package net.glowstone.entity;
import net.glowstone.GlowChunk;
import org.bukkit.Chunk;
import org.bukkit.Location;
import java.util.*;
/**
* A class which manages all of the entities within a world.
* @author Graham Edgecombe
*/
public final class EntityManager implements Iterable<GlowEntity> {
/**
* A map of all the entity ids to the corresponding entities.
*/
private final Map<Integer, GlowEntity> entities = new HashMap<>();
/**
* A map of entity types to a set containing all entities of that type.
*/
private final Map<Class<? extends GlowEntity>, Set<? extends GlowEntity>> groupedEntities = new HashMap<>();
/**
* The last assigned id value.
*/
private int lastId = 0;
/**
* Gets all entities with the specified type.
* @param type The {@link Class} for the type.
* @param <T> The type of entity.
* @return A collection of entities with the specified type.
*/
@SuppressWarnings("unchecked")
public <T extends GlowEntity> Collection<T> getAll(Class<T> type) {
Set<T> set = (Set<T>) groupedEntities.get(type);
if (set == null) {
set = new HashSet<>();
groupedEntities.put(type, set);
}
return set;
}
/**
* Gets all entities.
* @return A collection of entities.
*/
public Collection<GlowEntity> getAll() {
return entities.values();
}
/**
* Gets an entity by its id.
* @param id The id.
* @return The entity, or {@code null} if it could not be found.
*/
public GlowEntity getEntity(int id) {
return entities.get(id);
}
/**
* Allocates the id for an entity.
* @param entity The entity.
* @return The id.
*/
int allocate(GlowEntity entity) {
int startedAt = lastId;
// intentionally wraps around integer boundaries
for (int id = lastId + 1; id != startedAt; ++id) {
// skip special values
if (id == -1 || id == 0) continue;
if (!entities.containsKey(id)) {
allocate(entity, id);
return id;
}
}
throw new IllegalStateException("No free entity ids");
}
@SuppressWarnings("unchecked")
private void allocate(GlowEntity entity, int id) {
entity.id = id;
entities.put(id, entity);
((Collection<GlowEntity>) getAll(entity.getClass())).add(entity);
((GlowChunk) entity.location.getChunk()).getRawEntities().add(entity);
lastId = id;
}
/**
* Deallocates the id for an entity.
* @param entity The entity.
*/
void deallocate(GlowEntity entity) {
entities.remove(entity.id);
getAll(entity.getClass()).remove(entity);
((GlowChunk) entity.location.getChunk()).getRawEntities().remove(entity);
}
/**
* Notes that an entity has moved from one location to another for
* physics and storage purposes.
* @param entity The entity.
* @param newLocation The new location.
*/
void move(GlowEntity entity, Location newLocation) {
Chunk prevChunk = entity.location.getChunk();
Chunk newChunk = newLocation.getChunk();
if (prevChunk != newChunk) {
((GlowChunk) prevChunk).getRawEntities().remove(entity);
((GlowChunk) newChunk).getRawEntities().add(entity);
}
}
@Override
public Iterator<GlowEntity> iterator() {
return entities.values().iterator();
}
}