTIONS_NOARRAY="Definition of custom functions (returned by a vmshipmentrules plugin) is not a proper array. Ignoring."
+VMSHIPMENT_RULES_CUSTOMFUNCTIONS_ALREADY_DEFINED="Custom function %s already defined. Ignoring this definition and using previous one."

language/en-GB/en-GB.plg_vmshipment_rules_shipping.ini

@@ -59,3 +59,9 @@ VMSHIPMENT_RULES_EVALUATE_LISTFUNCTION_CONTAIN_ARGS="List function '%s' requires
 VMSHIPMENT_RULES_EVALUATE_LISTFUNCTION_UNKNOWN="Unknown list function '%s' encountered. (Full rule: '%s')" 
 
 VMSHIPMENT_RULES_NOSHIPPING_MESSAGE="%s"
+
+VMSHIPMENT_RULES_UNKNOWN_TYPE="Unknown rule type '%s' encountered for rule '%s'"
+
+
+VMSHIPMENT_RULES_CUSTOMFUNCTIONS_NOARRAY="Definition of custom functions (returned by a vmshipmentrules plugin) is not a proper array. Ignoring."
+VMSHIPMENT_RULES_CUSTOMFUNCTIONS_ALREADY_DEFINED="Custom function %s already defined. Ignoring this definition and using previous one."

rules_shipping_base.php

@@ -64,6 +64,34 @@ class plgVmShipmentRules_Shipping_Base extends vmPSPlugin {
 		$this->tableFields = array_keys ($this->getTableSQLFields ());
 		$varsToPush = $this->getVarsToPush ();
 		$this->setConfigParameterable ($this->_configTableFieldName, $varsToPush);
+		
+		// PLUGIN FUNCTIONALITY:
+		// Let other plugins add custom functions! 
+		// The onVmShippingRulesRegisterCustomFunctions() trigger is expected to return an array of the form:
+		//   array ('functionname1' => 'function-to-be-called',
+		//          'functionname2' => array($classobject, 'memberfunc')),
+		//          ...);
+		JPluginHelper::importPlugin('vmshipmentrules');
+		$dispatcher = JDispatcher::getInstance();
+		$custfuncdefs = $dispatcher->trigger('onVmShippingRulesRegisterCustomFunctions',array());
+		// Loop through the return values of all plugins:
+		foreach ($custfuncdefs as $custfuncs) {
+			if (empty($custfuncs))
+				continue;
+			if (!is_array($custfuncs)) {
+				$this->printWarning(JText::sprintf('VMSHIPMENT_RULES_CUSTOMFUNCTIONS_NOARRAY', $method->rule_name));
+			}
+			// Now loop through all custom function definitions of this plugin
+			// If a function was registered before, print a warning and use the first definition
+			foreach ($custfuncs as $fname => $func) {
+				if (isset($this->custom_functions[$fname])) {
+					$this->printWarning(JText::sprintf('VMSHIPMENT_RULES_CUSTOMFUNCTIONS_ALREADY_DEFINED', $fname));
+				} else {
+					vmDebug("Defining custom function $fname");
+					$this->custom_functions[strtolower($fname)] = $func;
+				}
+			}
+		}
 	}
 
 	/**
@@ -1087,6 +1115,13 @@ class ShippingRule {
 	
 	function evaluateFunction ($function, $args) {
 		$func = strtolower($function);
+		// Check if we have a custom function definition and use that if so.
+		// This is done first to allow plugins to override even built-in functions!
+		if (isset($this->plugin->custom_functions[$func])) {
+			vmDebug("Evaluating custom function $function, defined by a plugin");
+			return call_user_func($this->plugin->custom_functions[$func], $args);
+		}
+
 		// Functions with no argument:
 		if (count($args) == 0) {
 			$dt = getdate();