dusk/src/dusk/entity/component.h

/**
 * Copyright (c) 2026 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#pragma once
#include "entitybase.h"
#include "error/error.h"

#include <yyjson.h>

#define X(enumName, type, field, init, dispose, render, serialize, deserialize) \
  // do nothing
#include "componentlist.h"
#undef X

typedef union {
  #define X(enumName, type, field, init, dispose, render, serialize, deserialize) \
    type field;
  #include "componentlist.h"
  #undef X
} componentdata_t;

typedef struct {
  const char_t *enumName;
  const char_t *name;
  void (*init)(const entityid_t, const componentid_t);
  void (*dispose)(const entityid_t, const componentid_t);
  errorret_t (*render)(const entityid_t, const componentid_t);
  void (*serialize)(
    const entityid_t,
    const componentid_t,
    yyjson_mut_doc *,
    yyjson_mut_val *
  );
  errorret_t (*deserialize)(
    const entityid_t,
    const componentid_t,
    yyjson_val *
  );
} componentdefinition_t;

typedef enum {
  COMPONENT_TYPE_NULL,

  #define X(enumName, type, field, init, dispose, render, serialize, deserialize) \
    COMPONENT_TYPE_##enumName,
  #include "componentlist.h"
  #undef X

  COMPONENT_TYPE_COUNT
} componenttype_t;

typedef struct {
  componenttype_t type;
  componentdata_t data;
} component_t;

extern componentdefinition_t COMPONENT_DEFINITIONS[];

/**
 * Initializes a component of the given type for the entity with component ID.
 * 
 * @param entityId The entity ID.
 * @param componentId The component ID.
 * @param type The type of the component to initialize.
 */
void componentInit(
  const entityid_t entityId,
  const componentid_t componentId,
  const componenttype_t type
);

/**
 * Gets the pointer to the data of a component for the entity with component ID.
 * 
 * @param entityId The entity ID.
 * @param componentId The component ID.
 * @param type The type of the component to get, only used for assertion.
 * @return A pointer to the component data.
 */
void * componentGetData(
  const entityid_t entityId,
  const componentid_t componentId,
  const componenttype_t type
);

/**
 * Gets the index of a component for the entity with component ID.
 * 
 * @param entityId The entity ID.
 * @param componentId The component ID.
 * @return The index of the component in the component array.
 */
componentindex_t componentGetIndex(
  const entityid_t entityId,
  const componentid_t componentId
);

/**
 * Gets the entity IDs of all entities with a component of the given type.
 * 
 * @param type The type of the component to get entities for.
 * @param outEntities An array to write the entity IDs to, must be at least
 * ENTITY_COUNT_MAX in size.
 * @param outComponents An array to write the component IDs to.
 * @return The number of entity IDs written to outEntities.
 */
entityid_t componentGetEntitiesWithComponent(
  const componenttype_t type,
  entityid_t outEntities[ENTITY_COUNT_MAX],
  componentid_t outComponents[ENTITY_COUNT_MAX]
);

/**
 * Disposes of a component for the entity with component ID.
 *
 * @param entityId The entity ID.
 * @param componentId The component ID.
 */
void componentDispose(
  const entityid_t entityId,
  const componentid_t componentId
);

/**
 * Calls the render callback on every active component that defines one.
 * Iterates all active entities and all their component slots. No-op for
 * components whose definition has render == NULL.
 *
 * @return Error state.
 */
errorret_t componentRenderAll(void);

/**
 * Serializes a component's configurable state into a JSON object. The caller
 * is responsible for creating and owning the doc and obj.
 *
 * @param entityId The entity ID.
 * @param componentId The component ID.
 * @param doc The mutable JSON document to allocate values from.
 * @param obj The JSON object to write fields into.
 */
void componentSerialize(
  const entityid_t entityId,
  const componentid_t componentId,
  yyjson_mut_doc *doc,
  yyjson_mut_val *obj
);

/**
 * Deserializes a component's configurable state from a JSON object.
 *
 * @param entityId The entity ID.
 * @param componentId The component ID.
 * @param obj The JSON object to read fields from.
 * @return Error state.
 */
errorret_t componentDeserialize(
  const entityid_t entityId,
  const componentid_t componentId,
  yyjson_val *obj
);