CardinalityRuleGenerator.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.HashMap;
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.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.AllowedOccurrences;
import org.kie.workbench.common.stunner.core.rule.annotation.Occurrences;
import org.uberfire.annotations.processors.AbstractGenerator;
import org.uberfire.annotations.processors.exceptions.GenerationException;

public class CardinalityRuleGenerator extends AbstractGenerator {

    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 + "]");
        //Extract required information
        final TypeElement classElement = (TypeElement) element;
        final AllowedOccurrences occs = classElement.getAnnotation(AllowedOccurrences.class);
        if (null != occs) {
            int count = 0;
            for (Occurrences occurrence : occs.value()) {
                String role = occurrence.role();
                final String ruleName = MainProcessor.toValidId(className) + count + MainProcessor.RULE_CARDINALITY_SUFFIX_CLASSNAME;
                long min = occurrence.min();
                long max = occurrence.max();
                StringBuffer ruleSourceCode = generateRule(messager,
                                                           ruleName,
                                                           role,
                                                           min,
                                                           max);
                processingContext.addRule(ruleName,
                                          ProcessingRule.TYPE.CARDINALITY,
                                          ruleSourceCode);
                count++;
            }
        }
        return null;
    }

    private StringBuffer generateRule(final Messager messager,
                                      final String ruleName,
                                      final String role,
                                      final long min,
                                      final long max) throws GenerationException {
        Map<String, Object> root = new HashMap<String, Object>();
        root.put("ruleName",
                 ruleName);
        root.put("role",
                 role);
        root.put("min",
                 min);
        root.put("max",
                 max);
        //Generate code
        final StringWriter sw = new StringWriter();
        final BufferedWriter bw = new BufferedWriter(sw);
        try {
            final Template template = config.getTemplate("CardinalityRule.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 [" + ruleName + "]");
        return sw.getBuffer();
    }
}