PostRenderingService.java

/*
 * Copyright 2015-2016 EuregJUG.
 *
 * Licensed 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 eu.euregjug.site.posts;

import eu.euregjug.site.posts.PostEntity.Format;
import lombok.extern.slf4j.Slf4j;
import org.asciidoctor.Asciidoctor;
import org.asciidoctor.Options;
import org.asciidoctor.OptionsBuilder;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

/**
 * A post rendering service that supports only AsciiDoc at the moment.
 *
 * @author Michael J. Simons, 2015-12-28
 */
@Service
@Slf4j
public class PostRenderingService {

    @FunctionalInterface
    interface Renderer {

        String render(String content);
    }

    static class AsciiDocRenderer implements Renderer {

        private final Asciidoctor asciidoctor = Asciidoctor.Factory.create();
        private final Options options = OptionsBuilder.options().inPlace(false).get();

        @Override
        public String render(final String content) {
            String rv;
            try {
                rv = asciidoctor.render(content, options);
            } catch (Exception e) {
                log.error("Could not render AsciiDoc content!", e);
                rv = "<strong>Could not render content.</strong>";
            }
            return rv;
        }
    }

    private final Renderer renderer = new AsciiDocRenderer();

    @Cacheable(cacheNames = "renderedPosts", key = "#post.id")
    public Post render(final PostEntity post) {
        String renderedContent;
        if (post.getFormat() != Format.asciidoc) {
            renderedContent = "<strong>Could not render content.</strong>";
        } else {
            renderedContent = renderer.render(post.getContent());
        }

        return new Post(post.getPublishedOn(), post.getSlug(), post.getTitle(), renderedContent);
    }
}