/**************************************************************************/
/*  theme_db.h                                                            */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#ifndef THEME_DB_H
#define THEME_DB_H

#include "core/object/class_db.h"
#include "core/object/ref_counted.h"
#include "scene/resources/theme.h"

#include <functional>

class Font;
class Node;
class StyleBox;
class Texture2D;
class ThemeContext;

// Macros for binding theme items of this class. This information is used for the documentation, theme
// overrides, etc. This is also the basis for theme cache.

#define BIND_THEME_ITEM(m_data_type, m_class, m_prop)                                                                   \
	ThemeDB::get_singleton()->bind_class_item(m_data_type, get_class_static(), #m_prop, #m_prop, [](Node *p_instance) { \
		m_class *p_cast = Object::cast_to<m_class>(p_instance);                                                         \
		p_cast->theme_cache.m_prop = p_cast->get_theme_item(m_data_type, _scs_create(#m_prop));                         \
	})

#define BIND_THEME_ITEM_CUSTOM(m_data_type, m_class, m_prop, m_item_name)                                                   \
	ThemeDB::get_singleton()->bind_class_item(m_data_type, get_class_static(), #m_prop, m_item_name, [](Node *p_instance) { \
		m_class *p_cast = Object::cast_to<m_class>(p_instance);                                                             \
		p_cast->theme_cache.m_prop = p_cast->get_theme_item(m_data_type, _scs_create(m_item_name));                         \
	})

// Macro for binding theme items used by this class, but defined/binded by other classes. This is primarily used for
// the theme cache. Can also be used to list such items in documentation.

#define BIND_THEME_ITEM_EXT(m_data_type, m_class, m_prop, m_item_name, m_type_name)                                                               \
	ThemeDB::get_singleton()->bind_class_external_item(m_data_type, get_class_static(), #m_prop, m_item_name, m_type_name, [](Node *p_instance) { \
		m_class *p_cast = Object::cast_to<m_class>(p_instance);                                                                                   \
		p_cast->theme_cache.m_prop = p_cast->get_theme_item(m_data_type, _scs_create(m_item_name), _scs_create(m_type_name));                     \
	})

class ThemeDB : public Object {
	GDCLASS(ThemeDB, Object);

	static ThemeDB *singleton;

	// Global Theme resources used by the default theme context.

	Ref<Theme> default_theme;
	Ref<Theme> project_theme;

	// Universal default values, final fallback for every theme.

	float fallback_base_scale = 1.0;
	Ref<Font> fallback_font;
	int fallback_font_size = 16;
	Ref<Texture2D> fallback_icon;
	Ref<StyleBox> fallback_stylebox;

	// Global theme contexts used to scope global Theme resources.

	ThemeContext *default_theme_context = nullptr;
	HashMap<Node *, ThemeContext *> theme_contexts;

	void _propagate_theme_context(Node *p_from_node, ThemeContext *p_context);
	void _init_default_theme_context();
	void _finalize_theme_contexts();

	// Binding of theme items to Node classes.

public:
	typedef std::function<void(Node *)> ThemeItemSetter;

	struct ThemeItemBind {
		Theme::DataType data_type;
		StringName class_name;
		StringName item_name;
		StringName type_name;
		bool external = false;

		ThemeItemSetter setter;
	};

private:
	HashMap<StringName, HashMap<StringName, ThemeItemBind>> theme_item_binds;

protected:
	static void _bind_methods();

public:
	void initialize_theme();
	void initialize_theme_noproject();
	void finalize_theme();

	// Global Theme resources.

	void set_default_theme(const Ref<Theme> &p_default);
	Ref<Theme> get_default_theme();

	void set_project_theme(const Ref<Theme> &p_project_default);
	Ref<Theme> get_project_theme();

	// Universal fallback values.

	void set_fallback_base_scale(float p_base_scale);
	float get_fallback_base_scale();

	void set_fallback_font(const Ref<Font> &p_font);
	Ref<Font> get_fallback_font();

	void set_fallback_font_size(int p_font_size);
	int get_fallback_font_size();

	void set_fallback_icon(const Ref<Texture2D> &p_icon);
	Ref<Texture2D> get_fallback_icon();

	void set_fallback_stylebox(const Ref<StyleBox> &p_stylebox);
	Ref<StyleBox> get_fallback_stylebox();

	void get_native_type_dependencies(const StringName &p_base_type, List<StringName> *p_list);

	// Global theme contexts.

	ThemeContext *create_theme_context(Node *p_node, List<Ref<Theme>> &p_themes);
	void destroy_theme_context(Node *p_node);

	ThemeContext *get_theme_context(Node *p_node) const;
	ThemeContext *get_default_theme_context() const;
	ThemeContext *get_nearest_theme_context(Node *p_for_node) const;

	// Theme item binding.

	void bind_class_item(Theme::DataType p_data_type, const StringName &p_class_name, const StringName &p_prop_name, const StringName &p_item_name, ThemeItemSetter p_setter);
	void bind_class_external_item(Theme::DataType p_data_type, const StringName &p_class_name, const StringName &p_prop_name, const StringName &p_item_name, const StringName &p_type_name, ThemeItemSetter p_setter);
	void update_class_instance_items(Node *p_instance);

	void get_class_own_items(const StringName &p_class_name, List<ThemeItemBind> *r_list);

	// Memory management, reference, and initialization.

	static ThemeDB *get_singleton();
	ThemeDB();
	~ThemeDB();
};

class ThemeContext : public Object {
	GDCLASS(ThemeContext, Object);

	friend class ThemeDB;

	Node *node = nullptr;
	ThemeContext *parent = nullptr;

	// Themes are stacked in the order of relevance, for easy iteration.
	// This means that the first theme is the one you should check first,
	// and the last theme is the fallback theme where every lookup ends.
	List<Ref<Theme>> themes;

	void _emit_changed();

protected:
	static void _bind_methods();

public:
	void set_themes(List<Ref<Theme>> &p_themes);
	List<Ref<Theme>> get_themes() const;
	Ref<Theme> get_fallback_theme() const;
};

#endif // THEME_DB_H