--- a/libmlk-core/mlk/core/action.h	Fri Mar 03 19:45:00 2023 +0100
+++ b/libmlk-core/mlk/core/action.h	Sat Mar 04 08:52:57 2023 +0100
@@ -1,5 +1,5 @@
 /*
- * action.h -- action states
+ * action.h -- generic in game actions
  *
  * Copyright (c) 2020-2023 David Demelier <markand@malikania.fr>
  *
@@ -19,39 +19,162 @@
 #ifndef MLK_CORE_ACTION_H
 #define MLK_CORE_ACTION_H
 
+/**
+ * \file mlk/core/action.h
+ * \brief Generic in game actions.
+ *
+ * This module help creating user interaction within the gameplay by adding
+ * actions. They have the following properties:
+ *
+ * - Can handle user input and events,
+ * - Can be updated through the game loop,
+ * - Can be drawn.
+ *
+ * Most more high level objects can handle actions to add flexibility (like in
+ * battles, maps, etc).
+ */
+
 #include "core.h"
 
 union mlk_event;
 
+/**
+ * \struct mlk_action
+ * \brief Action structure
+ *
+ * Use this structure to create an action that may handle input, be updated and
+ * drawn.
+ */
 struct mlk_action {
+	/**
+	 * (read-write, borrowed, optional)
+	 *
+	 * Arbitrary user data.
+	 */
 	void *data;
-	void (*start)(struct mlk_action *);
-	void (*handle)(struct mlk_action *, const union mlk_event *);
-	int (*update)(struct mlk_action *, unsigned int);
-	void (*draw)(struct mlk_action *);
-	void (*end)(struct mlk_action *);
+
+	/**
+	 * (optional)
+	 *
+	 * Start the action.
+	 *
+	 * Use this function when the action should start.
+	 *
+	 * \param self this action
+	 */
+	void (*start)(struct mlk_action *self);
+
+	/**
+	 * (optional)
+	 *
+	 * Handle an event.
+	 *
+	 * \param self this action
+	 * \param event the event
+	 */
+	void (*handle)(struct mlk_action *self, const union mlk_event *event);
+
+	/**
+	 * (optional)
+	 *
+	 * Update the action with the given ticks since last frame.
+	 *
+	 * The callback should return non-zero if it is considered complete.
+	 *
+	 * \param self this action
+	 * \param ticks frame ticks
+	 * \return non-zero if complete
+	 */
+	int (*update)(struct mlk_action *self, unsigned int ticks);
+
+	/**
+	 * (optional)
+	 *
+	 * Draw the action.
+	 *
+	 * \param self this action
+	 */
+	void (*draw)(struct mlk_action *self);
+
+	/**
+	 * (optional)
+	 *
+	 * Terminate the action.
+	 *
+	 * In contrast to finish, this function should be called after the
+	 * action was considered complete.
+	 *
+	 * \param self this action
+	 */
+	void (*end)(struct mlk_action *self);
+
+	/**
+	 * (optional)
+	 *
+	 * Dispose resources allocated by/for the action.
+	 *
+	 * \param self this action
+	 */
 	void (*finish)(struct mlk_action *);
 };
 
 MLK_CORE_BEGIN_DECLS
 
-void
-mlk_action_start(struct mlk_action *);
-
+/**
+ * Invoke ::mlk_action::start function if not null.
+ *
+ * \pre action != NULL
+ * \param action the action
+ */
 void
-mlk_action_handle(struct mlk_action *, const union mlk_event *);
+mlk_action_start(struct mlk_action *action);
 
-int
-mlk_action_update(struct mlk_action *, unsigned int);
+/**
+ * Invoke ::mlk_action::handle function if not null.
+ *
+ * \pre action != NULL
+ * \param action the action
+ * \param event the event
+ */
+void
+mlk_action_handle(struct mlk_action *action, const union mlk_event *event);
 
-void
-mlk_action_draw(struct mlk_action *);
+/**
+ * Invoke ::mlk_action::update function if not null.
+ *
+ * \pre action != NULL
+ * \param action the action
+ * \param ticks frame ticks
+ */
+int
+mlk_action_update(struct mlk_action *action, unsigned int ticks);
 
+/**
+ * Invoke ::mlk_action::draw function if not null.
+ *
+ * \pre action != NULL
+ * \param action the action
+ */
 void
-mlk_action_end(struct mlk_action *);
+mlk_action_draw(struct mlk_action *action);
 
+/**
+ * Invoke ::mlk_action::end function if not null.
+ *
+ * \pre action != NULL
+ * \param action the action
+ */
 void
-mlk_action_finish(struct mlk_action *);
+mlk_action_end(struct mlk_action *action);
+
+/**
+ * Invoke ::mlk_action::finish function if not null.
+ *
+ * \pre action != NULL
+ * \param action the action
+ */
+void
+mlk_action_finish(struct mlk_action *action);
 
 MLK_CORE_END_DECLS