provider: Add API for loading and unloading provider plugins

This is also used for our tests. In order to avoid code duplication
this is being moved to calls-provider.{c,h}.

src/calls-provider.c

@@ -25,9 +25,11 @@
 #include "calls-provider.h"
 #include "calls-origin.h"
 #include "calls-message-source.h"
+#include "config.h"
 #include "util.h"
 
 #include <glib/gi18n.h>
+#include <libpeas/peas.h>
 
 /**
  * SECTION:calls-provider
@@ -156,3 +158,84 @@ calls_provider_get_origins (CallsProvider *self)
 
   return CALLS_PROVIDER_GET_CLASS (self)->get_origins (self);
 }
+
+/**
+ * calls_provider_load_plugin:
+ * @name: The name of the provider plugin to load
+ *
+ * Get a #CallsProvider plugin by name
+ *
+ * Returns: (transfer full): A #CallsProvider
+ */
+CallsProvider *
+calls_provider_load_plugin (const char *name)
+{
+  g_autoptr (GError) error = NULL;
+  PeasEngine *plugins;
+  PeasPluginInfo *info;
+  PeasExtension *extension;
+  const gchar *dir;
+
+  // Add Calls search path and rescan
+  plugins = peas_engine_get_default ();
+  peas_engine_add_search_path (plugins, PLUGIN_LIBDIR, NULL);
+  g_debug ("Scanning for plugins in `%s'", PLUGIN_LIBDIR);
+
+  dir = g_getenv ("CALLS_PLUGIN_DIR");
+  if (dir && dir[0] != '\0') {
+    g_debug ("Adding %s to plugin search path", dir);
+    peas_engine_prepend_search_path (plugins, dir, NULL);
+  }
+
+  // Find the plugin
+  info = peas_engine_get_plugin_info (plugins, name);
+  if (!info)
+    {
+      g_debug ("Could not find plugin `%s'", name);
+      return NULL;
+    }
+
+  // Possibly load the plugin
+  if (!peas_plugin_info_is_loaded (info))
+    {
+      peas_engine_load_plugin (plugins, info);
+
+      if (!peas_plugin_info_is_available (info, &error))
+        {
+          g_debug ("Error loading plugin `%s': %s", name, error->message);
+          return NULL;
+        }
+
+      g_debug ("Loaded plugin `%s'", name);
+    }
+
+  // Check the plugin provides CallsProvider
+  if (!peas_engine_provides_extension (plugins, info, CALLS_TYPE_PROVIDER))
+    {
+      g_debug ("Plugin `%s' does not have a provider extension", name);
+      return NULL;
+    }
+
+  // Get the extension
+  extension = peas_engine_create_extensionv (plugins, info, CALLS_TYPE_PROVIDER, 0, NULL);
+  if (!extension)
+    {
+      g_debug ("Could not create provider from plugin `%s'", name);
+      return NULL;
+    }
+
+  g_debug ("Created provider from plugin `%s'", name);
+  return CALLS_PROVIDER (extension);
+}
+
+void
+calls_provider_unload_plugin (const char *name)
+{
+  PeasEngine *engine = peas_engine_get_default ();
+  PeasPluginInfo *plugin = peas_engine_get_plugin_info (engine, name);
+
+  if (plugin)
+    peas_engine_unload_plugin (engine, plugin);
+  else
+    g_warning ("Can't unload plugin: No plugin with name %s found", name);
+}