/**
 * Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright ownership. Apereo
 * licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use
 * this file except in compliance with the License. You may obtain a copy of the License at the
 * following location:
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apereo.portal.rendering;

import com.google.common.base.Predicate;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Required;

/**
 * A Rendering Pipeline that proceeds down one of two branches depending upon a Predicate.
 *
 * <p>If the Predicate returns true, proceed down the true branch. If the Predicate returns false,
 * proceed down the false branch.
 *
 * @since 4.2
 */
public class BranchingRenderingPipeline implements IPortalRenderingPipeline {

    protected final Logger logger = LoggerFactory.getLogger(getClass());

    // dependency-injected
    private Predicate<HttpServletRequest> predicate;

    // dependency-injected
    private IPortalRenderingPipeline truePipe;

    // dependency-injected
    private IPortalRenderingPipeline falsePipe;

    @Override
    public void renderState(final HttpServletRequest request, final HttpServletResponse response)
            throws ServletException, IOException {

        // render either the true or false pipe, depending on the trueness or falseness of the predicate

        if (predicate.apply(request)) {
            logger.trace("Branching to the true pipe [{}].", truePipe);
            truePipe.renderState(request, response);
        } else {
            logger.trace("Branching to the false pipe [{}].", falsePipe);
            falsePipe.renderState(request, response);
        }
    }

    @Required
    public void setPredicate(Predicate<HttpServletRequest> predicate) {
        this.predicate = predicate;
    }

    @Required
    public void setTruePipe(IPortalRenderingPipeline truePipe) {
        this.truePipe = truePipe;
    }

    @Required
    public void setFalsePipe(IPortalRenderingPipeline falsePipe) {
        this.falsePipe = falsePipe;
    }

    @Override
    public String toString() {
        return "BranchingRenderingPipeline which considering predicate ["
                + this.predicate
                + "] proceeds down pipe ["
                + this.truePipe
                + "] when the predicate is true and proceeds down pipe ["
                + this.falsePipe
                + "] when the predicate is false.";
    }
}