com.predic8.membrane.core.interceptor.groovy.GroovyTemplateInterceptor Maven / Gradle / Ivy

/* Copyright 2017 predic8 GmbH, www.predic8.com

   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 com.predic8.membrane.core.interceptor.groovy;

import com.predic8.membrane.annot.MCElement;
import com.predic8.membrane.annot.MCTextContent;
import com.predic8.membrane.core.Router;
import com.predic8.membrane.core.exchange.Exchange;
import com.predic8.membrane.core.http.MimeType;
import com.predic8.membrane.core.http.Response;
import com.predic8.membrane.core.interceptor.AbstractInterceptor;
import com.predic8.membrane.core.interceptor.Outcome;

import static org.springframework.web.util.HtmlUtils.htmlEscape;

/**
 * @description
 * Uses the groovy template markup engine to produce HTML-based responses.
 * 
 * <groovyTemplate><![CDATA[
 *   html {
 *     head {
 *       title('Resource')
 *     }
 *     body {
 *       p('Hello from Membrane!')
 *     }
 *   }
 * ]]></groovyTemplate>
 * 
 * 
 * The word "spring" refers to the Spring ApplicationContext.
 * The word "exc" refers to the Membrane Exchange being handled.
 * The word "flow" refers to the current Membrane Flow (=REQUEST).
 * 
 *
 * @topic 4. Interceptors/Features
 */
@MCElement(name = "groovyTemplate", mixed = true)
public class GroovyTemplateInterceptor extends AbstractInterceptor {

    String src = "";

    GroovyInterceptor groovyInterceptor;

    public GroovyTemplateInterceptor() {
        name = "Groovy Template";
    }

    @Override
    public void init(Router router) throws Exception {
        super.init(router);
        groovyInterceptor = new GroovyInterceptor();
        groovyInterceptor.setSrc(createGroovyScript());
        groovyInterceptor.init(router);
    }

    @Override
    public Outcome handleRequest(Exchange exc) throws Exception {
        groovyInterceptor.handleRequest(exc);
        String html = (String) exc.getProperty("GROOVY_TEMPLATE");
        exc.setResponse(Response.ok(html).contentType(MimeType.TEXT_HTML_UTF8).build());
        return Outcome.RETURN;
    }

    private String createGroovyScript() {
        return """
                import groovy.text.markup.*
                def markupEngine = new MarkupTemplateEngine()
                def writer = new StringWriter()
                def markup = '''%s'''
                def output = markupEngine.createTemplate(markup).make(['spring':spring, 'exc':exc,'flow':flow]).writeTo(writer)
                exc.setProperty('GROOVY_TEMPLATE',output.toString())
                CONTINUE""".formatted(src);
    }

    public String getSrc() {
        return src;
    }

    @MCTextContent
    public void setSrc(String src) {
        this.src = src;
    }

    @Override
    public String getShortDescription() {
        return "Responds with the result of a Groovy Template.";
    }

    @Override
    public String getLongDescription() {
        return "Responds with the result of a the Groovy Template (see MarkupTemplateEngine):

"+
                htmlEscape(src.stripIndent()) +
                "";
    }
}