#pragma once

// IMPLEMENTATION_DETAIL_PROPERTY_TYPES

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

#include <ikarus/macros.h>
#include <ikarus/objects/property_type.h>
#include <ikarus/stdtypes.h>

IKARUS_BEGIN_HEADER

/// \defgroup entity_value Entity Values
/// \brief The values stored in entities.
/// \details Each entity has a value for each property it is associated with.
/// The value is of the type specified by the property and constrained by the property's settings.
/// A value may be indeterminate which means it is unknown or not specified.
/// \see PropertyType PropertySettings
/// @{

/// \brief A true/false boolean-like value. For example "IsDead".
struct IkarusToggleValue;

/// \brief An arbitrary numeric value. For example "Age".
struct IkarusNumberValue;

/// \brief An arbitrary textual value. For example "First Name".
struct IkarusTextValue;

/// \brief The value of an entity associated with a property.
struct IkarusEntityValue;

/// \brief Creates a toggle value from a boolean.
/// \param value The toggle value.
/// \return The entity value.
/// \remark Must be freed with #ikarus_free.
IKA_API IkarusToggleValue * ikarus_toggle_value_create(bool value);
/// \brief Creates an indeterminate toggle value.
/// \return The entity value.
/// \remark Must be freed with #ikarus_free.
IKA_API IkarusToggleValue * ikarus_toggle_value_create_indeterminate();
/// \brief Sets the value of a toggle value.
/// \param value The toggle value.
/// \pre Must not be null.
/// \param new_value The new value.
IKA_API void ikarus_toggle_value_set(IkarusToggleValue * value, bool new_value);

/// \brief Creates a number value from a number.
/// \param value The number value.
/// \pre Must be finite & not NaN.
/// \return The entity value.
/// \remark Must be freed with #ikarus_free.
IKA_API IkarusNumberValue * ikarus_number_value_create(long double value);
/// \brief Creates an indeterminate number value.
/// \return The entity value.
/// \remark Must be freed with #ikarus_free.
IKA_API IkarusNumberValue * ikarus_number_value_create_indeterminate();
/// \brief Sets the value of a number value.
/// \param value The number value.
/// \pre Must not be null.
/// \param new_value The new value.
IKA_API void ikarus_number_value_set(IkarusNumberValue * value, bool new_value);

/// \brief Creates a text value from string.
/// \param value The text value.
/// \pre Must not be null.
/// \return The entity value.
/// \remark Must be freed with #ikarus_free.
IKA_API IkarusTextValue * ikarus_text_value_create(char const * value);
/// \brief Creates an indeterminate text value.
/// \return The entity value.
/// \remark Must be freed with #ikarus_free.
IKA_API IkarusTextValue * ikarus_text_value_create_indeterminate();
/// \brief Sets the value of a text value.
/// \param value The text value.
/// \pre Must not be null.
/// \param new_value The new value.
IKA_API void ikarus_text_value_set(IkarusTextValue * value, bool new_value);

/// \brief Checks if a toggle value is indeterminate.
/// \param value The toggle value.
/// \pre Must not be null.
/// \return True if the value is indeterminate, false otherwise.
IKA_API bool ikarus_toggle_value_is_indeterminate(IkarusToggleValue const * value);
/// \brief Checks if a number value is indeterminate.
/// \param value The number value.
/// \pre Must not be null.
/// \return True if the value is indeterminate, false otherwise.
IKA_API bool ikarus_number_value_is_indeterminate(IkarusNumberValue const * value);
/// \brief Checks if a text value is indeterminate.
/// \param value The text value.
/// \pre Must not be null.
/// \return True if the value is indeterminate, false otherwise.
IKA_API bool ikarus_text_value_is_indeterminate(IkarusTextValue const * value);

/// \brief Fetches the underlying value of a toggle value.
/// \param value The toggle value.
/// \return The underlying value.
/// \warning If the value is indeterminate, false is returned.
IKA_API bool ikarus_toggle_value_get_underlying(IkarusToggleValue const * value);

/// \brief Fetches the underlying value of a number value.
/// \param value The number value.
/// \return The underlying value.
/// \warning If the value is indeterminate, 0.0 is returned.
IKA_API long double ikarus_number_value_get_underlying(IkarusNumberValue const * value);

/// \brief Fetches the underlying value of a text value.
/// \param value The text value.
/// \return A copy of the underlying value.
/// \remark The returned value is a copy and owned by the caller.
/// \warning If the value is indeterminate, an empty string is returned.
IKA_API char const * ikarus_text_value_get_underlying(IkarusTextValue const * value);

/// \brief Visits an entity value, calling the appropriate function for the value's type.
/// \param value The entity value to visit.
/// \param toggle The function to call if the value is a toggle value. Skipped if null.
/// \param number The function to call if the value is a number value. Skipped if null.
/// \param text The function to call if the value is a text value. Skipped if null.
/// \param data The data passed to the visitor functions.
IKA_API void ikarus_value_visit(
    IkarusEntityValue * value,
    void (*toggle)(IkarusToggleValue *, void *),
    void (*number)(IkarusNumberValue *, void *),
    void (*text)(IkarusTextValue *, void *),
    void * data
);

IKARUS_END_HEADER