io.knotx.knot.templating.impl.HandlebarsKnotProxyImpl.java Source code

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Here is the source code for io.knotx.knot.templating.impl.HandlebarsKnotProxyImpl.java

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/*
 * Copyright (C) 2016 Cognifide Limited
 *
 * 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 io.knotx.knot.templating.impl;

import com.github.jknack.handlebars.Handlebars;
import io.knotx.dataobjects.ClientResponse;
import io.knotx.dataobjects.KnotContext;
import io.knotx.knot.AbstractKnotProxy;
import io.knotx.knot.templating.HandlebarsKnotConfiguration;
import io.knotx.knot.templating.handlebars.CustomHandlebarsHelper;
import io.knotx.knot.templating.helpers.DefaultHandlebarsHelpers;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.vertx.core.logging.Logger;
import io.vertx.core.logging.LoggerFactory;
import java.util.Optional;
import java.util.ServiceLoader;
import java.util.Set;
import org.apache.commons.lang3.StringUtils;
import rx.Single;

public class HandlebarsKnotProxyImpl extends AbstractKnotProxy {

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

    private static final String START_WEBSERVICE_CALL_DEBUG_MARKER = "<!-- start compiled snippet -->";

    private static final String END_WEBSERVICE_CALL_DEBUG_MARKER = "<!-- end compiled snippet -->";

    private static final String SUPPORTED_FRAGMENT_KNOT = "handlebars";

    private Handlebars handlebars;

    private HandlebarsKnotConfiguration configuration;

    public HandlebarsKnotProxyImpl(HandlebarsKnotConfiguration configuration) {
        this.configuration = configuration;
        this.handlebars = createHandlebars();
    }

    @Override
    protected Single<KnotContext> processRequest(KnotContext knotContext) {
        return Single.create(observer -> {
            try {
                knotContext.setTransition(DEFAULT_TRANSITION);
                Optional.ofNullable(knotContext.getFragments()).ifPresent(fragments -> fragments.stream()
                        .filter(fragment -> fragment.knots().contains(SUPPORTED_FRAGMENT_KNOT))
                        .forEach(fragment -> fragment.content(startComment()
                                + new HandlebarsFragment(fragment).compileWith(handlebars) + endComment())));
                observer.onSuccess(knotContext);
            } catch (Exception e) {
                observer.onError(e);
            }
        });
    }

    @Override
    protected boolean shouldProcess(Set<String> knots) {
        return knots.contains(SUPPORTED_FRAGMENT_KNOT);
    }

    @Override
    protected KnotContext processError(KnotContext knotContext, Throwable error) {
        LOGGER.error("Error happened during Template processing", error);
        ClientResponse errorResponse = new ClientResponse()
                .setStatusCode(HttpResponseStatus.INTERNAL_SERVER_ERROR.code());

        return new KnotContext().setClientRequest(knotContext.getClientRequest()).setClientResponse(errorResponse);
    }

    private String startComment() {
        return snippetComment(START_WEBSERVICE_CALL_DEBUG_MARKER);
    }

    private String endComment() {
        return snippetComment(END_WEBSERVICE_CALL_DEBUG_MARKER);
    }

    private String snippetComment(String commentTemplate) {
        String debugLine = StringUtils.EMPTY;
        if (configuration.templateDebug()) {
            debugLine = commentTemplate;
        }
        return debugLine;
    }

    private Handlebars createHandlebars() {
        Handlebars newHandlebars = new Handlebars();
        DefaultHandlebarsHelpers.registerFor(newHandlebars);

        ServiceLoader.load(CustomHandlebarsHelper.class).iterator().forEachRemaining(helper -> {
            newHandlebars.registerHelper(helper.getName(), helper);
            LOGGER.info("Registered custom Handlebars helper: {}", helper.getName());
        });

        return newHandlebars;
    }
}