#pragma once

/// \file property_settings.h
/// \author Folling <folling@ikarus.world>

#include <ikarus/macros.h>

/// \defgroup property_settings PropertySettings
/// \brief Property settings add additional constraints to properties.
/// \details Each property has a certain set of settings. The options available depend on the type of the property.
/// Settings can be changed after the property has been created. Examples of settings are:
/// Note that the default value must be set using the concrete subtypes to ascertain type correctness.
/// - Minimum: The minimum value for a number property.
/// - Matches: A regular expression that the value of a text property must match.
/// There are also some common settings, shared among all properties:
/// - Default Value (default: PropertyType's default default (sic) value): The value that is returned if no value is specified
/// for some entity.
/// - List (default: false): If set to true, the property becomes a list. Instead of one number, you could then specify a series
/// of numbers. Note that each element in the list is subject to changes in values. E.g. when we say that all values are changed
/// in some way (e.g. reset to the default value), this applies to all elements in the list.
/// - Allow undefined (default: false): If set to true, you can specify an "unknown" value for a property.
/// It might not be known if a character is dead or not for example.
/// @{

IKARUS_BEGIN_HEADER

struct IkarusPropertySettings;

/// \brief Gets the default value of a property.
/// \param settings The settings to get the default value of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \return The default value of the property or null if an error occurs.
/// \remark Must be freed using #ikarus_free.
IKA_API struct IkarusValue const * ikarus_property_settings_get_default_value(IkarusPropertySettings const * settings);

/// \brief Fetches whether a property is a list.
/// \param settings The property settings.
/// \pre \li Must not be null.
/// \return True if the property is a list, false otherwise.
IKA_API bool ikarus_property_settings_is_list(IkarusPropertySettings const * settings);

/// \brief Sets whether a property is a list.
/// \details Noop if unchanged. A change from list -> single truncates to just the first element. A change from single -> list
/// sets the first element to the current value.
/// \param settings The property settings.
/// \pre \li Must not be null.
/// \param list Whether the property should be
/// a list.
IKA_API void ikarus_property_settings_set_is_list(IkarusPropertySettings * settings, bool list);

/// \brief Fetches whether a property may be undefined.
/// \param settings The property settings.
/// \pre \li Must not be null.
/// \return True if the property may be undefined, false otherwise.
IKA_API bool ikarus_property_settings_may_be_undefined(IkarusPropertySettings const * settings);

/// \brief Sets whether a property may be undefined.
/// \details Noop if unchanged. If the transition is from undefined -> defined, all undefined values will be reset to the
/// default value.
/// \param settings The property settings.
/// \pre \li Must not be null.
/// \param allow_undefined Whether the property should be allowed to be undefined.
/// \param allow_undefined Whether the property should be allowed to be undefined.
IKA_API void ikarus_property_settings_set_may_be_undefined(IkarusPropertySettings * settings, bool allow_undefined);

/// \brief Visits a property settings. Calling the appropriate function for the property's type.
/// \param settings The property settings.
/// \pre \li Must not be null.
/// \param toggle_property_visitor The function to call if the property is a toggle property. Skipped if null.
/// \param number_property_visitor The function to call if the property is a number property. Skipped if null.
/// \param text_property_visitor The function to call if the property is a text property. Skipped if null.
/// \param data Data passed to the visitors.
IKA_API void ikarus_property_settings_visit(
    struct IkarusPropertySettings * settings,
    void (*toggle_property_visitor)(struct IkarusTogglePropertySettings * settings, void * data),
    void (*number_property_visitor)(struct IkarusNumberPropertySettings * settings, void * data),
    void (*text_property_visitor)(struct IkarusTextPropertySettings * settings, void * data),
    void * data
);

IKA_API void ikarus_property_settings_visit_const(
    struct IkarusPropertySettings const * settings,
    void (*toggle_property_visitor)(struct IkarusTogglePropertySettings const * settings, void * data),
    void (*number_property_visitor)(struct IkarusNumberPropertySettings const * settings, void * data),
    void (*text_property_visitor)(struct IkarusTextPropertySettings const * settings, void * data),
    void * data
);

IKARUS_END_HEADER

/// @}