LazyResourceStateResolver.java

package com.temenos.interaction.core.hypermedia;

/*
 * #%L
 * interaction-core
 * %%
 * Copyright (C) 2012 - 2017 Temenos Holdings N.V.
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 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 Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * Resolves a {@link LazyResourceState} into real {@link ResourceState}
 * using a {@link ResourceStateProvider}.
 *
 * @author ikarady
 */
public class LazyResourceStateResolver {

    private static final Logger LOGGER = LoggerFactory.getLogger(LazyResourceStateResolver.class);

    private ResourceStateProvider resourceStateProvider;

    public LazyResourceStateResolver(ResourceStateProvider resourceStateProvider) {
        this.resourceStateProvider = resourceStateProvider;
    }

    /**
     * Attempts to resolve given {@link ResourceState} into a real {@link ResourceState}
     * if it is of type {@link LazyResourceState}.
     * In case of {@link LazyResourceState} it returns the resolved {@link ResourceState}
     * otherwise the original {@link ResourceState} that is passed in.
     *
     * @param   state   the {@link ResourceState} that is resolved if lazy
     *
     * @return {@link ResourceState}
     */
    public ResourceState resolve(ResourceState state) {
        ResourceState result = resolveState(state);
        if (result != null) {
            for (Transition transition : result.getTransitions()) {
                ResourceState targetState = resolveState(transition.getTarget());
                if (targetState == null) {
                    LOGGER.error("Invalid transition [{}]", transition.getId());
                }
                transition.setTarget(targetState);
            }
            if (result.getErrorState() != null && result.getErrorState().getId().startsWith(".")) {
                result.setErrorState(resolveState(result.getErrorState()));
            }
        }
        return result;
    }

    private ResourceState resolveState(ResourceState state) {
        ResourceState resolvedState = state;
        if (state != null && isLazy(state)) {
            resolvedState = getState(state.getName());
        }
        return resolvedState;
    }

    private ResourceState getState(String name) {
        ResourceState state = resourceStateProvider.getResourceState(name);
        if (state == null) {
            LOGGER.error("Invalid Resource state " + name);
        }
        return state;
    }

    private boolean isLazy(ResourceState state) {
        return state instanceof LazyResourceState || state instanceof LazyCollectionResourceState;
    }

}