#pragma once

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

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

/// \defgroup entities Entities
/// \brief Entities are the core building blocks of Ikarus.

IKARUS_BEGIN_HEADER

/// \brief Entities are the core building blocks of Ikarus.
/// \detials Blueprints and Properties define the structure of the data.
/// Entities define the data itself.
///
/// Properties can be associated with Entities in two ways:
/// - Directly: The property is linked to the entity.
/// - Indirectly: The property is linked to a blueprint the entity is linked to.
///
/// For each property an entity is linked to, it has a value. These values depend on the property's type.
/// For more information on the types see the property documentation.
///
/// Values are the core type of data within Ikarus.
/// Each value is associated with one page and one property.
///
/// \remark Values are typed, the type of a value is specified by its associated property.
/// For more information on the types see the property documentation.
///
/// \remark Values are guaranteed to be in valid format for a given type
/// but not guaranteed to be valid under the settings of the property.
/// This is because changing the settings can invalidate existing values without resetting them.
struct IkarusEntity;

/// \brief Creates an entity.
/// \param project The project the entity is part of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param name The name of the entity.
/// \pre \li Must not be null.
/// \pre \li Must not be empty.
/// \param error_out \see errors.h
/// \return The created entity or null if an error occurs.
/// \remark Must be freed using #ikarus_free.
IKA_API IkarusEntity * ikarus_entity_create(struct IkarusProject * project, char const * name, IkarusErrorData * error_out);

/// \brief Deletes an entity.
/// \param entity The entity to delete.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \remark The entity must not be accessed after deletion.
IKA_API void ikarus_entity_delete(IkarusEntity * entity, IkarusErrorData * error_out);

/// \brief Checks if an entity is linked to a blueprint.
/// \param entity The entity to check.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param blueprint The blueprint to check.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \return True if the entity is linked to the blueprint, false otherwise.
IKA_API bool
ikarus_entity_is_linked_to_blueprint(IkarusEntity const * entity, struct IkarusBlueprint const * blueprint, IkarusErrorData * error_out);

/// \brief Links an entity to a blueprint.
/// \param entity The entity to link.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param blueprint The blueprint to link the entity to.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \remark No-op if the entity is already linked to the blueprint.
IKA_API void ikarus_entity_link_to_blueprint(IkarusEntity * entity, struct IkarusBlueprint * blueprint, IkarusErrorData * error_out);

/// \brief Unlinks an entity from a blueprint. All values of the properties of the blueprint the entity is linked with
/// will be deleted.
/// \param entity The entity to unlink.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param blueprint The blueprint to unlink the entity from.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \remark No-op if the entity is not linked to the blueprint.
IKA_API void ikarus_entity_unlink_from_blueprint(IkarusEntity * entity, struct IkarusBlueprint * blueprint, IkarusErrorData * error_out);

/// \brief Gets the blueprints an entity is linked to.
/// \param entity The entity to get the blueprints of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param blueprints_out The buffer to write the blueprints to.
/// \pre \li Must not be null.
/// \param blueprints_out_size The size of the buffer.
/// \param error_out \see errors.h
/// \see ikarus_entity_get_linked_blueprint_count
IKA_API void ikarus_entity_get_linked_blueprints(
    IkarusEntity const * entity,
    struct IkarusBlueprint ** blueprints_out,
    size_t blueprints_out_size,
    IkarusErrorData * error_out
);

/// \brief Gets the number of blueprints an entity is linked to.
/// \param entity The entity to get the number of blueprints of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \return The number of blueprints or undefined if an error occurs.
IKA_API size_t ikarus_entity_get_linked_blueprint_count(IkarusEntity const * entity, IkarusErrorData * error_out);

/// \brief Checks if an entity has a specific property.
/// \param entity The entity to check.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param property The property to check.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \return False if an error occurs or the entity does not have the property, true otherwise.
IKA_API bool ikarus_entity_has_property(IkarusEntity const * entity, struct IkarusProperty const * property, IkarusErrorData * error_out);

/// \brief Gets the properties of an entity.
/// \param entity The entity to get the properties of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param properties_out The buffer to write the properties to.
/// \pre \li Must not be null.
/// \param error_out \see errors.h
/// \param properties_out_size The size of the buffer.
/// \see ikarus_entity_get_property_count
IKA_API void ikarus_entity_get_properties(
    IkarusEntity const * entity,
    struct IkarusProperty ** properties_out,
    size_t properties_out_size,
    IkarusErrorData * error_out
);

/// \brief Gets the number of properties of an entity.
/// \param entity The entity to get the number of properties of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \return The number of properties or undefined if an error occurs.
IKA_API size_t ikarus_entity_get_property_count(IkarusEntity const * entity, IkarusErrorData * error_out);

/// \brief Gets the value of a property of an entity.
/// \details If the entity has never set the value of the property, the default value is returned (which may be undefined).
/// \param entity The entity to get the value of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param property The property to get the value of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \return The value of the property or null if the entity does not have the property or an error occurs.
/// \remark Must be freed using #ikarus_free.
IKA_API struct IkarusEntityPropertyValue *
ikarus_entity_get_value(IkarusEntity const * entity, struct IkarusProperty const * property, IkarusErrorData * error_out);

/// \brief Sets the value of a property of an entity.
/// \param entity The entity to set the value of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param property The property to set the value of.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param value The new value of the property.
/// \pre \li Must not be null.
/// \pre \li Must be of the same type as the property.
/// \pre \li Must be valid for the property's settings.
/// \param error_out \see errors.h
/// \remark If the entity does not have the property, this function fails.
IKA_API void ikarus_entity_set_value(
    IkarusEntity * entity,
    struct IkarusProperty const * property,
    struct IkarusValue const * value,
    IkarusErrorData * error_out
);

/// \brief Casts an entity to an object.
/// \param entity The entity to cast.
/// \pre \li Must not be null.
/// \pre \li Must exist.
/// \param error_out \see errors.h
/// \return The entity represented as an object or null if an error occurs.
/// \remark This operation is guaranteed to be very fast and is intended to be used frequently.
IKA_API struct IkarusObject * ikarus_entity_to_object(IkarusEntity * entity, IkarusErrorData * error_out);

/// \see ikarus_entity_to_object
IKA_API struct IkarusObject const * ikarus_entity_to_object_const(IkarusEntity const * entity, IkarusErrorData * error_out);

IKARUS_END_HEADER

// @}