BaseCollection.java

package co.gem.round;

import co.gem.round.patchboard.Client;
import co.gem.round.patchboard.Resource;

import java.io.IOException;
import java.util.*;
/**
 * Base class for building Gem API collection objects.
 *
 * @author Julian Vergel de Dios (julian@gem.co) on 12/18/14.
 */
public abstract class BaseCollection<T> extends Base implements Iterable<T> {

    protected List<T> list = new ArrayList<T>();
    protected Map<String, T> map = new HashMap<String, T>();

    public static final String DEFAULT_ACTION = "list";

    public BaseCollection(String url, Round round, String resourceName) {
        super(url, round, resourceName);
    }

    public BaseCollection(Resource resource, Round round) {
        super(resource, round);
    }

    public T get(int index) {
        return this.list.get(index);
    }

    public T get(String key) {
        return this.map.get(key);
    }

    public void add(String key, T element) {
        list.add(element);
        map.put(key, element);
    }

    public void fetch() throws Client.UnexpectedStatusCodeException, IOException {
        resource = resource.action(DEFAULT_ACTION);
        list = new ArrayList<T>();
        map = new HashMap<String, T>();
        populateCollection(resource);
    }

    public int size() {
        return this.list.size();
    }

    public List<T> asList() {
        fetchIfNeeded();
        return list;
    }
    public Map<String, T> asMap() {
        fetchIfNeeded();
        return map;
    }

    public abstract void populateCollection(Iterable<Resource> collection);

    @Override
    public Iterator<T> iterator() {
        fetchIfNeeded();
        return list.iterator();
    }

    private void fetchIfNeeded() {
        if (list.isEmpty() && map.isEmpty()) {
            try {
                fetch();
            } catch (Client.UnexpectedStatusCodeException | IOException ignore) {
            }
        }
    }
}