MXS-1220: Expose module information via the REST API

The modules, their types and default values are exposed via the
/maxscale/modules resource. Currently, only a list of resources can be
exposed as the externally exposed module object (MXS_MODULE) does not have
the name and type information in it.

include/maxscale/modinfo.h

@@ -20,6 +20,8 @@
 
 #include <stdint.h>
 
+#include <maxscale/debug.h>
+
 MXS_BEGIN_DECLS
 
 /**
@@ -217,4 +219,76 @@ typedef struct mxs_module
 /** Name of the symbol that MaxScale will load */
 #define MXS_MODULE_SYMBOL_NAME "mxs_get_module_object"
 
+static inline const char* mxs_module_param_type_to_string(enum mxs_module_param_type type)
+{
+    switch (type)
+    {
+    case MXS_MODULE_PARAM_COUNT:
+        return "count";
+    case MXS_MODULE_PARAM_INT:
+        return "int";
+    case MXS_MODULE_PARAM_SIZE:
+        return "size";
+    case MXS_MODULE_PARAM_BOOL:
+        return "bool";
+    case MXS_MODULE_PARAM_STRING:
+        return "string";
+    case MXS_MODULE_PARAM_ENUM:
+        return "enum";
+    case MXS_MODULE_PARAM_PATH:
+        return "path";
+    case MXS_MODULE_PARAM_SERVICE:
+        return "service";
+    case MXS_MODULE_PARAM_SERVER:
+        return "server";
+    case MXS_MODULE_PARAM_SERVERLIST:
+        return "serverlist";
+    default:
+        ss_dassert(!true);
+        return "unknown";
+    }
+}
+
+static inline const char* mxs_module_api_to_string(MXS_MODULE_API type)
+{
+    switch (type)
+    {
+    case MXS_MODULE_API_PROTOCOL:
+        return "protocol";
+    case MXS_MODULE_API_ROUTER:
+        return "router";
+    case MXS_MODULE_API_MONITOR:
+        return "monitor";
+    case MXS_MODULE_API_FILTER:
+        return "filter";
+    case MXS_MODULE_API_AUTHENTICATOR:
+        return "authenticator";
+    case MXS_MODULE_API_QUERY_CLASSIFIER:
+        return "query_classifier";
+    default:
+        ss_dassert(!true);
+        return "unknown";
+    }
+}
+
+static inline const char* mxs_module_status_to_string(MXS_MODULE_STATUS type)
+{
+    switch (type)
+    {
+    case MXS_MODULE_IN_DEVELOPMENT:
+        return "In development";
+    case MXS_MODULE_ALPHA_RELEASE:
+        return "Alpha";
+    case MXS_MODULE_BETA_RELEASE:
+        return "Beta";
+    case MXS_MODULE_GA:
+        return "GA";
+    case MXS_MODULE_EXPERIMENTAL:
+        return "Experimental";
+    default:
+        ss_dassert(!true);
+        return "Unknown";
+    }
+}
+
 MXS_END_DECLS