fp-example.java

import java.util.Arrays;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.stream.Stream;

import org.junit.Test;
import org.slf4j.Logger;
import org.springframework.web.client.AsyncRestTemplate;

import com.fasterxml.jackson.annotation.JsonUnwrapped;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.Getter;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class LocalTest2 {

	private Logger log = LOG;

	AsyncRestTemplate asyncRestTemplate = new AsyncRestTemplate();
	UserMapper userMapper = new UserMapper();
	Connector accountConnector = new Connector();
	Connector cardConnector = new Connector();
	Connector pointConnector = new Connector();

	@Test
	public void example2() {
		UserDetail user = get("user-1");

		System.out.println(user);
	}

	public UserDetail get(String id) {
		// validate();

		try {
			return Stream.of(id)
				.map(userMapper::get)
				.map(user -> {
					final String externalId = user.getId();
					final CompletableFuture<Accounts> accountsFuture = accountConnector.getAccounts(externalId);
					final CompletableFuture<Cards> cardsFuture = cardConnector.getCards(externalId);
					final CompletableFuture<Point> pointFuture = pointConnector.getPoint(externalId);

					return CompletableFuture.allOf(accountsFuture, cardsFuture, pointFuture)
						.thenApply(ignore -> UserDetail.builder()
							.user(user)
							.accounts(accountsFuture.join())
							.cards(cardsFuture.join())
							.point(pointFuture.join())
							.build())
						.exceptionally(err -> {
							throw new ConnectorException(err);
						});
				})
				.map(CompletableFuture::join)
				.findFirst()
				.orElse(null);
		} catch (InvalidException | ConnectorException e) {
			log.debug(e.getMessage(), e);
			throw e;
		} catch (Exception e) {
			log.error(e.getMessage(), e);
			throw e;
		}
	}
}

class Connector {
	CompletableFuture<Accounts> getAccounts(String id) {
		return CompletableFuture.supplyAsync(() -> {
			return new Accounts(Arrays.asList(new Account()));
		});
	}

	CompletableFuture<Cards> getCards(String id) {
		return CompletableFuture.supplyAsync(() -> {
			return new Cards(Arrays.asList(new Card()));
		});
	}

	CompletableFuture<Point> getPoint(String id) {
		return CompletableFuture.supplyAsync(() -> {
			return new Point();
		});
	}
}

class ConnectorException extends RuntimeException {

	public ConnectorException(Throwable throwable) {
		super(throwable);
	}

}

class InvalidException extends RuntimeException {

}

class UserMapper {
	public User get(String id) {
		return new User();
	}
}

@Data
@Builder
class UserDetail {
	@JsonUnwrapped
	private final User user;
	private final Accounts accounts;
	private final Cards cards;
	private final Point point;
}

@Data
class Account {

}

@Getter
@AllArgsConstructor
class Accounts {
	private List<Account> accounts;
}

@Data
class Card {

}

@Getter
@AllArgsConstructor
class Cards {
	private List<Card> accounts;
}

@Data
class Point {

}