ConnectionRuleGenerator.java

/*
 * Copyright 2016 Red Hat, Inc. and/or its affiliates.
 *
 * 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 org.kie.workbench.common.stunner.core.processors.rule;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.processing.Messager;
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.Element;
import javax.lang.model.element.PackageElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.util.Elements;
import javax.tools.Diagnostic;

import freemarker.template.Template;
import freemarker.template.TemplateException;
import org.kie.workbench.common.stunner.core.processors.MainProcessor;
import org.kie.workbench.common.stunner.core.processors.ProcessingContext;
import org.kie.workbench.common.stunner.core.processors.ProcessingRule;
import org.kie.workbench.common.stunner.core.rule.annotation.CanConnect;
import org.uberfire.annotations.processors.AbstractGenerator;
import org.uberfire.annotations.processors.exceptions.GenerationException;

public class ConnectionRuleGenerator extends AbstractGenerator {

    public class ConnectionRuleEntry {

        private final String from;
        private final String to;

        public ConnectionRuleEntry(final String from,
                                   final String to) {
            this.from = from;
            this.to = to;
        }

        public String getFrom() {
            return from;
        }

        public String getTo() {
            return to;
        }
    }

    private final ProcessingContext processingContext = ProcessingContext.getInstance();

    @Override
    public StringBuffer generate(final String packageName,
                                 final PackageElement packageElement,
                                 final String className,
                                 final Element element,
                                 final ProcessingEnvironment processingEnvironment) throws GenerationException {
        final Messager messager = processingEnvironment.getMessager();
        messager.printMessage(Diagnostic.Kind.NOTE,
                              "Starting code adf for [" + className + "]");
        final Elements elementUtils = processingEnvironment.getElementUtils();
        //Extract required information
        final TypeElement classElement = (TypeElement) element;
        final boolean isInterface = classElement.getKind().isInterface();
        final String ruleId = MainProcessor.toValidId(className);
        final String ruleDefinitionId = classElement.getQualifiedName().toString();
        CanConnect[] pcs = classElement.getAnnotationsByType(CanConnect.class);
        List<ConnectionRuleEntry> ruleEntries = new ArrayList<>();
        if (null != pcs) {
            for (final CanConnect pc : pcs) {
                String startRole = pc.startRole();
                String endRole = pc.endRole();
                ruleEntries.add(new ConnectionRuleEntry(startRole,
                                                        endRole));
            }
        }
        Map<String, Object> root = new HashMap<String, Object>();
        root.put("ruleId",
                 ruleId);
        root.put("ruleDefinitionId",
                 ruleDefinitionId);
        root.put("connectionsSize",
                 ruleEntries.size());
        root.put("connections",
                 ruleEntries);
        //Generate code
        final StringWriter sw = new StringWriter();
        final BufferedWriter bw = new BufferedWriter(sw);
        try {
            final Template template = config.getTemplate("ConnectionRule.ftl");
            template.process(root,
                             bw);
        } catch (IOException ioe) {
            throw new GenerationException(ioe);
        } catch (TemplateException te) {
            throw new GenerationException(te);
        } finally {
            try {
                bw.close();
                sw.close();
            } catch (IOException ioe) {
                throw new GenerationException(ioe);
            }
        }
        messager.printMessage(Diagnostic.Kind.NOTE,
                              "Successfully generated code for [" + className + "]");
        processingContext.addRule(ruleId,
                                  ProcessingRule.TYPE.CONNECTION,
                                  sw.getBuffer());
        return null;
    }
}