package cn.tendata.jstart.service;


import cn.tendata.jstart.data.domain.AbstractEntity;

import javax.persistence.EntityNotFoundException;
import java.io.Serializable;

/**
 * Interface for generic CRUD operations on a service for a specific type.
 *
 * @author Xu Cheng
 */
public interface EntityService<T extends AbstractEntity<ID>, ID extends Serializable> {

	/**
	 * Saves a given entity. Use the returned instance for further operations as the save operation
	 * might have changed the entity instance completely.
	 *
	 * @param entity
	 * @return the saved entity
	 */
	<S extends T> S save(S entity);

	/**
	 * Saves all given entities.
	 *
	 * @param entities
	 * @return the saved entities
	 * @throws IllegalArgumentException in case the given entity is {@literal null}.
	 */
	<S extends T> Iterable<S> save(Iterable<S> entities);

	/**
	 * Retrieves an entity by its id.
	 *
	 * @param id must not be {@literal null}.
	 * @return the entity with the given id or {@literal null} if none found
	 * @throws IllegalArgumentException if {@code id} is {@literal null}
	 */
	T findById(ID id);

	/**
	 * Retrieves an entity by its id.
	 *
	 * @param id must not be {@literal null}.
	 * @return the entity with the given id
	 * @throws IllegalArgumentException if {@code id} is {@literal null}
	 * @throws EntityNotFoundException  if the entity with given id is {@literal null}
	 */
	T getById(ID id);

	/**
	 * Returns whether an entity with the given id exists.
	 *
	 * @param id must not be {@literal null}.
	 * @return true if an entity with the given id exists, {@literal false} otherwise
	 * @throws IllegalArgumentException if {@code id} is {@literal null}
	 */
	boolean exists(ID id);

	/**
	 * Returns all instances of the type.
	 *
	 * @return all entities
	 */
	Iterable<T> getAll();

	/**
	 * Returns all instances of the type with the given IDs.
	 *
	 * @param ids
	 * @return
	 */
	Iterable<T> getAll(Iterable<ID> ids);

	/**
	 * Returns the number of entities available.
	 *
	 * @return the number of entities
	 */
	long count();

	/**
	 * Deletes the entity with the given id.
	 *
	 * @param id must not be {@literal null}.
	 * @return the deleted entity
	 * @throws IllegalArgumentException in case the given {@code id} is {@literal null}
	 */
	T delete(ID id);

	/**
	 * Deletes a given entity.
	 *
	 * @param entity
	 * @throws IllegalArgumentException in case the given entity is {@literal null}.
	 */
	void delete(T entity);

	/**
	 * Deletes the given entities.
	 *
	 * @param entities
	 * @throws IllegalArgumentException in case the given {@link Iterable} is {@literal null}.
	 */
	void delete(Iterable<? extends T> entities);

	/**
	 * Deletes all entities managed by the repository.
	 */
	void deleteAll();
}