/*
	component.c

	Component handling

	Copyright (C) 2022 Bill Currke

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

	See the GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include "QF/sys.h"

#define IMPLEMENT_COMPONENT_Funcs
#include "QF/scene/component.h"

VISIBLE ecs_registry_t *
ECS_NewRegistry (void)
{
	ecs_registry_t *reg = calloc (1, sizeof (ecs_registry_t));
	reg->next = Ent_Index (nullent);
	return reg;
}

VISIBLE void
ECS_DelRegistry (ecs_registry_t *registry)
{
	free (registry->entities);
	for (uint32_t i = 0; i < registry->num_components; i++) {
		free (registry->comp_pools[i].sparse);
		free (registry->comp_pools[i].dense);
		free (registry->comp_pools[i].data);
	}
	free (registry->comp_pools);
	free (registry);
}

VISIBLE void
ECS_RegisterComponents (ecs_registry_t *registry,
						const component_t *components, uint32_t count)
{
	registry->num_components = count;
	registry->components = components;
	registry->comp_pools = calloc (count, sizeof (ecs_pool_t));
	size_t      size = registry->max_entities * sizeof (uint32_t);
	for (uint32_t i = 0; i < registry->num_components; i++) {
		registry->comp_pools[i].sparse = malloc (size);
		memset (registry->comp_pools[i].sparse, nullent, size);
	}
}

VISIBLE void *
Ent_AddComponent (uint32_t ent, uint32_t comp, ecs_registry_t *registry)
{
	ecs_pool_t *pool = &registry->comp_pools[comp];
	uint32_t    id = Ent_Index (ent);
	uint32_t    ind = pool->sparse[id];
	if (ind >= pool->count || pool->dense[ind] != ent) {
		if (pool->count == pool->max_count) {
			pool->max_count += COMP_GROW;
			pool->dense = realloc (pool->dense,
								   pool->max_count * sizeof (uint32_t));
			Component_ResizeArray (&registry->components[comp], &pool->data,
								   pool->max_count);
		}
		uint32_t    ind = pool->count++;
		pool->sparse[id] = ind;
		pool->dense[ind] = ent;
	}
	return Ent_GetComponent (ent, comp, registry);
}

VISIBLE void
Ent_RemoveComponent (uint32_t ent, uint32_t comp, ecs_registry_t *registry)
{
	uint32_t    id = Ent_Index (ent);
	ecs_pool_t *pool = &registry->comp_pools[comp];
	uint32_t    ind = pool->sparse[id];
	if (ind < pool->count && pool->dense[ind] == ent) {
		uint32_t    last = pool->count - 1;
		Component_DestroyElements (&registry->components[comp], pool->data,
								   ind, 1);
		if (last > ind) {
			pool->sparse[Ent_Index (pool->dense[last])] = ind;
			pool->dense[ind] = pool->dense[last];
			Component_MoveElements (&registry->components[comp], pool->data,
									ind, last, 1);
		}
		pool->count--;
		pool->sparse[id] = nullent;
	}
}

VISIBLE uint32_t
ECS_NewEntity (ecs_registry_t *registry)
{
	uint32_t    ent;
	if (registry->available) {
		registry->available--;
		uint32_t    next = registry->next;
		ent = next | Ent_Generation (registry->entities[next]);
		registry->next = Ent_Index (registry->entities[next]);
		registry->entities[next] = ent;
	} else {
		if (registry->num_entities == Ent_Index (nullent)) {
			Sys_Error ("ECS_NewEntity: out of entities");
		}
		if (registry->num_entities == registry->max_entities) {
			registry->max_entities += ENT_GROW;
			size_t      size = registry->max_entities * sizeof (uint32_t);
			registry->entities = realloc (registry->entities, size);
			for (uint32_t i = 0; i < registry->num_components; i++) {
				uint32_t   *sparse = registry->comp_pools[i].sparse;
				sparse = realloc (sparse, size);
				memset (sparse + registry->max_entities - ENT_GROW, nullent,
						ENT_GROW * sizeof (uint32_t));
				registry->comp_pools[i].sparse = sparse;
			}
		}
		ent = registry->num_entities++;
		// ent starts out with generation 0
		registry->entities[ent] = ent;
	}
	return ent;
}

VISIBLE void
ECS_DelEntity (ecs_registry_t *registry, uint32_t ent)
{
	uint32_t    next = registry->next | Ent_NextGen (Ent_Generation (ent));
	uint32_t    id = Ent_Index (ent);
	registry->entities[id] = next;
	registry->next = id;
	registry->available++;

	for (uint32_t i = 0; i < registry->num_components; i++) {
		Ent_RemoveComponent (ent, i, registry);
	}
}