#pragma once

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

/// \defgroup values Values
/// \brief Values are data in entities.
/// \details An entity is made up of any number of values.
/// Each value defines a certain aspect of an entity.
/// Values have a name, a type, and some data.
/// Examples of values would be:
/// - Is Dead (Toggle)
/// - Age (Number)
/// - ISBN (Text)
///
/// Values are either single or multiple.
/// We call this property "Cardinality" (\see IkarusValueCardinality)
/// because it's really hard to find a simpler name.
/// Each piece of data within a value is called a "datapoint".
/// Single values have exactly one datapoint, multiple values have any number of
/// datapoints. For example "Age" would be singular, while "Nicknames" would be
/// multiple. The type is unaffected by this. A pendant in programming languages
/// would be a List<T>. Note that all values are stored as a list of items,
/// even if the value is singular. Single values effectively act as a list with
/// one element. This is enforced by the API at runtime.
///
/// For a comprehensive list of value types, see \ref IkarusValueType.
/// @{

#include <ikarus/errors.h>
#include <ikarus/macros.h>

IKARUS_BEGIN_HEADER

/// \brief The common type for all value data.
struct IkarusValue;

/// \brief Visits an entity value,
/// calling the appropriate function for the value's type.
/// \param value The entity value to visit.
/// \pre \li Must not be null.
/// \param toggle_visitor The function to call if the value is a toggle value.
/// \remark Skipped if null.
/// \param number_visitor The function to call if the value is a number value.
/// \remark Skipped if null.
/// \param text_visitor The function to call if the value is a text value.
/// \remark Skipped if null.
/// \param data The data passed to the visitor functions.
/// \param error_out \see errors.h
IKA_API void ikarus_value_visit(
    IkarusValue * value,
    void (*toggle_visitor)(struct IkarusToggleValue *, void *),
    void (*number_visitor)(struct IkarusNumberValue *, void *),
    void (*text_visitor)(struct IkarusTextValue *, void *),
    void * data,
    IkarusErrorData * error_out
);

IKARUS_END_HEADER

/// @}